jester_587

I have a 86 IROC-Z, 305 TPI, AUTOMATIC. I have put 5 fuel pumps in the car in 6 months. Symptoms... Lots of pressure in the tank after driving a while on hot days. Fuel pump will start to whine off and on, and the fuel gauge will rise and fall with the whine. The car will then loose power and stall out. I had my last 3 pumps put in by NAPA and with the last pump change, when I got the car back it was Idling at 400 RPM. Now when I start it in the morning It will try to Idle at about 250 and Die as soon as I put it in gear, so I have to hold the gas down a little to avoid that happening. After i warms up a little it will stay running but will surge about 200 rpm both ways. When the off and on whining starts I can stop the car and open the gas cap and LOTS of pressure will come OUT of the tank. If I have a full tank of gas when this starts to happen and I open the cap, the gas will pour out of the tank. NAPA put a new harnes on the pump and new fuel filters, new pump and strainer. Still have the same problem but now I have a rough idle and a check engine light. Please help!!

maitlandtron

Maybe someone else will chime in but it sounds like your fuel line might be clogged. Or maybe something clgging your fuel pressure regulator. Have you tried checking your fuel pressure?

92 Z-28 Camaro

Hi Folks
You need to get a fuel pressure gauge hook it to the fuel rail; tape it on your windshield, and do some driving around – look at the pressure and the road. I think it should be about 40lbs for your car. The other question I have – do you keep the car ¼ to ½ full with gas or do let it run down. The reason for the question is this, fuel is used to lubricate the pump and keep it cool. Running low on fuel will only cause problems and burn them up, especially in turns. You might have plugged fuel injectors or low fuel pressure that is causing the low idle issue.
Thanks
Bill

8Mike9

My uneducated guess, is you have an issue with your fuel cannister, that big round plastioc thing on the drivers side of the engine bay...it's supposed to vent the fuel (via a check valve somewhere) so the fumes go into it, then a solenoid opens up during smoe start up period and reburns those spent fumes through the throttle body.

I'd just be guessing, but seems like you're not ventning anything?

Other thing, ans etioned before, is a clogged line..but it'd have to be the return line, sine the fuel pump is a positive displacement pump, it builds pressure of it's "deadheaded"...i/e the return line is clogged or pinched shut...so then theres no flow through the pump, although the pump is still turning, and it gets hotter and hotter until it fails.

Plese forgive the typos, I'm too lazy to correct.

jester_587

I disconnected the Fuel return line at both ends and blew compressed air through it and found no restrictions. From what I understand the Fuel Vapor canister up front will have a tell tail sign of failure and will have wet fuel leaking out of the bottom of it. Mine does not have this. I also had NAPA check it and they said it was fine but I dont trust auto shops. I usually Get a fill up every time I get gas and drive untill the car is about 1/4 tank, then fill up again. I had an 89 Camaro RS and I always ran it just about dry and never had to replace the fuel pump in the 8 years that I drove it, I am aware that the fuel cools the pump though. Fuel pressure was checked with every new pump that was installed and everything seems fine for a while then I get the same problem with the whining off and on. As for the pressure regulator I was told by every auto shop in town that the regulator is not the problem but like I said I dont trust auto shops. I got a 24 flash code today, so Im thinking MAF for the low Idle. The check valve new the charcoal canister has been swapped out with a good one and did not fix my problem with the eccessive pressure in the tank. Other Ideas??? I have been dealing with this problem for over 6 months and I have talked to everybody I can get ahold of. The only think I have not done is replace the fuel tank, fuel lines and charcoal canister, or pressure regulator, the injectors are stock also. The car is an 86 and only has 70k miles so I dont think the injectors are bad but I just dont know what to do at this point. Thanks for everybodys responses keep them comming.

Xlr8torZ28

iTrader: (19)

Allways do the simple stuff first. Get a new gas cap. And check the ventilation tube on the tank. You will have a rubber hose with a little plastic air valve on the end, that mounts to the body of the car near the gas tank.

Lo-tec

Something in the system is causing the pump to work too hard. Did you change the fuel filter, and did you check the vent line that goes to the charcoal canister to see if it's restricted?

jester_587

The Cap has been replaced already and the vent line on the bottom of the tank has also been replaced, although the vent line on the bottom of the tank is to let air in not out. The fuel filter was replaced with each new pump, so its been replaced 5 times now. There is no vent that goes to the charcoal canister, but I have checked all the lines to see if there is any restriction and there is none.

Xlr8torZ28

iTrader: (19)

is your exhaust too close to the tank? Gas expands very easy when temperature increases.

Lo-tec

There should be a vapor line that runs from the tank to the charcoal canister. It releases the pressure that builds up in the tank and burns it in the engine.

That sounds like it may be your problem.

jester_587

Exhaust too close to the tank, well since the muffler is mounted right underneith the fuel tank Id say yes, but this is a stock position. As for the vent line, there are only 4 lines that come from the tank. One is the feed line, two is the return line, three is the line that goes to the charcoal canister to store fumes that will be burned off later NOT A VENT, and 4 is the vent line that allows air INTO the thank and has a valve that sits right underneith the bottom of the tank on the drivers side. The line that goes to the Charcoal canister is clear and open line it should be. The feed and return lines are working, and the valve on the bottom allows air in as it should when needed. I have already mentioned all this in my previous posts for this problem. NAPA said they checked the Charcoal canister to see if it functioned as it should and they said it did, but again I dont trust autoshops, hence my writing to figure this problem out. I still am getting a check engine light now too, I am getting 6 sets of 4 flashes, so 24 but do I add that to the 12 original flashes at start up to get 36 or what, the manual doesnt specify.