First off my car is an 88 Firebird with a 305 TBI.

It first started when my girl and I went to a restaurant. When we left we got in the car and I cranked it up, then it died but i didnt notice. Then I started it again and it ran for a second and then died. I tried for a third time while holding the gas pedal and it started. Stupid me I wanted to see if it would continue doing the problem if I turned it off and cranked it again. Now it wouldnt catch, it would just crank. I took off the TBI housing and had my girl turn the key and I noticed the injectors barely squirting anything out. After a few tries, nothing would spurt out. I checked the fuses too and they are fine. Checked the codes and nothing. The problems that i see that point toward a faulty Fuel Pump is:

1. I would not hear a hum anymore when I turn the key slightly to enable the radio but not to crank it (I assumed that the fuel pump isnt engaging anymore).
2. Injectors would not spit anything out.
3. I had gas and even added 1 more glln just in case.
4. When in a long line waiting(at the Bank)when it's my turn to move, i step on the pedal slightly and it seems to want to die but then catches fine. I noticed this when the car gets hot.

Does this sound good enough to conclude that it is the fuel pump? What else could it be?

If it is the pump how difficult is it to remove the tank and replace it? Thanks.

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Shouldn't bother putting this but hey what the heck:
1988 Maui Blue Firebird 305 TBI stock (WITH NEW PAINT!! YAY! )

 

Check your fuel pump relay. If your relay is bad your fuel pump wont work. If your relay is ok it probably is your pump. Just replace the relay first, they are only like $5. Relays wear out over time so always check them and the fuses first.

 

Thanks Tod. But I replaced the FP relay about a 1.5 months ago, the fuel filter 2 months ago and the the EGR valve at about 3 months ago. How do you check the FP relay? I noticed when I replaced it it had 4 prongs sticking out. Unless I purchased and replaced the wrong relay. I noticed 2 relays on the driver's side and when I was replaced the FP relay i got curious and started the car up without the relay and it hesitated but it started. then I tried it with the other relay off and it started as well. Should the car not have started if the FP relay was disconnected?

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Shouldn't bother putting this but hey what the heck:
1988 Maui Blue Firebird 305 TBI stock (WITH NEW PAINT!! YAY! )

 

The fuel pump relay energizes the fuel pump so if you had it disconnected I dont think your car should have started. When you put the key in the run position the ECM energizes the relay for a couple of seconds then continues to energize it as long as it is receiving ignition pulses( i.e. the engine running ) The way to test it is either replace it or locate the relay and have someone turn the key to run and if it is working you should be able to hear it "click" or buzz when it is energized. I think your post said yours is a 88 so I think I'm not positive but I think your relay should be on your drivers side fire wall and have 5 wires going to it 1 dark green,1 tan/white,1 black/white and 2 orange/black though it may only have 1 orange/black and have 4 wires total. If that sound like the relay you relaced then it may be ok but I would check it again just to make sure, who knows you could have got a cheap relay that wore out allready. When you listen to the relay have the key turned just to run dont try to crank the engine that will make it harder to hear the relay should energize in run. Also check the electrical harness back by the fuel tank where the fuel pump wiring is there is a chance it could have come loose and disconnected. If that all checks out you probably will need to start looking at your pump.

 

My car used to do that exact same thing. I had the IAC changed and it stopped for about a month and a half. It starting doing that again last week and now it is currently in the shop. I'm either thinking it's the fuel pump relay or the damn IAC again. Good luck on figuring out what the hell is happening. l8r

 

Sounds like the pump to me! I've changed a few of then , and they suck! They're not so bad if you're in a shop with a lift and transmission jack, but I couldn't even imagine doing one in the driveway!

The reason your car ran with the FP relay unplugged is after the 2 seconds that the pump runs when the key is turned on, the pump is turned on by the oil pressure switch.

The way to test for a bad fuel pump is to test for 12 volts at the fuel tank connector (I forget which 2 wires) and if you have 12 volts there when the pump should be running, check for pressure with an in-line pressure gauge. If you can't hear the pump running, and you have the 12 volts, you can pretty much skip the pressure test. Try to listen from under the car, or at the filler neck with the gas cap removed.

