i've tried everything; fuel pump overheats and vaporlocks

[tompdog7]

i have tried everything. i have moved the fuel pump from the front of the engine mount to over the outside of the frame rail well away from the exhaust. i have vented the tank. i thought this would fix it but after running about 15 minutes the fuel pump is so hot i cant touch it and it vapor locks the fuel and dies. this is the fourth brand new pump that i have put on in two weeks. the only thing left that it could possibly be is some type of electrical problem. to see if it was some type of relay problem i ran wires directly to the battery and grounded it in the battery to try it that way and it still gets hot. i also hooked it up to the battery on my truck and it still gets hot. i had the battery tested today and it was putting out 12.7 volts. i have no idea what else to do. something is making the pump overheat and i cant figure it out. if anyone has an idea how to fix this please help. thanks

 

[tompdog7]

i was just talking to my father in law and he said that the pump should shut off when the line pressure fills up. it is a carter fuel pump and it runs continuously. i had a fuel regulator on at one time but i took it off. would that help. i dont see why it would because the carb will not let fuel in once it has its fill and the pump should stop pumping when pressure reaches a certain point. should the pump stop pumping at a certain point. i can still put the fuel regulator on between the pump and the carb. thanks for any help.

 

[ransil]

The pump should run continous. Maybe saet it up to push the fuel instead of pulling it. Mount it close to the tankl. also the fuel is used to cool the pump some type of return line should be used.
An air leak in the fuel line will cause vapor lock , make sure your fuel line is in good shape.

 

[broncnaz]

The pump will not shut off when line pressure has built up while some EFI setups do this yours will not. I would suspect that something is wrong with your pump I use carter pumps had one on for 25 years that still pumps athough I put in a new one because of its age.
You may want to pull the cover off your pump to make sure the screen is not plugged up possibly causing some of your problem or maybe the rotor and vanes are binding, another thing may be the fuel pickup in the tank it also has a screen that may become clogged sometimes once the vehicle has sat a while some of the debris will fall off the pickup and it will act normal then the crud will build back up and cause your vapor lock symptoms, and since you've gone through 4 pumps this may be your most likely problem. You'd be surprised at the junk that collects in your gas tank. also make sure your lines feeding the pump are in good condition any cracks could let air in causing your pump to heat up because its not drawing fuel.

 

[GRIZZLY]

It sounds like it's mounted up front. You might want to mount it closer to the tank. Electric pumps are designed to push.

 

[Socal Tom]

The instructions for most of those pumps will tell you to mount it within 3 feet of the gas tank. That means you should have less than 3 feet of fuel line between the pump and the tank. You should have a fuel filter between the tank and the pump. If possible mount the pump below the level of the tank.

Does the fuel recirculate, or just go to the carb and stop? if it's recirculating it could over work the pump. It's also possible that your tank pickup is plugged or damaged, or that the pump is sucking air from upstream somewhere.

Why did you replace the mechanical pump?
Tom

 

[tompdog7]

it is about two feet from the tank. i do not have a return line to the tank so it is probably sitting with fuel in it pumping and overheating. i dropped the tank about three weeks ago and it looked clean. i have not replaced the mech pump but i am about to give up on the electrical and put a mech pump on it. thanks for your help.

 

[cynrays]

Why don't you try this. Get a gallon container and run a rubber fuel line from the container to the pump. Mount or tie the container higher than the pump. Let it run and you should be able to tell before you run out of gas what is wrong. You may have to suck on the hose from the pump to prime it first.Then you should be able to tell if it is the tank or the pump...

 

[tompdog7]

fixed it!!!!!!!! took the elec fuel pump off and put on a new mech pump. works perfect. it is amazing how simple things can be if you just think about them. thanks for all your help!! ;D

 

[ransil]

When running the electric pump did you have the mechanical pump bypassed??