M931A2 won't start

[mikey]

Warm ether can be your friend. I heard that the A2 have 2 fuel filters. Do you know where they are and the part numbers? I might be headed into the same issues you currently have.

There are two. The big can under the drivers side fender in front of the firewall is NAPA 3401.

On the passenger side there is one that looks like an oil filter for a car. I have NAPA 3472.

I've gathered these from other posts, but have yet to install them myself.

Good luck!

Mikey

 

[KaiserM109]

…
I hit the TM's and read MANY threads. …

For what it’s worth I hit the TMs with regard to the Emergency Shutoff for both A1s and A2s. I searched every TM on 5 tons printed on the website and the only thing it says is that if it is pulled you have to report it to maintenance, typical army.

My US Army experience is a little dated, but there were three levels of maintenance: operator, motor pool, and depot. All the TMs on the website, as far as I can see, are at the operator level. The information on how to reset it is apparently in the motor pool level documentation.

I’m going to side strongly with ‘push it forward and try it.’ If that works great, but too bad you had to pay a tow bill to fix it.

 

[mikey]

Ok the first 2 pictures. Both are from 5.9B Cummins. its a little different. But the wiring and principal operation of the fuel shut off solenoid is the same.

The final picture is an 8.3 Cummins, its what you have in your truck. Thats just a civi model from a bus so things are a slight bit different.

If your truck wont run, you know its not getting fuel. The only thing to determine...is where.

It may be ass backwards but i start at the pump and work my way back to the tank.

When my cummins refuses to run {not the nhc250} i diagnose by cracking the fuel line on the side of the injection pump and pumping the **** out of the primer. If i cant get it to drip fuel i close the banjo and move backwards cracking lines closer to the lift pump till i get a dribble.

If the lift pump is starving, its usually because ive got an air leak in the fuel supply line somewhere. Ive had my fuel heater oring leak air and make it hard to prime. Ive had the check valve in the pump go bad so it loses prime {front banjo bolt with a bb lookin thing on top}. Ive had a cracked hard line from the tank, leaking rubber lines from the tank. Pretty much all of those things were diagnosed by take a shop vac, flipping the hose and using it to blow air into the tank. This will also help you find a plugged tank vent.

If you take the fuel cap off and u get a buncha suction, check ur vents and see if itll start with the fuel caps off.

Those are just my basic trouble shooting steps i follow for diesel no starts. Ive never really had an issue with a diesel that was bigger then something minor. like a fuel or air leak or plugged filter.

My daily driver has a warped plunger/tube whatever inside the pump. A bolt fell out somewhere over texas and i ran the pump dry for like 600 miles. Spewing the fuel that was supossed to cool it all over the highway. It rarely runs on more than 5 cylinders. But it runs, i drive it everyday, i tow with it.

I refuse to believe you have some sort of major issue that makes the truck a non runner on all cylinders. each cylinder is its own engine, the pump is divided internally so most failures are isolated and not systemic. There are things that will kill it, for sure. It could have slipped timing.

But given your engine kill cable looks like ****e, and its a new truck, it seems it almost has to be something simple.

With the switches in run, once you crank the engine, does the plunger on the solenoid stay up? or does it fall back down? key on it has power to hold, if you lift it by hand or bump the start it should lift and stay up there. If it falls back down the hold wire doesnt have power.

Does it spit or sputter when u crank it? or nothing?

You can always pull the fuel line off the pump and run it to a Fuel can. {boat ones with a squeeze bulb are easiest} prime it by hand and see if it goes.


and fwiw this is a fuel shut off on an nhc250. The nhc has 2 sep shutdown valves. it looks to me like the 8.3 only use the internal one in the pump, and both the cable and solenoid act against it {in opposite directions}. Unless that linkage somehow moves independently of one another.

View attachment 476621

Awesome advice. Thank you! Not spit or sputter, nothing.

Here is an off the wall thought. I noticed when switching tanks, for troubleshooting, that the driver side tank is full (on the gauge) and the passenger side is empty (on the gauge). During the recovery I topped the tanks off half way home. During the ride home, I used the passenger side tank. When I got home, I switched to the driver side tank (I did not want to leave it full because it was above the full line). I drove it about 50 miles since getting it home. Noticing that the gauge still said full after driving 50 miles, I checked the tank. It still has fuel above the filter screen. After 50 miles, I do not think it should. I also do NOT think my passenger side tank should be empty.

I KNOW for certain that the gauges change from full to empty when I hit the tank selector. But I'm not so sure when I select the driver side tank, that the passenger tank is not still being used to supply fuel.

