Help!! Electric Fuel Pump is Driving Me Nuts!!

[Martian R/T]

Driving my Charger a few weeks back, it dies and leaves me sitting on the side of the road, I tow it to a guys house and leave it overnight, next day I bring a transfer pump I borrowed from work and install it by the carb, it starts and I drive it home, I take the add on pump out, turn on the pump and its pumping fuel like nothing happened, there was nothing going to the carb when it died, so I take the fuel filter out (Mallory pro comp mounted by the tank) filter is dirty, alot of really fine particles in the can, so I change the filter, remove the sending unit and change the filter sock on there, change all the hoses back there, pump is running fine I put a hose on the pump and route it into the fuel filler tube and let it run for a half hour or so, everything is fine, good flow, no intermittent nothing, so I put it all back together, can't drive it again for a couple of weeks, take it out on Saturday running fine, on the road about 15 minutes it dies just like before, pump is still running, the sound is different from when it is actually pumping fuel, I sit there for about 20 minutes keep flipping the switch on the pump, still sounds the same, I finally hear it pumping again, so I start it and head for home, it dies going down the road to my house, luckily I was going fast enough to coast into the driveway, again no fuel in the carb but the pump is humming away,it is a carter electric 7gph, can electric pumps be effected by heat or am I missing something else, the pump has never just quit it always runs but no fuel, please help I am at my wits end.                                                           

[The70RT]

Have you had your sender out? If it is the original or an older one, the tube can rust above the fuel level and suck air. Just a thought

[Martian R/T]

The sending unit has been replaced, it looked great when I had it out to replace the filter sock and the plastic float, there was no rust anywhere on it.

[Steve P.]

did you try removing the fuel cap? Could be you don't have enough vent.

check for a kink in the line before the fuel pump.

Electric pumps need to be mounted as low and as close to the tank as possible. They are made to PUSH not pull..

[Martian R/T]

When this happened before it was just sputtering, not to the dying stage yet I popped the cap and it had a huge pressure release, so I went through and pulled out the vent tube and made sure it was clear and venting properly, never had anymore pressure build up after that, lines and tubes look good no real bad bends or kinks, the pump is mounted to the floor pan above the axle with the filter right beside it, I am really confused nothing looks out of sorts but it still keeps dying, I wondered if the filter sock in the tank could be an issue I have seen write ups both ways about taking it out and also for leaving them in, I am baffled, thanks for all the help.

[Steve P.]

It sure sounds like it is sucking itself into a vacuum and not venting. It doesn't take allot for this to happen. This is why they tell you to mount the pump as close to the tank and as low as possible. The fuel pump is made to push only. If you create a vacuum in the tank by removing fuel and it is not displaced with air you will get these results. If you can make it run out of fuel I would do so and then remove the fuel cap. Take note if it sucks in around the cap while removing it.

2nd test would be to see if it pumps after it dies, by removing the fuel line to the carb and running it into another container. Both ways you will need to replicate the problem.

[BrianShaughnessy]

Does the pump deadhead or do you have a bypass regulator or bypass fuel filter that goes to the 1/4" return line at the sender unit?

Deadheaded pumps heat up more.

[Martian R/T]

I am curious as to why this would start doing this, I have had the electric pump for 7 years or so and have never had a problem til the last year or so, the tank didnt vent or suck the last time this happened, that was the first thing I checked after it quit, there is no fuel at the carb, the bowl and the line are empty, the pump is running but you can tell by the sound that it isnt pumping any fuel, I dont have a return line from the pump or the filter, I was thinking about putting a filter with a vapor return up front like it had originally, but havent gotten that far yet, the pump and filter are mounted right across from the tank to the front of the axle tunnel, I dont think it is higher than the tank but I will check that, thanks for all the help.

[Martian R/T]

Ok I finally got a minute to look at the Charger and the fuel tank is lower than the fuel pump by at least 2", so I got thinking while I was looking at this, why did this start happening now, what has changed, and I think I have the answer, Back when I put the electric pump in I was running P275/60R15 rear tires with air shocks, so the Charger had a good rake to it, well I started leaving the shocks down, and recently I took off the 15" Cragars and went back to 14" Rallye wheels, and I am going to take off the air shocks,  but now the car is setting perfectly level, so the tank is lower than the pump, so I am guessing that this is the root of the problem, but when I started the Charger yesterday the pump was really noisy, it has never been this loud, so I wonder if I should just replace the pump anyway, I am about to the point of tearing the motor apart to get the mushroomed push rod out and going back to a mechanical pump, if anyone has any ideas about this mess let me know, all help is appreciated, Thanks.

[Steve P.]

With an electrical problem you always start looking from the source of power. Your battery. In this case I would absolutely start inside the tank. Pull the sending unit and fully inspect it. I don't care if it's brand new... Check the sock. Check to see if it has a crack in it or a hole. I would even do a water test just to be 100% sure. While the sending unit is out I would inspect the inside of the tank for anything that does not belong..
   (Years ago I pulled a piece of plastic wrap out of a tank that had intermittent starvation problems). I think it ended up in the tank by someone using a gas can with a temporary cap on it that they didn't remove before sticking the nozzle into the filler tube.   So look closely.

Next check the line from the sending unit to the fuel pump. If you have ANY question about it's performance, REPLACE IT.

The fuel pump can be checked by putting gas in a clean bucket and circulating it through a regulator and back into the bucket. Make sure you regulate it down to about 4-5 pounds to do this check. Also run this check for a while to make sure it isn't giving up the ghost after heating up. Regulating it down low will increase the heat.   

Any leaks AFTER the pump will show up on your garage floor when it DOES pump gas, so you would know of it already.

Last but not least, we had a huge problem similar to this with VegasMike's 68' Charger.  After many, many checks and burning up a few good pumps I talked him into putting a return style regulator on the car and a return line back to the tank. Problem solved... The pumps WERE designed to bypass and were high end pumps. 2 brands besides. Once the return line went in his fuel temps went down and he has been running the same pump now for over 2 years without so much as a hiccup.


Hope this helps....  Let us know.......