Electric Fuel Pump - Aftermarket

[cclaeys]

Hi guys, first post, but probably have read about 10000 on here so far...what a great resource. I bought a divorce on wheels last week and have been trying to get it baselined (want to be able to put the rubber to the road) - runs and drives just fine, but had some signal, light things that didnt work and subsequently figured that it was the non existent ground straps, starting with electrical because there was some hydraulic trailer brake and tons of other misc crap everywhere. It is a 1970 Jimmy with a 350 and sm465 4 speed, but there is an aftermarket electric fuel pump bolted to the rear cross support, found that after dropping the tank to figure out why the fuel gauge wire was disconnected. I know there is a mech fuel pump at the base of the engine, but how should I handle this other one...it was connected to some solenoid looking thing under the dash wit a bunch of zip ties and cheapo connectors so I am pretty sure it isnt factory. Thanks for the help and sorry for the rant....

Chris

[cclaeys]

in addition, it is still connected to the mechanical fuel pump...dunno what to do, any advice? It has an Edelbrock 1406 carb if that helps. Think I need to ditch that electric one and find out if the mech works?

[70cst]

Hey cclaeys ...

to the forums and from Ohio.


Here is a bump for you...

[old man jimmy]

I have no idea what the "solenoid thingy" would be for. But as far as running the two pumps, I don't see a problem their. Sounds like the po might have had some vapor locking problems. When I lived in Vegas, and they went to oxygenated gas. I couldn't drive two of mine when it was over 105 deg. outside. So I put electric pumps on them, and just left the mech. pumps in place. But I just ran my pumps through a toggle switch. It did seem to help the vapor lock problem. Just make sure it's fused. Or could that "selenoid" really be a relay?

[cclaeys]

I think it was connected to a trailer brake, this thing is a wiring disaster, has 3 trailer connections that I am trying to figure out as well - just dont wanna fudge anything up. I am considering just disconnecting that cheapo purolator electric fuel pump - if it is 105 I probably wont be driving anyways, will be hiding in the basement . Now I have to figure out how that last connection wires into the tail light harness, it is kinda roundish with 3 connectors, had a bunch of wire nuts so I assume it isn't stock, up behind the license plate.

[Firebirdjones]

If it were mine, and you are running a carbed engine, I'd concentrate on running the stock mechanical pump and ditch the electric.

The external electric pumps aren't as reliable, run hot and heat the fuel, and may or may not last 20,000 miles depending on the brand and style.


If you are having vapor lock issues, I'd suggest running a fuel return line and buy that particular style of mechanical fuel pump, then run the extra line along the frame rail if your truck is originally equipped with a returnless system. Simply dump it back into the tank.

This keeps the fuel moving at all times so it isn't sitting stagnent in the fuel lines collecting heat. That way,,,the only fuel that sits stagnent will be the line from the pump to the carb (when needle and seat is closed). This keeps a fresh cool supply of fuel available at all times. I've found this the best way to fight vapor lock issues. After that is done then you can attack the fuel lines themselves around the engine and make sure they aren't touching anything hot (usually an inch of clearance around the block is fine).
You could also run a thick carb gasket to absorb heat, and even a carb heat shield if you wish.
These issues become more important when running a quadrajet or edelbrock carb because they have such a small float bowl design and run out of fuel quickly.

Vapor lock issues will continue to be a problem as gas quality gets worse, the mixing of ethanol doesn't help, lower octane ratings don't help, and the winter/summer grades of fuel will continue to be an issue as well since the non-freeze properties of the winter grades are extremely prone to vapor lock and don't like heat at all. Some of your stations are very slow to change from winter to summer grades,,,,and usually you run into an overlap after the weather starts getting warm. Next thing you know,,,,,BAMB! You pull out into traffic and the car stumbles

[cclaeys]

disconnected that crapbagge electronic fuel pump and flow fine with the stocker, adios another wire and more trouble, thanks for the motivation fellas!