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another 2 Qs regarding electric fuel pump installation

Posted By: 440sat72

another 2 Qs regarding electric fuel pump installation - 03/08/09 08:51 PM

i'm in the process of converting to electric fuel pump and have 2 more questions:

- what do i do with the old stock mechnical pump? just unscrew it, pull it out and close the hole with a block off plate? or is there anything else to it?

- how do i properly hook the pump up? can i just go with a relay or do i need an additional circuit breaker? and (maybe the dumbest question: where is the best place to splice the pump into the ignition switch circuit?

i'd really appreciate your help!
Posted By: HealthServices

Re: another 2 Qs regarding electric fuel pump installation - 03/08/09 09:20 PM

To be honest with you unless you are running 10s and low 11 second times. There is really no need for a electric pump. A performance pump will be more than adequate for a 11 second car.
Posted By: Paul_B

Re: another 2 Qs regarding electric fuel pump installation - 03/08/09 09:45 PM

Use a blockoff plate where the old mechanical pump was.

I ran my pump off a relay and then fused the line as a precaution.
Posted By: 440sat72

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 04:59 PM

Quote:

To be honest with you unless you are running 10s and low 11 second times. There is really no need for a electric pump. A performance pump will be more than adequate for a 11 second car.



well, one of the reasons i am choosen an electric pump: from time to time the cars sits a week or two. after that it takes ages of cranking cause the fuel in the bowls has evaporated.

electric pump will cure that.
Posted By: Anonymous

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 05:32 PM

The ele pump is definitely a quick fix that you will probably never have to look back on but if I were you I would check all your connections/fittings.

It sounds like you may have air getting into the system somewhere and the fuel will siphon back to the tank when allowed to sit.

I have a holley mechanical pump that has a high flow rate, I can let it sit for 6 months and it will fire with very little cranking.
When I dropped the new motor in I also ran a 3/8 aluminum line and put a new fuel tank in with the larger 3/8 pickup. All lines and fittings were new, I'm sure that has something to do with it.

I also have a F150 wrecker with a 7.3L diesel.
Air is getting into the fuel system somewhere and if I let it sit overnight it I have to crank it while purging the air from the fuel filter housing before the injectors have enough pressure to pop.
I'm definitely chasing a gremlin on this one, what a PITA
Sorry if it sounded like a rant, hope it helped...
Posted By: HealthServices

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 05:52 PM

Here is a basic wiring diagram using a typical relay. You do not need the switch, but it is sometimes nice if the carb is flooding out. There are wiring kits out there you can buy too.

Attached picture 5081158-fuelpumpswitch.jpg
Posted By: DaytonaTurbo

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 05:52 PM

Mine does the same deal as you, even with a holley HV mechanical pump it still had to do a bit of cranking to refill the carb bowls.

When you go with an electric pump, my suggestion is to go with a return-style regulator and power the pump during the Run position on the ignition. This way you can get in the car, turn the key to the run position and just sit there for a few seconds while the electric pump fills up the carb. Then crank to start. The return style regulator prevents the carb from being overfilled, and not running the pump during cranking will not make a difference. If you have an available switched power source of a high enough capacity you can tap right into it, just put a fuse before the pump. If you run a relay, put the fuse before the relay and you're good to go.
Posted By: Silverbullet2

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 05:58 PM

matt,

On the 7.3 diesel, the return lines and O rings on the injectors will cause your hard start/long crank issues. If there's no smoke while cranking it's not getting fuel. The lift pump can also let air in the system, and in rare cases an injection pump will cause it.

The injector return lines and O rings are by far the most common and a quick and easy fix. The aftermarket has a kit with 16 O rings, 8 caps, rubber lines, and clamps. 1-2 hour job in most cases.
Posted By: Anonymous

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 06:06 PM

Sorry not to hijack this thread...

Yep, I replaced it all... even both the supply and return lines back to both tanks and the selector switch.
Phewwww... that was alot of lines to run...

I even did the "olives", thick o-rings that go on the supply line between the injector pump and filter housing.
I put a new fuel pump on it and think that might be the issue.
The threads might be screwed up, it was a pain to get 'em started...
Posted By: JimG

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 08:36 PM

You might want to consider using an oil pressure switch as a fuel pump cutoff. In case of a collision and the engine shut off, the pump would stop too. This would be a good thing. Especially if there was a fire.

The problem it creates is that you want to fill the float bowl before you hit the key, and with the oil pressure switch, that ain't happening.

Here's how I worked around that. I bought a 3-position toggle switch from the electronic supply house. Center is off, up is on, and down is on, but it is spring-loaded. If the car has been sitting for months, I hold the switch all the way down (the spring-loaded position) and the oil pressure switch is bypassed, running the fuel pump. Then I flip the switch up and start the car normally. As soon as oil pressure comes up, the pump starts.

If you're interested, I could dig up some links and sketch out a wiring diagram. I know the oil pressure switch came from Summit, but everything else is foggy. I did this about 15 years ago.

Jim
Posted By: gch

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 10:09 PM

Quote:

You might want to consider using an oil pressure switch as a fuel pump cutoff. In case of a collision and the engine shut off, the pump would stop too. This would be a good thing. Especially if there was a fire.

The problem it creates is that you want to fill the float bowl before you hit the key, and with the oil pressure switch, that ain't happening.

Here's how I worked around that. I bought a 3-position toggle switch from the electronic supply house. Center is off, up is on, and down is on, but it is spring-loaded. If the car has been sitting for months, I hold the switch all the way down (the spring-loaded position) and the oil pressure switch is bypassed, running the fuel pump. Then I flip the switch up and start the car normally. As soon as oil pressure comes up, the pump starts.

If you're interested, I could dig up some links and sketch out a wiring diagram. I know the oil pressure switch came from Summit, but everything else is foggy. I did this about 15 years ago.

Jim


Or you can lay a screwdriver across both terminals with the key on and fill the bowls up that way.
Posted By: HealthServices

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 10:26 PM

http://www.holley.com/data/Products/Technical/199R7914-3.pdf
Posted By: IronWolf

Re: another 2 Qs regarding electric fuel pump installation - 03/09/09 11:01 PM

Quote:

i'm in the process of converting to electric fuel pump and have 2 more questions:

- what do i do with the old stock mechnical pump? just unscrew it, pull it out and close the hole with a block off plate? or is there anything else to it?

- how do i properly hook the pump up? can i just go with a relay or do i need an additional circuit breaker? and (maybe the dumbest question: where is the best place to splice the pump into the ignition switch circuit?

i'd really appreciate your help!




Subscribing...

But, I plan to keep my mechanical pump "in serial" with my new Mr Gasket mini electric fuel pump. I'll switch the electric pump on in certain situations.

My Carter 6psi mechanical pump "decided" to start leaking, so I installed a wimpy stock fuel pump in its place.

Painless sells a nice wiring kit with relay. Mancini and Summit have this kit in stock.

I'm thinking of installing the electric pump on the rise in the trunk to floorpan transition.

PS Important safety tip : Wear steel toed shoes or sturdy boots when removing/installing fuel pumps. I did NOT follow this tip and dropped a new fuel pump from great heights upon my unshod foot's instep. Still hurts. Good luck.
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