Using fuel pump to empty tank

[raccoon]

There's a siphon port?

yup white vent looking like thing at the top rear of the tank.

[turboshad]

Ok, so I made a hose with a -6/hose barb fitting and then undid the line at the filter on my fender and pumped it into a can. While it was pumping the fuel would come in waves in a pulsing fashion. Is this normal? I expected it to be a steady flow but maybe I was wrong.

[turboshad]

Well after tuning and finding out I was short on fuel I decided to put in the 1200cc injectors. To make sure they didn't leak I figured I would crank up the fuel pressure and low and behold the darn pump wouldn't go past 60 psi and it eventually popped the fuse. I've been meaning to rewire the thing for a while and I guess I should have sooner than later. Wired it up with some 8Ga and it was like a new pump. Probably why I was running out of injector too. I'll see when I pump out the race fuel if it still surges or if that was the problem.

[4 l-bodies]

Ok, so I made a hose with a -6/hose barb fitting and then undid the line at the filter on my fender and pumped it into a can. While it was pumping the fuel would come in waves in a pulsing fashion. Is this normal? I expected it to be a steady flow but maybe I was wrong.

DJ,
Since I have been doing this for 20+ years this same exact way, I can tell you you are probably sucking air if you are getting a pulsing or foaming fuel. Mine always comes out clear and steady until I get very low on fuel. So to answer your question, no it's not normal. Your logic is sound, your fuel system is not.
I discovered I had a pump that was sucking in some air by noticing it would be foamy after it got below 1/2 tank. Dropped the tank and sure enough found the problem. Another possibility is if you have an electrical issue or had a battery that wasn't real strong. You can always put a charger on the battery and repeat the test if you suspect a electrical issue.
Good luck,
Todd

[86Shelby]

How are you guys jumping the fuel pump? I've always let the car idle and used the return line.

I have sat and let the car idle with the return line disconnected, but it takes quite a long time. On the R/T I simply turned the ignition on and jumped the ASD relay with a spare piece of wire.

I really like Todd's idea of having a long jumper harness. That sounds like it would be the hot ticket on an Lbody where the pump is easily accessible.

[Turbo3Iroc]

I have sat and let the car idle with the return line disconnected, but it takes quite a long time. On the R/T I simply turned the ignition on and jumped the ASD relay with a spare piece of wire.

I really like Todd's idea of having a long jumper harness. That sounds like it would be the hot ticket on an Lbody where the pump is easily accessible.

When I have had to drian fuel it hasn't ever been more than a few gallons. For a whole tank I would have been looking into something like this. Nice to know, I may try it for grins pretty soon since it it a lot more difficult on my car to get the return line off with the AN stuff. Just a placement thing.

[turboshad]

With my concern of the pulsing fuel when emptying the tank I pulled the pump today to take a look. I found that the pump will suck air if the canister doesn't have enough fuel in it. So when I disconnect the return line the canister doesn't stay full of fuel when the level gets lower. It does sort of "drain" fuel from the tank into the cansiter but it will only ever be as high as the tank level and the pump doesn't pull fuel through the in-tank filter off the bottom like the older ones do. I don't know how excited I am about that and it makes me want to upgrage the fuel system even more. I don't think it is an issue when the return is hooked up but the more fuel you use at the engine the less will return to keep the canister full. I couldn't see a good work around for the design. Any thoughts on it or has anyone found it to be a problem in higher HP builds?