M35a3 fuel problems

[spoolbooster]

Hello all. I have a m35a3 with the 3116 cat. The truck runs and idles great in neutral. You can rev it and its fine as soon as you put it in gear and put a load on it it starts to break up and the fall on its face. Pull over put it in neutral let it idle then it's fine in neutral put it in gear and put a load on it same crap.... I've cleaned the check valve in the tank changed the fuel filters and still same thing I'm lost. Could the pump be taking a sh&t or the seals on the injectors I don't know.. Just not sure on how you can rev it fine in neutral but the put it under a load (put it in gear) it falls on its face?? Any help would be great thanks

 

[mbehne]

No expert on the cat but I hear that comment almost daily on marine engines I work on... She revs good in neutral so it's getting fuel. If only that was the case. It takes very little fuel(volume or pressure) to spool the engine up with no load, but as soon as you ask it for power she will fall on her face. With that said, I would look for causes for low fuel pressure or flow...ie filters or fuel pump. I would imagine the specs and test procedures are in the tm's.

mike

 

[gimpyrobb]

You sure its not transmission related?

 

[spoolbooster]

We put a gauge on it under a load it's only putting out 15 lbs I believe normal is around 60lbs

 

[gimpyrobb]

What did you put a gauge on?

 

[spoolbooster]

I had put a cat primer/fuel filter housing on it. The line that comes out of the pump to the primer head is where I put the gauge.

 

[Floridianson]

http://schoolbusmechanic.blogspot.com/2009/07/cat-3116-troubleshooting-no-power.html

 

[Floridianson]

You might want to check the diaphram in the air/fuel ratio in the govenor also. Remove small meal tube that runs from intake passage to govenor. The fitting on the govenor will be on the side. Apply 10-12 psi of air pressure to the fitting in the governor. Snap the throttle back and forth and watch the exhaust. With air applied you should get a big bloom of black smoke and without air applied not much smoke.

 

[spoolbooster]

Thank you

 

[Floridianson]

Your welcome and let us know what you find. I have not had any problems with my A3 yet so it is a learning curve for me too.

 

[spoolbooster]

Will do I'm on vacation this week so I plan on getting into it.