Fuel Delivery ???? Gas tank issue

[chopnchaneled]

Just recently got my 68 stepper on the road and everything was going great untill sat, evening when it quit running.

A little back ground on it:
I installed a late model 350 engine that does not have provisions for a mechanical fuel pump. Installed a electric pump on the frame rail as close
to the tank as i could, have put several 50 plus mile trips on it since.

When it quit could hear the pump running like it had no gas, the see thur filter was dry.

Took the gas line loose at the tank, drained approx. 15 gallons of gas out.
checked the electric pump,it would pump out of a 1 gallon jug.
put 5 gallons of gas in the tank, still puzzled as to why it quit? Well the pump would not prime out of the gas tank, Pulled the line loose at the tank and NOTHING would come out even with the 5 gallons i had just put in even though i had just drained out 15 gallons thur the same tube.

My question is what is going on? how does the pick up work in the tank?
by the way there was no rust or trash in what i drained out, and the engine will start right up and run with a rubber line from the pump in to a gallon jug but will not hooked to the tank?

HELP PLEASE, I'm stumped.

[cdowns]

there is a filter sock on the pickup tube inside the tank that normally gets clogged up with crap// you need to take out the sending unit and pickup to check

[chopnchaneled]

Thanks, going to do that right now.
only thing thats puzzling is i just had drained out the gas thur the only line it has and it flowed fine. do you think i might have something floating around?

[chopnchaneled]

No sock on the pick up.

How long is the pick up susposed to be? cause there is 5 gals in the tank and
its not touching the end of the tube.

Inside of the tank looks really good, didn't see anything floating around.

Thanks for any help.

[LockDoc]

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This will give you an idea of what it should look like.

LockDoc

[chopnchaneled]

Originally Posted by LockDoc

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This will give you an idea of what it should look like.

LockDoc

Thanks, that looks like it except no sock and it ends at the first 90 degree that go's torward the float.

Like i said earlier, it ran really great untill this weekend and i drained out 15
gals of gas out of the same tube that won't do anything with 5 gals of gas in the tank now???????

[Sammy]

Guessing you have lost your suction or prime. Electric pumps need to be as close to the tank as possible and lower than the lowest part of the tank when mounted. Your pump is getting weaker from working so hard. My best guess.

[stsalvage]

i had the same problem on my 1965 n3/4 ton sending unit my sending unit had a stress crack in the tube and it was sucking Air Buy a new sending unit

[chevytruckluver]

If there is no sock someone has taken it off, therefore there is no filter of any kind before your pump. I would check the tube itself to be sure something isnt lodged inside, get another sock or sending unit and check for any trash in the line from the tank to the fuel pump.
good luck

[67ChevyRedneck]

Originally Posted by chopnchaneled

How long is the pick up susposed to be? cause there is 5 gals in the tank and
its not touching the end of the tube.

There's your problem??? No fuel to suck, no fuel. Pump is going bad too???

[chevytruckluver]

Originally Posted by 67ChevyRedneck

There's your problem??? No fuel to suck, no fuel.

He's got a good point there!

[chopnchaneled]

Well finally got to the bottom of this problem.

Sammy, you were right on the electric pump losing suction. It was mounted just past where the fuel line comes thur the cab floor and on the frame. come to find out the only way it was pumping at all was when i ran a line in a gallon jug in the bed it would push enough gas to run.

Stsalvage, you were also correct in that there was a small hairline crack
on the pick up tube that damn sure was not helping matters, it was located about two inches above where the pick up ended.

67chevredneck,the pick up was in the gas in the tank, but not by much as it had been cut off at an earlier time in its life.

Installed a new Airtex electric pump and sending unit, the engine started right up and ran fine. finished filling up the gas tank put on the gas cap and
headed down the road, got aprox. 30 miles from home and it started starving
on a long hill. Pulled off and looked under the hood and the see thur filter was almost empty. "Really ticked at this point" while i was trying to figure out how i was going to get home, it occured to me that a few days ago i install a new gas cap cause the old one was loose on the filler neck, Twisted the cap and there was one hell of a noise from vaccum. turned the switch on and the fuel pump started pumping again.

So there were several issues but the main one was self inflected, the cap was not venting and because both times it quit i had just filled the tank and there was not room for vaccum to build and was not getting enoughf gas. I have driven it over a 100 miles today and it ran perfect.

Thanks to everyone with suggestions as you also saved me from problems down the road.

[Ed 72 Sierra Grande]

Awesome Post and info. Thanks.