Engine dies after 20-30 minutes of driving

[dmruschell]

I've asked a couple of "local" experts in our DeLorean Mid-Atlantic club about what this issue could be, but figured I'd ask here as well.

Our car is VIN 3196, a Houston new build that was gone through by Josh at DPI before we purchased it.

Last week, I was driving the car home at cruising speed (maybe 2,000 RPMs) and noticed the tachometer would dip a few hundred RPMs for a split second every 10-15 seconds or so. Not enough to feel it with an automatic transmission though. So, I kept an eye on the tach, but about 2-3 minutes after I noticed the tach dipping, the car completely died. I tried to restart it, and the starter would crank, but the engine wouldn't fire up. After sitting for 2-3 minutes contemplating who to call and debating calling AAA, I decided to see if it would start if I primed the pump twice to get the engine some more gas. It started right up without any issue. I started to drive it and made it about 50 feet before the car died on me again. So, I call AAA and talk with one of the local DMA guy on the phone about a possible diagnosis. We figure the easiest thing would be to replace the RPM relay. The car started right up when the tow truck arrived, so I drive it onto the truck. It also started right up when the tow truck arrived at our house, so I drove it into the garage. We order some RPM relays and put in a new one on Monday, but didn't get a chance to drive it until today.

It's my girlfriend's car, and she was the one driving today when it died. We had been driving for about 25 minutes when she said the RPMs would drop to just about 0 while she was moving. She said that if she pumped the gas pedal, the engine would sputter back to life for a split second before it tried to die again. After a few seconds of pumping the gas pedal, the car finally died. She was only a few minutes away from our house, so I drive home to get a car that she could drive home (she doesn't drive stick) so that I could drive her DeLorean home. So, about 10 minutes passed and I get in and the DeLorean starts right up. As I get closer to our house, it starts running more roughly and the throttle response feels a bit sluggish. I parked it in our driveway and revved it up to about 2,000 RPMs and I can hear the car backfire, just as if I had revved it up to the redline and then completely let off the gas, except that I was holding it steady at 2,000 RPMs. I figure I should pull it into the garage before it dies, so I put it in drive and as soon as I shut the door, the car dies. It was only idling, so it didn't have a chance to sputter or anything. It also won't restart. By now, there's a Facebook comment thread from some helpful DMA members trying to figure out the problem. One of the comments mentioned checking the ignition coil by seeing if the tach needle jumps when you try to start it. I figured that the car had only been sitting a minute or two and wouldn't start, so I'd check to see if the needle bounced. Well the needle bounced for half a second before the car started right up. I pulled it into the garage and that's where it is now.

One thing that's interesting to note. Before the car died last week, the gas gauge read 3/4 of a tank. When I pulled it into the garage, it read 1/4 of a tank. Halfway through our drive tonight, we filled up our cars with gas, and the needle reads well above full. the needle is closer to straight up than it is to "Full."

It seems it is definitely heat-related, since the car won't restart right after it dies, but will once the car has cooled off for a minute or two.

Most people seem to think it's an electrical issue, especially because of the backfiring. But, there has been speculation about the fuel pump or a kinked fuel hose. I'm going to double check the coolant level tomorrow when it's cooled off (to make sure the low coolant shutoff switch isn't being tripped), though there haven't been any coolant leaks, and the level was fine 2 months ago when I checked. The car is driven about once a week, so any leaks should be on our garage floor. I've also been told to check the inertia switch, which I will do as well. Any other ideas of what it could be? Thanks in advance!

[NightFlyer]

When it runs, is there any kind of smoke or excessive amounts of water vapor coming from the tailpipes?

[ALEXAKOS]

I would have a drive, let it heat up and then try to short any relays that are responsible for "killing" the engine spark or fuel distribution.
I am not very familiar of those so why don't the older owners make a list of them below:thumbup2:

[WelmoedJ]

Any specific sounds coming from the fuel pump area?
Sounds that may point to a fuel pump on its way out (whining and then loss of engine power)?

Check the ground of the inertia switch (and its contacts!) as the fuel pump's power is routed through it.
Bitsyncmaster found the ground wire to be a bit undersized for the work.

Check the lead contacts in the connector and on the fuel pump.
Check if (in case you have the original pickup hose) that it's not torn causing air sucked into the pump instead of fuel.

[dmc]

Since you noticed the tach dropping off first, it is most likely an ignition problem.
Your ignition coil is probably heating up and cutting out. Pretty easy to swap it out.
Or hit it with a hair dryer while idling to see if you can make it happen

[jmpdmc]

Check the resource section of this site for the technical manual hybrid: http://dmctalk.org/showthread.php?2866-Searchable-Workshop-Technical-Bulletins-and-Volvo-Engine-Manuals. Page 122 starts a diagnostic tree that might help out.



