No voltage to CPR when key turned on.

[sweetp01569]

Hi,
I have a cold/hot starting issue. Hard starting and hesitation when pressing gas pedal once started when cold. CSV, TTS and fuel pressures test OK, except control pressure warm. I may have found problem. I get no voltage to CPR plug with key turned on. I have continuity from wires on plug to blue connector at bulkhead. Unplugged the connector, pins look good (not pushed in) and seem to be connecting. However, I get no voltage on male pin (#26) at bulkhead where Y/R wire connects. I also do not get continuity on male pin (#22) the black wire connects to and ground. Fuse No. 7 is new. Do I need to inspect behind the parcel shelf to see if there are wires disconnected to the male pins on the blue connector? Would no voltage to this connector cause my cold and hot start hesitations? Should power be provided to the CPR plug when the key is turned on or does engine need to be running?

Thanks!

Paul
Vin 10944

[Ron]

Hi,
I have a cold/hot starting issue. Hard starting and hesitation when pressing gas pedal once started when cold. CSV, TTS and fuel pressures test OK, except control pressure warm. I may have found problem. I get no voltage to CPR plug with key turned on. I have continuity from wires on plug to blue connector at bulkhead. Unplugged the connector, pins look good (not pushed in) and seem to be connecting. However, I get no voltage on male pin (#26) at bulkhead where Y/R wire connects. I also do not get continuity on male pin (#22) the black wire connects to and ground. Fuse No. 7 is new. Do I need to inspect behind the parcel shelf to see if there are wires disconnected to the male pins on the blue connector? Would no voltage to this connector cause my cold and hot start hesitations? Should power be provided to the CPR plug when the key is turned on or does engine need to be running?

Thanks!

Paul
Vin 10944
I'm not 100% sure but since the RPM relay supplies power along the Y/R wire, I suspect it has to be running.
The ground comes from the same junction that the RPM relay gets its ground, in the relay compartment.
Dead cold, the power & ground don't matter since the ambient temperature is what sets the CPR/WUR output. Same thing for when the engine is warmed up (>104F/40C) . In between is when the power & ground matters (see chart at D:02:01 In WS Manual). (If you know carbs, think of it as the spray pump and the electric choke.) Check that there is vacuum going to the black and white delay valve when the engine is below 104F/40C (for acceleration when cold), and, above 104F/40C it does not have vacuum but the distributor advance unit gets it (for acceleration when warm....works with throttle micro switch).

[Bitsyncmaster]

There are many different RPM relay configurations (even the stock OEM unit). One of the differences is the relay in the RPM relay unit may have separate contacts for the pump and CSV outputs. I have seen many (my car was one) where the CSV output pin did not work and the pump output did. Open your RPM relay and press the relay to see if both contacts will work. It could be a broken solder joint or just misalignment when it was built.

[sweetp01569]

There are many different RPM relay configurations (even the stock OEM unit). One of the differences is the relay in the RPM relay unit may have separate contacts for the pump and CSV outputs. I have seen many (my car was one) where the CSV output pin did not work and the pump output did. Open your RPM relay and press the relay to see if both contacts will work. It could be a broken solder joint or just misalignment when it was built.

Thanks Dave for clearing it up for me. I am actually using the solid state RPM relay I bought from you a couple of years ago. I will plug it back in and run the control pressure test with the engine running. Any tips on checking that relay from you?

How do I check the vacuum items on the CPR which you said may cause my cold running hesitation just after starting. I have a cold and hot starting issue, where both are difficult. I tested the TTS switch by using a test light on the CVS plug and it lit for about 5 seconds when turning the engine over and then shut off. Also, the CSV sprays properly when energized and does not leak or spray when the plug is disconnected. That testing seems to tell me those devices are working properly. Both have been replaced 5 or 6 years ago. Could there still be an issue with one of them causing my cold start problem. It's like it wants to fire immediately, almost kicking off then will take several cranks and some luck to fire up the engine. and then I get hesitation and little response pushing the gas pedal until a few minutes.

