Doesn't restart when hot

[konacat]

I have been having an intermittent problem starting my 2002 duramax. The problem occurs when the engine is at operating temperature and the engine is turned off it doesn’t want to start again. It will normally start in an hour or more when it seems the engine is cooler. When running it doesn’t exhibit any problems at all. There is no excessive smoking, no ruff idle, no stalling. Everything seems fine until it’s turned off and then it won’t start. The fuel filter has been replaced and is good.
While out of town I took it to a GMC truck location and they said I should replace all the injectors because when hot it would not hold pressure. They couldn’t do the work in time as I had to be back home for work. I then took it to the dealership that I purchased the truck from and they didn’t seem that swift. Although I explained what the other dealer said they had their own idea. They wanted to replace the expensive air flow senor except I convinced them that it runs fine when running. They ended up replacing the injector pump and it seemed to be running ok but then soon started the same problem. I had them replace my glow plugs (knew I had some out) and while working on it they say they found a water hose/pipe that needed to be replaced. I said go ahead only to find out later its up high in the front of the engine and together it ended up costing me about $900.00 (pump was under warrantee).
My feelings are to go and demand that they replace the injectors while I’m still under warrantee. By the way the truck has about 90,000 miles on it.
I would be happy to accept your comments or suggestions.
Regards,
Philip

[DieselMonk]

I put my money on the injectors. They must leak / bypass fuel. Cold fuel is more viscous that hot fuel, so engine starts better when cold. When the fuel is hot, the injector doesn't have enough fuel pressure, cause it's leaking by, so a no start occours.

[Spoolmak]

Have never had this happen on my diesels (duramax in truck and Universal on boat) but have had the identical problem several times on fuel injected gas cars. In all cases it was a defective pressure valve in the fuel pumps or the fuel injection rail, which allowed high pressure fuel to 'leak back' to the tank thus not providing enough pressure for injectors to work - but only on hot start up. If the cars sat for half an hour or more, there was no problem starting. A fuel pressure valve 'Teed" into the high pressure side romped down to zero pounds per inch within a few seconds of shut down. I believe when the system is hot, the fuel is very volatile, and the pump simply could not pressure the system enough for injectors to work properly to start the engine. Replacement of the defective pump or pressure regulator immediately cured the problem.
Don't know how this phenomenon might apply in a diesel engine. Is there a pressure valve in the high pressure pump? Lift pump? Fuel Rail? Could one or more leaking injectors cause the same thing?? Seems to me, properly functioning pumps ought to be able to overcome the pressure loss of a leaking injector.
Thought I'd share this experience with our 'gassers'. Look forward to hearing from you diesel experts.

[More Power]

They can measure "commanded" and "actual" fuel rail pressures during the starting and run phases. This is where I'd start the troubleshooting process as long as the cranking speed was normal.

Jim

[Frank Alexander]

Your injectors have a 7 year, 200,000 mile warranty. You can bet it is the injectors bypassing fuel. I was down 49 days last Summer with this issue. Dealer replaced the fuel pump ($3,200.00) It was not the pump, it was the injectors. Insist on all eight being replaced! The injector pump does not have a transfer pump built in. When the fuel is warm it is thinner.

[DmaxMaverick]

......The injector pump does not have a transfer pump built in......

It does. But the fuel circuit between the low pressure lift pump and high pressure pump does not leave the pump housing.

[hrsedrvr]

i just went through the same thing i have a 2001 which was'nt starting hot after about a half hour it would
i had it back a few times to where i had got it from a private dealer
they tried a few little things, fuel filter, fuel conditioner, etc.
nothing was working the last was same as you the mass air flow sensor which they said was $500.00 and they said i had to buy the part
i knew that was'nt it because it ran fine when it got going
i finally just took it from them and to the dealer
i know 2 mechanics at the dealer so i knew they would'nt jerk me around
sure enough it was injectors leaking back
good news was i found the problem, bad news was the cost!
they started at $4600.00 plus tax (13%) so i cried at my buddies and they dropped to $3500.00 plus tax for a complete injector job so i thought this was pretty fair.
now i just have to go back to where i got it and fight with them to cover some of the cost, good luck eh!!
anyway i just had to get it fixed and a lawyer will probably want more than the fix cost to fight with them but at least it will be fixed

[DealerDieselGuy]

Your injectors have a 7 year, 200,000 mile warranty. You can bet it is the injectors bypassing fuel. I was down 49 days last Summer with this issue. Dealer replaced the fuel pump ($3,200.00) It was not the pump, it was the injectors. Insist on all eight being replaced! The injector pump does not have a transfer pump built in. When the fuel is warm it is thinner.


I beg to differ with you about this, but the injectors do NOT have a blanket 7 year 200,000 mile warranty on them. They DO however have a special policy that only covers them for that time period if the injector(s) fail due to ball-seat cracks. If the injector fails say for an electrical issue, than only the standard 3 year/100,000 mile Diesel powertrain warranty will be in effect.

[DmaxMaverick]

I beg to differ with you about this, but the injectors do NOT have a blanket 7 year 200,000 mile warranty on them. They DO however have a special policy that only covers them for that time period if the injector(s) fail due to ball-seat cracks. If the injector fails say for an electrical issue, than only the standard 3 year/100,000 mile Diesel powertrain warranty will be in effect.

You should review the special policy. Ball seat erosion is among several failure possibilities covered. True, it isn't a "blanket" policy, but covers more than one type of failure. The injectors don't fail from "ball seat cracks". Other parts of the injector may crack, which are also covered by the special policy.