Hey guys, I’m hoping to get a little guidance. I have a 90 pickup 4x4 3vze manual with EGR delete. It was running really well for the better part of a year. Started fine, good idle, good gas mileage. Then in a cold morning last winter I ran it for five minutes or so, shut it off for five min, then couldn’t start it again. I let it sit and tried to start it the following day when it was warmer. It cranked a bit but fired up.

I assumed it was a problem with the cold start injector. I’ve had problems with the wiring. I replaced the connector and wiring, but they would work their way loose inside the connector from time to time. So I made sure they were connected properly and the truck started fine for a couple of months. Then it started getting hard to start from time to time, but it was happening when the engine was warm. Fired right up when it was cold. Finally it just refused to start at all when warm and was very hard to start wvwn when it had cooled down. So, hmm, maybe not the CSI, or not only the CSI.

When it wouldn’t start, it also threw an error code. Lean fuel condition. That pointed me to fuel. I’ve been working my way through the FSM, testing the EFI components after confirmed I have spark, and no air or vacuum leaks. The CSI tests fine for resistance. It runs when it should, the fuel volume is within specs, and it’s not leaking. The plugs are NOT wet after cranking it for a while trying to start it. I checked the fuel pressure with the engine off, fuel pump running and while it was idling. Pressure was within spec. But, after shutting the engine off I noticed that the fuel pressure bled down faster than it should. It was below 20 psi in about one minute instead of five minutes the FSM said it should take. So I’m guessing a pressure leak somewhere.

I don’t see any signs of a fuel leak. There’s no gas odor. The fuel injectors are al remanufactured as of two years ago (they’ve run about 5,000 miles total). The pressure regulator was replaced with OEM at the same time, the fuel rails were cleaned and most of the fuel lines were replaced. The FSM tells me to check the fuel pump, pressure regulator or injectors.

The TPS is tested and within spec. The timing is correct at 10 degrees before TDC. The oxygen sensor was replaced about two years ago as well, and the engine is a reman with about 5,000 miles on it. The coolant is topped off and the system was thoroughly burped about a year ago. The plugs and cables were replaced recently

Before I start tearing things apart, I wanted to see if there are any suggestions about where to start. Is the dropping fuel pressure after the engine stops a serious enough issue to cause hard starts? Things were gradually deteriorating for a few months instead of a sudden failure, so it feels to me like something is wearing out instead of a sudden failure. Could it be a problem with the fuel pump even though I get good pressure from it? Is the only answer to tear it down and test all the parts one by one?

I’m done for the night. I’ll check in tomorrow before I take the plenum off and start working on pulling the fuel injectors. Thanks in advance for any suggestions.