Jeff

[Bitsyncmaster]

Since you noticed the tach dropping off first, it is most likely an ignition problem.
Your ignition coil is probably heating up and cutting out. Pretty easy to swap it out.
Or hit it with a hair dryer while idling to see if you can make it happen

+1
Distributor pickup coil, Ignition ECU would also be things to check. Make sure your resistor connections are clean.

[Kenny_Z]

It sounds like the issue I had with mine. I ended up having a bad ground from the battery. I bypassed the normal ground and going from the battery to the transmission and then from the engine block to the frame.

[kenny]

I also had an issue with similar symptoms.
Unplug the lead to the distributor coil and check the resistance. It should be around 600 ohms.
Test while engine is cold and also after it has cut out when hot.
I tracked mine down to the distributor coil connector. It was corroded. Once it was cleaned problem went away.

As above, also check the ballast resistor and firewall connections and clean them all.

[David T]

I also had an issue with similar symptoms.
Unplug the lead to the distributor coil and check the resistance. It should be around 600 ohms.
Test while engine is cold and also after it has cut out when hot.
I tracked mine down to the distributor coil connector. It was corroded. Once it was cleaned problem went away.

As above, also check the ballast resistor and firewall connections and clean them all.

If it seems to die reliably after 20 minutes several times, it is most likely a bad impulse coil. Remove the distributor and replace it.
David Teitelbaum

[dmruschell]

When it runs, is there any kind of smoke or excessive amounts of water vapor coming from the tailpipes?

Only water vapor on cold startup, but that happens with just about every car :)

[dmruschell]

Any specific sounds coming from the fuel pump area?
Sounds that may point to a fuel pump on its way out (whining and then loss of engine power)?

Check the ground of the inertia switch (and its contacts!) as the fuel pump's power is routed through it.
Bitsyncmaster found the ground wire to be a bit undersized for the work.

Check the lead contacts in the connector and on the fuel pump.
Check if (in case you have the original pickup hose) that it's not torn causing air sucked into the pump instead of fuel.

There aren't any abnormal sounds coming from the car (though I've had a fuel pump die on me without making any sounds... made it a little difficult to diagnose), except for the backfire when it gets hot, which would point to no spark since the fuel ignites when it hits the exhaust.

I've got a DMA friend coming over this weekend to look at a few things to try and narrow it down. Even though our best guess is electrical, we're going to check the fuel parts just to be sure.

[dmruschell]

Since you noticed the tach dropping off first, it is most likely an ignition problem.
Your ignition coil is probably heating up and cutting out. Pretty easy to swap it out.
Or hit it with a hair dryer while idling to see if you can make it happen

That's actually genius. The guy who's coming over is the guy I talked to on the phone the first time it died, and his first thought was electrical. Since the relay is easier to change than the coil (and a known problem), we went with the relay first. Does the coil need to be ordered from a vendor or is there a cross referenced part that is readily available at a local store (AutoZone, PepBuys, etc)? EDIT: Also, to all the ignition coil responses/suggestions, we'll check the connections, etc. while we're back there even though (as seen in my next post) the engine was built and installed in October and should be clean, it doesn't hurt to check if things are apart and exposed any ways.

Also (to save on the number of replies) thanks to the guy who posted the links to the technical manuals. I don't have them yet, so those will probably come in handy until I do have them. :)

[dmruschell]

It sounds like the issue I had with mine. I ended up having a bad ground from the battery. I bypassed the normal ground and going from the battery to the transmission and then from the engine block to the frame.

Even after the car dies, the car still has electricity from the battery. I should have been more clear about this, especially since I've had a car go completely electrically dead on me while driving before.

RE: All the electrical contact posts: While checking everything we'll go through and make sure the contacts are clean. The car was "newly built" in 2008, so I'd hope that the contacts were clean and wouldn't have gone bad in 5 years, but you never know. DPI Josh built this engine and put it in right before it was delivered to us (When I saw it and was offered the chance to buy it, the engine compartment was empty), so the contacts on the parts he built should definitely be clean. But, things do happen, and it's good to rule the dumb things out.

[Kenny_Z]

Even after the car dies, the car still has electricity from the battery. I should have been more clear about this, especially since I've had a car go completely electrically dead on me while driving before.

