Cold Start Problem

[scotstern]

I have read everything that I can find about this subject in the search section. My car has sat for about three or four months and now it will not start. I tried the RPM relay jump and the pump ran fine but that was not the problem. I replaced the relay back in its socket.

I did the plug swap and it starts right away. I replug back in the blue plug and it will not continue to run or restart. I disconnected the thermo-tine wires and it will still not start. I tried grounding the blue wire on the thermo-tine and again, it will not start.

It will start right up if I put the grey plug back in the blue socket. What can I do to fix this problem? Is it a part or wiring?

Thanks,

Scot Stern
6452 San Diego

[DMCMW Dave]

If it starts with the plug swap then you know the coldstart injector is good. That leaves only the thermotime switch or wiring as the cause.

Check the connectors on the blue plug and the thermotime switch. It is common for the metal pins to push back into the connector and not make contact.

If the plastic on the thermotime switch breaks and you are now able to connect the thermotime switch backwards, the switch will burn out and will not work even after connecting it up correctly.

All the wiring for this circuit is within the engine harness.

[Bitsyncmaster]

All the wiring for this circuit is within the engine harness.

There is a jumper on the bulkhead connectors that failed on my car causing the CSV to never work.

You should start by checking that one pin on the CSV gets 12 volts when your cranking the engine. Then the other pin gets grounded through the thermal time switch. You can check that ground with the engine cold and not cranking.

[David T]

You need to start by making sure you have power to the Thermo-Time switch and Cold Start Valve during cranking. Refer to D:04:06 in the Workshop Manual. It has a simplified wiring diagram of the cold start circuit. Make sure there is nothing plugged into the hot start relay plug. It is located by the RPM relay laying on the wiring harness. The common problems are:
Bad Thermo-Time switch
Someone forced the plug into the TT switch and messed it up
Someone messed up the wiring on the starter
Someone reinstalled the TT switch and used too much sealer and insulated the TT from ground. The CSV is grounded by the TT switch.
David Teitelbaum

[scotstern]

Help,

I can get the car to start immediately if I do the plug swap and it will run very rich with no rpm's. If I try to accelerate it just runs very rough. If I unplug the grey plug after it starts the engine dies within seconds. It tries to fire with the CSV attached to the blue plug but it will only run for a brief time while it is cranking. I suspect that as soon as the cold start valve times out when the engine starts it is not getting any fuel and then it dies.

If the grey plug works, or even if the CSV works when it is cranking with the blue plug, then it would seem logical that the fuel pump and the CSV are working. I did try jumping the relay and the pump runs but it still will not start and run. It would appear to me that the issues seems to be that it is not getting fuel unless the cold start valve is running all of the time. Any thoughts on what else it might be? It ran perfectly three or four months ago when I last drove it. I did try the test of pushing down on the throttle plate and it does have resistance.

The accumulator, fuel pump, fuel lines, fuel distributor and "o" ring are relatively new (less than 1,000 miles but probably 6 years old). The car is bone stock and has only 12,800 miles.

Thanks,

Scot
6452 San Diego

[Bitsyncmaster]

Pull the PPR o-ring and look for a chip in it. The CSV will work with very little pressure but the FD needs that 75 PSI to work.

[scotstern]

Again, it will fire for a couple of seconds on the CVS and then it dies. If I hold the throttle all the way down it sounds like it wants to fire and when I let off the throttle, it will fire for a couple of seconds. I checked the O'ring on the fuel distributor and it looks fine. If I plug in the grey plug it will start right a way and run very rough but it will run. If I then unplug the grey plug it will die in a couple of seconds.

Thoughts..... I am 100 miles away from the nearest Delorean Service Center and that is a log push at my age. The car ran fine three or four months ago.

Scot Stern
San Diego
6452

[David T]

This is a guess but it sounds like you are not getting enough fuel pressure. I would open the tank and check the fuel pump and pick-up. BTW, how much gas is in the tank?
David Teitelbaum

[scotstern]

David,

Thank you for your input. I opened the pump area and the fuel pump seems to be working. It is humming so I suspect that it works. The gas was about an inch and a half deep so I added another 2 gallons. Still no luck. It will fire over with no throttle but it will not stay running. If I floor it it will try to start and then it will start when I take my foot off of the gas. It only runs for two or three seconds and it smells rich. I also think that it is a fuel pressure problem but the O'ring looks fine, the pump seems to work (I even tried jumping it) and still it will not run.

Any other thoughts?

Thanks,

Scot

[scotstern]

I wanted to post here so anyone that searches for a solution to a cold start problem will have the chance to see the solution. As it turns out, I called DMC in Orange County, CA to talk one last time about the situation and make some sort of arrangements to take the car there on a flat bed. Danny suggested that I take the fuel distributor off and clean the piston. He explained how to do it, the care that I needed to take and felt fairly certain that this was my problem since they had changed the accumulator, filter, fuel pump and distributor (fuel) a few years ago and less than 500 miles ago.

Tonight, I took the plastic handle of a good sized screw driver and "thumped" the fuel distributor a few good wackes. The car started right up and has been running fine since. Apparently, the piston was stuck. I am not sure if I should take it a part and clean it better or just leave well enough alone and take it to Danny. A special thanks to DMC and Danny and now at least the car runs. The amount of time and effort that I put into this problem was way more than I should have and I hope that this solution helps someone in the future. If all else fails, it seems that wacking it with a hammer is not such a bad solution.

Scot
San Diego
6452

[Ron]

Apparently, the piston was stuck. I am not sure if I should take it a part and clean it better or just leave well enough alone and take it to Danny.I'd give it a chance... But if it did it again, I'd remove the plunger (only), check it for scars and clean the bore out, rather than take it all apart.

[Spittybug]

Good to hear you are running. It's quotes like this:


Tonight, I took the plastic handle of a good sized screw driver and "thumped" the fuel distributor a few good wackes.
That prompted many of us to look into alternate fueling methods.

[David T]

If it did get stuck (and it seems so) I would get around to taking the unit apart and cleaning as per Danny's instructions. The other thing you could consider is running a bottle of Techron cleaner through the fuel system.

Definition of: HAMMER
Crude instrument used to find expensive parts near the part you are trying to hit.

David Teitelbaum



Good to hear you are running. It's quotes like this:


That prompted many of us to look into alternate fueling methods.