1985 J10 electric fuel pump install

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JDooney76
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1985 J10 electric fuel pump install

Post by JDooney76 »

Ok so i still have the mechanical fuel pump. Have the 360 v8. Gas tank is original plastic, with the pickup and return lines not on top but at the top of the front side of the tank. Hopefully that is explained well enough. And if i dont run this truck every once in a while, then i have to pump and pump on the accelerator, (still carbureted) then crank a bit to get it to start, then all is fine, and if i started it every day then it would be fine. But i must be losing prime or something when it sits. So i want to upgrade and add an electric fuel pump. Nothing fancy just picked one up from summit. But it is a gravity fed pump...outputs i think it said 7psi. But if i mount it on the frame, i think i can get it below the tank or just below the tank and close enough to the tank. But when i see the fuel lines coming from the top, i wonder if this will gravity feed enough when the tank is like 1/4 full. I mean i think it would work if tank is full (although i have a crack at the top corner of the tank that i probably will never fix, and they dont seem to make a replacement tank for the '85 J10 that i could ever find) So i would never be able to fill it up. And i plan to bypass and remove the mechanical pump. So i am wanting some input here if this sounds like it would work and i dont need to worry about the fuel supply line coming from the top of the tank. And do you guys think this would solve my problem of fuel supply on cold start. A buddy of mine told me this was the solution.
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Stuka
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Re: 1985 J10 electric fuel pump install

Post by Stuka »

My '81 J10 had the exact same issue. If it sat for more than 2-3 days, I got in the habbit of giving it a squirt of starter fluid so I would not have to crank it over a bunch. I had a glass fuel filter, and it would be bone dry, so the mechanical pump had to suck fuel all the way back up.

Also, those tanks cracking is extremely common. I put three different tanks in mine over the course of 17 years because that crack will grow, and eventually it will start spewing fuel out.

An electric fuel pump will fit the priming issue, as you can turn the key to run for a few moments, fill the carb up, and then crank it over and start it up. But long term you may want to consider putting in a fuel tank behind the rear axle. Such as a bronco or blazer tank. These are common (you can buy them brand new, while nobody makes a new tank for an 80+ J-Truck), and they are steel. Plus you can buy in tank pumps for them. Which, if you ever go EFI, would be a perfect fit. But you would have to fab up mounts for it.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

Topic author
JDooney76
Posts: 35
Joined: Thu Jun 21, 2018 7:49 am

Re: 1985 J10 electric fuel pump install

Post by JDooney76 »

ok so just to be clear, is my plan of installing the fuel pump on the frame, and bypassing the mechanical pump an acceptable plan? The fuel tank upgrade i like but i will have to wait on that. I am also wanting to get rid of the ICM and coil....and do the DUI/HEI conversion or whatever they call it. An ignition upgrade. Do you have any recommendations for that? The ones i have looked at are from BJ' Offroad and looks like this is the solution. What I think is happening is I do not have the ballast resistor....and the only time i ever took this truck on an extended trip in the summer....not too far but more than just to the store and back. It eventually died and would not restart until i replaced the coil. But the coil wasnt old...i just think whatever function the ballast resistor has, by it not being there it cooked the coil. Thanks for the info
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Stuka
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Re: 1985 J10 electric fuel pump install

Post by Stuka »

An electric fuel pump conversion is a good idea yes. Try to have the pump as close to the tank as you can. And be sure to run it through a relay.

As for HEI, I have used one from CRT Performance and from Z&M Jeeps. Both were pretty comparable, and from what I know BJ's is also fine. With the HEI conversion you wont have a ballast resistor or anything, just a straight switched 12V to the distributer and thats it.

As for your stock coil, it won't like a straight 12V. The Ballast resistor drops that voltage down to 7V. If it runs at a straight 12V, it will overheat and die prematurely, which is most likely what you were running into. The coil should get a full 12V when starting though (when key is in start position), it only passes through the ballast once the key is in run.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

mrtazwrench
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Re: 1985 J10 electric fuel pump install

Post by mrtazwrench »

I don't have the link handy, but there was a fuel pump controller on Amazon that had a 2 second prime pulse and cut off when RPM signal is lost. I too have the long crank after sitting and have been looking into an electric pump, my plan is to run it in tandem with the stock pump. If my truck was not already painted I'd do a tank behind the axle and move the fuel filler to the LR of the bed.

sirrus
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Re: 1985 J10 electric fuel pump install

Post by sirrus »

Good to know there are such controllers!

Recently I was thinking about how to wire a pump so it would give me a prime, be on with ignition on and when cranking too and shut off if engine has stalled. Best I could come up with was to replace oil pressure switch with a 3 prong one, add a diode to prevent backfeeding and wire it from ignition and cranking signals to control relay.

That’s what I’ll probably end up doing, but good to have other easy options as well
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

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Xplitive
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Re: 1985 J10 electric fuel pump install

Post by Xplitive »

https://www.revolutionelectronics.com/

This is the controller (probably closer to a relay with a timer). Use them on another off-road vehicle and they are great.
Erik
1989 GW, 31s on rancho front and general spring rear
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