1986 Camaro Z28 TPI LB9 Auto
BAH--As you all know i have been having this cutting out problem, well today, i drove it around the neighborhood like usual and it cut out some. But when i about got around the block it just would NOT want to move...it would idle barley, and if u give it gas it would flood like hell and die, start-up ok, but then just to die. One thing i noticed is it has about 10 psi pressure and i unhooked the fuel gauge on the shrader valve and fuel just kept coming and coming until i finally got the guage back on! how in the heck is the reading 10 psi and a WHOLE crap load of fuel spills out? i did check with another known good gauge and the same. The fuel pump does turn. The car WILL NOT start. When you first crank it, it kinda acts like it wants to start but for only a sec, just seems like no fuel getting to cylinders. Maybe the regulator is jammed, therefore making it seem as if 10 psi, and making all the fuel spill out constantly. The thing i dont understand is how is it all coming out? the pump should be on all the time, which i dont think it is. what do you guys think? i am also getting a code 34. Bad Pump, Regulator?

 

tpi engines need like 40 psi to the rail. it seems like the fuel filter is clogged. after that the fuel pump might be on its way out. the fuel pump will not stay on all the time. it primes then will turn back on when it gets the signal from the computer that the engine is running.

 

10 psi is still a pretty lot of pressure.. a carbed cars run way lower then that and i can guarantee if you leave the pump running with an eletric or crank a mech pump with an unhooked fuel line you will have a huge mess on your hands in a matter of seconds.. like jw said start with a new fuel filter sinces its the easiest and cheapest and may just be your problem.. if not you still have a new fuel filter and you've eliminated a suspect part.

 

Good. You've got a pressure gauge. Put it back on the Schrader valve. Pinch the fuel retirn line from the regulator (it's easier to access on teh left side of the engine bay) and turn on the key to read fuel pressure. If the regulator is "jammed", that will raise pressure to at least 45 PSIG. If the pump is failing or the filter is plugged, the pressure won't increase.

Either way, anything less than 34 PSIG is going to cause problems (just like it is now). Don't even consider the MAF issue until you resolve the fuel pressure problem.

 

Could any get me a picture of the fuel return line or tell me where it is?

 

the fuel return line is the smaller of the two fuel lines in the engine bay.

 

Ok--i put in a new filter and didnt change a darn thing. i pinched the fuel return line and let the pump run a couple times and still only 3 psi pressure. i think its pressure regulator....what do u guys think?

 

If you installed a new filter, and pinched the fuel return line shut, and still only produced 3 PSI, I'll bet the pump is failing. Pinching the fuel return prevents the regulator from relieving pressure back to the tank, so even if the regulator has failed, you should produce at least 45 PSIG with a good pump.

 

Well i may have pinched the wrong line!lol OK, there are two lines going to the fuel rail, they come up along the drivers side in the engine bay, and they go from metal lines to rubber, then back to metal, i pinched both those lines and no change. But above i didnt see Vader said the one by the regulator, well the ones i pinched werent by the regulator, so maybe the AFPR is trashed, because the fuel pump turns on and primes, so...i dunno..today after school i will go pinch the return line from the regulator and see if that help! *** i pray it does! I will update u guys, i wont have much time to test cause im going to church tonight. lol FYI something thats pissing me off is my dad has a ford and is really getting the best of my Chevy right now, so i gotta get her fixed before my wall gets a couple more hole--lol

Thanks,
Blue

 

On the left side of the engine bay, there are two rubber hoses that make the transition from the steel lines on the frame rail to the steel lines on the engine. One of these has a smaller diameter. The steel lines on the frame rail are also different sizes. The smaller one is the fuel return line from the regulator. Carefully pinch that rubber hose closed while monitoring fuel pressure. If the pressure increases, the regulator is suspect. If the pressure doesn't increase, the pump is suspect. Closing the line prevents the regulator from dumping excess fuel back to the tank, and should create fuel pressure at the rail up to the maximum output pressure capability of the pump. If that isn't at least 45 PSIG, your pump is suspect.

 

Since i cant start it i guess i can just get some vice grips and pinch it off and let the fuel pump run a few times and see if it changes?

 

Well, i feared the worst and it happend. I took the fuel filter off and let the line hang and put a container underneath and turned the key on and it primed normal, no fuel came out. So I did this a few more times, and still no fuel. The fuel pump makes this sound as if its bubbling inside!? So i guess i need a new fuel pump. Thanks for all you help guys...any more input appreciated....thanks

Blue

 

Can Anyone Verify the pump is bad? i know i have about 3-4 gallons of fuel and when i prime it nothing comes out. It turns on and all just no fuel.....

 

I'd say a good test would be to make sure there's a couple of gallons of fuel in it, and see how much comes out when it's supposed to prime. If no fuel cpmes out, it's a bad sign.

Also, listen to it, and see if it makes unusual noises, like maybe bubbling. That's another bad sign.

Seriously, it doesn't seem that there's any way around it; if the pump doesn't work, you need another one. You're just going to have to put a new one in if you want your car to run.

 

how long does the pump turn on? make sure the pump has time to pump out the line before you just replace the pump. ive actualy replaced a couple pumps and they stopped working(i couldnt hear them) im not saying yours is not on its way out but if you can hear it then it should be pumping a little bit at least.
maybe your pickup is plugged.

 

a little noise is normal. i hear my pump whine as soon as i hit the key and i have a constant 45psi at the rail. but ive never heard it bubble. you might have burned it out.

not to further discourage you, but changing a fuel pump on our cars is definatly in the top 5 of the list of "least fun things to do in a thirdgen" if someone hasnt already cut a hole in your trunk to get to it, then you have to pull the tank. and that means youre muffler, panhard rod, and axle all have to come out of there or at least be moved. not a very fun task. you have my sympathy...