Fuel spritzing out of tailpipe
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Fuel spritzing out of tailpipe We have a LM7 non-flex fuel 5.3 in a 1936 Auburn replica. It only has 200 miles on the car over a 7 year time span. So it likely has issues from only being driven short distances using old gas. It has a 112 Magneson supercharger as well.
I can be hard starting, with a weak cold idle. It is spritzing wet fuel out of the passenger tailpipe. We installed a fuel pressure gauge on the driver side fuel rail. Turning the key on and not running the fuel pressure goes up to about 58psi then drops down. When running cold at idle it is reading about 80 psi. We believe it should be no more than 58psi at idle. Is that right? Could the fuel pressure regulator be failing?
I can be hard starting, with a weak cold idle. It is spritzing wet fuel out of the passenger tailpipe. We installed a fuel pressure gauge on the driver side fuel rail. Turning the key on and not running the fuel pressure goes up to about 58psi then drops down. When running cold at idle it is reading about 80 psi. We believe it should be no more than 58psi at idle. Is that right? Could the fuel pressure regulator be failing?
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From: White Bear, Mn
I do not know if 80 psi would be enough or not to dump fuel out the exhaust but obviously 80 psi is also way high.
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We pulled the injectors and had them flow tested a few weeks back. It seems to me that to run this rich that one or more injectors are staying open, or the fuel pressure is so high that the injectors can't close. That's our hunch. What else could keep an injector from closing, or staying open too long? We have a lean tune downloaded.
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We had the injectors cleaned, flow tested, and did a resistance test. All passed to original specs. The injectors are 42lb injectors intended for marine or boosted applications. Something is telling the injectors to dump too much fuel.
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Verdad Gallardo TECH Junkie
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From: White Bear, Mn
If you wanted to make sure for yourself that the injector is not stuck open pull the rail and injectors, get 8 cups of water and put the end of the injectors in the cups attached to the rail. Put about 35psi of air to the rail and look for air bubbles
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NEW PROBLEM, or else the real problem manifested itself fully. The car has a Magneson MP112 supercharger for stock engines. I am getting a loud noise that may be coming from the supercharger. Next step is to disconnect the drive belt and see if the problem goes away. I am starting to hear a loud sucking sound nearing my wallet.......
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From: PNW
About your original problem - I don't think you're seeing fuel. Unless it's black, what you're seeing is water.
As for your second problem, you can't run a supercharged engine with the belt off. This isn't MadMax. The supercharger must be spinning at all times or else no air gets to the engine. All of this seems very over your head, I think you should just take your car to get tuned.
As for your second problem, you can't run a supercharged engine with the belt off. This isn't MadMax. The supercharger must be spinning at all times or else no air gets to the engine. All of this seems very over your head, I think you should just take your car to get tuned.
About your original problem - I don't think you're seeing fuel. Unless it's black, what you're seeing is water.
As for your second problem, you can't run a supercharged engine with the belt off. This isn't MadMax. The supercharger must be spinning at all times or else no air gets to the engine. All of this seems very over your head, I think you should just take your car to get tuned.
As for your second problem, you can't run a supercharged engine with the belt off. This isn't MadMax. The supercharger must be spinning at all times or else no air gets to the engine. All of this seems very over your head, I think you should just take your car to get tuned.
I have a LSA supercharger and use a Holley EFI to control the blower bypass so I can run without a belt if needed by commanding the ecu to keep the bypass open all the time. I hope I never need to but it's there if I pump in some crappy fuel or lose the belt.
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8.Lug: I was told by the supercharger vendor to take the belt off to see if the sound went away. The engine started right up and I ran it for a few moments. I would not do something like that without proper research. It is fuel that is coming out of the exhaust. It smells different than water. I have worked on cars for almost 50 years so I know what gas smells like, and I do know when to punt. I have spoken to 3 experts and they are all scratching their heads. I have also appreciated the input from the folks here.
I discovered that loud sound: The exhaust packing was soaked with, you guessed, fuel. It shrunk just enough to allow exhaust to leak. So that is being replaced and re-torqued.
But:
I think my son discovered the problem. He had a hunch the fuel regulator was the culprit, although I installed a gauge on the fuel rail and the pressure appears good (58psi running, and pressures up at first ignition, then drops until engine is running). The fuel regulator appears to be leaking fuel directly into the intake manifold. He discovered it by removing the vacuum line that operates it. Fuel came out. So that is what I will pull tomorrow to confirm. There should of course be no fuel in the vacuum lines, nor should the regulator be allowing fuel to enter the intake manifold. Wish me luck and I will report back.
I discovered that loud sound: The exhaust packing was soaked with, you guessed, fuel. It shrunk just enough to allow exhaust to leak. So that is being replaced and re-torqued.
But:
I think my son discovered the problem. He had a hunch the fuel regulator was the culprit, although I installed a gauge on the fuel rail and the pressure appears good (58psi running, and pressures up at first ignition, then drops until engine is running). The fuel regulator appears to be leaking fuel directly into the intake manifold. He discovered it by removing the vacuum line that operates it. Fuel came out. So that is what I will pull tomorrow to confirm. There should of course be no fuel in the vacuum lines, nor should the regulator be allowing fuel to enter the intake manifold. Wish me luck and I will report back.
I think my son discovered the problem. He had a hunch the fuel regulator was the culprit, although I installed a gauge on the fuel rail and the pressure appears good (58psi running, and pressures up at first ignition, then drops until engine is running). The fuel regulator appears to be leaking fuel directly into the intake manifold. He discovered it by removing the vacuum line that operates it. Fuel came out. So that is what I will pull tomorrow to confirm. There should of course be no fuel in the vacuum lines, nor should the regulator be allowing fuel to enter the intake manifold. Wish me luck and I will report back.
I am not certain if this will help. You have alot of issues here. But if fuel is actually leaving the tailpipe, then that maybe due to a cam or crank sensor problem. The timing could off and injecting fuel during the Exh stroke. Good luck with the car.
We have a LM7 non-flex fuel 5.3 in a 1936 Auburn replica. It only has 200 miles on the car over a 7 year time span. So it likely has issues from only being driven short distances using old gas. It has a 112 Magneson supercharger as well.
I can be hard starting, with a weak cold idle. It is spritzing wet fuel out of the passenger tailpipe. We installed a fuel pressure gauge on the driver side fuel rail. Turning the key on and not running the fuel pressure goes up to about 58psi then drops down. When running cold at idle it is reading about 80 psi. We believe it should be no more than 58psi at idle. Is that right? Could the fuel pressure regulator be failing?
I can be hard starting, with a weak cold idle. It is spritzing wet fuel out of the passenger tailpipe. We installed a fuel pressure gauge on the driver side fuel rail. Turning the key on and not running the fuel pressure goes up to about 58psi then drops down. When running cold at idle it is reading about 80 psi. We believe it should be no more than 58psi at idle. Is that right? Could the fuel pressure regulator be failing?
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