I'm going through the fuel portion of the TM's to see if this is even possible (fuel sending unit changes with switch, but not pump). I guess it would not hurt to put 50 gallons in the passenger tank, prime it and see if it starts. If it does, I can run it with the tank selector on the drivers side tank and monitor consumption from that tank.

Mikey

 

[mikey]

Sorry, I was referring to the 250. Didn't see your reference to A2. My A2's seemed to take a lot of cranking too.

Toby, I was not referring to anyone in particular. Just how frustrating the TM's and troubleshooting can be when I've never even seen under the hood of this truck before buying it a month ago. I'm no diesel mechanic, but I feel comfortable enough around an m35 multifuel to do a lot without posting on SS. The 939 is new and most of my frustration has to do with me not KNOWING how things should look.

Any and ALL help here by any member is appreciated. I know I'll get this resolved, and I KNOW the resolution will involve help from a member or two and not just come from the TM's.

TM's are great resources. But nothing compares to experience from fellow members.

Mikey

 

[mikey]

For what it’s worth I hit the TMs with regard to the Emergency Shutoff for both A1s and A2s. I searched every TM on 5 tons printed on the website and the only thing it says is that if it is pulled you have to report it to maintenance, typical army.

My US Army experience is a little dated, but there were three levels of maintenance: operator, motor pool, and depot. All the TMs on the website, as far as I can see, are at the operator level. The information on how to reset it is apparently in the motor pool level documentation.

I’m going to side strongly with ‘push it forward and try it.’ If that works great, but too bad you had to pay a tow bill to fix it.

I searched "Emergency Shutoff" and had the same result. Based on PP's post, I think the search to reset it would involve the term "fuel pump shutoff valve", although I did not search further because the step to reset it was provided in this thread.

At a quick glance, I thought all the relevant TM's were in section "5 Ton and up TM's". At a closer look I realized the last link in that section was a link to even more 939 TM's:

http://www.steelsoldiers.com/showthread.php?79228-TM-s-for-the-939-series-trucks

Not sure if you saw those. I admit, I missed them at first glance. D'oh

Mikey

 

[Suprman]

He was driving the truck when it died I doubt he pulled the shutoff

 

[tobyS]

One in-op that I was looking at read 1/2 tank of fuel but was completely empty.

 

[74M35A2]

Sorry if I missed, but does it fire with ether? If your ether injection cylinder is empty ($48 to replace, ouch), spray a good 10 seconds worth into and around the underside of the mushroom cap snorkel inlet. Will need to crank for about 10 seconds to suck that in. That will confirm if a fuel issue or not, depending upon if it fires up. The on-board ether injection system only injects during actual cranking, and only after you release the button. Crank, hold for 3 seconds, then release, and it sprays.

Next, remove one of the large plugs on the back-top of the injector pump, the one where you would adjust the governor spring tension a few clicks for more RPM, and see if the weights are swinging around when you crank it. Possibly the pump shaft or drive gear broke. Rare, but anything can happen. If the pump is rotating during cranking, then I would feed the engine a fresh line to the mechanical lift pump and into a gallon of diesel. Push the hand primer and see if it cranks up. If so, then it confirms your issue is downstream. Yes, there are 2 fuel filters, at least on my M925A2, the large one behind the driver side front tire, and the engine mounted one. Possibly one of them is loose, the drain is loose or broken off (sucking air), or a line is cracked. I had the dip tube fall off inside the fuel tank of my Bobcat, and it would not run no matter how much fuel was in the tank, but would fire on ether. Dip tube goes to the bottom of the fuel tank. Anything is possible. Start with ether, then the injection pump, and work backwards. You'll find it. Just be methodical about it, start at the engine and work backwards.

 

[doghead]

spray a good 10 seconds worth into and around the underside of the mushroom cap snorkel inlet. Will need to crank for about 10 seconds to suck that in

I strongly disagree.

If your going to use ether(in a hand held can), you better know how to use it correctly.

 

[doghead]

• Keep all starting fluid at room temperature. Inject starting fluid only while the engine is cranking.

 

[Suprman]

If you prime the 8.3 with charged batteries and its over 20 degrees the 8.3 should start with ease no fluid needed. Too much ether and you can eat a piston ring.

 

[mikey]

I have read that spraying ether through the mushroom is a bad idea because it doesn't distribute it evenly through the cylinders as the ether injection kit does. I'll pass on the ether for now. I have a plan to follow and some great ideas as soon as the batteries are charged and the weather warms up a tad.

