Sits out in the sun...won't start. Hmm...

[rundmc]

Ok, the short version. Car has always started reliably, but does hunt badly for a minute on cold start. Always garaged. Took it out for a Sunday constitutional, then came back and parked it outside for a few hours while my friend used the garage space so we could change the axles on his GTI. I had the DMC under its Wolf cover, but it was not in the shade after the sun moved. Parked at 11 a.m. Now the work is done - going to move the DMC back to the garage. It's now near 7 p.m. so this should be a very "cold" start, aside from the physical temperature of the car itself from being in the sun.

I have the Bitsyncmaster Solid State RPM relay, so I set the key, I hear the fuel pump prime. Now I start the car. The car fires, tries to start, dies. Tried to give it a nudge of gas on next attempt. A second of ignition, then nothing. Wait, try again. Same result. About 10 tries is what it took to get it to start "hanging on" in the lower RPMs long enough to cough to life.

Drove as normal to test. Came back - turned off ignition. Waited a few minutes, restarted DMC, fired up just fine. ???

Is this the fuel pump wearing out? Accumulator? Bad gas? (The tank is full of premium, but I only start the car once a week and because of the rainy summer, I've only driven it every two weeks if I'm lucky - maybe the gas is getting old - might be more than four weeks old in the tank.) I haven't heard any loud noises/buzzing from the fuel pump when driving.

Any theories are appreciated.

Mike

[Bitsyncmaster]

What was the air temp? Sounds like a warm start problem but 6 hours would normaly be enough to cool things down. If it was a warm start issue you can jumper the relay to help that problem.

[DeLorean03]

I'll just say this - it being in the sun or shade won't have any effect on the fuel system's reliability. Not trying to be a jerk - just making sure there's no "magical thinking" going on here ;).

What's the backstory on your car's ignition/fuel system(s) ? It helps us know what to suggest if we know the status for each component - are we dealing with 30 year old parts - anything been replaced? Let us know, and we can go from there. I ask this particularly with the fuel pump/sender combo shenanigans that have been going on - status of people's cars are all over the map with these lately.

[Bitsyncmaster]

If the air temp was above 95 deg. F, then it most likly did not cool enough to get the CSV working.

[rothsean]

Ok, the short version. Car has always started reliably, but does hunt badly for a minute on cold start. Always garaged. Took it out for a Sunday constitutional, then came back and parked it outside for a few hours while my friend used the garage space so we could change the axles on his GTI. I had the DMC under its Wolf cover, but it was not in the shade after the sun moved. Parked at 11 a.m. Now the work is done - going to move the DMC back to the garage. It's now near 7 p.m. so this should be a very "cold" start, aside from the physical temperature of the car itself from being in the sun.

I have the Bitsyncmaster Solid State RPM relay, so I set the key, I hear the fuel pump prime. Now I start the car. The car fires, tries to start, dies. Tried to give it a nudge of gas on next attempt. A second of ignition, then nothing. Wait, try again. Same result. About 10 tries is what it took to get it to start "hanging on" in the lower RPMs long enough to cough to life.

Drove as normal to test. Came back - turned off ignition. Waited a few minutes, restarted DMC, fired up just fine. ???

Is this the fuel pump wearing out? Accumulator? Bad gas? (The tank is full of premium, but I only start the car once a week and because of the rainy summer, I've only driven it every two weeks if I'm lucky - maybe the gas is getting old - might be more than four weeks old in the tank.) I haven't heard any loud noises/buzzing from the fuel pump when driving.

Any theories are appreciated.

Mike


Those symptoms are identical to what I had. I was losing rest pressure, fixed with a check valve.

I had issues after 4 hours of sitting once.

[Dangermouse]

If the air temp was above 95 deg. F, then it most likly did not cool enough to get the CSV working.

I live close to Mike and the air temp yesterday perhaps made it to 90-91 in mid afternoon, but it was in the low 80s by 7 pm.

[David T]

I live close to Mike and the air temp yesterday perhaps made it to 90-91 in mid afternoon, but it was in the low 80s by 7 pm.

A cold start is relative. If the ambient temperature is high it may never "cool" off enough for the TT switch to run the CSV. The next time you have a hard start problem try the pug swap. If it starts right up you are not holding rest pressure and/or you have a problem with the CSV system.
David Teitelbaum

[rundmc]

What's the backstory on your car's ignition/fuel system(s) ? It helps us know what to suggest if we know the status for each component - are we dealing with 30 year old parts - anything been replaced? Let us know, and we can go from there. I ask this particularly with the fuel pump/sender combo shenanigans that have been going on - status of people's cars are all over the map with these lately.

