LB7: Hard start issue fuel rated.

[Righteyeblind]

I have been chasing this issue for over a month now. My fiancee has a 03 LB7 68k miles, unmolested truck. It started getting a hard start about a month ago. I changed out the glow plugs and glow plug relay because it was getting a P0320 code. The code went away and still hard start. I though that I had an airleak somewhere so I changed the filter head with a known good one. Still no fix.
I logged the fuel pressure commanded 23k and only got 18k. I also logged it while cranking and it went real slow to 1700 psi and the fired. So I changed the fuel filter and it fired right up. No issues for 3 days and then it was back to no start or long crank before start. Changed the fuel filter two more times thinking she had got bad fuel.
She got a new tank of fuel again and I changed the filter on Sunday. Yesterday it was taking 3 crank cycles to start. It wont make enough rail psi to start.
All in all everytime it wasnt starting I put in a new filter. I put 4 new filters in it and Im still back to square one. Anyone have any ideas?

 

[Chevy1925]

collapsing rubber fuel line somewhere?

 

[Stingpuller]

Pressure

If it won't make pressure at idle it's the pump or injectors returning to much. Do a return test and you will know. Jeff

 

[BlkMax]

The last time mine was doing something like that, I had a bad FPR and some bad injectors.

The cold weather does not help things......:roflmao:

 

[Righteyeblind]

If it won't make pressure at idle it's the pump or injectors returning to much. Do a return test and you will know. Jeff

It will make pressure at idle once its fired. It just wont make the pressure to start it. Next is return rate test. PITA

 

[Righteyeblind]

collapsing rubber fuel line somewhere?

The problem goes away once I put a filter in there though. Then it does good for 3 days and then it shits the bed.

 

[Dan2289]

mine was doin the same thing, would have to change filter to get it to start. wont start with the key now. have to roll it off all the time, have to try the key first or it wont. then it drives like nothins wong. scaner siad it all good.

 

[RPM Motorsports]

Somebody's putting water in your tank

 

[sweetdiesel]

If it won't make pressure at idle it's the pump or injectors returning to much. Do a return test and you will know. Jeff

X2 but if it does and takes some time to do so its a supply issue


IIRC its 8000 to start but ive again IIRC got it at 6000 ish+ and it started

you also need a certain amperage to start so maybe check the batteries? You can log all of that with EFI....( Very nice)

Perhaps one of the supply lines has a leak and is letting air into the system?

Since the truck doesnt have a lift pump i would hook a gauge that shows vac/air to the GM test port.

but first i would check like Jeff said

 

[jlawles2]

Long shot here, but try anti-gel. Could be that the local supplier is saying that you are getting #1 blend for cold weather but it is not blended for the temps you are getting.

Filter is one of the first places fuel gels from what I have read. Even though there is a heater in the filter head. Check power to the filter head heater to see if it is on in the cold weather.

 

[24vchevy]

I have a customer truck doing thesame thing. He has already replaced the Cp pump ag the dealer and it got better but still a long crank. I scanned it and it takes along te to build rail pressure. Injector balance rate is also good. I think that it still may be the injectors leaking back. Going to do a return test and see if that is out to lunch.


Malcolm