Fuel Pressure

[usp55]

My car has a hard time starting and i want to test the fuel pressure but im not sure how. Where can i get the gauge? I found this on ebay , will it do the job? and where does this conect to my fuelline? The schrader valve? Also what numbers should i be looking for at pump prime? idle? highway? Thanks (94 3.4L)

[sweetbmxrider]

that looks like an ok kit and should fit. you screw a fuel pressure gauge onto the shrader valve on the fuel rail. i would go to an auto parts store though, easier to get what you need and return if necessary. i don't know the numbers for fuel pressure though, i'll look it up at work tomorrow if no one replies with it. i may be incorrect, but the pressure should stay consistent no matter what your engine speed is.

[usp55]

Yea that kit is just a reference. I go to AutoZone tomorrow and pick one up. I found info the Chevy recommends pressure b/w 41-47 acceptable. Someone posted that on another forum but they were talking about a 98ss.

[sweetbmxrider]

i would pick up carb clean and spray the throttle plates. just a little carbon will ef it up. when you spray it, try to have a towel in there to soak the crap up. it will run rough/not start at first but that is normal cuz its flooded. update tomorrow on how its going. those 3.4l's always suck when its cold. mine would hesitate real bad when i initially stepped on the gas in drive. it was just a split second then it was fine. idled fine too. never fixed it though, bought a z28 instead.

[usp55]

ill see what i can do tomorrow - class all morning but i should find time after. I had this random hard starting for a while now both before and after i got the engine rebuilt and in both the summer and now the winter. I assuming its the fuel pump but im in denial. Changed the fuel filter 2 weeks ago and no change.Two hard cranks after it sits for a while (overnight - sometimes 3) if i was running and lets say i went into the store and turned it back on 15-30min later it will start right up most times. I can clearly hear the pump prime so its not the relay.

Ill see what the pressure is tomorrow.

[Tru2Chevy]

Since you hear the pump prime when you turn the key, try turning the key partway, and letting the pump prime (should run for a couple seconds, then stop). Then turn the key all the way and start the car. If it fires right up then, your most likely problem is pressure bleeding out of the system while it sits. If it still hesitates, then the issue probably lies somewhere else.

- Justin

[usp55]

yea ill trun the key, hear the pump prime, wait a sec or two the trun the key all the way. The engine turns over and does not start the first time. Ill do it again ( fuel pump does not prime a second time unless i wait a good bit) trun all the way and still a hard crank - the oil pressure jump up to about 10psi and the engine starts up.

[usp55]

Ok got a pressure test kit today and got this:

At pump prime = 9PSI and dropped to ZERO!
At idle = 33PSI steady

Im pretty sure these are both completely unacceptable readings for a healthy running car. Where do I start?

[Fast92RS]

Sounds like your pump is going but I would also check your FP regulator first since its easier to get to.

[usp55]

yea i was just reading posts of fpr problems and i might look into changing that firsts then if it does not help ill do the pump. How hard is it to change the FPR? its on a 3.4l (where exactly is that even located?)