Francis Blake
Active Member
The engine in my 27 roadster came out if a fuel injected truck so I have to run an electric fuel pump. Does an elec pump require a relay or can it be ran straight from a 12 volt source?
electric fuel pump
- Thread starter Francis Blake
- Start date
Hotrod46
Member
A relay isn't required, but it's a good idea. The wires powering the pump need to be at least 14 gauge (12 would be better) so that you don't have a lot of voltage drop. The circuit should be fused too. Look at the fuse block or a wiring diagram for the truck you pulled the motor from to get a size for the fuse. If you're keeping the fuel injection, the relay should be part of the FI wiring harness since the pump is usually controlled by the ECM.
If you're converting to a carb, an oil pressure safety switch is a good idea. The pump won't run unless the engine has oil pressure. A small overide push button will let you prime the carb for startup.
Something else you might consider. Ford has some neat impact switches on their fuel injected cars and trucks. Wire this into the relay signal circuit. If you have an accident, the impact will trip the switch and kill the pump. At the pressures that most FI engines run, you could pump a lot of fuel out of a broken line. I've been running these switches on my 46 and my T for several years and never had a false trip.
Mike
You'll need a relay. the computer will operate the pump by compleating a ground for the relay. this allows the computer to prime the fuel pump for a few seconds, when you turn the key on.
Russ
Corley
New Member
Some good half answers, but the complete answer is: If you are running fuel injection / computer, then Northstar is totally correct, you need the relay. If your engine is a carb, but just doesn't have a mechanical fuel pump, then you can get by without the relay unless you have a really big honkin' pump that draws a lot of current.
Francis Blake
Active Member
I should have mentioned I converted to a carb and no computer, just an electric pump.
Francis Blake
Active Member
Thanks guys I will put a relay on it, just to be on the safe side.
Francis Blake
Active Member
My engine is a 4.3 v6 completely stock. It will be ready to go to modot this week for inspection and license, I have a boatload of recites for them to go through. I have been looking for this day for a long time!
good luck on the inspect. each state is different I recon, but here in Or I was amazed at how easily it went for my T. I also had a boatload of receipts, but he never asked to see a one of them. he took the numbers off the engine and ran them, but otherwise nada. my inspector (state trooper) was a car guy himself, so that's always a good thing as well.
Russ
Hotrod46
Member
Congrats on getting to inspection! :hooray:
Louisiana wanted the reciepts just to figure out how much to tax me. The trooper that did the inspection was just interested in the paper trail on the serial numbered parts.
Hope everything goes well.
Mike
