TBI to Carb swap, thumping in the tank?
05-04-2011, 06:22 PM
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Car: Bone stock 1989 Iroc T-Top,1991 Z28
Engine: 5.7, Carbed 383
Transmission: 700r4, T-56
TBI to Carb swap, thumping in the tank?
Mallory AFPR set to 6 PSI at the fuel log. After about 3 or 4 seconds of pump running(key on,no start) I hear a thumping,tapping,banging in the tank. Any ideas? Pump bad? I have a new Walbro 255 that I can swap.
05-04-2011, 09:53 PM
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Car: 1992 RS
Engine: Carbed 350
Transmission: 700R4
Axle/Gears: 3.42 posi
Re: TBI to Carb swap, thumping in the tank?
It's just the pump running through the restriction of the regulator - ahppens on mine as well until the car is running - like if I have the key to on but not started car yet, it makes that noise because ALL the fuel is being returned rather tha being used. No problem - just the pump 'thumping' since the regulator is reducing the pressure to less than 1/2 of what it used to be. When you start car and run it, fuel is getting used, and thus it will not make that noise.
Depending on your carb, you need to adjust lower psi - Edelbrock needs 5.5 or under, some Holleys want even less psi.
Depending on your carb, you need to adjust lower psi - Edelbrock needs 5.5 or under, some Holleys want even less psi.
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