Hey guys,

I have an 02 Express 3/4 w/ a gas v8. I bought it for dirt cheap from a kid who couldn't get it running and had done a poor man's camper conversion. I replaced the distributor and battery and it started up. Gas was super old. I didn't have a place to dump it. I swapped plugs, idle air control valve, and ended up filling it up with regular gas and some seafoam. The only code I get is a p0300. The vehicle starts and sounds fine, but I'm betting the seafoam fouled the plugs.

Anyways, it starts up right away. No issue. It doesn't matter if I run it for a minute or an hour, when I turn it off, it won't start back up without giving it some throttle for a few minutes or letting it sit for a few hours. I checked the fuel pressure and it stays around 60. If I turn it off, the pressure does slowly drop, but if the pump is on, it sits at 60.

Does anyone have a recommendation on where I should start troubleshooting? Guessing the plugs, but would love to hear your input. New to the platform.

 

Good idea to check the plugs for sure (visually verify spark)
but fuel injectors are affected by temperature so measure the resistance on those.
Water in the fuel can produce your symptoms too. If so then change the filter.
The system should hold fuel pressure within 5psi over a minute, and within 10psi running.

 

If you have a scan tool with live data I would look at that for anything odd. Just as an example a failed coolant temp sensor can cause a no-start when the engine is warm because when shorted out it tells the computer it's -68F or some absurdly cold temperature. But it won't set a code.

I would try a blast of start fluid when it won't re-start. You want to rule out a stuck fuel pressure regulator. The way these work on this engine if they fail you can have 60 PSI but it just goes back to the tank instead of to the injectors.

But all you can do is start with the basics, is it getting spark, is it getting fuel, is it getting enough fuel, is it getting spark at the right time.

 

I hesitate to suggest starting fluid because,,,,,,,,,,,,most folks have no idea how much is too much and have seen where pistons had holes in them, had tops blown off and other damage. Just as most folks don't have starting fluid or carb or choke cleaner, If they are going to use anything , carb and choke cleaner is closer to gasoline and won't do much if any damage.

 

Sounds like the injectors could be leaking down after shutoff.