M923A2 dies when put in gear, especially forward

[ichudov]

I finally had time to work on this.

*** THIS IS A MAJOR EDIT -- PREVIOUS CONTENT WAS INCORRECT ***

1) The button on the Hi/Low gear shift lever was indeed BAD. It would stay open and would not close. I cut two wires leading to it to experiment by manually open and close the circuit with alligator clips. If the circuit is CLOSED, the torque converter is LOCKED and the truck shudders very unpleasantly when put in gear, and the motor dies. If the circuit is OPEN, torque converter does not seem to lock up, and the truck gently shakes and the motor dies slightly slower.

2) When in neutral, engine acceleration seems to be sluggish.

3) As the truck ran out of fuel at least twice, I suspect that the fuel filter may be clogged, I will replace it today to see (Fram P8043).

 

[ichudov]

OK, more good news:

I replaced the fuel filter on the engine. The filter that I took out, was DISGUSTING and full of filth and grime.

I have NOT yet replaced the big filter cartridge on the fender.

After having done so, the engine has noticeably more power. I can rev it in neutral and it is very responsive. I can also drive this truck if I push on gas somewhat.

However, and here's the same problem, it dies if I brake the truck, as if it was in gear and would not disengage upon brakes applied.

It also still has the problem that if I put it in drive without adding gas, it dies.

I have a feeling that these are related problems and somehow are related to torque converter not unlocking, or some such.

 

[JohnnyBM931A2]

Fun stuff Why did you end up replacing just the one fuel filter?

 

[ichudov]

Fun stuff Why did you end up replacing just the one fuel filter?

This is what they had at Autozone.

I ordered the big (cartridge) one online.

 

[JohnnyBM931A2]

I think I'm going to do my fuel filters soon as well, now that I have my oil change and trans fluid change out of the way. Everytime someone talks about replacing their fuel filter(s) they make a point to mention how nasty the old filters are I have no idea when mine were replaced.

 

[ichudov]

I think I'm going to do my fuel filters soon as well, now that I have my oil change and trans fluid change out of the way. Everytime someone talks about replacing their fuel filter(s) they make a point to mention how nasty the old filters are I have no idea when mine were replaced.

I believe that the filter contamination reported here, is due to fuel tanks lined with material that softens and dissolves in diesel fuel. I know that it sounds too stupid to be believable.

 

[86m1028]

we had one of our trucks do the same thing and we had to have the fuel pump rebuilt.. would run with the skinny pedal mashed but not idle in gear and die when put in gear if you didn't hold her to the floor.

Define fuel pump ?

Lift pump or injecton pump ?

 

[Floridianson]

Define fuel pump ?
Lift pump or injecton pump ?

Looks like the last time he logged in was 08/2016