Fuel Pump Issue?

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Dizzydean

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Good Day, I am having a fuel issue and not sure what to check next. After driving about 45-60 mins the car stalls and my filter is dry. I have the 5/16 line from tank to pump then i had 3/8 to the carb. I have switched to 5/16 all the way, replaced the pump, blew air from the tank going forward and from the pump through the tank (not through the pump), opened the flip gas cap which is vented, and still have the same end result-a dry fuel filter with very little fuel being pushed even with high throttle. Very little is a trickle. When i check much later the filter ia about half full. Is it possible to install the pump incorrectly and if so would it make any strange noises? Everything sounds normal. This is on a 67 dart if it helps. Sure would like to drive and not have to call a tow to get home.
 
Go over to MyMopar.com and download a free factory service manual

There's a procedure in there for checking the pump. You need a cheap pressure/ vacuum gauge from the parts store.

Possibilities in no particular order:

Tank pickup sock is gummed up, or the pickup tube otherwise plugging AKA runs awhile and then sucks something in, gob of dirt in the sock, whatever

Flex fuel hoses PARTICULARLY the two on the suction side, are collapsing or deteriorated internally. "New" does NOT mean "terrific", "better than anything," or even "works as supposed to."

I see you are from WA so I'm guessing the wx is not terribly hot, but "it might be" that if you somehow mis-routed the line, it might be picking up exhaust heat and boiling/ vapor locking. Don't discount the weird--like an exhaust leak at a muffler/ connection, etc, blowing hot air directly onto the tubing.

This is likely not a vent problem, but they are simple. Look in the trunk. The tube running down beside the fuel filler tube simply open ends in the frame under the trunk. There are various things, mud daubers, etc, but you say you've opened the cap.
 
Also, there is a chance you have the little disk about the size of a dime / nickel of a paper type plastic floating around the tank. Ever so often it is getting sucked up and shuts off the pick up tube. Those disks come from “dry gas” or other fuel additives. It’s a sealing disk to make sure the bottles don’t leak. Sometimes they fall in the tank and cause all kinds of issues. Not all tanks have socks or the socks broke up and that is an issues since it is a plastic like filter.

“IF” this is your issue then the tank has to come out and be dried out and then blown out until the part / pieces are gone. Typically thru the sending unit hole.

I’ve not seen this be an issue in a long time. But it is a possibility.
Good luck
Syleng1
 
Us not knowing any history of the car, could be sludge in the tank for a 50 something year old car. I had that problem in a 70 Dart that was not driven for several years. Replaced the tank and problem solved.
 
Disconnect fuel line at pump going to the tank and blow air thru into the tank. If it temporarily fixes the issue drop the tank and investigate or at least pull the sending unit and see if the sock is dirty or clogged which would indicate dropping the tank anyway.
 
Kendog 170 said:
Disconnect fuel line at pump going to the tank and blow air thru into the tank. If it temporarily fixes the issue drop the tank and investigate or at least pull the sending unit and see if the sock is dirty or clogged which would indicate dropping the tank anyway.
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If you do that, do not use too much air pressure, and make sure you remove the fuel fill cap. It doesn't take much to "balloon" the tank.
 
Dizzydean said:
Good Day, I am having a fuel issue and not sure what to check next. After driving about 45-60 mins the car stalls and my filter is dry. I have the 5/16 line from tank to pump then i had 3/8 to the carb. I have switched to 5/16 all the way, replaced the pump, blew air from the tank going forward and from the pump through the tank (not through the pump), opened the flip gas cap which is vented, and still have the same end result-a dry fuel filter with very little fuel being pushed even with high throttle. Very little is a trickle. When i check much later the filter ia about half full. Is it possible to install the pump incorrectly and if so would it make any strange noises? Everything sounds normal. This is on a 67 dart if it helps. Sure would like to drive and not have to call a tow to get home.
Click to expand...
Posted this numerous times, should've popped in a search. if You actually searched. Rust & dust fines slowly covering the tank pickup while driving, after sitting they fall off until agitated/stirred up by driving.
 
