Mechanical pump to electric...can it be done?
 

Hey guys, something I've been wondering with my '86 F250 460 with dual tanks...

Right now it has a mechanical pump on it, but I like the idea of electric pumps a little more. How hard would it be to convert both over to electric fuel pumps? I know I would need a fuel pump block off plate. Both pumps, senders, and new floats, but what else would I need? The wiring harness should be there if I wanted to switch it over right?

No, no wiring harness is there, and the tanks for the pump-equipped senders have much larger holes where the senders go.

So you're telling me it would be a huge hassle?

No it would be easy. you dont mess with pumps in the tanks, the tank selector would work the same. you just blockoff the mechanical pump and mount the electric to the carb. I would wirer in a relay that gets power from the ignition switch and to close the relay ground terminal 85 and power up terminal 86 from the coil positive side. do it neat and put a inline fuse to the main power on the relay terminal 30. you should be fine, get a self priming pump in the 5-8 psi range and your good to go.

You have that tank switching valve right?
If so then you just need a blanking plate on the block and a single electric pump between the valve and carby.

Even though electric pumps prefer to push rather than pull, my electric pump is up in the engine bay and runs without hassle. Just ensure that the pump you use has sufficient flow rate, when running mine on the dyno recently they found the old pump didn't have enough flow and it was starving under load, so we banged a new higher flow unit in.

That doesn't sound all that hard :).

So rather than have a pump on the frame rail, or worry about in-tank pumps...just mount it near the carb and have it run both tanks?

I'm not 100% sure but I think the tanks will swap with later(87+) tanks. If so find a 87+ in a wrecking yard or something, take the tanks, wiring harness, etc. and swap it into yours.

IIRC the valve is different, which pump is on is selected within the valve along with the sender.


Having the pump up at the engine may not work any better then the mechanical pump depending on the issue you seek to solve. Lower and closer to the tanks is better and in tank is best.

Yeah, the switch shows a different level in the front tank compared to the rear, however, right now it doesn't pull from the front tank, so i'm trying to figure out what to replace? If the gauge is getting current, then its not a problem there, but rather the valve i'm guessing?

I'm not personally familiar with the dual tank set up but there have been a few threads lately showing troubleshooting and diagnosis on those valves.

I tried searching for that, and couldn't find anything. Could you help me locate them?

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Should get you started

That did the trick!! I'm stll a n00b to this.

Thanks! :-drink

The valve would be easier to fix/replace than installing an electric fuel pump. I just had to by pass my rear tank because it leaks and fuel was draining back to it after shut down. I disconnected the wire and swapped hose connections. Just a temp fix until I resolve my rear tank issue.

I am personally trying to keep simple systems simple if they are original. There are plenty of other things to re engineer but something like this would be pretty easy to resolve the factory way. Unless there are other reasons for you swapping to electric.

I couldn't find much info of the one wire valve that I have but I have deduced that it operates like a solenoid. When power is applied to it takes the feed from the top input. No power and fuel runs straight from the bottom input. I could be wrong but that's how I have it figured.

My front tank is now plugged into the bottom input (the default input if you will). The power is disconnected so it is basically acting as a coupler at the moment. I have my switch in the cab switched to front tank so that I get a fuel level reading on my gauge. It doesn't switch tanks though because the valve isn't receiving power.

There are aftermarket one wire valves but I can not attest to their quality. My dad did tell me he has seen them in marine applications. That may be another option. Again I can't say what's good or bad but that is some food for thought.

Best of luck

There are...

The main reason is because my first '86 F250 I bought had them in it. I liked turning the key and hearing the hum. I noticed that it seemed to start a lot easier than my mechanical pump one. Also, the mechanical pump relies on your bowl staying full to help it start. And in MN winters, when I need that truck to start...I really don't want to put a lot of strain on the starter and battery to pray it'll get enough fuel to kick over. Personally, i'd rather have something deliver fuel much faster than relying on either a full bowl, or the cranking of the engine to get the fuel moving.

Just seems a little easier to me ya know? Mechanical pumps may be reliable, but they can go out, and if I can do a smaller pump near the firewall for example and run the fuel to the carb that way...then I think that would be easier.