how do you know when a fuel pump's going bad?

[cooljayc]

I have a 97 formula. which is sputtering bad and gets worse as I press the gas. I'm almost sure its sputtering and not missing. any help is aperciated

[raroZ28]

when my pump died the car ran fine. Parked it, and started it the next morning and it stalled. Wouldn't start back up. Pump was dead. A weak fuel pump might make it sputter... Only way to tell is to check your fuel pressure with a gauge.

[xxRillixx]

sounds like it could be... i would check the fuel pressure first. At idle, driving, and WOT. The 97 has... i think its LT1, and should be between 37-43 psi. You should also change your fuel filter if you havent in the last 30-50k miles (prob wont fix it, but its a good idea to... pretty easy and inexpensive). Then I would also check the Fuel Pressure Regulator. If you can, check the psi coming from the pump before it gets to the FPR, should be like 60-100. If its only pushing like 10-40, its the pump.

... ill start looking for the web page i used, so you can do it w/out dropping the tank... Pretty easy.

[19Z2894]

I just crossed over from the Dark side (Ford) and this sounds like a common problem we had with mustangs. Check to see if the wires on the mass air flow sensor are clean.

[cooljayc]

tryed new filter. same thing. haven't check presure yet.

[xxRillixx]

next i would check pressure. Fuel pump problems are common w/ gm. http://www.geocities.com/formulapower2/fuelpump.html

Also, i would recommend going for the GM replacement if it is your fuel pump. Ive been through 2 Walbros in 4 months, never did run right (no warranty, but some people swear by them). Finally went w/ the Gm replacement... its been great for the last 3-4 months (1 year warranty).

[RyanB58]

Mine sputtered bad just like yours but it never quit running. The next morning it just plain wouldn't start. I would bet it is your fuel pump but do a pressure check to be sure.

[cooljayc]

ok I checked pressure at the fuel rail and got about 40psi. car starts but stalls out. Not sure how to check pressure before before the regulator.

[cooljayc]

fbut if the pressure is at 40 psi which is fine according to what you say then. the pump and the regulator should be fine right? because I checked at the fuel rail

[xxRillixx]

yea sounds ok. what does it test at when you prime it? and can you test it while driving?

[xxRillixx]

when it stalls, what happens to the FP? it stayes at 40psi? what happens when you rev?

[cooljayc]

Prime? didn't know you could prime these cars tell me more. when I rev the fp stays the same

[Dave M]

I'm not 100% sure, but when he says prime I think he's referring to when you just turn the key "on" without starting the engine, the FP runs for about 2 seconds to prime the system, build pressure.. You should be able to hear it running when you turn the key "on".

[Joe 1320]

If you suspect fuel pressure, you need to have a gauge with a long enough hose so that you can attach the gauge to the windshield wiper so that it can be viewed from the driver's seat while driving. Go WOT and see if pressure drops.

On another note, being almost sure is like almost winning the race. A scanner is going to help diagnose what is actually going on. Often times these same symptoms come from the ignition system starting to fail. How many miles? When was the last tune up? etc....

[cooljayc]

vac hoses

are there any vac hoses that would make my car rev up and down. from like 900 down to 450-500 up to 1200. and the cycle repeats its itself