A few words of advise from an outside source gave me a couple ideas that might be worth looking into for ya BenTX. One, possible vacuum leak, which I kinda thought would cause the issue whether in closed loop or not, but who knows...might as well take a couple minutes to take a quick look. Also, PCV valve. Pull it out while running just to see if your getting vacuum on the other side of it.
The only other thing he really had to say other than the fuel system we're already working on, was maybe the timing chain is going out. Hmmm.. I sure as hell hope not. Don't feel like messing with all of that. But I really dont think that has anything to do with our issues here.
But I'm still leaning towards the injectors or the check ball valve in the pump. Does anyone in here know which, or if both, of the pumps on these trucks have that valve in them?
Possible good news! I installed a new thermostat today thinking my old one was stuck closed. If this were the case the engine would have run until it overheated because there would have been no flow of coolant. Seemed like close enough to our problem to give it a shot. By the way it only cost me $12 to get the new one and some water pump/thermostat liquid gasket. After installation I refilled the coolant (didn't have to drain the whole thing but you lose a little when you take off the radiator hose going to the engine) and let it run in my driveway for a good ten minutes. I also boiled my old thermostat to see if it was working and it only moved about a sixteenth of an inch and I think they are supposed to move at least a half inch. I proceeded to drive my truck around the block several times and everything was still looking good. Started driving around town and after driving it for the better part of an hour it started doing the same thing. Thought I had it fixed! Although this isn't a complete fix I think it says a lot about our problem. I know for a fact the engine ran for a while at operating temp. This means that our problem isn't starting right at the moment it goes into closed loop. Also the only system this install affected was the cooling system. I drove the truck at least three times longer and farther than I was able to before. This big of a difference leads me to believe it is a cooling issue= maybe the truck is actually shutting off because it is overheating. I think the next thing I'm going to try is replacing the coolant temperature sensor. If I had a faulty sensor then my gauge might not read that it's getting too hot when it actually is. I was going to do that today but they are $22 and I don't get paid until the 20th haha. Also, at least for me, the hottest days of the summer have been this past week so overheating is a more likely culprit. Well I hope the rest of the fix will be as easy as it was today. There is nothing better that a simple solution! Hope this helps. -Ben
That's good to hear that you are getting somewhere. Today's update, I replaced my fuel pressure regulator, but still watching the fuel pressure guage drop at rest pressure. But then we started playin around with the vacuum lines and it seemed to almost always kick up the idle, but smoothed out the way the truck was running. Drove around with the air intake box open for a bit and the vacuum line running to the cruise control off and the truck kept running. Don't know exactly what all this might mean, but any progress is better than no progress.
Another thing, I pulled the TPS electrical connector off expecting it to do something erratic or wierd, but really pretty much nothing happend. Anyone else find that odd? Resistance test proved the sensor to be good.
That's about all I got done today. I'll look into that ECT sensor thought tomorrow as well as some possible vacuum culprits...IAC, MAF, PCV, etc.. Well good luck to ya, thanks for keeping posted.
Replaced the TFI Module today (aka Ignition control module). The module is known to go out and I couldn't find a local autoparts store that could test it to see if it was still good so I just bought a new one. Still no fix.
Has anybody heard of the fuel cutoff switch? Could that be the problem?
fuel cutoff? I think you're referring to the power inertia switch. But if that had been "hit" hard enough to knock the magnet loose, the vehicle shouldn't start at all. There should be like a little tab/button on it or something like that to reset it if you ever need to though.
That's good to hear that you are getting somewhere. Today's update, I replaced my fuel pressure regulator, but still watching the fuel pressure guage drop at rest pressure. But then we started playin around with the vacuum lines and it seemed to almost always kick up the idle, but smoothed out the way the truck was running. Drove around with the air intake box open for a bit and the vacuum line running to the cruise control off and the truck kept running. Don't know exactly what all this might mean, but any progress is better than no progress.
Another thing, I pulled the TPS electrical connector off expecting it to do something erratic or wierd, but really pretty much nothing happend. Anyone else find that odd? Resistance test proved the sensor to be good.
That's about all I got done today. I'll look into that ECT sensor thought tomorrow as well as some possible vacuum culprits...IAC, MAF, PCV, etc.. Well good luck to ya, thanks for keeping posted.
The engine is running off the idle air control valve at idle, so unplugging the tps would not affect it at idle.
Back from vacation for a couple days now, pulled the bed off the truck and been workin away on it. Though I'd check in and see if you were makin any progress BENTX, hope your gettin somewhere.
And that makes sense luthrobediesel. Didn't think about it that way.
Couple things... For one, I thought of a few other symptoms my truck had before I started tearing it apart: It backfired from time to time during deceleration, and while I had it running in the garage, a crazy amount of black dust like debris started covering the floor as it came out the exhaust. And now today I pulled the electrical connector off the pump assembly on the tank, cleaning up the area around it before opening it up. But then I decided to hit KOEO just to play around with the fuel pressure some more first. And go figure... pump didn't turn on. So I grounded a test lead to the test connector and it kicked right on. So...fuel pump relay perhaps? I'll keep digging and workin, but always open to any ideas. Thanks guys.
Well just tried hittin the key, and now the pump does kick on KOEO, but the rest pressure is now dropping faster than ever before. hhmmmm.... Am I just this bad/amatuer of a tech or what? Cause I've never been so lost!!!!
Oh ya, and BenTX,
Out of curiousity, do you have any exhaust leaks? Primarily on the manifolds or anywhere upstream from the O2s as this could throw off the sensor and give the pcm false readings creating a fuel delivery-like issue in closed-loop. Look forward to any feedback from you and/or anyone else.
Funny thing fellers...I just went thru these same symptoms with my boys' 89 ranger 2.9L auto. Started up fine, let it warm up, shut it down, when you tried to restart it seemed like it was getting no fuel. Well, after a couple weeks of fuel filters and the module in the distibutor not helping, I cashed in and took it for a few hundred dollars of MX. The tech replaced what he called a pickup in the distributor. After that it ran like a champ, passed emmissions testing and is almost on the road again.
Hopefully this will save some of you the $$ that I had to shell out!
I also think it is the pickups in the dizzy. Have been having the same problem that you have, although my truck will stay running after it has warmed up, but will die from time to time. It will run good then act up like it isn't getting enough fuel and if I step the gas to the floor it will come out of it and when I let off will go right back to running bad. I have replaced the fuel pump and I have good pressure. Mine is a 89 so there is only one fuel pump in the tank. The reason that I changed the fuel pump is because I was there and it was on the low end but within specs and I think it was the original pump with 168,000 on it, it was time for a new one. A dizzy from auto zone is around $100.00, but a buddy of mine has a junk yard so I am going to go out there and do a little swapping just to make sure that is it, then go and buy a new one or not depending on how the one I swap works.
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