89firebirdguy05

i had a mpfi v6 in it and i switched to carb. i got the 3 port holley fuel reg. but how do i ahve to rewire my pump now? cause wasnt it wired through the computer before? is there anything else I have to do to the fuel system to make it work with my carb?

KrisW

iTrader: (5)

Your fuel pump relay should still turn the fuel pump on... Did you remove the computer and everything????

The problem is that the fuel pressure will be WAY too high. I think they run in the high 40's on the mpfi engines and you need less than 10. You will need to put in a fuel pressure gauge (even if just for testing and then remove it later) and dial your pressure in appropriately.

You could just put a mechanical pump on it and then swap your tank sending unit to an 82-87 carburetor sending unit...

You could also power your fuel pump relay up from the fuse box to an oil pressure switch on the engine (like your 6 did) and run it that way...

Good luck!!

five7kid

iTrader: (14)

You say you have a 3-port Holley regulator - that probably isn't the right thing. The typical $30 Holley regulator has an inlet port and 2 outlet ports, and controls pressure by dead-heading flow. That's no good - you need a regulator that has an inlet port, outlet port (or ports - how many is immaterial), and a return port. The in-tank pump needs a constant flow of fuel to keep it from overheating, and the normal Holley 3-port regulator will quickly kill the pump.

I was under the impression that the V6 in-tank pump was powered via a timed relay for starting and ECM power for running. As stated, wire it to a switched 12 volt source through an oil pressure switch. It's also not a bad idea to wire it to the starter solenoid as well for priming purposes.

89firebirdguy05

well iwas talkin to a guy that builds smallblocks all day long and he said to just screw it and run a mechanical pump and leave the intank st uff alone..he did it b4 and worked fine.t.he only problem is is that this is a roller motor and the one guy said he does not think the roller motor has a lobe or whatever for a mechanical pump. so what do you think? and if i do decide to use the intank pump..can someone explain how i should wire it.i am not sure of how to wire it to the oil pressure switch, thanks guys!

five7kid

iTrader: (14)

Some factory roller cams (up through '89-'90, from what I gathered) and most aftermarket roller cams have the fuel pump lobe. I know the ZZ4 cam does.

If you don't use the in-tank pump, you need to drop the tank and remove it. There's a sticky on the Carb forum that has good pics of what to do.

Egg83

From what i remember when i did my 2.8 mpfi to 350 carb... Yes, the three port regulator is the correct regulator for your needs. This allows a provision for a return line so that you burn out your pump (The return line allows for pressure AND flow). The return line is essential to keep your stock pump working. You have a 45+ psi pump in tank in your car. The regulator will stage that down to whatever you want. I have the aeromotive 3 port regulator, this can be found in the summit catalog. Take a look at it compared to yours. The inlet port is on the bottom of the regulator which has an adjustable ball valve within the regualtor which regulates the flow to the carb. The other ports can be used to hook up the return line and your carb psi.
Now as for the fuel pump wiring, I know what your talking about. When you turn the key on the pump primes. Then when you attempt to crank it the pump doesnt run. That is because the 2.8 has an oil pressure switch which is a closed switch when there is oil pressure present. This closed switch will complete the circuit for your fuel pump and will give you fuel pressure when the engine is cranking/ running. All you need to do is set up a switch of similair design to make it work. I do not know if the 1.8 oil pressure switch can be re-used. I made a relay for mine. Hope I could help you. -Bob

net_coma

iTrader: (3)

WTF effing nuts...aka read.