Pontiackid

on my 91 bird, 305 tbi it wont fire now. i had put the car away a month or more ago, and i went to just fire it up recently and nothing, it ran fine when put it, but i left it with very low gas. It runs if you dump a little gas down the throttle body. when i turn on the car i dont hear the pump at all. could the line be frozen or pump be frozen? or cold the pump just could of went out on it? how can i tell for sure before i rip it all apart. thanks

Pontiackid

also before i put the car away, my oil pressure gage would be really low, even when flooring it. anyone know about this??

ringo234

When mine did that it was the fuel pump. Apparently if you try to start our cars when there out of gas it doesn't take too long before the pump burns out.

TexasSilhouette

Check for power to the fuel pump connector, if you are getting power to the pump but it still does not run then there is little else it can be. Make sure you have gas.

The in tank pumps use the fuel to keep them cool, there is a wrapper around them that soaks up some fuel to keep them cool when you are low. If you run them too long on empty, it can and frequently will burn them up. Plugged filters make them run hotter than usual and will shorten their life as well.

Pontiackid

alright, well i had put 3 gallons in though. another possibility is a mouse could've chewed the wire/s. could it possibly be the oil sending unit that could be causing it to do this?

TexasSilhouette

The symptom of a bad sender is that the car dies after starting. Cranking causes the pump to run, oil pressure keeps it running.

Checking the power at the pump answers the question.

Pontiackid

it never dies. but ill have to do that this weekend, i dont have a manual though. how do i check the wires to the pump?

Pontiackid

well i did the by pass thing where u find the red wire with a connector on the passenger side. and i put the wire in it and the pump turned on, and then i tried starting it while someone put it on there and it stilll woulnt fire. anyone know what it could be now?

deadbird

Just correction.. the sender is for the gauge.
The oil pump switch is a failsafe for the fuel pump. It has zero to do with the fuel pump running unless, the relay has 'bought the farm' (died).

The oil pressure switch can be omitted from the harness and the fuel pump will run.
The fuel pump relay is switched by the ECM and stays that way as long as there is a tach signal to the ECM (read: the engine is cranking/running).

THe oil pressure switch is a very common misconception about saving the car if the oil pressure drops below 'X'psi (3-5psi is when it closes btw) or making the fuel pump run.

It, the oil pressure switch, is only there to assure the pump will keep running in the event the relay fails.

Pontiackid

well today i was working on it and i took the gas line off right by the tbi, by passed the fuel pump and fuel sprayed out. then i went and bought a new relay ( the one by teh drivers side firewall, there is two) and put that in and still no start. i also checked the fure down by the batter the 20A one and it was blown so i switched that and still no start. its also got spark and everything. what could be wrong now?

Pontiackid

anyone have a clue?

goalieforlife

Did ya change the filter?

Gramps

how old is that gas?

__________________

Quote "i dont play with engines with less than 8 cylinders"

Pontiackid

no didnt change the filter. but the pump isnt priming when i turn the key so i dont think its that. and the gas was new, it was pretty low, and the car was sitting a month and i tried starting it. no start. so i put 5 gallons of new stuff in adn still no start.

deadbird

Have you tested the pressure ? Pushing it out the unrestricted line and building pressure are two different things.
Have someone crank the engine and observe the spray from the injectors. Or, just make sure the injectors or even pulsing (they are on a fused circuit).

The pump should be priming for 2 seconds when you turn the key to the 'run' position. You should also be able to hear the relay switching. There is no fuse for the relay (excluding the 20A under the hood which is power to the pump & ECM), the ECM controls power and ground for turning the relay on/off.

This just recently happened to a friends truck I put a TPI on. He let it sit for a period and the pump went to the the great beyond. The pump will run just fine (audibly since the tank is in the cab) and fuel will come out the schrader valve on the rail (not impressivly) but, 1-2psi at the rail doesn't do much for a TPI trying to start.

Pontiackid

alright. well it has no prime when i turn the key. only way it primes is if i jump the red wire for it. and even with it primed by hot wiring it, it still wont start. where is the relay located for the pump, is it the one by itself on the passenger side, or is it one of the two on the drivers side next to each other. yea i just had the line diconnected and it sprayed out. do i just take the air cleaner off and look down there to see if fuel spits out or what?
thanks

mystikkal_69

try reseating the ecm connections. drop the ecm and physically disconnect the ecm for few minutes and reconnect it. see if will prime then.

i had the same problem with the tbi in my 89 and the ecm was at fault.

Pontiackid

alright, where exactly is the ecm located. i need to get a manual for it.

mystikkal_69

passanger side. right above where your feet would be. there should be (3) - 7 mm screws holding the plastic cover in place. once the cover is removed you will see an aluminum box with a **** load of wires attached to it. that is your ecm (engine computer).

Pontiackid

ok sounds good, i will try that this week. messed around today with it for a little bit and i had a friend try to start. i took off the air cleaner and look down the tbi and i didnt see any fuel spraying in, is that where you look?

deadbird

Yes, you should see some fuel spraying (in pulses) at the throttle blades.

Pontiackid

well even with the pump prime jumped, i still didnt see any fuel spray in. im thinking its the fuel pump.

Pontiackid

alright well i pulled the ecm down and unplugged it for about 5 minutes. i plugged it back in and still no prime.

mystikkal_69

when you turn the forward watch the ses light carfully. does it blink once before staying on solid? or does just turn right on without blinking?

Pontiackid

sorry i went down to see the light what it did, but i left the hatch open so the battery was almost dead. which light is the ses. i was getting the securty light and another red one. which one is the ses?

mystikkal_69

SES = Service Engine Soon(Orange Colored Indicator). if it's not even coming on at all, and ALL the fuses have been checked then the ecm is bad.

Pontiackid

well i know right before i had put the car away. the light would come on sometimes and go off. i dont have a cat though so it could be from that. last night even though the battery was almost dead. that light wasnt coming on.i know there was a 91 or 92 firebird at the junkyard with a 305 tbi in it. would that ecm work?

Pontiackid

i got a different ecm and put it in my car and still has no prime. i also checked again and no fuel spraying out of the injectors at all. when i primed the pump fuel shot out of the hose when i disconnected it from the tbi, so could the injectors be plugged or what?

Pontiackid

im going to try putting a new fuel pump in on tuesday, so i will see what that gives me.