Also, I am confused by my hot start issue. If I take it for a 15 minute ride, run into a store for 5 minutes and try to start the car, it will not start. I need to wait for 15 to 20 minutes and then it starts up. Sounds like lost resting pressure, but the resting pressure holds at about 40 psi for over 2-1/2 hours. I changed the accumulator and the pressure regulator O-ring in the past.

I did test the fuel pressures. System pressure is 65psi, control pressure cold is 16 psi, but couldn't check that warm control pressure until I connect the RPM relay back and run the engine so that the CSV is energized.

Sorry for the long post, but glad I caught your attention as reading your past posts have prompted me to thoroughly test everything. I even bought the maintenance book by Charles Probst. I am hooping you can give me some suggestions for things to check or test to solve the frustrating starting problems.

Thanks,

Paul

[sweetp01569]

I'm not 100% sure but since the RPM relay supplies power along the Y/R wire, I suspect it has to be running.
The ground comes from the same junction that the RPM relay gets its ground, in the relay compartment.
Dead cold, the power & ground don't matter since the ambient temperature is what sets the CPR/WUR output. Same thing for when the engine is warmed up (>104F/40C) . In between is when the power & ground matters (see chart at D:02:01 In WS Manual). (If you know carbs, think of it as the spray pump and the electric choke.) Check that there is vacuum going to the black and white delay valve when the engine is below 104F/40C (for acceleration when cold), and, above 104F/40C it does not have vacuum but the distributor advance unit gets it (for acceleration when warm....works with throttle micro switch).

Ron, thanks for your advice, too! I didn't mean to dis you when I replied back to Dave. I was just reading a lot of recent posts by Dave on these issues. Do you know how I can check the vacuum to the delay valve? I appreciate the advice!

Paul

[sweetp01569]

Ron, thanks for your advice, too! I didn't mean to dis you when I replied back to Dave. I was just reading a lot of recent posts by Dave on these issues. Do you know how I can check the vacuum to the delay valve? I appreciate the advice!

Paul

I do have a new TTS switch. Could it possibly be failing intermittently, allowing the CSV too spray extra fuel? Would that cause starting issues cold or hot, and hesitation after start-up when I press gas? Maybe I should just change it?

[Bitsyncmaster]

Test the resistance of the CPR, pin to pin and pin to case (ground). You may have a burned up heater in the CPR. That's another thing that was wrong with my car. It's also why I suggested fusing that wire with a 3 amp fuse. With only 16 PSI control pressure, you defiantly have something wrong with the CPR.

[sweetp01569]

Test the resistance of the CPR, pin to pin and pin to case (ground). You may have a burned up heater in the CPR. That's another thing that was wrong with my car. It's also why I suggested fusing that wire with a 3 amp fuse. With only 16 PSI control pressure, you defiantly have something wrong with the CPR.

What reading should I have with the resistance testing pin to pin and pin to case? Also, I thought that 16 psi was OK when the CPR circuit is not energized, and then increases as it warms up? I plan to test this once I plug the RPM relay back I and run the engine to check the pressure.

Thanks!

[Bitsyncmaster]

What reading should I have with the resistance testing pin to pin and pin to case? Also, I thought that 16 psi was OK when the CPR circuit is not energized, and then increases as it warms up? I plan to test this once I plug the RPM relay back I and run the engine to check the pressure.

Thanks!

From memory around 20 ohms pin to pin. Infinity pin to case. The lowest CPR pressure I see is about 20 PSI engine idle and cold but it climbs so quickly you have to have someone else start the car while you watch the gauge.

[Ron]

Ron, thanks for your advice, too! I didn't mean to dis you when I replied back to Dave. I was just reading a lot of recent posts by Dave on these issues. Do you know how I can check the vacuum to the delay valve? I appreciate the advice!

PaulNot at all!!!

First, I agree with Dave on the 16psi being too low, unless the engine is a little less than 50F.

