alright in my last thread i thought it was the fuel pump.

tonight i replaced the fuel filter. had my dad, my buddy both mechanics couldn't figure out whats wrong with it. had it scanned. its running lean.

heres what its doing:

give it full throttle bogs down.
cuts out while your driving,
dies/ stalls at times.
crank back up runs better but then goes down hill.
from a stop u have to slam the throttle let up then go to accelerate.
if your driving it will not go above 2000 rpms or will bog out. if u keep it at 1900 it will go pretty far before dieing.

need help. were all stumped.

im sure theres a few things i left out but if i remember ill post.

any imput is greatly appreciated. thanks

 

forgot to add. its a 90 formula. auto 5.7 tpi stock

 

first off is it throwing any codes? have you checked the maf? try unplugging it, and let it idle to see if it runs better in closed loop. My friends vette had very similar problems to yours for the longest time he could not figure out what was wrong with it I suggested the maf he didnt believe cause there was no code sure enough it turned out to be the problem

 

no codes.

however i did unplug it today. nothing changed. did the same to the iac. nothing changed. unplugged tps it changed.

but when i unplugged the maf couldn't drive far at all. but only code it throws its 44.

 

i dont have a maf on the car. never have since ive owned it. i was referring to unplugging the maps

 

o thats right you have speed density my bad well did you say it ran with MAP sensor unplugged? it shouldn't it should have just instantly died iirc

 

yeah seem to run a tad better at times with it unplugged. but try and drive it wont get far.

 

cleaned off the iac. ran alot better before it started acting up. did the same thing again. ran a tab better but when it started bogging down it was the worst yet.

 

also if you keep on the throttle when bogging. back fires externally and internally abit.

 

sounds like a intake leak whats your iac counts ? also take a spraybottle with soap and water and spray arount the intake and the hoses and see if it changes any. another alteratice is brakeclean but make ure its not to hot when you do it its a little more dangerous but it if reves up then its a dead giveaway of a vacume leak.

 

it will rev up sometimes. ill try the spray bottle. right now when i start it up runs ( not great ) get down the street then starts cutting out and stalling. i put some 93 in there because it only used to run on it while back. ran a good distance before cutting out and what not. been playing with the map sensor tho. when it runs decent ill unplug it and the computer picks up that its been unplugged. when it runs bad like it has been unplug the map and nothing changes til you plug it in. not sure if it has anything todo with it.

 

(alright in my last thread i thought it was the fuel pump.) Does this mean you checked the fuel pressure and you have ruled the pump out?

 

lol ive put 3 pumps in from last week til now. runs good with new one. then slowly goes down hill til it gets the way it is now. but his last one ive put in it started right away doing what its doing now. weird.

 

thanks guys for your help again.

it was yet again fuel pump. this is the 5th i put it in but its running good now.