Need help priming NHC250

[3poffroad]

Just changed the fuel filter on the truck last week. Filled the canister with diesel prior to putting it back on. Now this dang thing won't start at all. The primer pump on the side, do you Crack the petcock open behind it while priming? Is there a bleeder valve like the 8.3?

Thanks for the help fellas!

 

[jerry v]

turn the bolt open then pump til fuel comes out that worked for me

 

[3poffroad]

The petcock behind the primer? I pumped that bad boy for 20 min and still got nothing!

 

[jerry v]

did you check the fuel lines to make sure there is no cracks and foel running back?

 

[wrenchturner6238]

You might have an air leak! It also could be the check balls in the hand primer are gummed up or something. there should be 2 screws you can take out to get to the check balls

 

[3poffroad]

It's weird cause I've never had a single issue until I changed the filter. Now no start at all. Pressure the tank maybe?

 

[HMMWV Nut]

The petcock behind the primer? I pumped that bad boy for 20 min and still got nothing!

Might have to replace the o rings on the plunger to get a good seal for prime.The o rings get dry rotted over time, crack and then your standing there all day priming the pump for nothing

 

[jerry v]

how about the area you worked on is the canaster on tight sealed ?did you pinch a hose up close to the connection causing small crack? , just thinking of anything right now? try starting it with either may it will vacuum up?

 

[3poffroad]

I'll check it out again tomorrow. Got it fired off a gas rag and won't hold prime.

 

[sandcobra164]

Pressurize the fuel tank or perform the dreaded prime by ether. Both methods work but many people on here do not like starting fluid. It got a horrible reputation back in the day when sprayed from the can. On a cold day, my M923 will run the batteries down if I try to start on diesel alone but it has a factory installed ether injection system.... That helps!!

 

[73m819]

On top of the fuel filter head under the bolt head of the long bolt that holds the canister on there is rectangle plate that seals a O ring under it, if this plate is NOT IN the rectangle recess on top of the filter head, the system WILL draw air, to fix this, remove the rectangle plate, straighten it (it is bent now), reinstall IN the recess.

 

[MtnSnow]

This! As it was the filter you changed and started your issue...

 

[3poffroad]

Got it figured guys. O-ring on fuel filter has a small split I didn't see at first. An plastic hose on primer was cracked as well. After I replaced both it primed right up and RUNS a million times better than it ever has before!!!!!!

 

[jerry v]

glad it worked out for you, the men on this site ,are some of the most kind people,and they are very smart im grateful for ss site.

 

[TurboJoe]

Do you remember what size/where you got the replacement hose for the primer? I haven't dug into yet to see how it changes.

 

[3poffroad]

TurboJoe. It's just standard 1/8 plastic tubing. I had some extra laying around from my MightyVac and picked up some ferrules from Napa.

 

[Floridianson]

The primer pump on the side, do you Crack the petcock open behind it while priming?

YES

 

[captcarc]

I'm just preparing to change the fuel filter on my M934 with Cummins NHC-250. The filter is in the driver's side wheel well and is the hard, canister-housing type. Filter is $60 and spin-on canister conversion kit, with filter, is $195. Which direction should I go? I guess that buying the conversion kit is the best long-term solution and should be the direction that I go. The truck is a keeper. Hearing from anyone who has done the conversion, with tips, is appreciated, i.e. is it a simple bolt-on? Do you use Teflon tape on the threads? If I stay with the original configuration, do I need to buy a large canister wrench to spin off the large diameter canister housing? Thank you very much!

 

[Zadvark]

For future reference, O-Ring #0562 (3/8" ID X 1/2" OD X 1/16") from Lowes/HomeDepot, etc plumbing department is the correct size for the priming pump itself.

 

[Scar59]

The stock canister filter housing is held in place by the long center bolt. Do Not attempt to "unthread" it. The existing system works well and does a good job at water separation. Get a case of filter elements from SS member Stonepicker. A case will last a very long time. If anything, upgrade the engine oil filter assembly to a spin on filter adapter. This mod will save time , mess, and money. The original filter elements are expensive and a little tricky to procure. Kits are listed in the classified.