If you need any more specifics, let me know, I have access to the troubleshooting charts, specs., wiring diagrms, etc... for about just about anything!

Good luck!

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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Starting to look like the Kicker poster child!

 

Well the car started this morning (i also heard the FP engage)and once i shut it off it wouldnt start again. I check the fuel filter and it's fine. Im sure that the intake isnt getting any fuel. Im not sure if this is safe but i use a pipet to squirt some gas into through the top of the TBI and started the car and it ran for a second or two and then died. I tried again with the same results.

I see from what you all said that i need to check is:

1. The fuel pump
2. Oil pressure switch
3. Fuel pump relay (it makes a click or 2 at the same time that i normally hear the FP engaging when i turn the key).

The questions are:
1. Im not good with a volt/multimeter but how would i use it to check connection near the FP?
2. Where is the oil pressure switch located and what does it look like? My Haynes book says it's located on the driver side near the brake booster and distributer. I see something on top of the intake manifold(next to the distrib.) and it looks like a rounded cylinder with a wire coming out of the top of it. Is this it?
3. Since the FP relay makes a click or 2 does that signify that it is working? Can I check it with a volt/multimeter if the latter doesnt mean a anything.

Thanks


[This message has been edited by Highwind (edited November 11, 2000).]

 

PlEASE read and reply to my previous questions...I need my car to get to work and school and all I have is tomorrow (Sunday) to work on it.

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Shouldn't bother putting this but hey what the heck:
1988 Maui Blue Firebird 305 TBI stock (WITH NEW PAINT!! YAY! )

 

When it wouldn't start again, did you hear the pump running? If not, did you hear the relay click, but not the pump run?

You are right on the location of the oil pressure switch.

Unfortunately, without the wiring diagrams in front of me (They're on the computer at work) I'm not sure where to tell you to check with the meter. I wish I could remember, but I usually look it up every time I need it!

I still say it sounds like the pump, but it's a lot of work if that's not it.



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Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Starting to look like the Kicker poster child!

 

JP84Z430HP: Well it doesnt want to start anymore(I just tried right now 11:29 PM), but the FP relay still makes a click when i turn the key. I hear no sound at all from the FP though.

 

The easiest way to check the circiut is to measure voltage directly at the passthrough connector. Get under the rear of the car and look up at where the rear seats go inside the car. You will see a 3-wire connector that attaches to the body. This is the passthrough/connector. You need to check the GREY wire for 12V for the first 2 seconds that the key is on, or while the engine is cranking. If you have 12V (or lights a test light) for both, than the FP relay and oil pressure switch is OK. The hard part is, you can't test it on the harness side, you need to check it at the passthrough side. If you unfold a small paperclip, you can insert it into the back of the connector, just slide it into the connector right next to the grey wire and push it all the way in untill it bottoms out. Then you can plug the connector back in and run your tests. This is known as "backprobing". They do make dedicated backprobing pins, but a small paperclip will work in a bind. If you do have Voltage, than you probably need a fuel pump.

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'87 Trans Am
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'97 Bonneville SSE

 

Actually, ignore the oil pressure switch completely. It's a "backup" to the "real" system. As in, if that oil pressure switch was shot, your car should still run on the "real" system- the relay. It's a nice thing to check if you're checking everything, but don't go nuts diagnosing that part.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

VICTORIOUS!!! Thanks guys, with out your advice i wouldnt have had the courage to take this head on. Ususally with certain things on the car i wouldnt touch. It did turned out to be the pump. I checked the voltage at the electrical switch near the FP and it was getting some current. So i decided to go ahead and take the darn thing apart. Luckily the bolts to the cat werent rusted too much and took little effort to remove it. I got the tank out with the tail pipes and muffler in the way by slightly bending(not cracking) the filler neck. The most trouble I had putting it together was with reinstalling the tank. I couldnt get it to set so that the 2 straps would properly place. After putting it all together I forgot to put the heat shield (oops). Another 10 min past and finally I finished. Thanks to you all and and thanks to my girlfriend who stuck with me the whole day and helped me...Thanks Deni!! Signing out...

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Shouldn't bother putting this but hey what the heck:
1988 Maui Blue Firebird 305 TBI stock (WITH NEW PAINT!! YAY! )