2001 4.3L Engine.

Engine will not start (easily) when cold. Crank and crank and crank. When you let off of the key while starting, the engine will jump and try to run. If you immediately re-engage the starter, SOMETIMES you can catch it right and the engine will run. It will then run okay, but often with some surging for about 10 minutes until the engine is warm.

We've replaced fuel filter, and fuel pump assembly. Garage reports that the system is holding pressure, and that the off and running pressures are within tolerance (of course they were testing when the engine was warm).

I've looked at the 96+ fuel guide sticky--and have concluded it could be the fuel pressure regulator.

I've also looked at the 98+ electrical guide sticky. Garage said we had good spark at the plug wires. Plug wires, plugs, d-cap were all replaced less than 60 days ago. In step 2 it says if you have spark to check for intermittent problem--how do I do this?

This is frustrating and has killed one battery from cranking so much thus far. Garage insisted it was fuel pump (as the initial pressure readings were low). However, a significant time and money investment later, we're still stuck with the same problem.

I also see that a pulse signal is sent if the engine is running or cranking to tell the VCM to energize the fuel pump. What sensors originate this pulse signal? Could I have a sensor not telling the engine to start when it's cranking? This doesn't make sense, as the engine starts fine when it's warm.

Any advice would be greatly appreciated!

Thanks in advance,

Ryan

 

Purchased and installed a new fuel pressure regulator today. Also removed EGR valve and gave it a good cleaning.

First cold start was instant--no problems! Fuel pressure was about 65psig when turning the key on--and the engine running pressure was about 55psig. Hopefully my problems are solved.

However, it looked as if the system was losing pressure quite quickly after turning off the pump. I'm going to search around and see what values I should expect, and remmedies (consider we now have a new fuel pump assembly, new fuel pressure regulator and fuel filter). Seemed to be leaking about 1 to 2 psig per second until around 28 to 30 where it dropped only 1/2psig or so every couple of minutes.

Could this be a leaky injector? Should I consider converting to the MFI system.

Any comments/opinions/advice?

Thanks,

-Ryan