To check the vacuum start the engine dead cold, remove the line that comes out of the Tee and goes to the delay valve, put your finger over it to see that there is vacuum (from the tee). Put it back together. Remove the line that goes to the distributor vacuum advance and see that it does not have vacuum when you raise the RPM. Once the engine reaches ~104F the controlling valve (down in the VOD) should reverse this IE there should not be vacuum coming off of the tee to the delay valve and there should be vacuum to the advance when you rev the engine a little bit (only). Note the valve in the VOD can be bad such that it sends vacuum to neither, both, or never switch from one to the other. And that if the vacuum to the delay valve seems OK but not to the advance, the advance solenoid valve (behind the FD) could be unplugged etc, bad, or the throttle micro is unplugged etc, bad or needs adjusting (it should make/break electrical contact when you come on/off of idle).

Maybe getting too far ahead, but if there was vacuum to the distributor advance when you set the timing (due to problem above), it will be way too to low when you go to crank up (hot or cold)!
EDIT: But again, if it is dead cold, it should still start if the WUR/CPR is at 16psi and everything else OK.

[sweetp01569]

From memory around 20 ohms pin to pin. Infinity pin to case. The lowest CPR pressure I see is about 20 PSI engine idle and cold but it climbs so quickly you have to have someone else start the car while you watch the gauge.

I measured 20 ohms pin to pin but 0 ohms one pin to ground and 20 ohms the other pin to ground. Per your spec, I should show open to ground instead of the short I have does that mean I have a bad CPR?

I changed TTS anyway and still starts a little tough. I assume TTS will remain open after test cranking a bit. What allows the car to get fuel after cranking for several seconds?

Thanks,

Paul

[Bitsyncmaster]

I measured 20 ohms pin to pin but 0 ohms one pin to ground and 20 ohms the other pin to ground. Per your spec, I should show open to ground instead of the short I have does that mean I have a bad CPR?

I changed TTS anyway and still starts a little tough. I assume TTS will remain open after test cranking a bit. What allows the car to get fuel after cranking for several seconds?

Thanks,

Paul

I just checked mine. It has 18 ohms pin to pin and one pin does go to ground. I forgot about the thermostat in the CPR that increases the heater power cold and reduces the power after some ?? temp. I think that is what grounds one pin. Have you checked if you get power to the CPR when the engine is running?

The TTS is just for running the CSV and has nothing to do with warmup. You can unplug the CSV to test if the TTS is keeping the CSV running all the time.

[sweetp01569]

I just checked mine. It has 18 ohms pin to pin and one pin does go to ground. I forgot about the thermostat in the CPR that increases the heater power cold and reduces the power after some ?? temp. I think that is what grounds one pin. Have you checked if you get power to the CPR when the engine is running?

The TTS is just for running the CSV and has nothing to do with warmup. You can unplug the CSV to test if the TTS is keeping the CSV running all the time.

Yes, I do now have voltage to the CPR with the RPM relay back in and the engine running. I was able to check control pressure with that power on the CPR, and it only went to 28 psi, which seems low. Cold control pressure is 16 and warm is 28. Too low, Dave, and if so, is that a CPR problem or something else? Do I need to add or remove a shim to the primary pressure regulator to boost pressure overall?

Quick question on TTS. Say the car starts right up after the TTS allows the CSV to squirt fuel for a few seconds. If I shut off the car and want to start again, isn't the TTS opened already after the few seconds it was needed to start the first time. What if the metallic switch in the TTS is still too warm to close the CSV circuit for the second start? How does fuel get in for that or subsequent starts if you shut off the car and restart again, or is it expected that people wouldn't have a reason to shut it off quickly and restart a second time? Perhaps upon each start, the TTS has a fresh several seconds of energizing the CSV?Just curious.

One more thing. Fuse no. 7 (20 amps) that controls the CPR circuit, was somewhat melted in the fuse holder, and I replaced it. A separate fuse holder was installed for this fuse by the previous owner, because the slot for Fuse 7 on the fuse block was also melted! What is making this fuse melt?

Thanks for all your help!

Paul

[Bitsyncmaster]

Yes, I do now have voltage to the CPR with the RPM relay back in and the engine running. I was able to check control pressure with that power on the CPR, and it only went to 28 psi, which seems low. Cold control pressure is 16 and warm is 28. Too low, Dave, and if so, is that a CPR problem or something else? Do I need to add or remove a shim to the primary pressure regulator to boost pressure overall?

