finicky 2.9 v6

[Primosboy]

My 87 STX is finaly on the road,and I've discovered an issue. It has this on and off lack of power and erratic idling. It will be idling fine and all the sudden start choking like it's gunnu die. After a couple minutes it will go back to normal for anywhere from 1-10 minutes,and then it starts choking again. The same while I'm driving. It will be running strong and then all the sudden it starts choking and won't have any power. At times I can pull off the road,shut the truck off,wait a minute and start it up again and it's fine,other times it will go back to normal on it's own. I've replaced the fuel filter twice and the fuel pump relay. I'm told it's most likely the in-tank fuel pump,but I can hear the pump prime when I turn the key. What's the deal??

 

[jaymegriffiths]

i have the same problem. yet to figure it out although some have claimed it may be related to my nuetral sensing circuit. is yours a manual? any recent tranny, clutch, etc work?

 

[Primosboy]

i have the same problem. yet to figure it out although some have claimed it may be related to my nuetral sensing circuit. is yours a manual? any recent tranny, clutch, etc work?

Yes it's manual and it's got a new tranny..not sure how many miles it has on it. I want to say 7,000 is what the guy said,but I'm not sure. We've pulled codes and we're getting 1s and 11s all the way. odd

 

[jaymegriffiths]

Yes it's manual and it's got a new tranny..not sure how many miles it has on it. I want to say 7,000 is what the guy said,but I'm not sure. We've pulled codes and we're getting 1s and 11s all the way. odd

my codes have a 67 code then a 14 and a 95. but the 14 was explained. so mine is either related to the fuel pump ground, or the nuetral sensing circuit

 

[IMenriched]

Yes it's manual and it's got a new tranny..not sure how many miles it has on it. I want to say 7,000 is what the guy said,but I'm not sure. We've pulled codes and we're getting 1s and 11s all the way. odd

start with simple stuff 1st....when was the last time the fuel filter was changed?
what experiencing is symptomatic of a TFI (ignition module) going bad ...remove and test...so you can rule it out

when was the last time a tune up was done? plugs wires cap rotor?

you have 2 fuel pumps...1 on the frame and 1 in the tank.
the 1 you hear is the fram the one in the tank is harder to hear, usually you can feel it activate on the tank.

 

[Primosboy]

start with simple stuff 1st....when was the last time the fuel filter was changed?
what experiencing is symptomatic of a TFI (ignition module) going bad ...remove and test...so you can rule it out

when was the last time a tune up was done? plugs wires cap rotor?

you have 2 fuel pumps...1 on the frame and 1 in the tank.
the 1 you hear is the fram the one in the tank is harder to hear, usually you can feel it activate on the tank.

Agreed. The tune-up "new plugs and wires,new fuel filter,changed oil and filter,air filter,and octane booster" doesn't even have 20 miles on it. I replaced the fuel filter again very recently just incase. I'll check out the TFI when I get the chance. If I feel the in-tank pump prime does that mean it's still good? Thanks for all the info.

 

[IMenriched]

Agreed. The tune-up "new plugs and wires,new fuel filter,changed oil and filter,air filter,and octane booster" doesn't even have 20 miles on it. I replaced the fuel filter again very recently just incase. I'll check out the TFI when I get the chance. If I feel the in-tank pump prime does that mean it's still good? Thanks for all the info.

Ok, great resent tune up

yes and no on the in tank pump....feeling it vibrate the tank wall is only indicating that it is running...a good sign for sure. the filter sock on the pick up tube maybe all gunked up...missing..etc...other issues maybe afoot in there. so even though it vibrates it may not working correctly.

you can remove the hose and see how much it's able pump into another container...over say 1/2 min. if you get a 1-2 gal...in that time....i don't think that would be the problem. not sure what that pump GPM rating is...can't imagine needing more that.

other things to check any and all grounds and connections....
fuel pump relay

it may have a bad coolant temp sensor, (the one for the engine computer, not the one for the gauges)

odd that no codes are tripping

 

[IMenriched]

Agreed. The tune-up "new plugs and wires,new fuel filter,changed oil and filter,air filter,and octane booster" doesn't even have 20 miles on it. I replaced the fuel filter again very recently just incase. I'll check out the TFI when I get the chance. If I feel the in-tank pump prime does that mean it's still good? Thanks for all the info.

