86 M1008 Boggin down/stumbling Problem

[86M10086.2L]

I Just made it home from a 500 mile round trip to snowmobile in the adirondak mountains. It was again a succesful trip in the 1008 but this time only successful in the fact I made it home. About 50 miles or so from the camp I was staying at the truck started to stumble or bog down when traveling up a incline. So I pulled over checked all my fluids and despite having checked all these before I left I found the transmission to be a little low. So I added about a pint and continued on. Problem seemed to go away. On the way home it started again. So when I stopped for fuel I checked everything again. All the fluids levels were fine, tranny fluid had a few bubbles in in but nothing to speak of. Couldn't find any leaks, so I fueled up and continued on my way. As I continued home it slowly got worse but never to the point where the truck would drop under 45 mph. It would start about halfway up a incline or hill and stop when you got to the top and started decending. And occasionly happen on level surfaces as well. If you let up on the accelerator it would make it any better and if you mashed it to the floor no difference either. I did however spot that whenever the truck would start to stumble a little blueish/white smoke would come out both exhaust pipes then clear up as soon as it stopped. My air filter is fairly new and clean. MY fuel filter was replaced last summer and has about 15-20K on it. My injection pump has leaking throttle shaft seals but has been since I got it. And I replaced my CDR valve about 5K miles ago. Any thoughts? I orignally thought it was the tranny til I saw the blue smoke. Is my IP giving up the ghost? Bad injector? Clogged filter? Bad lift pump? Bad fuel or water in the fuel? I ran about 2 fullt ankes of fuel through the truck duriing the course of the trip. I also have a clear fuel line going into my fuel filter base with a check valve to counter act the leaking throttle shaft seals and saw no air/bubbles in the fuel line. I also cracked the air bleed and water drains open into a old water bottle with the truck running and fuel did come out but at a rather slow rate compared to what I remeber when I changed the fuel filter originally. the thing I can't figure out is why its a intermitant problem. It happens all all speeds and all grades of roads. And when its not occuring the truck runs fine. The only other thing I noticed, is that when I give it full throttle to pass someone or enter a highway it doesn't produce any grey or black smoke like it used to. I'll start with the normal course of filter changes and fuel pump tests. But other than that I'm stumped. My headlights also stopped working but they are not a priority at the moment.

 

[Armada]

Hmmmm.... sounds fuel related. How many miles on it? Is the fuel pump original? I would start with replacing the fuel filter like you said. You may have gotten a tank of bad fuel. Could have been pushing a slug of water through. Make sure your fuel line connections are all tight, especially the hoses on the fuel filter that are held on with hose clamps. They can loosen over time. Also, how cold was it? Maybe your fuel was starting to gel?

 

[Somemedic]

Check the fuel return line injector. I would bet it is clogging up. Its on the front of the motor, top and has a J or horse shoe shaped hose on it. Pull the hose off the injector and then take the injector off. Hold the injector up to the light while looking through and it should be clear or maybe opaque but you should not see anything inside it. What ur looking at is a check valve, the injector has a glass bead the pivots up and down with the pressure of the fuel pumped through it. With the gasket inside your truck deteriorating some of the loose material is clogging the bead and not allowing it to move freely up and down inside the injector. If you blow it out onto a towel it will look like reddish coffee grounds, kinda. You can keep a can of gumout with the straw and blow it out time to time, making sure it moves properly and that will keep the truck operating just fine. I wouldnt recommend "breaking" the bead out, Im guessing its there for a reason. Long distance trips at near WOT or +60mph will ncessitate the need to do this at fuel stops or even as needed depending on how long your gasket has been breaking apart. This is the swan song of the IP however and a rebuild is in your future.

or it could be the lift pump too, or partially clogged/watered up fuel filter. Check and let us kno.

 

[IRWFO]

Fuel Filter.

 

[86M10086.2L]

The lowest I saw the temperature get while I was there, was about 2 degrees. And that was when I woke up at about 6 in the morning and the sun was already up. Who knows how low it got during the night. It was around 30 while i was driving home and maybe in the teens going up. I was running anit gel treatment in the tank just before and during my trip, STP in a blue bottle. I don't know how good it is as I've never used it before. It's one of those anti gel/injector cleaner combos. Thats all the parts store had in stock before I left. I usually use the Power Services stuff they carry at wallmart and Pep Boys in the white and silver bottles and I've never had a problem with them. Total mileage on the truck as I'm understand it is 59K. I got it with 43K. The condition of the rest of the truck and under carriage aside from some minor colision damage makes me think thats pretty acurate. But other than that I don't know. The IP and the fuel pump are original as far as I know. All I've done to the truck in terms of the engine was basic maintianance and tune ups when I got it. Filters, hoses and such. I have been perpared to put an IP in the truck since I got it because of the throtle shaft seals. So if thats the case then I rode the bull long enough before it bucked. Gotta run and pick up the filter and I'll check out that injector and let you know what happens.

 

[scottc]

If it is a clogged return check valve on the ip. Cleaning it will only be a temp fix. It will get worse. Get it rebuilt or get a replacement.

 

[86M10086.2L]

Well, I drove it to the parts store to pick up a new fuel filter and couldn't get it to repeat the symptoms but it did seem a little slower than normal. I replaced the old Purolator fuel filter with a new AC Delco one and all seems well. I did notice that during the bleeding process a much stronger stream of fuel came out of the air bleed than when I tried it at the rest stop. I should also mention prior to this I removed the old plastic caps and valves on the filter base and replaced them with brass needle valves making draining/testing/bleeding the filter assembly easy and a lot cleaner. When I bleed the filter on my trip home the flow was not much more than a steady drip. With the new filter it was almost like a fire hose. Leading me to believe and confirming many of your suspicions that it was indeed the fuel filter. I'm not going to try anything else unless the symptoms return. This way I'll know if it really was the filter. But if they do I'll try everything you guys suggested one at a time and see what happens. My truck and I thank all of you.

 

[tourdog]

fuel filter and at them temps you should be sure to have put aditive in fuel power sevice or someting try power serice 911 with the fuel in tank .really shouldnt be that many miles between fuel filters should be every oil change do feul filter .really importdent in winter months .

 

[86M10086.2L]

Thats news to me. I've never read anywhere that they should be changed that often. I just figured that they should be treated like a regular car and done every year. If thats the case then I'll adjust my schedule accordingly.

 

[nk14zp]

I second changing fuel filter when doing oil change. Also recomend having a spare fuel filter and a quart of 911 with you.

 

[86M10086.2L]

There is a brand new WIX filter sitting in my truck for just that. Diesel 911 is not that common around me, I've seen it but I always forget to get it and where it was. Eventually I'll put 2 and 2 together. For now the power services stuf will stay in my truck and get put in with each fuel up.

 

[nk14zp]

The 911 is made by power service good if you gel up. Irun power service cetane boost in my truck and house furnace to prevent gel ups. In the house furnace i ruin no2 heating oil in an outdoor tank no problems with geling.

 

[motormayhem]

Mine did the same thing with a bad fuel filter. At first it was intermittent, but then it just got worse and finally would stall on every hill.