Quick question on TTS. Say the car starts right up after the TTS allows the CSV to squirt fuel for a few seconds. If I shut off the car and want to start again, isn't the TTS opened already after the few seconds it was needed to start the first time. What if the metallic switch in the TTS is still too warm to close the CSV circuit for the second start? How does fuel get in for that or subsequent starts if you shut off the car and restart again, or is it expected that people wouldn't have a reason to shut it off quickly and restart a second time? Perhaps upon each start, the TTS has a fresh several seconds of energizing the CSV?Just curious.

One more thing. Fuse no. 7 (20 amps) that controls the CPR circuit, was somewhat melted in the fuse holder, and I replaced it. A separate fuse holder was installed for this fuse by the previous owner, because the slot for Fuse 7 on the fuse block was also melted! What is making this fuse melt?

Thanks for all your help!

Paul

My guess is your CPR needs work. It should run about 50 PSI when the engine is warm. I've never attempted to adjust it so you need to find that info from someone who knows.

My guess it the TTS would cool down quickly unless the engine coolant is above the threshold (I think 95 deg F). I don't use a TTS on my car.

Fuse 7 always seems to have melting problems. Don't really know why but I can guess when the fuel pump gets old the current increases. I also think some of the melting is caused by shorted heater wires in the CPR.

[Ron]

Yep:
TTS: 95F
Control Pressure: >104F 49.3--55.1psi.
There is a chart showing all of this and the values during the warm up period in the WS manual (D:02:01)

[David T]

You do not need the CSV to squirt if the engine is warm and the rest pressure is high. Fuse #7 melts because the fuel pump circuit draws too much power but not enough to blow the fuse. Usually a sign you have bad connections in that circuit and/or the fuel pump is going bad. Your CPR needs to be rebuilt and recalibrated. SpecialT does it or you can replace it. The RPM relay also gets damaged from the excessive current and should be checked.
David Teitelbaum

[sweetp01569]

My guess is your CPR needs work. It should run about 50 PSI when the engine is warm. I've never attempted to adjust it so you need to find that info from someone who knows.

My guess it the TTS would cool down quickly unless the engine coolant is above the threshold (I think 95 deg F). I don't use a TTS on my car.

Fuse 7 always seems to have melting problems. Don't really know why but I can guess when the fuel pump gets old the current increases. I also think some of the melting is caused by shorted heater wires in the CPR.

Dave, you say you adjusted the system pressure to 75 psi with the shims in the PPR? My system pressure is 65, which is low per the manual which says 4.9 to 5.5 bar (about 71 to 79 psi). Is my system at a disadvantage being that low? If so, is it just a matter shimming, or other factors? If I need to shim, it looks like I'd need about 4 or 5 (each adds 2.2 psi, as I read in the Charles Probst book), and where can I buy those?

Thanks,

Paul

[DMCMW Dave]

You can unplug the CSV to test if the TTS is keeping the CSV running all the time.

The TTS can not keep the valve running all the time unless someone has hacked the wiring. It is powered by the crank lead (white/red) from the ignition switch and is therefor only powered when the starter is engaged.

[Bitsyncmaster]

The TTS can not keep the valve running all the time unless someone has hacked the wiring. It is powered by the crank lead (white/red) from the ignition switch and is therefor only powered when the starter is engaged.

Agree. But I have seen it happen on one car. Thing would not idle and unplugging the CSV would fix it so that car must have been rewired.

[sweetp01569]

The TTS can not keep the valve running all the time unless someone has hacked the wiring. It is powered by the crank lead (white/red) from the ignition switch and is therefor only powered when the starter is engaged.

Thanks, Dave. I think the TTS is good. I tried a light bulb across it and it only stayed lit for about 5 seconds when cranking, then went out.

My issue I think is with the CPR. Control pressure cold is about 16 psi, and warm is only 28. I believe per spec, warm control pressure should be about 50 psi. If that pressure remains that low, can that cause a hot start issue, if I can't start it 5 or 10 minutes after I shut off the hot engine? I am holding rest pressure at about 40 psi for over 2 hours, so I don't think it's due to lack of holding pressure. If I wait 15 or 20 minutes, I can start it again. I ordered a new CPR and hoping it corrects the control pressures.

