fuel pressure issue

[avbcon12]

i am having trouble keeping pressure in m fuel lines after the engine is shut off. i have replaced the fuel pump (190), regulator (kirban), and injectors (24#). and i still lose pressure within an hour and a half after shut off, sometimes sooner.

to check the regulator i put my stock one back on. it does the same thing as the kirban. and before i replaced the pump it did the same thing (stock pump). i dont know about the injectors though. i do know that they are brand new (not eve 200 miles yet). i cant say whether or not it held pressure when the system was stock because i didnt have a guage then.

i dont have gas in the vacuum line in the regulator either.

is the pressure supposed to drop that fast?

if its leaking into the tank (via return line) i really dont care. im just worried about it getting into the block (through injectors). because then it would thin out the oil and cause excess wear...


the last time i changed my oil (first time after rebuild this winter) it smelled like gas. is there a way i can find out if its returning to the tank?

thanks,
adam

[PKRWUD]

90 minutes is considered acceptable. Truthfully, the gauge should not move for 30 minutes after shutting the engine off, and there should be some pressure the following day, but if you are not experiencing a hard start condition, I would not really worry about it. If you really want to isolate the problem, you will need either a pair of fuel line clamps, or vise grips. As you shut off the engine, clamp the fuel supply line, and see what happens. If things improve, then the problem lies in either the pump, or a crack in the hose that the pump feeds inside the tank. If things don't improve, do it again, but clamp the return line. If things get better, you have a problem with your regulator. If they don't get better, it's your injectors.

Take care,
-Chris

[avbcon12]

hmm, thanks Chris. ill do just that...

take care,
adam

[avbcon12]

where is it safe to crimp the lines though? there not just rubber hoses. they have hard plastic linings that i dont really want to take the chance of cracking...

thanks,
adam

[Lethal5Oh]

I have a similiar problem with my 95 only sometimes the pressure will stay but on the next try the pressure will drop to nothing immediatley after shut off. let me know what you find out. maybe it will help with my problem.

[avbcon12]

well this is what i found out so far...

i had to replace the end gaskets on the lower intake because they were leaking oil. so i took the upper intake off and primed the fuel pump. i was looking down the lower intake (cobra) and watching the injectors, no drips. anyway, after watching them for drips while the pressure was still dropping i took the lower intake off, i raised it a good 4 inches and yet again primed the pump (the fuel rails were still intact). now i was watching the actual pintle caps. there was nothing.

after replacing the gaskets on the lower intake (meanwhile the lower intake is completely out of the car) i put it all back together. and now (over night) the pressure has only dropped to 10 PSI (from 38). i dont know what it was, its the strangest thing... but i dont even know if it will stay this good because i havent even run the car yet after replacing the gaskets.

let me know what you guys think.... im still looking for the right answer!

take care,
adam

[jimberg]

Adjustable FPRs tend to leak down because of the way they are designed. Putting back the stock FPR was a good idea, but if it was old, however, it could be defective as well. Mine would leakdown so I replaced it with a Paxton that leakeddown, also. That FPR went bad because of a bad reaction with an additive that I used so I replaced it with a stock replacement. It held pressure just as it should but I wasn't getting enough fuel so I replaced it with a BBK FPR. The new one doesn't hold pressure either.

[avbcon12]

hmm, i guess ill chauk it up to adjustable regulators then...

thanks,
adam