musclecar70sfan

iTrader: (1)

Literally a few days before I was going to park her for the winter, my 91 TA (LB9 engine) has crapped out on me on my way to school this morning. Here's the chain of events:

This morning I noticed that the gas level was really low, however I figured that I'd make it if I drive gently (no time to go get gas lol).

When I stopped at a red light, the engine suddenly started idling very roughly, and when I was pulling out of there the engine was sputtering and popping badly (intake backfire?).

I was barely able to hit 10 mph and the thing finally died 80 feet later. Fortunately this was (literally) right in front of the school parking lot and a couple of guys helped me push it off of the street and into the parking lot.

I filled it up with some gas and it would barely start, run like crap for a few seconds, then die.

And now I don't hear the fuel pump buzzing when I turn the key. Fortunately AAA is gonna tow the car home a little later (typing all of this during a break between classes right now LOL).

I'm not sure how old the pump is (car has 105k mi), and maybe me running it really low finally did it in?

musclecar70sfan

iTrader: (1)

Bump.... I'm pretty sure it's the fuel pump but I just wanted to double check with you guys in case there's anything else that might've gone bad, like the relay. How do I check that?

tavert91

iTrader: (1)

Could be you plugged the fuel filter with junk pulled from the bottom of the tank if you were really that low on gas. If you do not have a way to check the fuel pressure, you might try swapping out the filter for a new one before doing anything with the pump.

camaro1185

If you don't hear the FP prime, its most likely the FP. It can also be the FP relay or fuse, check those first. I guess it can be the oil pressure sensor that may not be sensing a min of 6? psi when you crank the car. If that was the case though you would still hear the FP prime I think.

I'd look at the fact that you don't have much gas in the the tank as a plus, you ever tried to wrestle with a full fuel tank, its not fun at all.

bluers91

If your SES light is on check for ecm error codes. Mine threw a code 54 when my pump went out.

On my tbi I could test if it was fuel related by spraying starter fluid into throttle body while cranking and it would try to start.

musclecar70sfan

iTrader: (1)

Well back at school when I was desperately trying to start it, I saw the oil pressure gauge rising slowly as it cranked. I will check out the fuses sometime though. But yeah, I only have a couple gallons in there from when I was poured some in thinking it was just out of gas.

The SES light came on when the engine stalled, so I'm guessing it's just the normal Code 12 (no pulse) because the engine just doesn't run. But I'll check what the ECM has to say when I get the chance.

And the thing is that the TA isn't stored at my house and I have work and finals coming up in school, plus my DD (94 Jimmy) needs a new starter very soon, along with an ignition module, and possibly an alternator. Soooo I am SWAMPED right now! As a result, I'm not sure when I'll be able to visit the TA and confirm the diagnosis myself and then begin fixing it. Oh well, at least it's time for the TA's hibernation anyway... I've seen salt dumped on our roads here in CT a few days ago. But my winter break is coming up soon so I'll have a lot more spare time.

stealth908

iTrader: (2)

Change the fuel pump. Gas lubricates the pump. If there is no gas, the pump runs dry and seizes after so long.

musclecar70sfan

iTrader: (1)

Uh... as strange as this sounds, my TA seems to be working again.

Today I decided to stop by the place where it's stored after work and just for kicks I turned the key. I heard the pump prime and it fired up like nothing happened. I even revved it to 4000 rpm without any troubles. I didn't take it for a ride though.



It's been sitting untouched since last Tuesday, when it broke down. Considering how it miraculously started and ran well, I'm thinking that maybe I have a squirrely fuel pump relay or other electrical issues? Or maybe the pump got clogged with crud from me running it so low on gas, and now that it's been sitting with some more gas in the tank, the fuel pump was submerged a bit and some of the crud came out?

I'm not gonna leave the car alone now, I still wanna know why it stalled and I wanna prevent that from happening again.

Let me just run over the symptoms and conditions in case somebody else can think of any other problems....