I also have system pressue at 65 psi, where I think it should be about 75 psi, correct? Should I add shims to the PPR to build it up to abotu 75?

Thanks,

Paul

[Bitsyncmaster]

Dave, you say you adjusted the system pressure to 75 psi with the shims in the PPR? My system pressure is 65, which is low per the manual which says 4.9 to 5.5 bar (about 71 to 79 psi). Is my system at a disadvantage being that low? If so, is it just a matter shimming, or other factors? If I need to shim, it looks like I'd need about 4 or 5 (each adds 2.2 psi, as I read in the Charles Probst book), and where can I buy those?

Thanks,

Paul

Most cars I've checked run around 70 PSI. I guess a 10 PSI pressure change would have some effect on the warmup mixture. Remember to readjust your mixture if you change it. I just used some junk box flat washers on mine.

[sweetp01569]

Most cars I've checked run around 70 PSI. I guess a 10 PSI pressure change would have some effect on the warmup mixture. Remember to readjust your mixture if you change it. I just used some junk box flat washers on mine.

Interseting that you used any old washers. I thought those would have to be precise. So I'd just add them to increase pressure?

[David T]

Interseting that you used any old washers. I thought those would have to be precise. So I'd just add them to increase pressure?

I would not mess with the Primary Pressure Regulator to "fix" starting problems. If the control pressures are not correct, changing the primary pressure is not going help. Fix or replace the CPR to get the control pressures right. A good general rule is to try to not touch things you don't have to when trying to diagnose and repair a problem. In the process you can cause more problems. From your description it now seems like your CSV system is working. Other systems that operate during starting include:
Ballast resistor bypass
Vacuum and mechanical timing advance
If they are not working correctly it can cause hard starting.
David Teitelbaum

[sweetp01569]

I would not mess with the Primary Pressure Regulator to "fix" starting problems. If the control pressures are not correct, changing the primary pressure is not going help. Fix or replace the CPR to get the control pressures right. A good general rule is to try to not touch things you don't have to when trying to diagnose and repair a problem. In the process you can cause more problems. From your description it now seems like your CSV system is working. Other systems that operate during starting include:
Ballast resistor bypass
Vacuum and mechanical timing advance
If they are not working correctly it can cause hard starting.
David Teitelbaum

I would like to properly check these items too. Can you tell me how to test each of these? I have dwell meter and timing light. I do not have a vacuum guage. Can I test vacuum without? Can you tell me which hoses to check vac on? Should I wait until I get new CPR installed and correct control pressures before checking other items, or can they be checked independantly for my starting issues?

Thanks!

[Bitsyncmaster]

Interseting that you used any old washers. I thought those would have to be precise. So I'd just add them to increase pressure?

The "shims" are just a place where the spring seats. All your doing is changing the amount of compression on the spring. Ordinary washers tend to be thicker than the shims so you may have to remove some shims to use a thick washer. I found it took a lot of change (thickness) to bump my pressure up 5 PSI.

[Ron]

Did you miss my post here (http://dmctalk.org/showthread.php?7681-No-voltage-to-CPR-when-key-turned-on&p=112991&viewfull=1#post112991) ???
It tells you which vacuum hoses and how to check them. You should perform them first since the distributor vacuum could be a major contributor to your starting problems...
If it is confusing/unclear/??, just ask.

About what temp do you think the WUR/CPR was when you got the 16psi?

[sweetp01569]

Did you miss my post here (http://dmctalk.org/showthread.php?7681-No-voltage-to-CPR-when-key-turned-on&p=112991&viewfull=1#post112991) ???
It tells you which vacuum hoses and how to check them. You should perform them first since the distributor vacuum could be a major contributor to your starting problems...
If it is confusing/unclear/??, just ask.

About what temp do you think the WUR/CPR was when you got the 16psi?

Sorry Ron. I guess I lost it in the shuffle and didn't refer back to it. Thanks very much for the info on checking the vacuum. Which vacuum port on the distributor vacuum advance am I checking? If it the port between the electrical connector and the other vaccum tube, or the outer vacuum port?

