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Electric fuel pump install help... please

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Gliderman8

Gliderman8

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I am getting ready to install a new electric fuel pump and I have multiple questions.
Here's my questions in no particular order:

Plumbing the new pump:
What is the best "plumbing route"?
Do I install the electric pump before the mechanical pump and pump through the mechanical pump so both are pumping simultaneously?
Do I remove the mechanical pump all together and blank off the opening?

Electric hookup:
What's the best source for the +12v supply?
Obviously, I want the pump to stop if the engine is not running.
Can it be tied into the oil pressure switch?

Diagrams/photo's and help from those who have already installed electric pumps is appreciated!
 
Hi Elliot,

I put one on my TR4A. I mounted outside of the trunk behind the left rear tire. I ran a new wire from it from switched power. I used the stock fuel line routing, removed the old fuel pump and blanked it off. I put an inline filter before the pump and one in the engine compartment where the old fuel pump had been. Of course all that is different now, since I installed the Electronic Fuel injection.

Dan B
South Charleston, WV
 
Thanks dan... I'm looking for a power source that will stop when the engine isn't running and the "switched" power is on... in other words in case of an accident, I want the pump to stop.
Also, do you have a source for a blanking plate?
 
You mentioned the OP switch, Elliot.
I'm thinking that if you used it to establish a ground, yes it woiuld break the connection if the engine died, but you wouldn't have a ground when you went to start the engine until the OP hit about 5 psi.
As long as there was residual fuel in the carbs float chamber, the engine would start right up w/o the fuel pump running, but if the carbs were dry, you'd have to depend on the starter to raise the OP enough for the fuel pump to kick on. It might not take too long, but still there would be some cranking involved.

At least that's the way I sees it.
I hear the Brits talk about an "inertia switch". That might be what you want.
 
PM sent Ken
 
There was a neat fuel pump relay used on early VW fuel injection cars, that had a line to the coil to sense when the engine was running and kill the pump when the engine was stopped. It would also run the pump for just a few seconds when you first turned the key on. The one my Rabbit (aka Golf) had also incorporated a fuse for the line to the pump.

I'm not positive, but this looks like the same thing:
https://www.ebay.com/itm/KAE-Fuel-Pump-Re...ies&vxp=mtr

If you want a little more safety, you might also want to incorporate an inertia switch like the later Triumphs used. The idea being that it cuts power to the pump after a serious accident, even if the engine is still running.
 
I thought the inertia switch only worked in case of a roll over accident. The last time I looked at one of those switches, they were pretty pricey.
 
Get one from a late MGB. Mounted on the left side interior fire wall. They have a magnetic breakaway connector inside that is supposed to kill the pump on any significant impact or roll over. You can also use it as a theft deterrent by pulling the red knob up, as the fuel pump won't run. PJ

Looking different than the original,
Moss replacement at $56.95


 
We had these in our modern delivery fleet, mostly Ford Escorts and later Pontiac Vibes. The occasional fender bender in a fleet that ran 57 million miles a year had them actually turn off so the drivers could not start the car till a button was pushed. I don't know if the new ones re-set on their own but I doubt it.

Jerry
 
TR3driver said:
There was a neat fuel pump relay used on early VW fuel injection cars, that had a line to the coil to sense when the engine was running and kill the pump when the engine was stopped. It would also run the pump for just a few seconds when you first turned the key on.
Click to expand...

Thanks Randall. This relay looks like it will do exactly what I want to do.... power the pump when I turn the key to start, and kill the power to the pump when the engine is not running.
Of course, I'll still have to add an inertia switch to make it fail-safe.
 

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I put my electric fuel pump in the trunk too. but seeing that the mechanical pump is lower than the tank I be you could mount the electric pump in the engine bay as long as its the same height as the mechanical pump, maybe make a bracked and put it where the original one is, then I got a T fitting and screwed it in to the block where the oil pressure switch is and got a switch that is open on no oil pressure and closes on 5 psi, so when the engine is off there is no power to the pump.

Hondo
 
I thought about wiring the pump that way to Hondo... but as you say there will be no continuity until approx. 5 psi. Yes there is probably fuel in the carbs to start it but if it sat for a while I didn't want to crank the engine until I got power to the pump.
I'm going to give the relay with the "pulse" lead a try. It does the same thing by cutting the power to the pump when the engine is not running and also powers the pump on start-up.
 
if I had saw that relay when I was doing mine I would have gone that route too, my car ususally starts before the oil pressure comes up, and if I had an issue all you have to do is short the 2 terminals and the pump will prime the carbs

Hondo
 
We just made a blanking plate out of steel. I cut it out with a hacksaw and cleaned up the edges on a bench grinder, then drilled holes using the gasket for location.

Dan B
 
hondo402000 said:
if I had saw that relay when I was doing mine I would have gone that route too, my car ususally starts before the oil pressure comes up, and if I had an issue all you have to do is short the 2 terminals and the pump will prime the carbs

Hondo
Click to expand...

I like the relay too. I used that method to tap into an accessory line to run (and not nun) a radio in another car - not quite as sensitive an issue though.

One concern for me using the relay would be an accident/fire where you were not able to cut the power.
 
njmikec said:
One concern for me using the relay would be an accident/fire where you were not able to cut the power.
Click to expand...

Which would be why to use the inertia switch in addition to the relay.
 
Randall- Am I correct that the "sensing" relay keeps the relay coil energized as long as the engine is running?
I can only assume that's the case so it would make the power connection to the pump. If that's true I wonder what the duty cycle/life of the relay coil would be if it's continuously energized.
Tell me more....
 
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