Fuel Pressure Loss

[drenmaster]

I am trying to troubleshoot fuel pressure loss. 1990 Pickup 22RE. Had an LCE engine installed. I'd say 400 miles into the break-in period, it would lose fuel pressure while sitting. So, overnight or after sitting for a few hours, when I try to start, I would have to crank excessively (20-30 seconds) before the engine would run. I started using the diagnostic port to have the fuel pump come on when the key is on for 20-30s to basically prime the line, and the truck starts in 5 seconds or so. Driving, I have zero issues with stutter or anything that seems like a fuel pressure loss. Performance is great once it's started.

The fuel pressure regulator and fuel pump have both been replaced, but I still have the same issues.
Looking for any ideas on the next steps to take.

 

[gnob]

if the pump is indeed good you have leaking injector(s)

 

[drenmaster]

if the pump is indeed good you have leaking injector(s)

Is there any diaginositcs I can do prior to pulling the injectors and replacing the orings? I am assuming that's what needs to be done to fix a leak on them.

There is no signs of fuel leaking, so thats why I am so baffled at this one.

 

[gnob]

you should also verify your fuel pump relay is working properly.

have you actually put a gauge on it to verify pressure is the issue?

 

[drenmaster]

you should also verify your fuel pump relay is working properly.

have you actually put a gauge on it to verify pressure is the issue?

As far as I know, the fuel pump relay is fine. I have swapped it with other relays, and the fuel pump is on when the truck is running, and there are no issues while driving.

A shop was working on it and put a gauge on it to verify pressure loss while it sat overnight. Holds pressure while running, just loses it while it's off. Troubleshooting was getting expensive, so I just took the truck back and will figure this out on my own.

 

[gnob]

if your "shop" can't figure out this simple issue, you need a different shop anyway.

loss of pressure is either an external leak, the check valve in the pump or injectors as mentioned.

regardless the pump should pressurize the system almost immediately even if it is falling off. 30 seconds of cranking is a bit much.

maybe your short hose on the pump or the pump cradle hard tube is leaking.

 

[pappy]

First choice is leaking fuel injectors. BTDT. If you pull the plenum you might see fuel pooling in the runners on the intake manifold. Check this after the engine has sat overnight.

Second choice is fuel pressure regulator, located at the firewall side of the fuel rail.

Third choice is check valve on the fuel pump.

You can get the injectors rebuilt/cleaned, or you can buy new ones. Injector Master, RC Fuel Injection, and Witch Hunter Performance are places that clean injectors. I've used the first two and recommend Injector Master. I was having your problem. He was able to determine that two of my injectors were not able to be cleaned where they would not leak.

 

[drenmaster]

@pappy LCE cleaned and tested the injectors. Fuel pump and FPR have been replaced.

Guess i'll go the injector route next.. I know it's just a oring kit for each injector, other than pooling of fuel any other tips to spot leaks before I remove them?