For the record, this truck has not started well below 40f since the day I got it home. Of course, that could be part of the problem or a different problem altogether. However knowing that it's a hard starter, I won't crank it again until it's warmer or it could complicate trying to troubleshoot the existing problem.

Thank you all for your input and advice.

Mikey

 

[74M35A2]

OK, I'll agree 10 seconds is probably overkill. The point here is to simply see if his no-start issue is a fuel issue or not. I'm not sure what the shortest amount of ether shot is that will fire the engine as sprayed into the mushroom. A lot is going to evaporate just by doing that, it has a long way to travel, and the air filter is going to absorb some and hold it. In this case, you don't want to spray too small of an amount and have the engine not fire over, and then come back here and say it won't start on ether either.

Restated to calm the fury: Spray an appropriate amount of ether into the intake to see if the engine will start on that. If so, the engine mechanicals are OK. His no-start may not be fuel related at all.

Personally, I've sprayed a ton of ether into my mushroom trying to reprime after changing all filters. There was no bomb, no lunched piston rings, and the engine started just fine. The amount of ether to use could likely always be disputed, and one should lean to the least amount as possible, but how is that amount determined? Yes, the engine should not require it at all, but in this case it is being used as a diagnostic tool to see if his no-start is fuel related or not.

 

[doghead]

I disagree, again.

 

[73m819]

OK, I'll agree 10 seconds is probably overkill. The point here is to simply see if his no-start issue is a fuel issue or not. I'm not sure what the shortest amount of ether shot is that will fire the engine as sprayed into the mushroom. A lot is going to evaporate just by doing that, it has a long way to travel, and the air filter is going to absorb some and hold it. In this case, you don't want to spray too small of an amount and have the engine not fire over, and then come back here and say it won't start on ether either.

Restated to calm the fury: Spray an appropriate amount of ether into the intake to see if the engine will start on that. If so, the engine mechanicals are OK. His no-start may not be fuel related at all.

Personally, I've sprayed a ton of ether into my mushroom trying to reprime after changing all filters. There was no bomb, no lunched piston rings, and the engine started just fine. The amount of ether to use could likely always be disputed, and one should lean to the least amount as possible, but how is that amount determined? Yes, the engine should not require it at all, but in this case it is being used as a diagnostic tool to see if his no-start is fuel related or not.

What happened to PRIMING BEFORE you try to start the engine, trying to start with a DRY ip running on ether is REALLY REALLY hard on it.

 

[Scott88M]

I'm not an expert it's been since 99 since I've driven a m931. But did mikey say something about the tank not changing over with the switch? Could it be he assumed the dash switch changes tanks and not just sending units? I'm pretty sure there's a lever on the floor that switches actual tanks. Is it possible everyone is over thinking the problem and is just that his first tank finally ran empty?

 

[doghead]

Good point!

 

[1 Patriot-of-many]

I'm not an expert it's been since 99 since I've driven a m931. But did mikey say something about the tank not changing over with the switch? Could it be he assumed the dash switch changes tanks and not just sending units? I'm pretty sure there's a lever on the floor that switches actual tanks. Is it possible everyone is over thinking the problem and is just that his first tank finally ran empty?

Yes that is definitely possible. The fuel tank selector is indeed on the floor next to the drivers door. It's kinda a problem in waiting if you forget to switch one or the other with each other.

 

[1 Patriot-of-many]

Also a good point. When my p7100 IP runs out of fuel, its REALLY hard to press the accelerator pedal. If ur cranking the engine and the pedal is really hard to depress you can guarantee the pumps empty.

I still think its not switching tanks and the trucks more or less out of fuel. Balance your tanks and light the fires! {hopefully}

Just because one persons never seen anything bad happen with ether, doesnt mean i havent. Ive seen air filters turned totally inside out. Intake manifolds blown apart. Top rings cracked. The list is endless. Spraying a basically unstable low flashpoint fuel into a compression ignition engine is just begging for disaster. Dont really care what anyone says on the subject. I don't/wont use it.

These trucks come with a metered ether system. For a reason. Some of them will simply not start even with 4 new batteries cranking away until they are dead.

 

[1 Patriot-of-many]

http://www.steelsoldiers.com/showthread.php?117516-Another-M923A2-Question Look at post#9 in that thread. If your lever isn't fully forward against the wire stop, it will either run poorly or not at all. My lever would catch on a kinked section of the wire and not move fully forward resulting in running badly/dying or not running.