• I was driving with no issues to school last Tuesday morning while I was pretty low on gas.
• It didn't start giving me trouble until I stopped at a red light. Started idling rough, and it was barely able to hit 10 mph when I was pulling out of the intersection. The engine was running like crap and popping really loudly (intake backfire?). Does an engine normally pop like that when it's getting starved of fuel?
• I poured a couple gallons of gas into it thinking it ran out.
• It died a few dozen feet later and did manage to restart but it still ran like crap to the point it died again and I wasn't able to get it started at all. I did NOT hear the fuel pump priming when I was trying to start it.
• Got it towed to my garage, and I tried cranking it one more time that. No noise from the pump, no fire. My dad was there as a witness lol.
• Sat in a cold garage for over a week up to today when I stopped by and it somehow started like normal.

What is going on?!

camaro1185

Sounds like some sort of problem that may have been caused by heat (heat soak on the relay or pump) or a loose connecton.

I would ohm out the wires going to the FP, but if it were me I would splice in a new pigtail. Also, I would get under it, wiggle the connector and then try and prime the pump. I would also replace the FP relay just for some peace of mind. Then again, depending on your mileage, it could very well be the pump.

musclecar70sfan

iTrader: (1)

I'll definitely check that out. As for mileage, I got about 105k on it. I bought it from the PO with 98k about a year and a half ago. I guess it's worth noting that the car has been sitting in the previous owner's backyard for about a year (owned it for 2 years, drove it the first and parked it the second) and he told me that when he bought the car, it's been sitting for a while as well. I'm sure that didn't do much good for the FP.

musclecar70sfan

iTrader: (1)

Well I had a chance to tinker with the car again a few days ago, and it started up like normal. I ran it for 10 minutes, occasionally revving it, with no problems.

camaro1185 might be right when he suggested a heat-soak issue, but that still wouldn't fully explain it. After the car crapped out on me that day, it sat for about 7 hours in the parking lot before it got towed, and I tried starting it again at around that time with no luck. I'm sure that's enough time to have it cool down completely, especially with temps being in the low 40s all day.

Can it be a screwy TPS? Maybe a fuel relay or oil pressure switch? Although I do hear the fuel relay clicking and the pump buzzing like normal right now.

I always thought that a fuel pump failure would be instant with the car crapping out with no warning, am I wrong?

What kind of numbers should I see on the meter if I the resistance to the fuel pump?

Sorry if this is a dumb question (I'm still learning), but is my only option right now to let the engine run in the driveway until it gives me trouble again? It's hard to diagnose a problem when it's not occurring.

But on the bright side, it turns out that my Jimmy just had a weak battery and ignition coil. Replaced those and it cranks fine and voltage is nice and solid; don't trust the Autozone battery/starter/alternator tester, it was telling me that it was time for a new starter and alternator.

Thanks and Merry Christmas!

jak

Fuel pump may still be the way to go here..I have had many pumps go out on me hit the bottom of the fuel tank a few times and wala pump " miracously" works again...Check the relays and fuses as previously stated..If you find no definate reason for that pump not working When it stalled on you...Replace it...Also as previously stated 2 gallons of gas makes it easier to drop the tank lol...

Krik

iTrader: (4)

If you ever suspect a furl pump problem with a car that won't stop, spray some starting fluid into the intake. Its dangerous so don't use it for very long, but as a diagnostic tool its very helpful.

Zig

I agree with the FP. I have had FPs work when cold then fizzle out after a while. If you do replace it, get a good one. As someone stated earlier, you don't want to wrestle with the gas tank and rear end more than once.

By the way, when the fuel pump starts to crap out when it gets warm, you can actually hear it's whine start fluctuating. Drove my 91 Z28 from CA to TX and made it to the AZ border when I started hearing mine fluctuate. about 10 minutes later I was sitting along the side of the road. Fortunately we had two vehicles (the other was capable of towing 9000 lbs) so I was able to rent a trailer and get it to the new house. I didn't head my comment above replaced the FP again (with another poarts store OEM type). 18 months later when that FP went out, I put a Walbro in it. So far so good.

Krik

iTrader: (4)

Do not cheap out on a fuel pump

Get the best pump you can find, even if it means waiting till you get a bit more money, or borrow some if you have to. DO NOT BUY AN AIRTEX FUEL PUMP! Don't ask me how I know lol.

musclecar70sfan

iTrader: (1)

Thanks guys, I was thinking about buying the factory Delco pump (or whatever GM used 20 years ago), either that or the Walbro like Zig suggested. Any other recommendations? And Zig, when your Camaro died, was it popping through the intake shortly before it did? Just wondering.