TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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I have some questions that I hope somebody can answer because nobody else can including the Chevy Dealer. I have a 1986 Iroc-Z28 with a 305 TPI, I am having a problem with my fuel system, here is whats happening. On warm days with regular driving, after the engine is warmed up I will hear the fuel pump in the tank start to wine VERY loud. I know the fuel pump wines all the time and I know what that sounds like, this noise will get very loud then return to the normal level of noise. This will happen on and off, the engine will sputter and shut off. The fuel pump has been replaced on this car 5, yes 5 times. I have replaced it with OEM and Aftermarket pumps, replaced the wiring harness and still have the same problem that returns. After either I stop the car and turn it off or it shuts off on its own, if you open the cap on the tank filler neck, there will be a lot of air pressure that will come OUT of the tank. There has been so much pressure that if the gas tank was over 3/4 of a tank when this happens, fuel will pour out of the tank and all over the side of the car and ground. I have checked the valve behind the left rear tire and replaced it, I have checked the charcoal canister and fuel pressure and return lines for obstruction. Everything is fine. The car runs fine until that pressure builds up enough to cause the fuel pump to strain, eventually it gets damaged and I have to replace it. I cant think of anything else accept the FUEL PRESSURE REGULATOR. Gotta be, but dont want to take off all that stuff to find out that there is nothing wrong with it. The car does run rich and I get very bad gas mileage. I get about 11 mpg. The car seems to run great minus these problems. It was backfiring during deceleration until I removed the smog pump. The RPM's are kinda slow to come down to idle if you rev the engine. The car has Edelbrock headers and a custom exhaust all the way back with 3" pipes, 160 Temp, but those are the only mods, everything else is stock. It has 74K miles and is in great shape minus those problems. I gotta figure this out, please help. I have been all over this site and forum, I have no answers, somebody must know.
I have some questions that I hope somebody can answer because nobody else can including the Chevy Dealer. I have a 1986 Iroc-Z28 with a 305 TPI, I am having a problem with my fuel system, here is whats happening. On warm days with regular driving, after the engine is warmed up I will hear the fuel pump in the tank start to wine VERY loud. I know the fuel pump wines all the time and I know what that sounds like, this noise will get very loud then return to the normal level of noise. This will happen on and off, the engine will sputter and shut off. The fuel pump has been replaced on this car 5, yes 5 times. I have replaced it with OEM and Aftermarket pumps, replaced the wiring harness and still have the same problem that returns. After either I stop the car and turn it off or it shuts off on its own, if you open the cap on the tank filler neck, there will be a lot of air pressure that will come OUT of the tank. There has been so much pressure that if the gas tank was over 3/4 of a tank when this happens, fuel will pour out of the tank and all over the side of the car and ground. I have checked the valve behind the left rear tire and replaced it, I have checked the charcoal canister and fuel pressure and return lines for obstruction. Everything is fine. The car runs fine until that pressure builds up enough to cause the fuel pump to strain, eventually it gets damaged and I have to replace it. I cant think of anything else accept the FUEL PRESSURE REGULATOR. Gotta be, but dont want to take off all that stuff to find out that there is nothing wrong with it. The car does run rich and I get very bad gas mileage. I get about 11 mpg. The car seems to run great minus these problems. It was backfiring during deceleration until I removed the smog pump. The RPM's are kinda slow to come down to idle if you rev the engine. The car has Edelbrock headers and a custom exhaust all the way back with 3" pipes, 160 Temp, but those are the only mods, everything else is stock. It has 74K miles and is in great shape minus those problems. I gotta figure this out, please help. I have been all over this site and forum, I have no answers, somebody must know.
My IROC makes the same noise when I shut it off after driving around town. Makes a hum noise and when I release the gas cap, lot's of pressure is released and then the sound is gone...but it comes back in a few minutes....never could figure it out.
