Test the cold start valve?

[dn010]

Hey everyone! I used to be a member here years ago as well as DML & DMCnews-even have a few articles posted in the tech section. Seems my account here is long gone, don't even see any old posts...

Anyway, I used my DeLorean as a daily driver from '01 to about '06 and then '08 to '09. Now it sits in my garage with flat front tires and collects dust. I know, it is a shame - I miss driving it and I plan on getting it out to the beach at least a few times. I do start it up on the weekends, let it run - all that good stuff.

I have an issue where it doesn't want to cold start though. If the car sits for longer than a few days without being started - I have to pour fuel into the manifold in order for it to fire. And when it does fire it runs really rough like it is missing a cylinder and then a moment later it will finally run normally. In the near future I will take the intake off to see if there are any vacuum leaks or electrical problems that is causing the misfire.

My question is - is there a way to test the cold start valve? I know to jump the thermo time switch which I'll try, but what about the valve itself for operation? I rebuilt my entire car back in...04 or 05.. I don't remember which. Most components were replaced back then except the valve...
Thanks for any & all help -----Dani B. #5003

[Farrar]

Welcome back, Dani. Have a thread bump. :) If no one responds to this by the time I get home, I will look up the test procedure in my old fuel injection handbook and copy it here for you.

Best,
Farrar

[TTait]

I just used an allen driver to remove the CSV from its pipe, and put it in a bottle - had the wife crank the car for 3 seconds and looked at the spray... Gas came out - I figured I was good.

[Farrar]

Make sure the engine coolant is below 86 degrees F. Preferably the engine should sit for several hours. Disconnect the electrical connector from the cold start valve and move it aside, away from the work area - there will be fuel vapor present. Remove the two screws holding the valve to the intake chamber and take the valve out. The fuel line must be left connected to the valve. Pull the coil wire out of the center of the distributor and connect it to a good ground. Turn the ignition On and operate the fuel pump for one minute. There must be no fuel dripping from the nozzle. If there is, the valve is faulty and must be replaced. Switch off the ignition.

Now put the stem of the valve in a container. Reconnect the plug to the valve. Unplug the electrical connector from the thermo-time switch and connect a jumper over the plug terminals. Have an assistant turn the ignition On and operate the starter. The valve should squirt a conical-shaped spray into the container. If the spray is correct the valve is working properly. If the spray pattern is irregular, the valve is damaged and should be replaced.

[DeLorean03]

Pull the coil wire out of the center of the distributor and connect it to a good ground.

O_O ....

Unless you're a contortionist, I can't imagine doing this without the fuel dist and mixture control unit being moved out of the way D: ...

Can you do this with the fuel dist and mixture control unit connected?

[TTait]

If you have your old wires you could disconnect the wire at the top of the coil and use your old wire for the ground...

[DeLorean03]

If you have your old wires you could disconnect the wire at the top of the coil and use your old wire for the ground...

I'm sorry - I don't understand. Are you saying disconnect the wire from the ignition coil and connect it to a good ground (like the engine hoist handle between the coolant bottle and the waterpump?

I just want to make sure I understand.

[Bitsyncmaster]

Just pull the white/yellow wire off your resistor block to stop any voltage going to the coil. That may however stop the OEM RPM relay from priming so you want to jumper the RPM relay connector to run the fuel pump.

[DeLorean03]

Just pull the white/yellow wire off your resistor block to stop any voltage going to the coil. That may however stop the OEM RPM relay from priming so you want to jumper the RPM relay connector to run the fuel pump.


So do what Farrar's writeup says but instead of toying with the coil wire just unhook the one wire you referred to and jumper the RPM plug?

The CSV I've always wondered how to test properly, that's why I'm asking so many questions =)

[Bitsyncmaster]

If your coolant temp is below what Farr said (86 deg.) then when the starter is turning the engine over your CSV should be shooting fuel.

So as Farr suggest, stop the spark (his way or mine) so your engine won't start.

Put the CSV in a jar.

Jumper the RPM relay so you have fuel pressure.

Crank the engine over (try to start it) for a few seconds.

You should have fuel in the jar.

note: It's been > 90 deg here for about a month now so you would not be able to test the CSV unless you jumpered the thermo time switch.

