New to me M936A2 engine idle / load issues

[dcowan]

Biodiesel sounds like an easy try. What causes it to clean things up. The fuel had a heavy varnish smell when I drained it. I smelled no hint of vegetable oil and I'm familiar with the smell of it as it goes bad. The varnish smell did have a slight sweet smell so I could buy into the sugar theory.

 

[WillWagner]

Careful with bio, it is highly corrosive and the early Cummins junk didn't like it, BUT, since it is corrosive, it might help! I agree, looks like water or something water based. There are other fuel system cleaners out there, I just have never seen them work, so if the FG part can't be located, try something else.

 

[dcowan]

I had a hard time finding the FG cummins cleaner so I was able to get some Penray Total Diesel Fuel System Cleaner off amazon and from what I read it is really good at cleaning up deposits, especially asphaltene. It seems to have helped. I dosed it pretty heavy in the tank and ran it for an hour at 1250 rpm then was able to drive it around my field for about 45 minutes and it was much better. Still will die at close to idle, but now that is like 650 rpm instead of 850 rpm. Also seems to recover from low rpm better. I will just continue running it as it is and hope that it continues to get better before I resort to biodiesel. I may mix up a small mechanic tank with a high dose of this penray and hook up at the lift pump and run that through to try and quicken things. What idle RPM do most people run? I see 575-650 in the TM.

 

[simp5782]

Does it respond and run well with the power divider on? That is a load versus a just high idle

 

[dcowan]

Not really sure what you mean by power divider. At high idle it runs fine. It does not seem to handle load as well. For example in neutral transfer case in gear for the transmission with PTO locked in I can kill it at low idle very easy. Have to rev up over 1000RPM to not kill it.

 

[simp5782]

Not really sure what you mean by power divider. At high idle it runs fine. It does not seem to handle load as well. For example in neutral transfer case in gear for the transmission with PTO locked in I can kill it at low idle very easy. Have to rev up over 1000RPM to not kill it.

When you place the transfer case to neutral. And engage the lever behind the seat, then place it in 1-5 it should automatically rev up 1650 rpms. The lever behind the seat is the power divider. That is for the transfer case pto only to engage the wrecker body and rear winch

You should not have to toucb the throttle it should go up on its own.

 

[silverstate55]

Seafoam works wonders for me, especially on varnish-like coatings/deposits in fuel system. Available at any auto parts store and even some walmarts.

 

[98G]

When you place the transfer case to neutral. And engage the lever behind the seat, then place it in 1-5 it should automatically rev up 1650 rpms. The lever behind the seat is the power divider. That is for the transfer case pto only to engage the wrecker body and rear winch

You should not have to toucb the throttle it should go up on its own.

This directly conflicts with my experience.

Here's what I experienced with operating the rear PTO on my M936A2 -

Transmission in neutral.

T-case in neutral.

Engage the rear PTO.

Transmission in 1-5. (Remains at idle).

Immediatley adjust throttle for 1500+ rpms.

 

[simp5782]

This directly conflicts with my experience.

Here's what I experienced with operating the rear PTO on my M936A2 -

Transmission in neutral.

T-case in neutral.

Engage the rear PTO.

Transmission in 1-5. (Remains at idle).

Immediatley adjust throttle for 1500+ rpms.

Some have had the auto governor removed by the units They came factory with them to prevent burning the transmissionup. They had even added them to the 816s as well

 

[dcowan]

Mine does not auto-throttle up. I have to manually adjust it with the hand throttle.

 

[dcowan]

So I have continued to fight this. I did a flush of the injector pump with straight fuel injector cleaner overnight. Basically filling the spin on filter with cleaner and hand pumping through and letting sit overnight. It seems to have helped a little but not much. I also tried adjusting the aneroid valve to see if it helped the low end and that didn't seem to help. I then tried to adjust the idle screw up to see if I could get it to idle. I can hand throttle it down to 700 rpm now, but foot throttle dies when let off. I hand throttled it to 700 then shut it down and adjusted the idle screw to touch the throttle linkage. Then tried to start and it would not start. I could only get it to start after screwing the idle screw back down were it was. To start I have to let it crank then hit the throttle a little. I'm guessing there is something in the IP that will not let it start unless it see's idle to begin with. I'm hoping someone has some ideas before I start attacking the injector pump as the culprit or injectors. One other piece of info is that I took some of the deposits and put them in jars and poured seafoam in one and injector cleaner in the other. Seafoam did nothing and injector cleaner did dissolve a little but not much.

 

[EO2NMCB]

Any update on the fuel issues?

 

[dcowan]

Yeah, glad you reminded me. So I had the injector pump removed and they found that it required a complete rebuild which was going to cost about $2500. So I bought an already reman'ed unit from one of common vendors and it fired right up and have had no troubles since. I was concerned I also had a transmission issue based on the way it acted with the old injector pump, but that has not turned out to be the case. It starts and runs perfectly now.