DEAD AFTER 3500 RPMS

[BILL S]

i have a basiclly stock 5.0 lx, olny mods are 1 5/8 shorty headers,mac cold air intake,2 1/2 mac exhaust,3.55 rearend,pro 5.0 shifter. the problem is after 3500 rpms it will lose all power, below 3500 runs fine. replaced mass air sensor,tps sensor,plugs ,wires ,cap and rotor button.i have about 35 to 38psi fuel pressure. this is driving crazy, please help!!!!!

 

[HISSIN50]

Does it start to lose performance (only) or does it actually start missing or having some mechanical issue?

Good luck.

 

[BILL S]

it just loses performance, no missing

 

[mustangjoe87]

i had a similar problem in mine, i couldnt get over 2k rpm without it bogging majorly, turned out to be a bad fuel filter.

 

[BILL S]

just changed fuel filter, runs better ,but still boggs at about 4600 rpms . you think maybe fuel pump is weak, pump sound very loud an drops pressure at higher rpms

 

[DouglasOhio]

hook a fuel pressure guage up and have someone rev it up while you watch the guage. If it loses pressure, youll have your problem.

 

[HISSIN50]

Kyle has a good idea, but one really needs to have the engine under load to see the drop in fuel pressure.

In addition to the fuel possibilities, dont overlook something like a weak coil.

A look at the codes might give you a hint as to which direction to go.

Good luck.

 

[mustangjoe87]

When I had my problem the car wouldnt start because the fuel pump was bad. I replaced the pump and then i couldnt get it over 2k, once i put a new filter in it was good as new. Hope that helps you, they could be both bad.

 

[BILL S]

thanks everyone, i am going to try replacing fuel pump, fuel pressure regulator(adjustable). if that does not work i will check on the coil. will let you know soon.

 

[mackey]

Might want to check the timing first. First of all check that the spout connector is in. Then take it out and check where your timing is. This could have caused it