[dn010]

I appreciate it guys! I am about to go test it right now to see what happens. My car is sitting in a nice cool garage (its probably 90+ out right now) so it should be all set to test. I'll let you know the outcome. Thanks again!

[dn010]

I finally had a chance to look at my cold start situation (been very sick since Saturday!). It appears that when I bench test my cold start valve, it works fine. But when I plug it in and jump the TTS, nothing! I'm in the process of going through some archives to figure out what is the deal... I'd also like to add that while tracing the wiring through the wiring diagram, I'm looking at #143-CSV and 147 which says is the thermal time contact. It shows there is a white/red wire and blue/black coming from the TTS but my car has blue/yellow and blue/black from the thermo-time switch... Am I looking at the wrong thing?? Any suggestions in the mean time? Thanks for any & all help!

[Farrar]

Might be time to test the thermo-time switch:

Remove the plug from the cold start valve and bridge the contacts with a test light or voltmeter. The test must be done with a cold engine (coolant below 95°F). Remove the coil wire from the center of the distributor cap and connect it to a good ground. Operate the starter for ten seconds. Depending on the coolant temperature, the bulb should light or the voltmeter register for a period of between 3 and 10 seconds and then cease to light or register. If the circuit is not broken in ten seconds, your thermo-time switch is bad.

If the bulb doesn't light or the voltmeter register at all, check that there is voltage supplied to the switch. If there is no voltage, check your fuel pump ("RPM") relay.

Farrar

[dn010]

I changed start inhibit relay, and fuel relays. Took the RPM relay out and contacts are good, insides look fine. The frequancy valve works, and the car will start - fuel pump will run. Not sure what else to test - the starter is on the same wire as the thermo-time switch according to the diagram... I'm having a difficult time because the diagram shows a blue/black wire and white/red coming from the tts while I have blue/yellow and blue/black... I'd imagine that the w/r is the same as the b/y....

[Farrar]

Not sure what else to test

Have you tested the Thermo-Time Switch? I assumed not, which is why I posted the above how-to.

Glad you're feeling better.

Farrar

[Bitsyncmaster]

I changed start inhibit relay, and fuel relays. Took the RPM relay out and contacts are good, insides look fine. The frequancy valve works, and the car will start - fuel pump will run. Not sure what else to test - the starter is on the same wire as the thermo-time switch according to the diagram... I'm having a difficult time because the diagram shows a blue/black wire and white/red coming from the tts while I have blue/yellow and blue/black... I'd imagine that the w/r is the same as the b/y....

I found the same problems with my car's wiring. It was not done as shown on the schematic but it works logically the same. I ended up just jumpering the white/red and blue/yellow wires anyway because I have the starter without the "bypass" connector.

[dn010]

I did test the switch but there was no voltage coming from the wires, that's why I moved onto the relays. I meant, I'm not sure what else to test on the RPM relay. I do have an aftermarket starter but I have the white / red attached to the same post as the blue / yellow on it. I cleaned up the bulkhead connectors, I think now I'm going to start cutting some electrical tape off wires!

[Farrar]

Does the green wire running to the fuel pump relay socket have voltage when the key is on?

Farrar

[dn010]

Yes, +12.

[Farrar]

OK, this means the pump runs when you bypass the relay, correct?

Farrar

[dn010]

Bypassed - pump runs.

[Farrar]

Bypassed - pump runs.

What is the fuel system pressure when the engine is not on and the pump is running?

Farrar

[dn010]

That - I have no idea, and no means to test unfortunately. I know that the valve is full of fuel, and that the screen inside is clean. If I apply manual voltage to the valve it sprays a good pattern. The only issue with the fuel system is a bum accumulator. The car runs and drives with no issues, so I've never really had a need to test the pressure. Everything aside from the accumulator have been replaced probably 5 years ago... Thanks for your replies by the way. I feel like I am ruling things out at least!

[Farrar]

Fuel accumulator is fairly easy to replace, I'm told.

Does the control pressure regulator check out?

Farrar

[dn010]

My regulator is working fine. In fact, I have a spare in case it doesn't. I don't think it is fuel related issue, I am thinking that I have a broken wire somewhere in the mix!

