loss of power after 4000 RPM's
09-06-2015, 12:39 AM
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loss of power after 4000 RPM's
I found a few threads that are similar to my problem but not the same. My girlfriend has (she bought the car New) an 83 Z28 with a carb 305 and a 5sp manual and the motor is Bone stock. when you hit 4000 RPM's you can hear the motor bog like it's starving for air or gas. it runs GREAT up to that point. the motor has 159,000 mi on it i rebuilt the carb, new plugs, wires, cap, rotor, ignition module, and all vac lines. I read on 1 post that it might be the valve springs starting to float. But after that post the guy said he was going to do a valve job and he never posted again. that was 9 years ago. Another guy had a post where he said it might be the magnetic pick up in the dist. But again no more post after that so i don't know if these suggestions fixed the problems. Any help would be Greatly Appreciated.
09-06-2015, 09:58 AM
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Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: loss of power after 4000 RPM's
Sounds like it's running out of fuel.
Changed the fuel filter lately?
Start with the simple stuff first.
Changed the fuel filter lately?
Start with the simple stuff first.
09-06-2015, 04:06 PM
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Re: loss of power after 4000 RPM's
I changed the filter when i rebuilt the carb. there was rust in the tank so i replaced it along with the sock filter in the tank and added a filter back by the tank also. Replaced the fuel pump last year. I really don't think it has anything to do with fuel. I had the same problem before i changed the gas tank and everything is new now and same problem.
09-15-2015, 06:21 PM
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Car: 90 IROC 2-92 Zs blk vert & prpl
Engine: stealth ram brodix track 1 ful port
Transmission: 700r4 4l80e
Axle/Gears: iroc 375 lokr 92 Z 277 pos vert 327
Re: loss of power after 4000 RPM's
I have heard of rubber bellows collapsing and air filters getting wet and old and collapsing when enough suction hits them.
09-17-2015, 10:24 AM
#6
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Re: loss of power after 4000 RPM's
"and added a filter back by the tank also"
Take it out.
To test for fuel delivery issues you hook up a fuel pressure gague THAT YOU CAN ACTUALLY SEE WHILE YOU ARE DRIVING. It's the only way to know for sure what's happening at WOT under load at high RPMs.
Take it out.
To test for fuel delivery issues you hook up a fuel pressure gague THAT YOU CAN ACTUALLY SEE WHILE YOU ARE DRIVING. It's the only way to know for sure what's happening at WOT under load at high RPMs.
09-17-2015, 01:28 PM
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Re: loss of power after 4000 RPM's
Take it out.
To test for fuel delivery issues you hook up a fuel pressure gague THAT YOU CAN ACTUALLY SEE WHILE YOU ARE DRIVING. It's the only way to know for sure what's happening at WOT under load at high RPMs.[/QUOTE]
I put the filter in the back because the tank had rust in it. I'll take it out and get a fuel gage and see how that goes.
To test for fuel delivery issues you hook up a fuel pressure gague THAT YOU CAN ACTUALLY SEE WHILE YOU ARE DRIVING. It's the only way to know for sure what's happening at WOT under load at high RPMs.[/QUOTE]
I put the filter in the back because the tank had rust in it. I'll take it out and get a fuel gage and see how that goes.
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