Truthfully, I'm not sure about the make of the fuel pump. The fuel pump/sender system is the one area of the vehicle I haven't had to deal with on the car in 4+ years of ownership. It was replaced by the P.O. (by PJ Grady) in 2006 and at that time he used the orange fuel hoses I've heard people are moving away from. He also swapped the accumulator to the dark green one (is that a Hervey part?)

I have replaced the fuel filter twice since ownership. I also did engine tune-up work two winters ago that required the disassembly of the intake manifold. However, after reassembly, despite some cold start hunting, the vehicle has been very reliable on startup without exception - until Sunday.

rothsean - When you lost rest pressure, can you explain the "check valve" repair you made?

[DeLorean03]

My thoughts are your fuel pump is fine. It either works or it doesn't.

While normally an 8 hour sitting time may translate to a cold start, numerous variables play a part on getting the car back to that "cold" start status. With summer weather still in full bloom, your car may have still been in "warm" start mode. Biggest factor - at least to my understanding - is the ambient engine temperature. Basically, if the engine is too warm, it bypasses the cold start system. If it was too warm, it may be that your fuel accumulator is starting to wear out or the O-rings in the primary pressure regulator (within the fuel distributor) may need to be replaced. Best way to determine this is to get your hands (buy) on a set of KJet specific fuel pressure gauges and measure your rest pressure. If your rest pressure is bad, it would be indicative of a warm start issue.

[rundmc]

OK, now I'm frustrated. I tested the vehicle today - Cold start was fine - let the engine warm up for a good while. Then turned it off and waited about 10 minutes. Sure enough, the car would not start. I did the plug swap - putting the WUR grey plug onto the CSV. The car still would not start!

What does that mean??? The CSV works on cold starts for sure!

[Bitsyncmaster]

OK, now I'm frustrated. I tested the vehicle today - Cold start was fine - let the engine warm up for a good while. Then turned it off and waited about 10 minutes. Sure enough, the car would not start. I did the plug swap - putting the WUR grey plug onto the CSV. The car still would not start!

What does that mean??? The CSV works on cold starts for sure!

This makes more sense. It was not that your car sat in the sun for 6 hours, something has failed and now you have the hot start problem. First thing to check is if you're losing rest pressure.

[David T]

This makes more sense. It was not that your car sat in the sun for 6 hours, something has failed and now you have the hot start problem. First thing to check is if you're losing rest pressure.

I have seen many Deloreans start up quite well even with a non-functioning CSV system. Easy to check, you just pull the valve and see if it squirts while cranking when the motor is cold. Oftentimes it is not just 1 problem but a combination of several. If it didn't start with the plug swap it is not necessarily a rest pressure problem (but it *can* be!). How's that for a definitive answer!
David Teitelbaum

[DeLorean03]

I did the plug swap - putting the WUR grey plug onto the CSV. The car still would not start!

What does that mean??? The CSV works on cold starts for sure!

Try pumping your gas pedal (like Marty does near the end of part 1 when it's "time" to go with the alarm clock ringing) when you do the plug swap. I used to be in your boat, and I would pump the gas, and it would help the car start. It may start and run really roughly until you can get back there and put the plugs back on where they go, but it'll at least get you started.

To really diagnose what's going on with your car, you need a set of KJet fuel gauges and measure the rest pressure, just like Bitsync said. Without the gauges, no offense, you're playing hide-n-seek in a pitch black room - pure luck if you catch it.

[DMCMW Dave]

Try pumping your gas pedal (like Marty does near the end of part 1 when it's "time" to go with the alarm clock ringing) when you do the plug swap. I used to be in your boat, and I would pump the gas, and it would help the car start. It may start and run really roughly until you can get back there and put the plugs back on where they go, but it'll at least get you started.

To really diagnose what's going on with your car, you need a set of KJet fuel gauges and measure the rest pressure, just like Bitsync said. Without the gauges, no offense, you're playing hide-n-seek in a pitch black room - pure luck if you catch it.

All pumping the gas pedal does is flap the throttle blades. The benefit is probably the delay you introduce between attempts.

[rothsean]

It may be a bad impulse coil in the distributor.

[rundmc]

I'm starting to wonder if it's the impulse coil or the CSV. Cold starts fire and then die. Take a lot of gas pumping and many starts to get the car to hang on and idle. Will be testing the CSV this week.