1990 M929A2 starting problem

[jdavidso]

I recently purchased a 1990 M929A2 at auction. Batteries had bad cells so I am replacing them and in the meantime put two HD batteries in series to check the engine. initial attempt gave a nice white smoke cloud with a 20 to 30 second rough running start at about half throttle (won't start at idle) with continued smoke and stall after release of half throttle. The air pressure pumped up to 90 PSI and the oil pressure did not rise more than a nudge but not on any numbers. I changed the oil and when I drained it appeared to have been more than a gallon over filled. I checked the oil pressure sending unit and it functions normally, bled the fuel lines to the high pressure pump, checked the air intake and filter and it is all clean/clear. Tried several more times and just get lots of white smoke and she seems to be on the verge of starting but just doesn't at idle throttle. The engine shows no signs of binding or seizing. Any recommended troubleshooting procedure or test I should perform would be appreciated. Thanks for any advice or suggestion you might have.

Joel
1990 M929A2

 

[Gunzy]

I'm not an expert but white smoke generally indicates lean(not enough fuel) and this is likely why it won't start/run. Check the fuel filters for restrictions and ALL fuel lines for leaks(sucking air) and the fuel tank switching valves are prone to leaking air. If all looks good see if you can Bypass the tank switching valve and retest start/run. This is a good place to start as it sounds like fuel delivery issue.

 

[porkysplace]

Also check the emergency shut-off lever ( on the pump) to make sure it is completely reset , there is also a manual fuel shut-off by-pass for the electronic fuel soleniod .
If you already have not done so download the TM's there are trouble shooting sections in the -24 manuals.
[h=3]TM's for the 939 series trucks[/h]

 

[jdavidso]

I got it started with some persistence. It still runs rough and puffs a smaller amount of white smoke but after running at 600 rpm for about a half hour stalled and wouldn't restart. I am beginning to suspect the pump where the primer button is. I am replacing all filters in the fuel line and will see if there is a rebuild kit for the primer/pump. Thanks for the replies.

Joel

 

[Csm Davis]

I got it started with some persistence. It still runs rough and puffs a smaller amount of white smoke but after running at 600 rpm for about a half hour stalled and wouldn't restart. I am beginning to suspect the pump where the primer button is. I am replacing all filters in the fuel line and will see if there is a rebuild kit for the primer/pump. Thanks for the replies.

Joel

Replace all of the rubber fuel lines it sounds like a air leak in one. It is very common on the a2s not sure why but they seem to be more sensitive to small amounts of air getting in the line than the 250.

 

[Jeepsinker]

Yep. Sucking air. Put some air pressure to the fuel tank.