LS6 Cobra
Larry do you think the MAF could be reading maxed out?
Jon
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Jon
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Thread Starter
TECH Apprentice
Joined: Jan 2002
Posts: 366
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From: Gilbert, AZ
Yah he found the valve. I told him there was one there but he couldnt see it with the FRCs on. We will get that done this week. Weather has been raining so can't drive it since it has no roof. Looks like Wednesday will be clear.
Thread Starter
TECH Apprentice
Joined: Jan 2002
Posts: 366
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From: Gilbert, AZ
You guys nailed it. Fuel pressure. 58psi at idle and cruising all around. As soon as you go WOT it dropped to ~30psi. He is going to pull the pump and see what is going on. It has to be something in the tank.
I don't know what type of wiring harness that was used but make sure the pump is getting the correct voltage. Since it doesn't to it till higher RPMS it might not be getting enough power to move that much fuel. Or it could be as easy as the pump is bad and can't move enough fuel. Glad you found out what it was.
Also, what type of tank does it have in it and is it baffled? The reason I ask is depending on the fuel level in the tank it can uncover the pump. It is interesting that you can replicate the problem and it does it at the same RPM.
Also, what type of tank does it have in it and is it baffled? The reason I ask is depending on the fuel level in the tank it can uncover the pump. It is interesting that you can replicate the problem and it does it at the same RPM.
Thread Starter
TECH Apprentice
Joined: Jan 2002
Posts: 366
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From: Gilbert, AZ
It was worse and worse. Started to cut out any time he floored it. Wouldn't rev much past 3k. Sounds like the pump is dieing. It was a cheap ebay "walbro" but when it showed up didn't look like a real walbro. Aeromotive 340lph is on the way.
I'll ask him about the tank.
I'll ask him about the tank.
I have a feeling he'll be much happier with the genuine article, let us know how it goes.
edit to add: here's an article on the subject with lots of good info on detecting the cheap knockoffs:
http://www.fuel-pumps.net/walbro-forgeries.html
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Your second one worked fine though right?
Thread Starter
TECH Apprentice
Joined: Jan 2002
Posts: 366
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From: Gilbert, AZ
Car hasn't been tuned besides turning off CE lights and doing what is needed for the swap. Still just running factory fuel/timing maps. Fuel trims were +8 or so. We can mess with the fine tuning once it runs correctly.
Thanks for the feedback. I am the owner of the Cobra. When I took the pump out of the box and saw that it was a Walbro Knock off I was almost ready to send it back and not install it. In hindsight I knew better but thought that I would get away with it. I was obviously wrong as the pump will not keep up with the engine at WOT. The moral was that the Ebay vendor had Walbro 255 written all over his ad but when I get the pump it is a cheap knock off.
So I should have got the "real" Walbro or Aeromotive from the start and saved me some grief. As UNREAL mentioned I did order the Aeromotive 340 so I am hoping for a resolution.
By the way the Nova that UNREAL mentioned is a 1966 and I will start to work on that when the Cobra is 100% done. More tinkering........
Thanks for all of the assistance and feedback. It is great to be able to post issues and questions on this forum and all of your collective help.
So I should have got the "real" Walbro or Aeromotive from the start and saved me some grief. As UNREAL mentioned I did order the Aeromotive 340 so I am hoping for a resolution.
By the way the Nova that UNREAL mentioned is a 1966 and I will start to work on that when the Cobra is 100% done. More tinkering........
Thanks for all of the assistance and feedback. It is great to be able to post issues and questions on this forum and all of your collective help.
When I finished the car I could not believe how cramped and small it was. I am 6'4" and UNREAL is 6'3" and we look like two gorillas in a clown car when we drive it to tune it. I am only good for about a 20 minute ride before my leg starts to go to sleep. Not a cross-country cruiser for tall folks.
I am planning on installing the pump in the next day or two and will let you know how it works.
I am planning on installing the pump in the next day or two and will let you know how it works.
I installed the Aeromotive 340 pump and redid the wiring so that I have a hot wire from the alternator to the relay. I figured that if I was in there working and I had my 18 year old son helping I would put him to work so I redid the wiring slightly. I put an access panel in the trunk floor..(I know I ruined the originality of the car)
so it was easy to R&R the pump.
I am surprised at how much better the car drives just cruising around. The wife even noticed it. I ran it up in RPM and can tell that it does not cut out as before. I did not run it hard as I would like to have UNREAL have the laptop hooked up to it so I can monitor the knock or anything that may be non-normal.
I wish I would have bought the good pump from the start and not tried to save the money on Ebay. Lesson learned. The Aeromotive pump was a simple replacement and the quality looks great. Too bad I had to hide in the gas tank.
so it was easy to R&R the pump. I am surprised at how much better the car drives just cruising around. The wife even noticed it. I ran it up in RPM and can tell that it does not cut out as before. I did not run it hard as I would like to have UNREAL have the laptop hooked up to it so I can monitor the knock or anything that may be non-normal.
I wish I would have bought the good pump from the start and not tried to save the money on Ebay. Lesson learned. The Aeromotive pump was a simple replacement and the quality looks great. Too bad I had to hide in the gas tank.