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Bad Fuel Pump?

RonJones

Contributor
Full Member
Joined
Jun 30, 2001
Messages
347
Tried firing up my 302 today. In pieces for 5 years, the bronco has a new metal fuel line, electric fuel source selector, and engine driven fuel pump. I put in 5 gals of gas into the main tank, and diverted the fuel flow before the inline carb fuel filter into a bucket, as I wanted to clear the lines of any debris. I tried about five 15 seconds of starter cranking, but no bucket fuel. So, I tried the old gas in the carb intake trick. The engine started right up, and ran for a few seconds. Did that a half-dozen times, but still no fuel.

Under the bronco I went, and found a slightly loose fitting near the tank, which was tightened. I was able to easily suck fuel before the fuel select valve, and past that up to the fuel pump inlet hose. I hooked a long hose to the fuel pump; no appreciable suction at engine crank speed, but some suction when the engine revs up with a poured gas start.

Shouldn’t I be getting suction at engine crank speed?

Thx!
 

EPB72

Contributor
Bronco Guru
Joined
Jul 13, 2019
Messages
1,208
Loc.
Pleasant Hill, CA
If you put a vacuum gauge on the inlet side of fuel pump and crank engine you should see steady or slight fluctuation around 6 to 8 inches,,if weak or fluctuations drop back down to zero then theres pump issues..
 
OP
OP
R

RonJones

Contributor
Full Member
Joined
Jun 30, 2001
Messages
347
Defective Fuel Selector Switch - sucking air:
 

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