[Bitsyncmaster]

I did test the switch but there was no voltage coming from the wires, that's why I moved onto the relays. I meant, I'm not sure what else to test on the RPM relay. I do have an aftermarket starter but I have the white / red attached to the same post as the blue / yellow on it. I cleaned up the bulkhead connectors, I think now I'm going to start cutting some electrical tape off wires!

You only get voltage when the starter is engaged. Best way to test the CSV is stick it in a jar, kill the spark (so engine does not start) and crank the starter for about 5 seconds.

Does the jar have any fuel in it?

[Farrar]

OK, good luck! I am interested to see what it turns out to be, once you've replaced the accumulator.

Farrar

[dn010]

Hah yes - I've tested the valve that I placed in a cup by trying to start the car - coil wire removed - with the TTS jumped, not jumped and no fuel in the cup. I removed the CSV and emptied the fuel - bench tested - it activated. Hooked it back up to the fuel line and primed. Then I manually applied voltage to the CSV and it sprayed a good pattern in the cup. Tested relays, tested the TTS, and there is just no voltage there for some reason.

I'll definitely let you know how it pans out.

Thank you guys again for all the help here, I definitely appreciate it!

[dn010]

I found the same problems with my car's wiring. It was not done as shown on the schematic but it works logically the same. I ended up just jumpering the white/red and blue/yellow wires anyway because I have the starter without the "bypass" connector.


Out of curiosity, where did you place the jumper for this?

[Bitsyncmaster]

I jumpered the wires up near the bulkhead connectors. One of my bulkhead connectors had a bad connection. It was the one that tied to that CSV circuit. So I just cut those two wires off and tied them all together. What are the odds yours has the same problem? Million to one.

I had it posted in the old forum but it was the jumper on the back side of one bulkhead connector that went to another bulkhead connector and it read about 30 ohms.

[sean]

Fuel accumulator is fairly easy to replace, I'm told.

Farrar

As low as 20 minutes and as long as...well we gotta wait for buddy to put his car back together for that :smile:.

[dn010]

Is the job of the thermo-time switch to provide a ground to the cold start valve during operation (given engine temp is in the correct range)??

[Farrar]

Is the job of the thermo-time switch to provide a ground to the cold start valve during operation (given engine temp is in the correct range)??

Exactly. The thermo-time switch contains a bimetallic spring. The spring senses coolant temperature and an electric coil (powered during cranking only) limits the cold start injector spray to 12 seconds.

Farrar

[dn010]

Okay, i understand now. So then, there would actually be no operation of the cold start valve if you put a jumper on the thermo-time switch plug because it wouldn't be routing any ground... which could be part of why I'm not getting any operation from my valve. That, and my bulk head plugs are disgusting with corrosion and what not! I have a few broken wires to clean up, all that corrosion and junk to clean up and then I'll have another test session with it. I was also having a condition where my engine would misfire terribly upon initial start up so hopefully after cleaning all this up will do me some good with that too... Thanks for the response.

[dn010]

The issue seemed to have been bad connections in the bulkhead connector and some broken ground wires. With that fixed, the valve now works as it should. Now, my car wont run! Guess I'll be starting a new thread!

[DeLorean03]

I suggest portions of this thread go under the "how-to" resources of the forums. Some of these ideas are GREAT, and they warrant being placed in the how-to section.

[sean]

I suggest portions of this thread go under the "how-to" resources of the forums. Some of these ideas are GREAT, and they warrant being placed in the how-to section.

I've started a "useful technical thread" link list here (http://dmctalk.org/showthread.php?1297-Useful-technical-threads). PM me if you know of others that belong there.

[Chris Burns]

Does this also apply to hot start issues?

[David T]

Short answer: No
Long answer: The Cold Start Valve (CSV) system does not operate if the Thermo-Time switch senses the coolant is NOT cold. A hard hot restart usually means the fuel system is not holding rest pressure long enough. That is typically caused by a bad accumulator, a bad or missing fuel pump check valve, or a leaky Primary Pressure Regulator. You can test to confirm this with a pressure gauge but that won't tell you which part is bad. Doing the plug swap basically confirms a rest pressure problem so you don't need the pressure gauge.
David Teitelbaum