momomo

The car will start up, take a long time to start sometimes, then start. It will run for a few minutes and then it will just cut off out of no where. I can be driving, my foot probably half throttle on the freeway, I can feel the car stop and it will have no gas to it at all, and then randomly catches back on and speeds up again. It feels like the car shut off, and then randomly catches. It stalled multiple times on my way to work today, the only was I was able to get it to even start was spraying starter fluid. With out that it just keeps cranking but wont turn over. It would start and stall after a while. When the car is on, it runs beautiful. Idle is always perfect. I've replaced the wires, distributer cap, plugs, fixed all vacuum leaks, cleaned the MAF, replaced the fuel pressure regulator, fuel pump, whole fuel system, and more. But, when I took it to a different mechanic, he noticed and told me that the old mechanic replaced the fuel pump(trap door), but not the housing on it. Could that be caused by this? Some days it'll run nice, other days it'll stall all the time. What else should I check for? (update) Now it wont turn over even if I use the starter fluid. All it does is crank like it wants to turn over and start, but doesn't.

Injuneer

Basic checks - scan the PCM, check the fuel pressure. In particular, check for rapid fuel pressure drop after the pump primes and shuts off.

momomo

Did a scan, no codes. Fuel pressure is good.

Injuneer

Just to clarify what you mean by "good".... it primes to at least 40psi, does not lose pressure rapidly, and holds at least 40psi while trying to start the engine?

No problem using the old fuel pump bucket. If there was a problem, it would show up as low fuel pressure. As would a dirty sock on the pump inlet.

What is the system voltage, as indicated on the dash gauge, while cranking the enigne?

Is the engine modified in any way?

momomo

I'll double check the fuel pressure today i believe it was holding at around 37 psi. I have a stock lt1 racing cam and some bolt ons here and there. The voltage usually at a cold start is above the half way mark, regardless i do have a new battery and alternator.

momomo

Also i did just install the cap and rotor. So im gonna check to make sure those parts are good and installed properly. After i installed the parts i ran the car really hard. And that same night pulling into my drive way it stalled. But after i installed the parts the car was running flawlessly the whole time.

momomo

One more question, I have now confirmed that when the fuel pump was replaced, the housing was not. Can this cause any symptoms?

Injuneer

Not sure if you are actually reading our posts... or if you mean something other than the bucket which encases the pump. That is the only "housing".... unless you mean the fuel sending unit skeleton frame, which is not a housing. Either way, not the cause of the problem.

When you replaced the Opti rotor, did you loc-tite the rotor screws?

momomo

I did. I'll keep you updated on what happens when i take the cap off. Im also going to try and clean my MAF. See if that helps.

momomo

So on a weird note, my car is now saying its at 30 psi during idle. Keep in mind, new fuel pump, injectors, o-rings, fuel lines. What else could it be.

Injuneer

Is the 30psi with or without the vacuum compensation line hooked up to the pressure regulator? Without the vacuum line, that's about 10 psi too low. With vacuum line hooked up, that's only a few psi low.

What brand pump? From eBay?

Faulty fuel pressure regulator.

Leak in a line, particularly the flex line from the pump, in the tank.

Clogged fuel filter.

momomo

Turns out the jack that installed my fuel pump, installed the wrong one. So i bought one and installed it myself, my fuel pressure is perfect. Turns out i needed an opti. The only thing i haven't replaced in the car lol. Im getting the opti put in as we speak. Ill keep you guys updated in case this happens to any one else. Thanks for your help, i really appreciate it.

Injuneer

Hopefully you bought an AC Delco or Delphi Opti. And hopefully the person installing it knows how to index it correctly.

A faulty optical cam position sensor in the Opti should have set one or two codes. Odd they didn't show up in your scan. And odd that the wrong fuel pump gave you "good" results, at least initially.

momomo

I got an AC delco, i printed out the diagram for the proper order. The wrong fuel pump gave me bad results, when i bought the right one, it fixed my fuel issue.

Injuneer

Do you understand the frustration here? It's very difficult to help, when the story changes.