Fuel Systems Issues

[skiziks]

Well this has be causing me issues for a while!

I have a '69 F-100 that I have swapped the 240 for a newly rebuilt 302. The engine ran like a champ on the run stand and is fully broken in but now that it is in the truck it is running like crap.

After blowing all the lines out with compressed air I decided to pull the fuel tank out of the truck.

The tank was fully flushed it out and it does not look bad inside at all.

After putting it back in the truck the problems have continued. I have mounted an electric fuel pump on the frame rail below the fuel tank.

Now there is no problem with the electric fuel pump taking fuel out of a gas can and pushing it forward to the carb. The problem is if I hook it up to steel fuel line that pulls from the tank but it will not pull anything.

The tank has about 7 gallons of gas in it so that is not the issue.

I am pulling my hair out trying to fugue out what the heck I need to try next.

Anyone have any ideas?

Thanks in advance!

Larry

[Twisted_Steel]

I'm assuming it is a carbed 302 and it is the 5-7psi fuel pump. If you've blown out all the lines and found no blockages, your next step may be to pull the line loose at the carb and put the line into a jug. Turn on the switch to operate the fuel pump and check for flow. If nothing happens, remove the gas cap and try again. If all that fails, you'll need to prime the pump to get a good vacuum pull in order to get your fuel up and out of the tank and down to the frame rail.
I hope that helps. Good luck

[Twisted_Steel]

Forgot to say.. you may have to get a vented gas cap if you keep losing prime at the pump

[tsherry]

Have you changed all the rubber lines between the tank and the pump? (I've posted this about a dozen times, but it's worth looking at).

Most fuel lines have an inner and outer tube, with a nylon reinforcing mesh between. Gas (especially new ethanol gas) can cause the inner rubber to separate from the nylon. Under suction, the inner liner can suck shut. At idle, might run fine, under increased demand though, closes up and starves the engine.

I've had this happen three times or so, on my '66 Mustang, my '67 -250, and on a Falcon or two.