1987 Firbird 305 TPI

Fuel pump always runs and i cant figure it out ive searched and searched


With everything unplugged ( fuelpump relay and Oil pressure switch) Pump still is always on.... tried a new relay also still no luck. I have to unplug the weatherpacked fuse to get to shut off. when i fire her up she stumbles a bit and when driven she sometimes bucks. loss of power.

Every sensor new except op switch. i was told that with the op switch unpplugged it would shut down the fuel pump. No go tho. cant figure why the pump wont shut off.

she used to chirp into second.....haha. I refuse to drive it like this because it dont feel right, and i may cause further damage.

Thanks guys once again

 

Bump

 

Has it always been like this or has it worked properly before?

You might check the wiring. Maybe someone put a 12v run hot wire to the pump wiring.

 

yeah it just started acting up about a month ago. it did run properly before. i will be putting in a new pump when i do my rear end swap. but from what i know that wont fix this issue.

I also want mention when i plug the weather packed fuse in i can hear a bubbling noise in the fuel rail for a few seconds. never did this before.

Fireturd350 as far as i can see there is no extra 12v run hot wire rigged , that i can see from engine bay or under car.

 

Bump

 

It sounds like you've tried everything. Just to clarify, you unplugged the OP switch behind the distributor ( not the one by the oli filter)? that's about the only other thing I could think of, except for a wire getting 12V from somewhere it shouldn't...

 

yes i unplugged the op and the pump still runs.

 

If it ran correctly before. It has to be either a sensor that is bad somewhere, frayed wire, relay, or run-hot only wire that is making a connection where it shouldn't. You'll just have to start tracing wiring back to see what is tripping the relay or has frayed that's causing the issue. Wiring problems can sometimes be a real pain to find. It took me 2 weeks just to figure out I forgot a ground wire that fell down ontop of the transmission bellhousing out of sight that was required for my speedometer to work.

 

i will look into it this week some time.

 

Have you checked the connectors themselves to confirm power is not passing direct from the batt to the pump

The early non weatherpack connectors have a habit of loosing the insulation allowing shorts to ground or relay bypass when the wires touch

 

IIRC, there is a way to jump power to the fuel pump through the ALDL connector. You may want to look there as well.

 

Yes my weather pack does have some insulation missing i will post pictures soon.
i will also check the aldl also.
I will keep updating this post until i figure it out.

 

OK. so i wiggled all the relays nothing..... Then i wiggled grabbed the wire harness behind the motor and sure enough it shut the pump down. found my problem. Now would this cause running issues at idle? stumbling ect?

Cause i figure it might not be my running issue because i think the pump is supposed to run full time anyways while engine is fired up.

I'm also worried about having to replace the harness.... Any suggestions?)

Thanks guys, as always a big hand indeed.

 

Mine look exacly the same

 

Anybody?

 

A 2010 as a rat rod

 

wrong thread whoops

i meant to say i fixed the issue with the wire grounding out. had to pull harness back and make repairs.
NOW I HAVE A WHOLE OTHER SET OF ISSUES!!!!! AHAHAHAHAHA

 

1. Where exactly are the connectors from the above pics located? I need to check them preemptively on my car.

2. As I recall the oil pressure sensor serves as a backup for the fuel pump relay when that relay dies. Perhaps your relay died and the oil pressure unit is also defective, resulting in this weird combination?

3. Bubbling in the fuel rails? The fuel from the rails usually returns to the tank when the engine is shut off, at least so much that the pressure reduces itself. So the sound may be normal when the pump primes the lines and sends fuel into the rails to build pressure. If you suspect your running issues to be fuel related, you may want to check the fuel pressure regulator for issues.

 

Somebody else's pic

 

That would result in a open circuit giving no power to the pump.
Other than a wiring fault injecting 12V into the pump circuit , the only way to get the pump to run fulltime is for the relay
or the OP switch to be permanently in the closed position

 

Looks like after reading the rules as long as it sits in a structure it will be legal. Sounds like your chassis guy is on it.

In for pics for sure!