I get the 16psi control pressue with the power connector unplugged from the CPR with the engine cold. With the engine still cold, I plug in the connector and the control pressure climbed only to 28 psi in a couple of minutes, where I believe it should climb to about 50 psi.

Paul

[Ron]

Sorry Ron. I guess I lost it in the shuffle and didn't refer back to it. Thanks very much for the info on checking the vacuum. Which vacuum port on the distributor vacuum advance am I checking? If it the port between the electrical connector and the other vaccum tube, or the outer vacuum port?

I get the 16psi control pressue with the power connector unplugged from the CPR with the engine cold. With the engine still cold, I plug in the connector and the control pressure climbed only to 28 psi in a couple of minutes, where I believe it should climb to about 50 psi.

Paul
How cold was the engine?
If it was ~47F, 16psi is about right. When you start the engine the pressure will start to climb because of heat from the engine AND being plugged in, until it reaches 104F. From then on the control pressure should be ~50psi.

You said the engine was still cold when you plugged it up... running or just the key on?
28psi would be about right if the engine heat and/or the plug brought the WUR/CPR up to ~60F.

[sweetp01569]

How cold was the engine?
If it was ~47F, 16psi is about right. When you start the engine the pressure will start to climb because of heat from the engine AND being plugged in, until it reaches 104F. From then on the control pressure should be ~50psi.

You said the engine was still cold when you plugged it up... running or just the key on?
28psi would be about right if the engine heat and/or the plug brought the WUR/CPR up to ~60F.

Hot summer day in MA was about 80 to 85 degrees in garage, so that is the "cold" temp. When I plugged in CPR power I ran engine for about 5 minutes to get the 28 psi. Engine was run for both tests and was warm, not hot, to the touch when I shut it off.

[Ron]

If the ambient (and engine) was 80-85F and you jumped the RPM Relay (or started it up and checked quickly), the Control Pressure should have been ~40 psi.

20661


I agree with David T that one should not mess with the Primary Pressure Regulator to "fix" starting problems, especially as a starting point.. But if it is off, it needs to be corrected -- everything is based off of it.
(If you have good rest pressure, don't be tempted to change the PPR o-ring, even if it looks conical, etc.)

[sweetp01569]

If the ambient (and engine) was 80-85F and you jumped the RPM Relay (or started it up and checked quickly), the Control Pressure should have been ~40 psi.

20661


I agree with David T that one should not mess with the Primary Pressure Regulator to "fix" starting problems, especially as a starting point.. But if it is off, it needs to be corrected -- everything is based off of it.
(If you have good rest pressure, don't be tempted to change the PPR o-ring, even if it looks conical, etc.)

I was just concerned about system pressure of 65 psi. Regardless of start issues. Is that too low?

[Ron]

Yes.
You are ~6psi below the acceptable range -- 11psi below target.

From the WS manual:
4. Primary Pressure
Checking value -- 4.9 - 5.5 Bar (71.50 - 79.75psi)
Setting value ---- 5.1 - 5.3 Bar (73.95 - 76.85psi)

IMHO: fix it!

[sweetp01569]

Yes.
You are ~6psi below the acceptable range -- 11psi below target.

From the WS manual:
4. Primary Pressure
Checking value -- 4.9 - 5.5 Bar (71.50 - 79.75psi)
Setting value ---- 5.1 - 5.3 Bar (73.95 - 76.85psi)

IMHO: fix it!

Thanks, Ron. I plan to fix the system pressure, but should I correct that before or after I check the control pressures with the new CPR I am waiting for?

Also, what is proper test for ballast resistors, I see resistance check in manual. How do I ensure the relay is working properly that works with the ballast resistors, and what is proper check for ignition coil? Perhaps my hard starting is attibuted to poor ignition voltage?

For the vacuum testing, what hose am I checking for this intruction you gave me, "Remove the line that goes to the distributor vacuum advance and see that it does not have vacuum when you raise the RPM." I want to make sure I am checking the right one.

Thanks for your help, Ron!

Paul

[Bitsyncmaster]

You can set your primary pressure now. The CPR should not change that.

