81 DMC cranks but wont fire

[monstertruck_gnar]

Good Afternoon all,
Ive gone over the threads and my problem is a bit different than most of the no start/hard starts. This summer it was getting a bit harder to start from cold, sometimes from hot. The past couple months it just cranks but will not turn over. A squirt of starter fluid would get her to fire if she was sitting for longer than a few days. I replaced the old battery with an Optima and ensured that it has 12v. The car turns over strong and smells of fuel at the engine bay after 2 or 3 attempts to start. If I do the plug swap on the CSV, the car starts immediately but after 3 or 4 seconds will start to spudder and will die after 10 seconds. Unplugging the CSV plug swap, returning it, kills the car before it dies on its own. I thought it was the thermotime switch as it was broken at the connector, replaced that with no change. Checked all fuses and they look good. Fuel pump is turning on when the key, no fuel leaks, checked connections to the coil and looks good. I cant imagine its spark, seems to be a fueling issue somewhere. I have a multimeter but never have messed too much with electrical.

My DeLorean was a premium example from DMC and had been gone through before purchase a little over a year ago. I brought it back to Florida on a trailer about 8 months ago and DMC couldnt find any issues and the car was running ok. Id get her on a trailer and send her back to DMC but getting it out of my driveway is about impossible. Sorry if this has been asked a million times, I'm kind of stumped here.

Lurked on the site for a while, first post.

[82DMC12]

There's a lot to unpack here. I just so happened to be dealing with my own starting problem but my car at least starts but then dies immediately LOL.

Have you gone into the fuel pump area and inspected the pump? Do you know if you have the original style or the new style pump?

For fuel problems, it really helps to have a K Jetronic fuel pressure testing gauge kit.

You say you don't think it's spark, but Try checking all the wires on your ballast resistor and the ignition coil. Maybe one of the wires is loose or has fallen off.



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[David T]

Sounds like you have more than 1 problem. You have to tackle them one-at-a-time. I would start with getting it to start well, cold. If it hasn't been tuned up in a long time, start with that. If that doesn't improve the starting, then you need to check the operation of the systems that function during a cold start like the vacuum and mechanical advance, the Cold Start Valve, and the ballast resistor bypass relay.

[monstertruck_gnar]

Sounds like you have more than 1 problem. You have to tackle them one-at-a-time. I would start with getting it to start well, cold. If it hasn't been tuned up in a long time, start with that. If that doesn't improve the starting, then you need to check the operation of the systems that function during a cold start like the vacuum and mechanical advance, the Cold Start Valve, and the ballast resistor bypass relay.

The car was just at DMC this summer and they checked over everything when the starting issue was "intermittent" and couldn't find anything. Fresh tune up, freshly rebuilt Bosch fuel block, new fuel lines, new fuel pump and accumulator. The fusebox is a new unit with new solid state relays. All vacuum lines were replaced last year, and all are connected. Engine was rebuilt around the same time, so that is fresh as well. During the summer, the hard starts when cold became more common and then it just stopped running unless I swapped plugs on the CSV, moved em back and I could at least drive the car to move it. Now this just causes the car to start and then die.

The ballast resistor appears to be new, no corrosion on the connectors but cleaned them and reseated. Im not sure of the age of the coil but it is a bosch unit and doesnt appear to be too old. I know it could still be bad, I need to test it.

[Jonathan]

Sounds electrical to me too, but that's just a guess.

You also say it was running fine, so I would normally say that it couldn't be a spark plug wire or vacuum hose connected to the wrong spot, but considering the intermittency and unknowns here, I would go back to checking everything over again.

That being said, you might benefit from taking a few photos of things in your engine bay and posting them here. Lots of people looking for you and someone might spot something not right. Take photos of the engine bay showing the whole thing from the left, centre and right. Zoom a little closer on the ballast resistor and also the ignition coil with the cover removed. Zoom in photo of the throttle linkage under the deice shield. A picture from underneath showing the connections on the alternator. Also, take a picture of your instrument cluster while your key is turned to accessories... and if certain lights go out quick, make a note of which ones they are and mention that here.

[David T]

Since you say it had a tune-up and everything is relatively new, your problem could be a bunch of small vacuum leaks. It is possible the rubber got old and the problem came on slowly and got progressively worse as the leaks got worse. One theory. Another is a bad electrical connection somewhere, another is dirty injectors. Just because DMCH "went over" the car doesn't mean they replaced everything. If you don't have the tools, skills or time to do this, you need to get the car to someone who can.

[Helirich]

The car was just at DMC this summer and they checked over everything when the starting issue was "intermittent" and couldn't find anything. Fresh tune up, freshly rebuilt Bosch fuel block, new fuel lines, new fuel pump and accumulator. The fusebox is a new unit with new solid state relays. All vacuum lines were replaced last year, and all are connected. Engine was rebuilt around the same time, so that is fresh as well. During the summer, the hard starts when cold became more common and then it just stopped running unless I swapped plugs on the CSV, moved em back and I could at least drive the car to move it. Now this just causes the car to start and then die.

The ballast resistor appears to be new, no corrosion on the connectors but cleaned them and reseated. Im not sure of the age of the coil but it is a bosch unit and doesnt appear to be too old. I know it could still be bad, I need to test it.

Fuel filter can cause intermittent issues that become worse. But I would assume if they changed all that stuff, it would be new also. They said it ran fine or did they admit they couldn’t find the problem?

[monstertruck_gnar]

I just found out how a multi meter worked. Tested the coil and she is hotter than a lady boy in Thailand. The bulkhead connections are strong. my Bosch fuel distributor was rebuilt last year so i dont think its fuel.

[David T]

A quick way to figure out if it is fuel or spark is to shoot a LITTLE bit of Ether (starting fluid) into the air intake while trying to start the motor. If you can get it to run, even a little, it means you have a fuel delivery problem. Checking spark at the coil is good but to really check it completely you need to check it at a spark plug.

[monstertruck_gnar]

Jumpered the RPM relay for good measure, pulled the coil, yanked the CSV and put it in an old cup. Cranked the engine....nothing in the cup. So its either no fuel getting to the CSV or the Valve is bad. Going to try ether and to see if spark is working. Test plug light should be here today.