ok, so I have a 1961 F-100 with an original 292. Yesterday, all of a sudden, it bogs under load. As soon as I hit the gas, it bogs and is almost impossible to keep moving. It had an aftermarket, clear fuel filter that was a little dirty, but also looked mostly empty. The truck would idle like a champ and I could see a little flow in the filter, but not what I would expect to see. When I disconnected the fuel line not a drop of fuel came out. I replaced the line all the way back to about six inches from the fitting on the bottom of the tank. Again, when cut the line didn't have a drop. Once all connected with a new filter it started right up and idled fine. Fuel started flowing (slowly). Again, it would not run under load. The fuel flow was minimal at best.

2 questions

Does the tank have a vacuum activated valve in it and do you think it may just be the fuel pump is ready to completely die?

Thanks in advance for any insight.

 

No valve, but the tank might have some crud in it. Rust, scale, etc.


Every time I disconnect the fuel line anywhere between the tank and pump I've got gas all over the place, which makes me think your tank line is plugged possibly.


Sometimes you can at least temporarily get a flow going by blowing compressed air back into the tank through the fuel line. Make sure you remove the gas cap first. This blows any possible crud back out of the lines and into the tank where it came from.


Also, make sure your gas cap is vented properly.


Some of the fuel pumps have a filter built in inside of a canister, either metal or glass typically. People often forget there is one and it can get plugged up with crud and slow the flow to a trickle, too. But to me, that would be secondary to getting a good syphon flow out of the tank first.




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Thanks! I tried blowing air with an air gun back through the line, but got nothing. It was a nozzle with 75 psi behind it. That is what precipitated the valve question.

I will try to get it to at least gravity flow before replacing any more parts.

 

Not really, it's been 54 years.

Sent from a pay phone

 

HA! True... and I am glad someone still has pay phones

 

Don't forget to replace that hank of rubber hose and the clamps under the cab, it connects hard line from the cab to hard line that continues along the frame rail.

Sent from a pay phone

 

ok so maybe not all original... Under the cab is a brass 90 with a flare fitting to tube. Perhaps the clog is in the 90 and I just need to clear that out....

I can shine a light into the filler tube and see that the tank is pristine. Not sure what kind of junk could be in there.

 

OK, so I am not sure what was blocking the line, but it cleared out and runs great now.

When I got it to flow the gas that came out for a few seconds was cloudy and the only way I had to dispose of it was to burn it. It smelled really foul. I have never come across that before.

 

Good! How'd ya get it unblocked? Sounds like it had spoiled and turned to paint/varnish.