Hi all. Just got my motor up and running tonight. I have a problem though. I am running an electric TPI pump in the tank with an aeromotive regulator meant to convert EFI to carb pressure. When I turn the key to accesory, the gauge on the carb feed line goes to 7 or so PSI, and as soon as I start the car, it drops to 0 and stays there. The car will run for a few minutes and then shut off. Does the vacuum port on the reg have to be hooked up? I thought I read in the directions that that was only for forced induction, but I could be wrong.

The pump is only a few years old, and it had good pressure with the EFI setup which was only removed a few months ago. Any ideas? Fuel filter is new, carb is fairly new. Should I be looking for anything?

 

Sounds like you're getting the timed relay powering the fuel pump when you turn on the ignition, but the pump isn't getting running power. Something must have been disabled when you went to carb.

 

Check the oil pressure switch wiring.

 

I have a frankenstien motor. The engine itself is a 92, wiring harness is an 88
, and the car is an 86. PROM is burned based on an 89 L98 though. I don't have that big oil press sensor on it.....the one that goes down by the oil filter. The oil pressure sensor for the gauge that goes in the back of the block is there though. Could this be the problem, and if so, can I "hotwire" the pump somehow?

 

Without the oil pressure switch you've got nothing powering the fuel pump after the initial prime.

 

So do I NEED that switch to be there, or can I get around it? I'd hate to spend 30$ on the thing when all it does is keep the pump going.

 

You can get around it, but the oil pressure switch is the best way to do it.

 

Well, I got the car to stay running today and it ran BEAUTIFULLY. I jumped the big orange wire and the white/tan wires for the fuel pump relay. Does that mean it's just a bad relay, or do you think it's possibly still the switch too?

Also, another question now. When the car was EFI, I had a Holley 255 LPH pump in the tank. Now that it's carbed and I bought a regulator, I can't get the regulator to go below 8 psi, even with the screw all the way out. Is this too high, or should it be fine? I'm just wondering if this is because of the high flow pump or if there could be something else wrong. . .

I am pretty stoked about this, this is the closest this car has ever been to being streetable in the past 3 years!!!!!!

 

The relay is probably fine, but without the original computer-controlled distributor the ECM won't ever know the car is running, so it won't know to energize the fuel pump relay.

8 PSI is a little high for a carb. Usually they don't like any more than 6 1/2 PSI or so.

 

Yea thats what I figured on the psi. Unfortunately, I don't know how to get it lowered! I would rather not change out my pump to a lower flow one, but It might come down to that.

I'll get that switch hooked up and screw around with the reg a little bit and let ya know how it goes. Thanks for all the help this far!!