I just finished droping a new engine in my camaro (see sig.) and i am using a quadrajet insted of the tbi. The thing is though that i am going to use the factory fuel pump with a regulatory/bypass. That is all well and good but i cant figure out why the pump is cutting off after the intital priming cycle that it runs after the ignition is turned on. I am also not using the oil pressure switch that controls the fan. I broke it in half when pulling it out so to tune it i just put a plastic tiestrap around the bottom on the actually pressure "button". This worked for a little while but I am wondering if there is some other part of the computer that is controling the fuel pump. I have not yet tested the oil pressure switch to see if it just decided to up and die while i was tuning it but if that isn't the problem I dont have anymore ideas. I looked in my Hayes manual and there is not a wiring diagram for a 305 with TBI injection so I dont know exactly what I am looking for. I might have to end up hard wiring it to the ignition circut but I would prefer to do that last. Any help would be appriciated...

 

I figured out a lot about the function of the fuel pump when my own died about a year ago.

The fuel pump only primes the system for a good 2 seconds. It is by design that it shuts off. After it has primed and not started, the pump will not prime again for a good 20-30 seconds. It is also by design.

The power to the pump comes from the fuel pump relay. In my own car the wire to the pump is a tan/white stripe color it follows along the inside of the car from the center of the rear seat along the top of the driveshaft to the driver's side door joining the wiring harness from the rear to the driver's side interior light then through the firewall to the relay I think.

Only 3 wires go to the tank, ground, 12 V power and the fuel level sender.

When my pump had died I tied in a 12 V direct feed to the pump to keep it running and was able to get the pump to come a live a few times with some "massaging" of the tank <ie hit the tank at the top with a rubber hammer>.

You can feed a 12 V line from say the circuit based off the stereo since that has 2 power feeds that 1 is tied to ignition and the other to the "radio" on position of the key as well.

 

Fix the oil pressure switch and your problem will be solved. If it doesn't sense oil pressure it shuts it down for safety reasons. The computer is thinking the engine isn't running.

Lon

 

lol.. not this again. That's not an oil pressure cutoff. It's a backup unit. But he's right, it'll fix the problem. That switch is there to supply power to the fuel pump in case of failure of the fuel pump relay while you're in traffic. If you replace the switch and spend a few extra seconds cranking the motor so the oil pressure switch sees pressure, it'll kick the fuel pump itself. Without the relay working, it *will* act as a cutoff, though (obviously if it's the only power source and it fails, it kinda becomes a cutoff), so make sure you keep that switch happy.

 

I have a 2005 Ford Taurus 3.0L. It hs a new fuel pump, fuel filter, fuel rail pressure sensor. The fuel pump comes on as the is being cranked. Once it starts, the fuel pump turns off right away.. what switch are you guys talking about that fixes this issue?

thanks in advance!!

 

we're a forum for 82-92 camaros and firebirds. We don't have any wiring diagrams or experience on a Taurus to help you out. I don't know if theres Taurus forums but that would be a place to start.

 

oh I misread, sorry and Thnks

 

No. Not correct at all. I can't believe this lore still persists and a moderator of all people, posted it.