Engine/Transmission (1994 - 1998) What happened Need Counsel #3

[CKHeller]

As a recap: My truck ran fine but suddenly at about a quarter of a tank it started to hesitate, RPM's would go down and the truck would nearly stall while running and it would blow out clouds of white smoke. Some guys here gave me some tips and things to check as well as general counsel about how to diagnose the problem. Look back to last week if you want to read the whole history.



At this point the truck is running better but I don't think it is fixed. I might have figured this out but don't know how to test my theory without major work that is beyond my ability to do and I don't want to pay anyone to test my hunch. I think I already told you that I cleaned the pre filter on the bottom of the fuel heater, it was pretty cruddy but cleaning it out didn't help the truck run any better. The next thing I did was make sure the intercooler boots were not leaking. I looked for water in the fuel filter water separator. I took the filter off and carefully dumped it into a jar. There was a tiny bit of water in the fuel. I asked my mechanic friend that finally finished my daily driver what he thought and he gave me a new piece of information. Several months ago I had the fuel sending unit replaced by this man. Today he told me that the module that holds the sending unit was in terrible shape, held together with wires and in fact he needed to put some screws in it to better hold it together. This made me think about Darl Absher III's post to me where he said about his truck:



<<The truck started stalling once the fuel level started getting low and I found out, when I went to replace the fuel pick-up and sender unit in the tank, that it had fell apart. The unit is two piece and the bottom piece came loose, with the only thing holding them together was fuel pick-up line. The bottom part is made to float up and down with the fuel leveland my guess is when it separated it started floating upside down and when the level would get to low it would start sucking air, making it stall or run rough. If it died it would start back up with a little work and run fine for a bit, then do it again. I think one thing to try would be to fill the truck up with fuel and see from there. >>



That sounded so much like my truck's problem that I put 5 gallons of fuel in it after replacing the fuel filter. I started the engine up and after a rough start the truck is running much better but I don't know how to fully test the theory before spending over $300 for the fuel module and another new fuel sending unit (they don't sell them separately) plus $200. for the labor because that is not a job I feel safe doing in my driveway.



Is there any way to test this theory other than dropping the tank and visually checking or running the tank down to the point the thing falls apart again stranding me someplace?



Kru Heller

Powhatan, Va.

 

[CKHeller]

What happened Need counsel #3 - Correctee

I don't know what happened to the first post but somehow the quote was removed. Here is the post as I intended it.



As a recap: My truck ran fine but suddenly at about a quarter of a tank it started to hesitate, RPM's would go down and the truck would nearly stall while running and it would blow out clouds of white smoke. Some guys here gave me some tips and things to check as well as general counsel about how to diagnose the problem. Look back to last week if you want to read the whole history.



At this point the truck is running better but I don't think it is fixed. I might have figured this out but don't know how to test my theory without major work that is beyond my ability to do and I don't want to pay anyone to test my hunch. I think I already told you that I cleaned the pre filter on the bottom of the fuel heater, it was pretty cruddy but cleaning it out didn't help the truck run any better. The next thing I did was make sure the intercooler boots were not leaking. I looked for water in the fuel filter water separator. I took the filter off and carefully dumped it into a jar. There was a tiny bit of water in the fuel. I asked my mechanic friend that finally finished my daily driver what he thought and he gave me a new piece of information. Several months ago I had the fuel sending unit replaced by this man. Today he told me that the module that holds the sending unit was in terrible shape, held together with wires and in fact he needed to put some screws in it to better hold it together. This made me think about Darl Absher III's post to me where he said about his truck:



"The truck started stalling once the fuel level started getting low and I found out, when I went to replace the fuel pick-up and sender unit in the tank, that it had fell apart. The unit is two piece and the bottom piece came loose, with the only thing holding them together was fuel pick-up line. The bottom part is made to float up and down with the fuel leveland my guess is when it seperated it started floating upside down and when the level would get to low it would start sucking air, making it stall or run rough. If it died it would start back up with a little work and run fine for a bit, then do it again. I think one thing to try would be to fill the truck up with fuel and see from there. "



That sounded so much like my truck's problem that I put 5 gallons of fuel in it after replacing the fuel filter. I started the engine up and after a rough start the truck is running much better but I don't know how to fully test the theory before spending over $300 for the fuel module and another new fuel sending unit (they don't sell them separately) plus $200. for the labor because that is not a job I feel safe doing in my driveway.



Is there any way to test this theory other than dropping the tank and visually checking or running the tank down to the point the thing falls apart again stranding me someplace?



Kru Heller

Powhatan, Va.

__________________

94, 2500, 4WD, 5 Speed, Std cab, Long bed

 

[JFaughn]

I remember answering some on the other post , one thing that occures to me is to disconnect the fuel line at the lift pump , and maybe with just the pressure that you can make with your mouth or about 2 lbs. from compressor , then listen with fuel cap off , for bubbles , what you'll need to do is run a gal. or 2 at a time to find the level that the bubbles go away and you can just hear or feel the air pass without bubbling the fuel , then you know the level of the pickup leak .
Unless it gets to the bottom , then you know that the problum is elswhere .

 

[CKHeller]

Thanks John for your counsel. I wanted to wait until I tried what you suggested until I replied. Today I disconnected the fuel line and hooked a tube up to blow bubbles then learned I had to disconnect the fuel intake to the tank because there is this green ball thing in the fill tube - what's that for? - Then I got my siphon down in the tank and it wouldn't work. I don't know what the problem is. I put it all back together and I guess it will have to go to the shop. I'm not dropping that heavy tank in the driveway with the limited tools I have. Thanks everyone. I think you helped me figure it out but I'm going to have to pay someone to fix it.



Kru Heller

Powhatan, Va.

 

[Oaksford]

just went through this with my 94'. after pulling tank and months of searching problem turned out to be fuel line leak on back side next to frame rail where it had rotted. it would run great until below 1/2 tank and under heavy load. then would skip and run poorly. i stop and shut down for 5 min. and all was well again. always ran well with full tank. i think wieght of fuel when full helped push fuel up lines. pressure dropped as fuel was used up. any way runs fine now. hope this helps some.