Basic Mods For The M939 Series With The NHC 250 Engine...

[archmark]

I've got the Baldwin spin-on oil filter adapter with a Fleetguard filter and the Those Military Guys air filter modification "cage" with a 546664 filter, now I need a suggestion for the fuel filter setup. I've read several of the threads that talk about using a Baldwin spin-on fuel filter adapter; is the Baldwin adapter the consensus for going to a spin-on fuel filter or is there something else out there that I haven't come across in my reading?

I've made all the Westfolk swaps on my Deuce multifuel and it makes a world of difference come fluid change time, so now I'd like to add the same easy filter changes to my M934.

Thanks for any suggestions...

Mark

 

[MWMULES]

Scar59 sell a great kit for the oil http://www.steelsoldiers.com/showth...lter-Adapters-130-00-Shipped&highlight=filter

 

[Scar59]

Mark,
As MW stated I stock the Baldwin filter kits, sound like you got the oil filter adapter taken care of, I also stock the spin on filter adapter to replace the left hand fender fuel/water separator, you will need to fab up a attach bracket and reuse the fittings from the stock housing. Adapter and fuel/water separator filter are $80 shipped.
JC

 

[rhurey]

Beyond fuel, I'd add a coolant filter.

 

[Jayco36REQS]

Add a 2nd fuel line to the back of the motor, turn the fuel screw a tad, shim and pill the pump.... made a nice difference on my 923A1. Smoother idle, easier starts, and runs 68 all day long.

 

[DeuceDaddy]

sorry to be such a newb but I searched and couldnt find anything. What is this pilling the pump you speak of? I turned the fuel screw at bit, but it made no difference. I'd love a little more pop from this motor.

 

[Jayco36REQS]

"Pilling the pump"... sorry that's slang for putting a smaller fuel button in the PT pump. The smaller the number, the more fuel that is allowed to flow to the engine from the pump. Turning the screw will only get you so far unless you change the fuel button as well. I dropped from a stock 32 in my 923A1, to a 23... I tried a 20, but my egt's ran too hot on the hills. Anytime you mess with fuel, MAKE SURE you put a EGT gauge to monitor your heat. With the 2nd fuel rail to the back of the motor, it helps even out the fuel flow and I think helps it run stronger as well. Mine starts and idles great now... I'm still planning to put a turbo on mine, and drop to a 20 or 17 fuel button... but a move to FL and new house, etc... just has taken up all my time.

 

[sed6]

I thought putting a smaller button in actually restricted the return of fuel to the pump and built up fuel rail pressure. Whereas turning out the screw is what allows more fuel from the pump to the engine. Do I have that wrong?

 

[sed6]

I thought putting a smaller button in actually restricted the return of fuel to the pump and built up fuel rail pressure. Whereas turning out the screw is what allows more fuel from the pump to the engine. Do I have that wrong?

Did some reading. I'm wrong. The button impacts pressure going to the rail. Just as stated above.

 

[Floridianson]

Did some reading. I'm wrong. The button impacts pressure going to the rail. Just as stated above.

Yes and the throttle center screw does too. The best performance as said to do. Duel fuel line, shim the rpm up to around 2350 and decrease the idle plunger number and adjust the throttle shaft center screw. I myself would stay below 200psi rail pressure and as said pyro.

 

[sed6]

Yes and the throttle center screw does too. The best performance as said to do. Duel fuel line, shim the rpm up to around 2350 and decrease the idle plunger number and adjust the throttle shaft center screw. I myself would stay below 200psi rail pressure and as said pyro.

Thanks. Can I shim it myself? I have my pump off right now after a rebuild at the pump shop. They had already completed their bench test before I mentioned the shims and button. They did though say the pump was running strong. I'm anxious to get the truck running again and might want to tackle the shims and button later, or am I missing a golden opportunity to take it back to the shop and have it done 'right'?

 

[Jayco36REQS]

I did all my mods with the pump on the engine while sitting on the drivers side front tire. lol I have a magnetic tray for holding small parts and screws. Just have a handful of clean rags/paper towels, starter fluid (for cleaning any parts), and the few tools you need. Piece of cake!

btw, the dual fuel line was by far the most time consuming part... getting the doghouse off the truck was a PITA!! But once that is done, I did it with off the shelf parts from NAPA, and a hand tube bender/flair tool.

Line I said earlier, these basic mods will smooth out the motor, idle better, start easier, and give a little more power. Don't expect a hot rod by any means.... To really boost power you need a turbo to go along with these mods!

 

[Floridianson]

Thanks. Can I shim it myself? I have my pump off right now after a rebuild at the pump shop. They had already completed their bench test before I mentioned the shims and button. They did though say the pump was running strong. I'm anxious to get the truck running again and might want to tackle the shims and button later, or am I missing a golden opportunity to take it back to the shop and have it done 'right'?

Yes can be done at home but you should have a gage that goes to 200 psi so you can check pressures. It's like trying to time a motor with no timing light. The advantage of the injection shop is they can spin it up. If they will tweek it would be nice but some just set it to the code for that motor. What was your rail pressure before defuel. You could ask them if they could or would bring up the RPM and bring up the idle pressure. Now if you do raise the RPM you do not have to operate that high just keep your left foot red line at 2100rpm. I was told that by raising the rpm to 2350 2400 it moves the scale of the pump and keeps it pulling at 2100 and not defueling. Best thing I might do is ask the shop if the will work with you like a brother would.

 

[tim410]

I want to change the fuel button and springs. where is the best place to buy the buttons and springs for the pump. Any pics or video on how to swap the parts out.