Engine cuts out --- HELP

[wemulroy]

I have an 81 Delorean that is having an issue. When I start it up it will warm up for approx 2 minutes and then the whole engine will cut off. I go to try and restart it and it wont start back up. I wait about an hour and it will start back up again. If I turn on the radio or the AC, it cuts off again. Any ideas on what I can do?

[Ron]

Do you have to jump it off every time?

[Bitsyncmaster]

What does your volt gauge read when the engine is running? How long have you owned the car and how long did it sit without running (storage)?

[wemulroy]

I dont have to jump it, I just have to wait about 1 hour then it will start again, then cut off.

I have owned the car for 7 years, It did sit for 3 months without being started as I was away for work, but it was doing this before I left. I just would start it once a month and it would cut out. I changed the alternator, but that did not do anything to help. The battery was recharged and it did the same thing, on for a couple of minutes then just stop. The volt meter is just under the 13.

[Spittybug]

How does it "cut off"? Instantly like there is suddenly no more ignition? Or RPMs just start dropping off and it stumbles and dies? When you say it "won't start back up", does it crank but not catch? Can you confirm that you are getting fuel or spark during that attempted restart?

A little bit more information on the symptoms and the conditions will really help the experts on this board help you out. Everything is a guess otherwise.

[Patrick C]

I would first advise cleaning every electrical connection...grounds to the frame behind the driver front wheel, connections to fuel pump, connections to alternator, connections in rear bulkhead, etc. Use sandpaper to get the metal shiny and coat with a thin layer of dielectric grease to prevent corrosion.

That probably won't immediately fix the problem, but we can move forward from there knowing your electrical connections are sound.

[Ron]

Dying when turning on the AC could be caused by the engine not being tuned well enough to take on the extra load. But dying when turning on the radio is very odd (especially if the battery and charging system is OK)...could be it has been miswired involving the ignition system somehow (very very odd).

When it fails to start, pull a plug wire and see if it will jump spark (use a spare spark plug grounded to the engine block, OR, a philips screwdriver held ~1/8-1/4" away from the block).
If OK, unsnap the retainer, pull an injector and see if it will deliver fuel (into a container, carefully).

As Spitty said, lots of history and details help diagnose the problem (even things you may think don't matter!)

[DMC5180]

What do the Fuse Box connections look like? Poor grounds?

This could be so many things or combination of different things. Dying like that seems like a poor electrical connection (high resistance) when it gets hot the terminal may lose it's connectivity. (check terminals on the Ballast resistor for looseness) clean them and tighten the female terminals if needed. Confirm that the Fuel pump is running if and when the next time it dies and you try to restart it. If it is running, but does not start, you may have signs of the classic NO START WHEN HOT SYNDROME. Try moving the CPR connector to the CSV method for HOT STARTING. See if that gets it going again. If the engine fires up disconnect the CPR plug from the CSV quickly or you will flood it.

Report back with the results for more suggestions.

[Elvis]

I don't believe in that A/C or radio feedback.
Well you still can check the voltage drop at the two main relays. I never heard that they fail
but that could explain how the radio could affect the engine / ignition.

You do own a multimeter, right ?


Are the connections at the resistors OK ? pull the wires, clean them and push them back on.

Take the airfilter off and check if the air metering plate can travel all the way down.
maybe the piston is stuck.

Or the WUR has a problem -> pressure/force of the air measuring plate can tell a lot here.

[DMCMW Dave]

Are the connections at the resistors OK ? pull the wires, clean them and push them back on.

.

My money's on that one.

[Jonathan]

I have an 81 Delorean that is having an issue. When I start it up it will warm up for approx 2 minutes and then the whole engine will cut off. I go to try and restart it and it wont start back up. I wait about an hour and it will start back up again. If I turn on the radio or the AC, it cuts off again. Any ideas on what I can do?


Are the connections at the resistors OK ? pull the wires, clean them and push them back on.


Which resistors?

These ones. Ensure the wiring connections are on the correct posts too.

18436

[David T]

I am not so sure. Typically if you have bad connections there, you get a no start. It sounds like there is a problem with one of the systems that is active during the warm-up cycle. This includes the vacuum advance, the control pressure regulator, and the idle speed thermistor. Start by going over all of the vacuum hoses. Check for leaks and routing.
David Teitelbaum

[Ron]

I don't believe in that A/C or radio feedback.
Well you still can check the voltage drop at the two main relays. I never heard that they fail
but that could explain how the radio could affect the engine / ignition.

You do own a multimeter, right ?


Are the connections at the resistors OK ? pull the wires, clean them and push them back on.

Take the airfilter off and check if the air metering plate can travel all the way down.
maybe the piston is stuck.

Or the WUR has a problem -> pressure/force of the air measuring plate can tell a lot here.


My money's on that one.
+2

IMHO, forget checking this and that, it is a waste of time -- divide an conquer! The engine starting and running a while eliminates a lot... So, check what is left, basically, spark and fuel at the plugs. When it quits, determine which one you lost (or prove it it something else): If you have spark at the plugs, you eliminate everything in the ignition system (distributor, coil, relays, resistor block, ..., battery, etc). If it's OK, go to the fuel system...pull a few injectors and see if they are working (or just give it a shot of ether and see if it tries). If you're getting fuel, it may be flooding (which starting only after sitting can indicate... You didn't say anything about smelling fuel. If that's the case, there are several things to check, many of which were previously mentioned, including spark, but putting the cart before the horse to me in this case).

Keep plugging, systematically, you'll find it!

[wemulroy]

Here are a couple of links to what is happening:

First one is starting up and then the engine just cuts off
http://www.youtube.com/watch?v=GR1COZ0soLo&feature=youtu.be

Second one is attempting to restart after it cuts off
http://www.youtube.com/watch?v=LJJ2JRvQUC8&feature=youtu.be

[D Knight]

Ignition coil thermal breakdown maybe? First looks like you may have a pretty bad vacuum leak for it to hunt like that. You need to check for spark at the plugs like mentioned first.

[Bitsyncmaster]

I've seen a hunt that bad before. It was caused by thermal throttle enrichment stuck (shorted) on. It could also be the WOT switch is always on since it shares the same wire as the throttle enrichment. I would not think that caused your not start problem but who knows. Check with an ohm meter if the light/green wire on the WOT switch is grounded.

What you can try is to cut the light/green wire in the harness near the lambda ECU. I have done that anyway when I put in my wideband unit. I did not want the lambda unit go rich in cold starts.

[DeLorean03]

New person sticking their head in for a quick second:

I've been seeing WOT switch a lot lately....what does that acronym mean?

Back to the OPs situation, I wonder if the pulse coil in the electrical distributor is bad?

[Ron]

(W)ide (O)pen (T)hrottle

[David T]

The symptom for a bad impulse coil is typically the motor quits after it gets warm, about 20 minutes or so depending on ambient conditions. It is possible though, however unlikely. Maybe the voltage is getting dragged down and killing the motor? To check that you just have to stick a voltmeter on and watch the voltage.
David Teitelbaum

[DeLorean03]

To check that you just have to stick a voltmeter on and watch the voltage.


On................what ?

Not trying to be a jerk - just didn't know where he would measure voltage ?

Thanks Ron for the acronym help!

[Elvis]

Back to the basics - did you check the rpm relay ?

It cuts off so quickly that I'd say it's something electrical.


That hunting is really really bad, try what Dave said and let's know if
you can smell a lot of fuel during that hunting period.