Ok, great resent tune up

yes and no on the in tank pump....feeling it vibrate the tank wall is only indicating that it is running...a good sign for sure. the filter sock on the pick up tube maybe all gunked up...missing..etc...other issues maybe afoot in there. so even though it vibrates it may not working correctly.

you can remove the hose and see how much it's able pump into another container...over say 1/2 min. if you get a 1-2 gal...in that time....i don't think that would be the problem. not sure what that pump GPM rating is...can't imagine needing more that.

other things to check any and all grounds and connections....
fuel pump relay.

it may have a bad coolant temp sensor, (the one for the engine computer, not the one for the gauges) it can be a multitude of things yet

odd that no codes are tripping

 

[Primosboy]

Ok, great resent tune up

yes and no on the in tank pump....feeling it vibrate the tank wall is only indicating that it is running...a good sign for sure. the filter sock on the pick up tube maybe all gunked up...missing..etc...other issues maybe afoot in there. so even though it vibrates it may not working correctly.

you can remove the hose and see how much it's able pump into another container...over say 1/2 min. if you get a 1-2 gal...in that time....i don't think that would be the problem. not sure what that pump GPM rating is...can't imagine needing more that.

other things to check any and all grounds and connections....
fuel pump relay.

it may have a bad coolant temp sensor, (the one for the engine computer, not the one for the gauges) it can be a multitude of things yet

odd that no codes are tripping

Well I've already dropped the tank and the filter sock looks like new. No tears or gunk at all. The tank was super clean inside also..no gunk or anything. That's a good idea though..disconnecting the hose and draining it...so would I do that by running the truck? Also we just replaced the fuel pump relay"it was missing when we bought the truck". The guy who had it before me had cut the harness to the fuel pump relay and bypassed it. Stuuuupid. Well I'll put all this we're talking about into action as soon as I can. I've got a broken ankle and I'm stuck on the couch for a while.

Yeah it is weird..I thought for sure it would be throwing out some codes. The check engine light isn't on though. The oil light is on. Not sure if it's the check oil lvl,or oil pressure. It shows an oil can dripping. Oil lvl is good though.

 

[IMenriched]

ell I've already dropped the tank and the filter sock looks like new. No tears or gunk at all. The tank was super clean inside also..no gunk or anything. That's a good idea though..disconnecting the hose and draining it...so would I do that by running the truck? Also we just replaced the fuel pump relay"it was missing when we bought the truck". The guy who had it before me had cut the harness to the fuel pump relay and bypassed it. Stuuuupid. Well I'll put all this we're talking about into action as soon as I can. I've got a broken ankle and I'm stuck on the couch for a while.

Yeah it is weird..I thought for sure it would be throwing out some codes. The check engine light isn't on though. The oil light is on. Not sure if it's the check oil lvl,or oil pressure. It shows an oil can dripping. Oil lvl is good though.

well clean tank on the inside is a good indicator for sure
I guess what i was trying to say about disconnecting a hose from the tank ...was testing out put of the in tank pump,(just put the key on)...which would prove it capability....but knowing the condition now of it, the in tank pump, and the inside of the tank is also good to know...sorry if that wasn't clear.

was the fuel pressure ever tested?

 

[Primosboy]

well clean tank on the inside is a good indicator for sure
I guess what i was trying to say about disconnecting a hose from the tank ...was testing out put of the in tank pump,(just put the key on)...which would prove it capability....but knowing the condition now of it, the in tank pump, and the inside of the tank is also good to know...sorry if that wasn't clear.

was the fuel pressure ever tested?

Not sure is they do that in smog or not? Because It won't pass smog right now. Prolly should've mentioned that before. Duuh. The only place it's not passing in smog is the HC output. It's too high. Maybe that's got something to do with it...it doesn't seem likely,but it could. How would I get the fuel pressure tested if smog doesn't do it?

 

[IMenriched]

Not sure is they do that in smog or not? Because It won't pass smog right now. Prolly should've mentioned that before. Duuh. The only place it's not passing in smog is the HC output. It's too high. Maybe that's got something to do with it...it doesn't seem likely,but it could. How would I get the fuel pressure tested if smog doesn't do it?

so it now running?? just not passing the smog test?

as for the fuel pressure...need to have a fuel pressure guage..it screws onto the shraider valve on the injector manifold. (it kinda looks like a tire stem valve) Needs to have 32-40psi

 

[Primosboy]

so it now running?? just not passing the smog test?

as for the fuel pressure...need to have a fuel pressure guage..it screws onto the shraider valve on the injector manifold. (it kinda looks like a tire stem valve) Needs to have 32-40psi

Well yeah it runs,just badly. No it won't pass smog either. Hmmmm...what i the shraider valve? So I'd need to buy a fuel pressure gauge to check? Can I get that at like Kragen or Autozone?

 

[IMenriched]

Well yeah it runs,just badly. No it won't pass smog either. Hmmmm...what i the shraider valve? So I'd need to buy a fuel pressure gauge to check? Can I get that at like Kragen or Autozone?

yes most major auto part stores should carry a fuel pressure test set.
thinking I got mine at sears.

sure would hesitate to get the TFI checked again ....most parts store will check them