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Gumby
09-01-2014, 09:08 AM
Hi my 81 delorean has a prob no start. It has a rebuilt fuel distributor the air box has been re-sealed no vacuum leaks
Have pulled the injectors pulled the rpm relay and shorted brown/purple white wire to run fuel pump the spray pattern is great. adjusted spray perfectly. When I re-installed the rpm relay and replaced the injectors nothing no gas getting to the intakes as the plugs are bone dry.. have swapped rpm relays same problem.

Question. There is a pulse received from the distributor to activate the rpm relay for the fuel pump is there a way to check using ohm meter to see if a signal is getting to the rpm relay or can I dump a bunch of fuel into the cylinders by shorting the relay brown/purple wires to have it run continually to check if is a fuel issue?

P.s. checked spark coil beautiful fat blue spark...to plugs.... Hmmmm..

So many questions so little time..
Thx gumby.

Bitsyncmaster
09-01-2014, 09:53 AM
Was it running before you replaced the FD? Did it just die overnight without any parts changing?

Jonathan
09-01-2014, 10:23 AM
You seem to have already covered much of the obvious stuff.

Can you elaborate on what you meant by or how it is you resealed the air box? Where or what portions and with what type of sealant?

I ask only because maybe the problem isn't something very obvious and could have been overlooked. Your description sounds like you have fuel and spark for the most part so I got wondering about the air piece.

DMCMW Dave
09-01-2014, 10:53 AM
Hi my 81 delorean has a prob no start. It has a rebuilt fuel distributor the air box has been re-sealed no vacuum leaks
Have pulled the injectors pulled the rpm relay and shorted brown/purple white wire to run fuel pump the spray pattern is great. adjusted spray perfectly. When I re-installed the rpm relay and replaced the injectors nothing no gas getting to the intakes as the plugs are bone dry.. have swapped rpm relays same problem.

Question. There is a pulse received from the distributor to activate the rpm relay for the fuel pump is there a way to check using ohm meter to see if a signal is getting to the rpm relay or can I dump a bunch of fuel into the cylinders by shorting the relay brown/purple wires to have it run continually to check if is a fuel issue?

P.s. checked spark coil beautiful fat blue spark...to plugs.... Hmmmm..

So many questions so little time..
Thx gumby.

How do you know there are no vacuum leaks if it won't run?
No
Yes

Gumby
09-01-2014, 11:08 AM
The air box plate is very hard to push down when cranking no (vacuum leaks) the injectors fire strong when in jars for flow control and rpm relay removed and fuel pump bussed to 12volts. when relay re-installed and injectors put back Spark plugs dry tried 2 different rpm relays.
Question does the rpm relay receive a signal from the distributor to forward info to the rpm relay to begin pulsing?
Have worked on many cars motorcycles etc. but this has me a bit stumped
Can I check,the distributor pulse coil for resistance without removing the intake etc?

Bitsyncmaster
09-01-2014, 12:13 PM
The signal from the ignition distributor drives the ignition ECU. The coil voltage (pulses) then drive the RPM relay, idle ECU and Tach.

DMCMW Dave
09-01-2014, 12:25 PM
If you are getting spark the distributor pickup and ECU are working. You can also verify this when cranking- does the tach move?

You can jump the RPM relay (brown to white/purple AND yellow/red) and make the pump/FI control run. If it won't run like that you have other issues. Dry plugs is not enough of an indication, as the fuel distributor may be way out of adjustment and no fuel will flow when cranking.

I don't really know why but I've found that a freshly rebuild fuel distributor will almost always be way too lean, often too lean to run the car. It should start on the cold start injection and then die. At least once. Although in warm weather one try may be enough to time out the thermotime switch for hours.

You may be chasing a second problem - does the cold start valve open/spray when you first crank the car?

When you installed the fuel distributor did you adjust anything?

Gumby
09-01-2014, 03:03 PM
Hi yes the tach goes too about 500 rpm when cranking I did adjust the fuel distributor made it rich ( have also tried lean) is that the brown to yellow red? The wireing and what is fi control?.. So brown 12volts to yellow red? What should that override??

DMCMW Dave
09-01-2014, 03:14 PM
Hi yes the tach goes too about 500 rpm when cranking I did adjust the fuel distributor made it rich ( have also tried lean) is that the brown to yellow red? The wireing and what is fi control?.. So brown 12volts to yellow red? What should that override??

That will turn on the fuel injection (Lambda) computer and you should hear the frequency valve buzz. White/purple is the fuel pump. Brown is B+

Gumby
09-01-2014, 03:15 PM
Hi the reply is only adding half of my response the rest is not coming thru.

Gumby
09-01-2014, 03:19 PM
Hi Dave is that brown to yellow red for lambda? Should I force fuel bypassing (removing the rpm relay) by shorting brown to purple red and try to start that way?

Gumby
09-03-2014, 08:52 PM
Hi my cold start valve is not fireing pulled the wires on the thermo time switch measured the resistance of the switch
And it measures 40ohms also checked the wires going to the switch and they measured 7 ohms also measured the cold start and it measures 6 ohms so no shorts..

Question could the thermo time switch and the cold start valve prevent the injectors from fireing? Also what pins on the rpm relay connector would tell me if a pulse from the distributor is being sent? And of course what voltage to look for?

Jonathan
09-03-2014, 10:12 PM
Since you're new here, ah, I'm gonna cut you a break...

Just kidding...

Have a look at these as it will answer some of your questions:

http://dmctalk.org/showthread.php?17-DMC-12-color-wiring-diagram

And these individual ones might answer some others:

http://dmctalk.org/showthread.php?40-All-Wiring-Schematics

Bitsyncmaster
09-04-2014, 05:39 AM
Hi my cold start valve is not fireing pulled the wires on the thermo time switch measured the resistance of the switch
And it measures 40ohms also checked the wires going to the switch and they measured 7 ohms also measured the cold start and it measures 6 ohms so no shorts..

Question could the thermo time switch and the cold start valve prevent the injectors from fireing? Also what pins on the rpm relay connector would tell me if a pulse from the distributor is being sent? And of course what voltage to look for?

Try a squirt of starting fluid into the air inlet plate to see if it fires. If it "pops" that would tell us you probably have a fuel problem and the ignition is working.

DMCMW Dave
09-04-2014, 03:15 PM
Hi my cold start valve is not fireing pulled the wires on the thermo time switch measured the resistance of the switch
And it measures 40ohms also checked the wires going to the switch and they measured 7 ohms also measured the cold start and it measures 6 ohms so no shorts..

Question could the thermo time switch and the cold start valve prevent the injectors from fireing? Also what pins on the rpm relay connector would tell me if a pulse from the distributor is being sent? And of course what voltage to look for?

The thermotime switch only fires the cold start valve, and only during cranking. It does not turn on the pump or anything like that.

You measure the two pins on the thermotime switch to ground, not to each other.

One will typically read 50 ohms (heater) and the other will read short if cold and open if hot. If you read 50 across the two pins it's probably good.

The white/slate wire on the RPM relay is tach pulse from the ignition ECU. Do not ground or apply power to it.

Gumby
09-09-2014, 09:01 AM
Well maybe my lambda relay is screwing up have tried 2 different rpm relays hmmm onward..