Fuel pressure issue
Thread Starter
Teching In
Joined: Sep 2025
Posts: 5
Likes: 0
Fuel pressure issue My 6.0/4l80 swap seems to idle fine but bogs under load when trying to drive it like its misfiring but shows no codes when scanned. Ive checked coils and have fire when pulling the wire off when running but on 4 of 8 cylinders there is no change in the way the engine idles when the coil wire is pulled. All 8 injectors have power and pulse with a noid light. Fuel pressure at idle is 90+.psi. Could a, or multiple, plugged injectors cause the fuel pressure to be that high? Fuel system in a return less rail, stock injectors, 3/8 rubber line, Wix corvette style regulator, new tank and sending unit, quantum in tank pump.
It idles "fine", but is no different when 4 of 8 coil wires are pulled, lol. Are these 4 dead cylinders all on the same bank? If so, you probably have your coil packs on backwards front to back. Your fuel pressure issue either means a bad regulator or too much fuel pump overpowering the stock style filter/regulator thing. Both issues need to be fixed.
Thread Starter
Teching In
Joined: Sep 2025
Posts: 5
Likes: 0
It idles "fine", but is no different when 4 of 8 coil wires are pulled, lol. Are these 4 dead cylinders all on the same bank? If so, you probably have your coil packs on backwards front to back. Your fuel pressure issue either means a bad regulator or too much fuel pump overpowering the stock style filter/regulator thing. Both issues need to be fixed.
In that case, the 90+psi may be just enough to lock 4 of the injectors closed, but not the others. Either way, the pressure issue has to be fixed before it can ever be right. Once that is done if a problem remains, then go through the usual diagnostics again.
Teching In
Joined: Oct 2018
Posts: 6
Likes: 0
The Wix and AC Delco C5 Fuel Pressure Regulators have been infamous lately.
Lots of people have been having this issue from around 2022+
(Here's one published piece)
The FPR in the filter seems to fail and has an extremely high pressure at idle and lowers at higher RPMs (anything higher than idle).
I'm usually seeing 70-80psi on startup and when warm, then getting to 38psi at cruising speed.
There's not many good options sadly. Most people are going to aftermarket Regulators and filters.
Aeromotive and Racetronic both have some options
Radium has options as well with much better customer support.
Racetronic hasn't answered 12 phone calls or 5 emails over the last 2 weeks from me about trying to spend $2000+ with them to get 4 cars ready for next Race Season.
Lots of people have been having this issue from around 2022+
(Here's one published piece)
The FPR in the filter seems to fail and has an extremely high pressure at idle and lowers at higher RPMs (anything higher than idle).
I'm usually seeing 70-80psi on startup and when warm, then getting to 38psi at cruising speed.
There's not many good options sadly. Most people are going to aftermarket Regulators and filters.
Aeromotive and Racetronic both have some options
Radium has options as well with much better customer support.
Racetronic hasn't answered 12 phone calls or 5 emails over the last 2 weeks from me about trying to spend $2000+ with them to get 4 cars ready for next Race Season.
Thread Starter
Teching In
Joined: Sep 2025
Posts: 5
Likes: 0
I wondered if the high fuel pressure could lock the injectors but couldnt find any info to back that thought up. I used a Wix regulator but will be changing it just to see if my pressure issue goes away.
Trending Topics
TECH Regular
Joined: Dec 2022
Posts: 444
Likes: 158
Why even waste your time? Just put an adjustable regulator on it. Unlike that guy above said there are plenty of good options that will solve your pressure issues.
Even the cheaper aeromotive look alike on Amazon thats like 40$ or something works better than that filter. It actually works exactly as well as the aeromotive one. I bought them both and took them apart. The aero is no nicer than pqy or whatever brand it was.
Even the cheaper aeromotive look alike on Amazon thats like 40$ or something works better than that filter. It actually works exactly as well as the aeromotive one. I bought them both and took them apart. The aero is no nicer than pqy or whatever brand it was.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
Teching In
Joined: Sep 2025
Posts: 5
Likes: 0
Why even waste your time? Just put an adjustable regulator on it. Unlike that guy above said there are plenty of good options that will solve your pressure issues.
Even the cheaper aeromotive look alike on Amazon thats like 40$ or something works better than that filter. It actually works exactly as well as the aeromotive one. I bought them both and took them apart. The aero is no nicer than pqy or whatever brand it was.
Even the cheaper aeromotive look alike on Amazon thats like 40$ or something works better than that filter. It actually works exactly as well as the aeromotive one. I bought them both and took them apart. The aero is no nicer than pqy or whatever brand it was.
TECH Regular
Joined: Dec 2022
Posts: 444
Likes: 158
Ive used k-motor, pqy and aeromotive. No issues with any of them. Yea you can mount them wherever.
Ive used a bunch of evil energy stuff with no issues but havent tried a regulator from them.
Just remember to leave the vacuum port uncapped and open if not using a reference from the engine.
Ive used a bunch of evil energy stuff with no issues but havent tried a regulator from them.
Just remember to leave the vacuum port uncapped and open if not using a reference from the engine.
Thread Starter
Teching In
Joined: Sep 2025
Posts: 5
Likes: 0
I installed an adjustable regulator and the fuel pressure is now 58 verses the 90+ the WIX regulator/filter was putting out BUT I still have the same issue of what Ill describe as no combustion lol. Cylinders 4,6,8 on passenger side are cold at the header like they arent firing but injectors have power, they pulse with a noid light, coils all have spark, plugs are dry. Next step Ill try is swapping the injectors. Ive read about an injector hydro locking but thought that was only when under high pressure, could the high pressure have permanently damaged them? I didnt check anything on the driver side so no info on 1,3,5,7.