End of Rope

[adsm08]

So I'm about at the end of my rope with this one guys. Hoping someone here has ideas that I haven't had yet.


1987 2.9L 5 speed, 4x4.

Symptom is intermittent low power. It feels like there is a low fuel issue or timing issue when it happens, and you can hear the exhaust putter kinda oddly. It never acts up at idle, and never stalls out. RPM does not fluctuate, fuel pressure does not drop off or spike up during an episode. Cycling the key makes it go away for a while. Hammering the gas to wide open makes it kick up to full power again and act normally for a while. Shifting, or just putting the clutch in seems to make it act normally for a while as well, but for a much shorter length of time.

Pretty everything under the hood that is electrical is new within the last 18 months except the injectors and the EGR flow sensor and coolant temp sensor.

I unplugged the EGR vac solenoid and that actually made it run worse which leads me to think fuel delivery issue.

I'm gonna try running it with the flow sensor unplugged, and then with the coolant temp sensor and see if those have any effect. Also going to try cleaning the flow sensor.

If all else fails, I have another truck that runs like a top that I can pull the injectors from.

PCM is a NAPA reman, about 2 years old.


So, any ideas?

 

[r1hatman]

Does it have a code reader on it?

 

[adsm08]

No codes. Otherwise I'd be chasing those down.

 

[holyford86]

I had a crappy TFI do something similar to that, on me

 

[adsm08]

I had a crappy TFI do something similar to that, on me

I'm heading over to Downey's place tomorrow to check and see if the timing is doing anything screwy. I also have a spare TFI sitting around. Might have to try throwing that in.

 

[r1hatman]

My 83 has a computer are you sure your 87 doesn't have a way to check the computer?

 

[mhughes165]

he meant he is tripping no codes, did u happen to check the map sensor, when they were goin bad in the past it would give me similar problems

 

[adsm08]

My 83 has a computer are you sure your 87 doesn't have a way to check the computer?

mhughes is right. I have a computer, and I have a way to pull the codes. When I did, I got 2 instances of a fuel pump circuit code, which isn't valid for diag because I stalled the truck pulling out leaving work the night before, and at home the next morning trying to not spin out on the ice in the lots.

he meant he is tripping no codes, did u happen to check the map sensor, when they were goin bad in the past it would give me similar problems

I have not checked the MAP, but it's only about a year old and OEM parts, so it's low on my list of suspects.

I do still have (somewhere) my old one which I think is actually still good, so I can throw it in and see if anything changes of I can find it.

 

[mhughes165]

i got to the point where i carried spares of everything with me because of how tempermental all the parts on the 2.9 coould be....

ummm the only other thing that ive encountered that is odd that could be the culprit, is when resistance build up inside the pill from age sometimes shit acts wierd, i replaced a entire wiring harness before checkin the resistance on the pill.....

lol...if u cant figure it out i got a 78 f-250 ill trade ya for it LOL.....just a thought....i want another ext cab lol

 

[Earl43P]

These things are notorious for fuel pump relays.

I'd install a new one. Might also jumper out the inertia switch connector's wires for a few drives to see if it is intermittently opening.

In short, I believe your codes. Stalling the engine shouldn't trip a fuel pump circuit code whatsoever.

 

[kimcrwbr1]

Can you take the egr off and check/clean it along with a new pcv. If you have messed with any sensors you need to erase the memory and reset the computer. Then you can run the codes again. It coud be just a cracked vacuum line or fitting giving you an intermittent fault make sure everything fits tight and the hoses are not hard. It kinna sounds vacuum related to me EGR, MAP,PCV.

 

[adsm08]

i got to the point where i carried spares of everything with me because of how tempermental all the parts on the 2.9 coould be....

ummm the only other thing that ive encountered that is odd that could be the culprit, is when resistance build up inside the pill from age sometimes shit acts wierd, i replaced a entire wiring harness before checkin the resistance on the pill.....

lol...if u cant figure it out i got a 78 f-250 ill trade ya for it LOL.....just a thought....i want another ext cab lol

Which pill, and don't want an F-250. Like my truck, just want to be able to drive 5 miles in a row without it acting up.

These things are notorious for fuel pump relays.

I'd install a new one. Might also jumper out the inertia switch connector's wires for a few drives to see if it is intermittently opening.

In short, I believe your codes. Stalling the engine shouldn't trip a fuel pump circuit code whatsoever.

Pump relay is new, pumps are both fairly new, and I've seen stalling it that way cause a fuel pump code to set.

Also, drove it with a fuel pressure gauge on it. Even at the worst of the bog down the pressure never dropped from where it should be.

 

[mhughes165]

Which pill, and don't want an F-250. Like my truck, just want to be able to drive 5 miles in a row without it acting up.



Pump relay is new, pumps are both fairly new, and I've seen stalling it that way cause a fuel pump code to set.

Also, drove it with a fuel pressure gauge on it. Even at the worst of the bog down the pressure never dropped from where it should be.

the pill is what u remove when u have to set ur base timing, if there is resistance in the circut at the pill it might think its out and is trying to run at base timing

the pill will be on the passenger side of ur intake manifold, prolly shoved down between the valve cover and intake

 

[adsm08]

the pill is what u remove when u have to set ur base timing, if there is resistance in the circut at the pill it might think its out and is trying to run at base timing

the pill will be on the passenger side of ur intake manifold, prolly shoved down between the valve cover and intake

Oh the SPOUT connector. I know where that is.

There are about 7 different items on this engine that I have heard called "the pill".

 

[adsm08]

Ok, so I think I got this one fingered out.

I put my spare TFI on at lunch today and it behaved for a good bit. I think I'm probably gonna get a new one. I had my reservations about this module which is why I replaced it in the first place.