Thank you guys for the input. Items I forgot to include: Tank and sending unit are both new, all rubber lines were replaced, I also cleaned the steel line using brake clean then blowing it out before installing everything, fuel pump was replaced week. Still having the same issue with the new pump.
 
Dizzydean said:
Thank you guys for the input. Items I forgot to include: Tank and sending unit are both new, all rubber lines were replaced, I also cleaned the steel line using brake clean then blowing it out before installing everything, fuel pump was replaced week. Still having the same issue with the new pump.
Click to expand...

Then I would be checking for fuel lines close to heat sources.
 
I would run the fuel pump from a can, and check pressure and volume at the carb. If good, work back from there (ie connect gas can to line at the tank). If pressure/volume were bad when connected at the pump, problem is either a bad pump (not uncommon even with a new pump) or the lobe on the cam is worn.
 
There was the very same issue a coupla weeks ago iirc, new rubber hose at tank was bent and kinked .
www.forabodiesonly.com

Hose from Tank to Line 72

Obviously someone changed some stuff back here. It's not getting fuel, and this doesn't look right. There is no vapor port in the tank or sending unit, and I know that isn't correct because turning it over creates a huge vacuum in the tank unless the fuel cap is off. Is the end of the fuel line...
www.forabodiesonly.com www.forabodiesonly.com
 
Charrlie_S said:
I would run the fuel pump from a can, and check pressure and volume at the carb. If good, work back from there (ie connect gas can to line at the tank). If pressure/volume were bad when connected at the pump, problem is either a bad pump (not uncommon even with a new pump) or the lobe on the cam is worn.
Click to expand...
i tried this and the result was the same little to no flow, i even took the pump off and reinstalled still no better, So it looks like the electric is my next move. Any tips on the flow rate for a lightly modified 6?
 
If you go electric, do it the correct way. Either with an oil pressure safety switch to shut off the pump if the engine is not running, or/and an inertia switch to shut the pump off if in an accident.
 
If this is a slant six, no mention of which engine this is, the cam has an eccentric lobe on the cam to run mechanical fuel pump. If a lot of miles possible lobe is worn down not giving pump enough movement. Also no mention of mileage or condition of engine.
 
Dizzydean said:
Thank you guys for the input. Items I forgot to include: Tank and sending unit are both new, all rubber lines were replaced, I also cleaned the steel line using brake clean then blowing it out before installing everything, fuel pump was replaced week. Still having the same issue with the new pump.
Click to expand...
What type and how many clamps are installed on the New neoprene rubber jumper at the back, from the sender to the main line?
If this jumper sucks air, you will get exactly what you describe. Because this jumper is higher than the tank, it does Not leak liquid fuel.
If gearclamps, you need two on each side, staggered 180 degrees and as close together as possible, and NOT overtightened. This to squeeze shut the tiny gap that usually forms right next to the screw of the first clamp.
If factory spring clamps are used, the fuel line must be properly sized for them, then one per side will be enough.
Make absolutely sure that NONE of your rubber jumpers are kinked. The kink, under suction, will cause the fuel to boil right there due to the vacuum that the pump is creating. By the time it gets to the carb, it should have returned to liquid form. But if the kink is severe, you could end up with a 5/16ths line full of vapor from pump to tank, and the pump cannot pump vapor. When this happens the little return spring on the pump-arm, does not return the arm ready for the eccentric to stroke it again. So the arm just flops around a bit.
After the engine quits running, the check valves in the pump, seal the line there. And so the vacuum still in the line, continues to tug on the fuel sender, and syphons fuel up the line until the vacuum dissipates which simultaneously allows the vapor to condense back into fuel. Since the lowest point in this line is usually very close to the pump, on the next cold-start, the pump easily purges whatever vapor might remain, and pumps the fuel behind it, filling your filter with a bit of a bubble, which just sits there in the high point of the horizontal line. But fuel gets by on the low side, and eventually the fuel bowl fills up. Then off you drive...... until the cycle repeats.
 
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