I still had enough to run the lights and even turn the starter but not enough to spark the plugs. I meant to say engine ground. A simple test is to get a short cable like this:http://www.autozone.com/autozone/parts/Duralast-Battery-Cable/_/N-8gcx6?itemIdentifier=570475&_requestid=2255616 and go from an exhaust bracket bolt below the alternator to the frame ground on the passenger side engine compartment. You could use the black lead from a jumper cable but it's not possible to drive with something like that tangled around everything. I guess you could heat up the car to the point where it fails and then hook up the jumper cable.

[NightFlyer]

Only water vapor on cold startup, but that happens with just about every car :)

You had previously mentioned that it might be losing coolant, but not leaking it onto the floor in your garage, thus why I asked the question.

If coolant is being lost but there are no visible signs of a leak, then I would have to suspect a faulty head gasket.

[Delorean Industries]

I would look into the fuel cell for starters if you haven't already. This car has had documented pump/pick up issues over the years. (I haven't read back through the entire thread, just saw this and facebook) We had the fuel cell out while replacing the front crumble zone in 2011. In Delorean years that is a long time ago!

As a reminder to how bad fuel is becoming. I purchased a Delorean and gutted/replaced the entire fuel system with premium parts back in April. Yesterday I had to replace the fuel pump support again due to swelling. Gasoline is becoming more and more caustic due to the additives in relation to rubber components.

I am out of the country until Sunday evening. Feel free to email me with your findings!

[kings1527]

As a reminder to how bad fuel is becoming. I purchased a Delorean and gutted/replaced the entire fuel system with premium parts back in April. Yesterday I had to replace the fuel pump support again due to swelling. Gasoline is becoming more and more caustic due to the additives in relation to rubber components.


Is there anything we can add to the fuel or do to help combat today's fuel additives and makes things better for our fuel systems?

[opethmike]

I had this same EXACT issue with 01049 a few years ago. Does the car keep running if you hold the key in the start position? (Don't do that very long!) If it does, you have the same problem I did.

The connections on the ballast resistor were very loose, and very dirty. I cleaned the blades on the resistor, and put new terminals on the wires. Was never a problem again.

[Delorean Industries]

Is there anything we can add to the fuel or do to help combat today's fuel additives and makes things better for our fuel systems?


I'm testing a new pick up hose/return on material now. Unless we manufacture the support boots in Viton options are limited. My quote on Vition was crazy expensive and I haven't moved forward on it.

[dmruschell]

You had previously mentioned that it might be losing coolant, but not leaking it onto the floor in your garage, thus why I asked the question.

If coolant is being lost but there are no visible signs of a leak, then I would have to suspect a faulty head gasket.

I only mentioned the coolant level because I was told there's a shutoff switch that will shut the car down if the coolant gets low. As far as I know, the car isn't losing coolant, but was told to check to rule it out :)

Considering the engine has less than 3,000 miles on it, I would hope the head gasket is okay lol.

Thanks for the suggestion though :)

[David T]

I only mentioned the coolant level because I was told there's a shutoff switch that will shut the car down if the coolant gets low. As far as I know, the car isn't losing coolant, but was told to check to rule it out :)

Considering the engine has less than 3,000 miles on it, I would hope the head gasket is okay lol.

Thanks for the suggestion though :)

There is no "switch" to shut the engine down on coolant loss or overheat. No need for one, it will shut itself off anyway! The only switch that will shut the engine down besides the ignition switch is the inertia switch which, in case of a collision, shuts the fuel pump off and is supposed to unlock the doors (assuming the central door locking system is functioning).
David Teitelbaum

[rothsean]

I've asked a couple of "local" experts in our DeLorean Mid-Atlantic club about what this issue could be, but figured I'd ask here as well.

Our car is VIN 3196, a Houston new build that was gone through by Josh at DPI before we purchased it.

Last week, I was driving the car home at cruising speed (maybe 2,000 RPMs) and noticed the tachometer would dip a few hundred RPMs for a split second every 10-15 seconds or so. Not enough to feel it with an automatic transmission though. So, I kept an eye on the tach, but about 2-3 minutes after I noticed the tach dipping, the car completely died. I tried to restart it, and the starter would crank, but the engine wouldn't fire up. After sitting for 2-3 minutes contemplating who to call and debating calling AAA, I decided to see if it would start if I primed the pump twice to get the engine some more gas. It started right up without any issue. I started to drive it and made it about 50 feet before the car died on me again. So, I call AAA and talk with one of the local DMA guy on the phone about a possible diagnosis. We figure the easiest thing would be to replace the RPM relay. The car started right up when the tow truck arrived, so I drive it onto the truck. It also started right up when the tow truck arrived at our house, so I drove it into the garage. We order some RPM relays and put in a new one on Monday, but didn't get a chance to drive it until today.

