firebirdpower7

hi, i just swapped out the 305tbi in my 91 firebird with an ol '72 350 with a q-jet carb. when feeding fuel to the carb i just hooked it up to the original feed and return lines in the engine compartment using a holly fuel pressure regulator (i dont remember what model i think its 12-803 but i can double check in the morning if you want).

the problem is that im not getting any fuel pressure, the pump kicks on for a second when you first turn the key on but then wont turn on again. since its not kicking on it obviously isnt keeping any fuel pressure.

i dont know what is wrong. did i not plug in a wire that i needed to ?(by the way its using the older style distributer, it has a kit inside it that makes it pointsless) do i need to rewire it? plumbed wrong? i still have the mechanical pump that originally came on the engine, will it be easyer to hook that up? ...

any help would be greatly appreciated

Brando5641

iTrader: (-1)

Yea its wired wrong. The ecu will prime it untill it see's rotation from the engine and then it will turn back on. Problem is you pulled all that out. You just need to put a key on 12v wire to the signal terminal on the fuel pump relay and it will come on with the key. If it where me i would pull the pump out of the tank and run the mechanical pump.

flyingputz

Brando or anyone else out there in yhe know; I'm soon gonna be installing a carbed 383 in my '89 RS. Whats the best and safest way to run the 12 volt "key on" power to the fuel pump relay? Also, with my ecm removed, will engine crank over, or will more rewiring be necessary? My car has the VATS setup, so I'm not sure if this will interrupt cranking when ecm is removed. Thanks.

firebirdpower7

thanks alot for the help. i'lll get on that as soon as possible.

i thought about doin the mechanical pump but i already have it all plumbed up this way with some steel braided line(not cheap) and custom fabricated a bracket for mounting the regulator/pressure gauge.

but if i have any more issues after i rewire it i'll just have to go with that, would there be anything to keep in mind if i do end up using the mechanical?

fireturd350

iTrader: (8)

Wiring the relay to run hot should fix it. Worked fine with mine.

Going to mechanical is way too much work in my opinion. You'd probably have to do research to see if it would draw through the unpowered fuel pump in tank. If not you'd have to drop the tank and remove it for a carb pickup. You'd have to plumb different lines like stated.

firebirdpower7

ya i am going to just rewire that relay but i was just wondering about the mechanical incase i had any more problems with it

Brando5641

iTrader: (-1)

No you can not pull threw the dead pump in the tank. I was told on here by some one that you could and that's false. All that will need to be done is the pump in the tank needs to be removed and extend the steel pickup tube in the tank to the same length as when the pump was in it.

FYI you will have to do somthing about the VATS as "flying" mentioned if you havent already worked out that issue. If not just find the starter relay ( i think its behind the drivers side kick panel) and run the 12v "crank" wire off the ignition switch to power the relay. Im pretty sure its a yellow wire but its been a while. Just crawl under there with a test light or meter and start hitting the key and probing wires till you find it.

Damon

The factory fuel pump has a second path to get voltage, even without the ECM. It's through the oil pressure sending unit (driver's side, screwed into the block just above the oil filter). This is the circuit through which power is supplied to the fuel pump under normal running conditions in most carb-swap applications that use the existing in-tank pump. Including many I have done myself.

If you look at the plug that goes on the oil pressure sending unit you will see 3 wires. One is a "resistance to ground" connection that supplies reference to the oil pressure gague in the dash. The other two are specifically to run the in-tank fuel pump. One wire is 12V hot all the time (direct battery voltage), the other wire runs to the in-tank fuel pump. When oil pressure hits about 5-6 PSI it directly connects the 12V hot wire to the wire leading to the in-tank fuel pump to run it. In other words, if there is any significant oil pressure present it will run the fuel pump.

But only if it's hooked up and the OPSU is in good operating condition.

Fixing a problem with this circuit/sender is usually a lot easier than adding your own fuel pump activation circuit.

redneckjoe

i pulled the pump out of the tank and made my own pickup. im using a mechanical pump and have had no problems at all. also using a holley fuel pressure regulater.

although not everybody will agree, i went carb for the simplicity and reliability. keeping the electric pump in the tank just seemed to oppose my goals.

Ozz1967

iTrader: (4)

If you run a mechanical fuel pump that's mounted to the engine block, you don't need a regulator unless you pick up one of the racing pumps that kicks out like 60psi or so. As for electric pumps, I dumped my mechanical and installed an in-tank electric pump. I like it much better than my old mechanical one. I also won't have any vapor lock issues.

MYZROCKCamaro

I have an issue where I have a new pump in the tank, new return regulator and a new gauge. Engine runs fine and no issues there. But I am getting no reading on the gauge what's so ever. It's a new 4411 autometer. fuel is there but no movement on the dial at all. Any thoughts?