Pull the white wire off the resistor block. You car should start but will stop quickly when you relase the starter.

[Ron]

Thanks, Ron. I plan to fix the system pressure, but should I correct that before or after I check the control pressures with the new CPR I am waiting for?
I agree with Dave. Fix it now.



Also, what is proper test for ballast resistors, I see resistance check in manual. How do I ensure the relay is working properly that works with the ballast resistors, and what is proper check for ignition coil? Perhaps my hard starting is attibuted to poor ignition voltage? Do the test Dave posted.

You can eliminate poor ignition voltage to the coil by running a 12V jumper wire from the battery (+) to the (+) side on the coil itself -- Remove it after the test!

To check the relay operation:
Unplug the Blue/Yellow wire.
Connect a volt meter to it and Ground(See below).
When you turn the key to Start the meter should show ~12V +.

20666



For the vacuum testing, what hose am I checking for this intruction you gave me, "Remove the line that goes to the distributor vacuum advance and see that it does not have vacuum when you raise the RPM." I want to make sure I am checking the right one.

It goes on #8 here (http://store.delorean.com/c-279-3-4-0-distributor.aspx).

[sweetp01569]

I agree with Dave. Fix it now.


Do the test Dave posted.

You can eliminate poor ignition voltage to the coil by running a 12V jumper wire from the battery (+) to the (+) side on the coil itself -- Remove it after the test!

To check the relay operation:
Unplug the Blue/Yellow wire.
Connect a volt meter to it and Ground(See below).
When you turn the key to Start the meter should show ~12V +.

20666




It goes on #8 here (http://store.delorean.com/c-279-3-4-0-distributor.aspx).

Excellent! Thanks, Ron and Dave. For the ballast resisitor check, you say to do the test Dave posted. Do you mean this,
"Pull the white wire off the resistor block. You car should start but will stop quickly when you relase the starter." That will tell me the resistors are OK?

Paul

[Ron]

I think he meant white wireS. If you remove the two white wires (upper right on the block), the test will confirm power is coming from the starter solenoid when it should. (It's just to boost it up while cranking).

EDIT: There is some overlap in the tests.

[Bitsyncmaster]

I'm working from the schmatic which does not have the relay change they did on all cars. Pulling the white wire (maybe two wires) off that resistor terminal will prove your relay and wiring is good if the car starts (will dye when you relase the key).

[sweetp01569]

I'm working from the schmatic which does not have the relay change they did on all cars. Pulling the white wire (maybe two wires) off that resistor terminal will prove your relay and wiring is good if the car starts (will dye when you relase the key).

Here's an update on the tests I did today.

Vacuum
The vacuum works properly as described. Upstream of the vacuum delay valve near the CPR, vacuum was there when cold and gone when the engine heated up. On the tube to the vacuum advance (#8 on the diagram referenced), vacuum was not there cold when throttle increased and was properly there when warm and I increased the throttle. Looks like this test was a success.

Coil/Ballast Resistors
I reseated the ballast resistor plugs and relay in the socket to help ensure good connections.I'm not sure if this is a factor or not, but I installed a Petronix Flamethrower coil about 8 years ago when I bought the car. The ballast resistors is the original setup. In case this was causing any issues (is that coil a cause for concern with original ballast resistor setup?), I replaced it with an original Bosch coil I had. As Dave said, I removed one white wire from the right side of the ballast resistor, the car started and only ran with the starter engaged and stopped after I released the key. If I took both wires off the right side of the resistors, the car would not fire. I didn't perform the voltage test on the relay connector as Ron suggested, but can do that soon.

I also gave my battery a good charge during the day today and the car started right up several times in a row, without any issue. Perhaps hard starting cold was just a matter of a weakened battery, as I haven't been driving it regularly. Still concerned about hot start, with adequate rest pressure. Perhaps that is still related to low control CPR pressure or could the Petronix coil have anything to do with that?

