Lately I have benn noticing that on start up, the car will start, then it will bounce around the RPM's for a while. I then hear a sucking noiece, like fuel. Sometimes when it is cold, I also get a BIG hesitation. My dad thinks its the carbrauter, but I think it is the fuel pump. What is it? And how much does this cost to get fixed?



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1991 Pontiac Firebird
51k Miles
T-Tops
Fire Engine Red
305 TBI

 

How about a vacuum leak?

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1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley module, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Streetdampr, Ruger P95DC, hot wife, new oil filter, !cats, !TBC, !AIR.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

91,

#1. Jethro identified a solid possibility. Check the PCV, brake booster, tbi mounting bolts, intake bolts, and all hoses;

#2. You should also hear a muffled "sucking noise" when starting a cold engine due to the extra air being admitted by the IAC. The target idle for a cold engine is much higher than for a warm engine, due the IAC should be open wider. If you have an open element air cleaner, or have removed the air cleaner for diagnosis, the sound will be very apparent;

#3. Tell your father that there is no carburetor, only a TBI220 injector/throttle body;

#4. Don't be too quick to condemn a fuel pump. Typically, a failing pump will cause low pressure, and TBI units tend to run very rich at idle with low fuel pressure, not lean as you would expect. If you smell a lot of unburned fuel at cold idle, you may have a fuel pressure problem;

#5. Even if you do suspect the pump, you should test the pressure first, rahter than just throw money at parts unnecessarily. Fuel pressure at idle should be at 11-13 PSIG. And if it is low, replace the fuel filter before you replace the pump. If you haven't replaced the filter within the last 24,000 miles, you are overdue anyway.

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Later,
Vader
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Justice and Freedom will Prevail

[This message has been edited by Vader (edited September 29, 2001).]

 

Alright, thanks. Where is the PCV valve located? It is getting me mad because the car sometimes stalls out on start up, because the RPM's aren't high enough. That sucking noise sounded like it was coming from the engine, but the fuel pump is in the tank. I found a mechanic that would install it for $75, which isn't that bad. How long do these pumps usually last? Also, the hesitation is getting longer and more frequent. I also replaced the fuel filter, air filter, and plugs about 2 months ago.



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1991 Pontiac Firebird
51k Miles
T-Tops
Fire Engine Red
305 TBI

 

The PCV valve is toward the front of the left rocker cover, right through the top of the cover. Check the valve for sticking and cleanliness, and inspect the hose for splits, cracks, holes, deterioration, etc.

My fuel pump has lasted 16 years and still holds well over stock fuel pressure (as long as the filter is clean).

------------------
Later,
Vader
------------------
Justice and Freedom will Prevail