M923A1 won't start/IP not moving fuel.... need Assistance

[mmerz]

This is my first post and would like to say thank you for all the valuable information on this forum. Here is my issue. I've had the truck since March 2015. M923A1 with Cummins NHC250. Truck was running good and then I changed the fuel filter as regular maintenance. I searched and read all the posts on filter change and getting IP prime back. The hand pump won't work so I back filled the fuel line from IP to canister until I got fuel to come out value. The truck started ran for 20-30 seconds then stopped. I changed the primer hand pump and pumped a gallon of fuel through the system. Truck won't start. Added pressure to fuel tank and this forced fuel through system and out an open primer pump. There was no leaks in the fuel line with closed pressurized system and fuel came out the value on canister when depressed. I pumped another gallon of diesel through system and out primer pump to make sure no air was in the system. I opened the IP small screen filter cap (cleaned) and there is fuel in the IP. Primer pumped the system again. There is fuel at the IP but still won't start. Truck will start for a couple seconds with starter fluid but IP is not moving fuel. My guess is the IP is air locked somehow. Attached is a photo of the IP. Is there an air bleed on the IP? or how do I get fuel in the IP to force any air out. I read a post on the 8.3 that showed a bleed screw on the IP pump itself. I figured the prime pump should remove all the air so now I'm stumped. Thank you in advance, Matthew

 

[porkysplace]

Has the emergency shut-off been pulled or moved while you were working on it ? It needs to be reset manually if it was.

 

[Jmag]

I just picked my M923 up last month and had the same issue. For me it was a loose nut that held the power supply under the fuel injector . Not sure if this helps. Good luck !!

 

[mmerz]

Thank you for the quick responses. I checked the emergency shut off and made sure it wasn't engaged. I'll have to check all the wires to make sure all connections are tight. Then I'll have to wait for the batteries to charge as I ran them almost dead trying to start it.

 

[WillWagner]

Maybe a failed FSOV. Turn the knurled knob in and see if it will fire. If it does lite, the ign switch will not shut the engine down, you will need to use the e-stop or turn the screw out. PT pumps do not need to be bled, they are a positive displacement pump.

 

[WillWagner]

I just picked my M923 up last month and had the same issue. For me it was a loose nut that held the power supply under the fuel injector . Not sure if this helps. Good luck !!

What?

 

[mmerz]

Turned screw in and no start. I will have to go through all the lines and canister again to make sure no air leak. I'm wishing I hadn't changed the filter as I need the truck for an event on the 23rd. Hoping I get this issue solved soon.

 

[machinist75]

Sorry I don't have anything to add but what the others have said, but I would like to know where you got the new fangled hand primer pump. I don't think mine is working and would like another option than the stock replacement. Thanks

 

[74M35A2]

I know this is not what most agree with, but when this happens and you have bled air from all the places you can, we have shot a stream of ether down its throat, and it takes off running and is fine after. Not sure why, by sometimes just cranking by itself cannot seemingly overcome a small air pocket, but an actual start and run can and will. Have the pedal full throttle when doing so to move as much fuel through the system in the brief time it will run, if/when you do.

 

[mmerz]

Reference the hand pump, search the following on google "ebay item #171813055924" $49.95 shipped. The hand pump has one way filters but 2psi will open it so I added a needle valve to be able to close it off prior to the hand pump.

I will wait for the batteries to fully charge to try the ether trick. I went through the lines/canister again and no leaks detected.

 

[WillWagner]

The primer pump is rebuildable, just a few o-rings.

OP, hold the throttle to the floor and crank it. It will lite if all you did was change the filter....unless you messed up an o-ring on the can, but when you pressurized the tank you should have had a leak if the ring rolled.

 

[Jmag]

I should have sated that I also needed the ether to help get it going as well, better part of 1/4 of the can

 

[WillWagner]

I should have sated that I also needed the ether to help get it going as well, better part of 1/4 of the can

THAT it not a good thing. Ever see what happens when you use too much starting fluid? It turns the carbon soft, it gets pushed down into the ring lands, re solidifies and then you have stuck rings, no compression. A little goes a long way. If one of these pigs won't light, there is an issue. Don't push it, troubleshoot the no start, it is most likely self induced if you just worked on the fuel system and the truck ran before you worked on it.

 

[mmerz]

Update: I believe the IP is functioning properly because the truck ran prior to the filter change. So I did the following 1)replaced all fuel lines 2)removed stock canister filter and replaced with two remote filters (fuel and fuel/water separator). Was able to get prime with no air present. Bypassed electric fuel shut off, and dropped fuel line into tank to make sure it wasn't a pick up tube problem. Will not start. Cranked with fuel supply line open (after manual shutoff valve) and IP is pumping good fuel without air present. Used following troubleshooting guide "Oregon Diesel" cummins-pt-pump-diagnosti PDF. I'm leaning toward an obstructed fuel supply between shutoff valve and injectors. So how do I test or check if fuel is getting to the injectors? and how much pressure from the IP does it take to open or fire injectors? If I pressurize the fuel supply line with air (not sure if I should do this) will or should the pressurized air return out the return supply line to the fuel tank?