When I have more time, I will adjust the system fuel pressure with the shims. I'm waiting for the new CPR to arrive and hope that corrects the control pressures. If it does correct the pressures, will I need to adjust fuel mixture with higher pressures? In doing so, do I just adjust using the dwell meter, or do I need to set a base mixture with the method of jumping the RPM relay and run the pump, adjusting the mixture allen screw until fuel just starts to drip out of the injectors (into jars) and then back off until flow stops? I saw that process in older posts.

I have learned more about my car in the last week from this site than I have in the 8 years I've owned it. Just decided to learn what I can and take care of it myself, as mechanics don't seem to know what they're doing when I ask for a tune up.

Thanks again,

Paul

[David T]

Definately YES, a weak battery and some dirty connections and the car can be hard to start. Sounds like you are getting close to having it fixed. Get the battery fully charged, clean up some electrical connections, replace the CPR and you might just have it! Do not mess with the PPR if you don't have to. Many who have substituted from the stock, Bosch coil have had problems. Make sure you get all of the connectors back onto that ballast resistor correctly. BTW, there is NO official mention anywhere of the ballast bypass relay. It looks like an afterthought and was added after all of the service literature was created. It basically jumps out 1/2 of the ballast resistor during cranking to increase voltage to the coil to aid in starting, especially on a weak battery!
David Teitelbaum

[DMCMW Dave]

Agree. But I have seen it happen on one car. Thing would not idle and unplugging the CSV would fix it so that car must have been rewired.

That's why I put the "unless" comment in there. I've seen some pretty well-hidden DPO wiring modifications that are an absolute bear (and time-waster) to find.

[Ron]

. If I took both wires off the right side of the resistors, the car would not fire.
I should have mention that when you do this, don't separate the White wires from each other too (should be on a Tee like connector).


When I have more time, I will adjust the system fuel pressure with the shims. I'm waiting for the new CPR to arrive and hope that corrects the control pressures. If it does correct the pressures, will I need to adjust fuel mixture with higher pressures? In doing so, do I just adjust using the dwell meter, or do I need to set a base mixture with the method of jumping the RPM relay and run the pump, adjusting the mixture allen screw until fuel just starts to drip out of the injectors (into jars) and then back off until flow stops? I saw that process in older posts.
l

Almost sounds like you can skip the voltage tests...and about the Petronix coil -- If it starts good cold, I'd play with the CPR.:devil:

Yeah, upping the pressure will change the CO. Just set the CO with a dwell meter. The other procedure is great to rough it in, but you are close enough already.

[sweetp01569]

I finally had time to replace the CPR, as well as put a shim washer in the PPR to increase the system pressure. The shim increased the pressure from 65 psi to 72 psi, now in the right range. The new CPR also corrected the control pressure - cold control pressure is now about 26 psi and warm control pressure a little above 50 now. So looks like I have the fuel pressures under control.

I also adjusted the dwell, which stayed at a steady 30 when warmed up. I adjusted the mixture setting until it climbed up and started swinging back and forth between 40 and 50.

The car seemed to start more easily and run smoother. I final feel like I have a handle on the performance of the engine, which has been frustrating me for several years.

Thanks for everyone's help here!

Paul



I should have mention that when you do this, don't separate the White wires from each other too (should be on a Tee like connector).



Almost sounds like you can skip the voltage tests...and about the Petronix coil -- If it starts good cold, I'd play with the CPR.:devil:

Yeah, upping the pressure will change the CO. Just set the CO with a dwell meter. The other procedure is great to rough it in, but you are close enough already.

[Bitsyncmaster]

Sound like your engine is running pretty good. All it takes is a little understanding of K-jet to get things working.

[Ron]

I finally had time to replace the CPR, as well as put a shim washer in the PPR to increase the system pressure. The shim increased the pressure from 65 psi to 72 psi, now in the right range. The new CPR also corrected the control pressure - cold control pressure is now about 26 psi and warm control pressure a little above 50 now. So looks like I have the fuel pressures under control.

I also adjusted the dwell, which stayed at a steady 30 when warmed up. I adjusted the mixture setting until it climbed up and started swinging back and forth between 40 and 50.

The car seemed to start more easily and run smoother. I final feel like I have a handle on the performance of the engine, which has been frustrating me for several years.

Thanks for everyone's help here!

Paul:thumbup: Cool Beans!