It's my girlfriend's car, and she was the one driving today when it died. We had been driving for about 25 minutes when she said the RPMs would drop to just about 0 while she was moving. She said that if she pumped the gas pedal, the engine would sputter back to life for a split second before it tried to die again. After a few seconds of pumping the gas pedal, the car finally died. She was only a few minutes away from our house, so I drive home to get a car that she could drive home (she doesn't drive stick) so that I could drive her DeLorean home. So, about 10 minutes passed and I get in and the DeLorean starts right up. As I get closer to our house, it starts running more roughly and the throttle response feels a bit sluggish. I parked it in our driveway and revved it up to about 2,000 RPMs and I can hear the car backfire, just as if I had revved it up to the redline and then completely let off the gas, except that I was holding it steady at 2,000 RPMs. I figure I should pull it into the garage before it dies, so I put it in drive and as soon as I shut the door, the car dies. It was only idling, so it didn't have a chance to sputter or anything. It also won't restart. By now, there's a Facebook comment thread from some helpful DMA members trying to figure out the problem. One of the comments mentioned checking the ignition coil by seeing if the tach needle jumps when you try to start it. I figured that the car had only been sitting a minute or two and wouldn't start, so I'd check to see if the needle bounced. Well the needle bounced for half a second before the car started right up. I pulled it into the garage and that's where it is now.

One thing that's interesting to note. Before the car died last week, the gas gauge read 3/4 of a tank. When I pulled it into the garage, it read 1/4 of a tank. Halfway through our drive tonight, we filled up our cars with gas, and the needle reads well above full. the needle is closer to straight up than it is to "Full."

It seems it is definitely heat-related, since the car won't restart right after it dies, but will once the car has cooled off for a minute or two.

Most people seem to think it's an electrical issue, especially because of the backfiring. But, there has been speculation about the fuel pump or a kinked fuel hose. I'm going to double check the coolant level tomorrow when it's cooled off (to make sure the low coolant shutoff switch isn't being tripped), though there haven't been any coolant leaks, and the level was fine 2 months ago when I checked. The car is driven about once a week, so any leaks should be on our garage floor. I've also been told to check the inertia switch, which I will do as well. Any other ideas of what it could be? Thanks in advance!



My guess is that the impulse coil in the distributor is going bad. PM me and I can tell you how to test that.

[David T]

There is no good way to easily check the impulse coil when the motor is hot. If it dies after around 20 minutes and won't start on Ether and you check for spark and there is none, you can assume the coil is bad. They somehow become thermally sensitive and loose continuity. They are a LOT of fun to replace. Make sure to properly regap the reluctor or your idle will be all over the place! While the distributor is out you should check the mechanical and vacuum advance.
David Teitelbaum

[dmruschell]

Update: I checked the coolant level and it was fine. The inertia switch is functioning properly. All the electrical contacts i checked were clean. The fuel pickup and system all checked out fine. The coil in the distributor is seeing 600 ohms resistance. However, it's now dying after just running for a few minutes, both with the rpm relay installed or jumpered. After it dies, the tach does not bounce when it's started. The best guess we have is the ignition coil might be the culprit, but would that cause the tach to not bounce when cranking? Thanks in advance!

[LEVY]

To me, the most accurate answer was Josh's.

Fuel pick up hose collapsing would cause that problem.

Next time you have that problem take the fuel cap off, that may help for testing purposes.

I don't believe it is electric system related.


LEVY

[dmruschell]

To me, the most accurate answer was Josh's.

Fuel pick up hose collapsing would cause that problem.

Next time you have that problem take the fuel cap off, that may help for testing purposes.

I don't believe it is electric system related.


LEVY

We took out the fuel pump and inspected it, and everything was working properly and the hoses were in good condition (the car has a Hervey pump). The car died even after we inspected the pump and made sure it was pumping fuel. The fuel gauge sender is malfunctioning and causing the faulty gauge readings.

I mentioned in my last post that after the car died and we tried to restart it, the tach needle was dead and wouldn't bounce, which means its an electrical problem. Through testing various connection points after it died, we narrowed it down to either the ignition coil or the ECU. The coil is cheaper, so were going that route first lol.

[dmruschell]

I replaced the coil and the car started right up. It idled for a half hour without dying and I drove it around for another half hour and no incidents. It hasn't died since we unplugged and replugged the ECU, but I'm not convinced that's what fixed things, though its certainly possible. But, with a new coil, the problem seems to be solved. Thanks to everyone who chimed in for the benefit of future troubleshooters as well as myself. And thanks to the DMA members that helped me with the car.