Author Topic: 1981 truck convert to electric fuel pump?  (Read 3738 times)

singleboost

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1981 truck convert to electric fuel pump?
« on: October 03, 2012, 01:11:37 AM »
First thread yay!
Anyway, my friend has a 81 truck that had a 22r with a mechanical fuel pump. He wants to put in a 20r/22r hybrid but the 20r head does not have a spot for the mechanical fuel pump because it used an electric fuel pump. My question is, how do you hook up an electric fuel pump? I have heard and read you can buy one from checker and install it anywhere on the truck. Will it need a relay or just hook it up to ignition power?

SDSK

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Re: 1981 truck convert to electric fuel pump?
« Reply #1 on: October 03, 2012, 07:31:41 AM »
I'm assuming you know how to hook up the fuel lines and everything that goes with it? Twincharger would be the ideal guy to ask as I'm fairly sure he has two. I could be wrong about that though.

twincharger

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Re: 1981 truck convert to electric fuel pump?
« Reply #2 on: October 03, 2012, 09:08:54 AM »
Yea, a low-pressure 4-7 psi pump is what you need.

They're about 50 bucks at any auto parts store... probaby cheaper online.

Don't bother with a high pressure pump and then a low pressure regulator...  Its just not needed.

I'd put it on a relay, if you don't, then the extra current will go thru your ignition switch and could eventually burn it out.

You don't need the fancy EFI hoses either.

singleboost

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Re: 1981 truck convert to electric fuel pump?
« Reply #3 on: October 05, 2012, 07:13:22 AM »
Thanks. I'll get the pump and relay this weekend. The pump can be mounted anywhere right?

twincharger

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Re: 1981 truck convert to electric fuel pump?
« Reply #4 on: October 05, 2012, 11:19:57 AM »
...almost.

The way they make a low pressure pump that can tolerate its output being blocked off when your carb is full, is to make the pump with sloppy tolerances...  lots of clearance between the impeller and the housing, lots of internal leakage around the pump.  That keeps the pressure low, and allows the motor to spin without much resistance.

That is fine except when there is air in the pump.  Due to the large tolerances, the pump can't make any pressure or vacuum in air, so the pump should be mounted low enough that fuel runs into the pump.  The pump can't suck fuel uphill when there is air in it.

So, it does not matter if the pump is mounted in the rear, by the tank, or up front by the engine, but mount it low so that it can't fill with air.    High on the front of the engine would be the worst place for a pump.

overspool

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Re: 1981 truck convert to electric fuel pump?
« Reply #5 on: October 05, 2012, 07:30:35 PM »
i used a Mr Gasket 12S when I still had a 4AC. Internally regulated, i installed a fuel pressure gauge to see what FP was doing, would go up to 7 psi and stop. It worked really well for me.

singleboost

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Re: 1981 truck convert to electric fuel pump?
« Reply #6 on: October 06, 2012, 08:32:10 AM »
Thanks guys. I will be trying this set-up today.