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M923A2 Fuel Filter Change Nightmare

Suprman

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A2 back of inj pump towards front of motor is small bolt only open 2 turns it can fall out. Press hand primer 100x till steady fuel comes out tighten bolt. Repeat if needed.
 

WV New Guy

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I thought it was a stream but maybe it was a dribble . The top of the canister filter has an air chuck I hooked to that and only head fuel bubbling in tank did I screw up completely ?
 

doghead

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Yes, you do not add air into the system.
 

doghead

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The whole point of priming and bleeding the fuel system is to remove any air in the fuel system.

Blowing air into the top of the filter would just push all the fuel out of the lines. That is not what you want to do.

I'm sure this whole procedure is covered in a TM, and should take you about 3-5 minutes tops.

I'll never understand why people refuse to help themselves by reading(educating themselves) before tackling something that they do not know.

Thank goodness for the internet.
 

gottaluvit

Well-known member
Air into the top of the fuel tank may help as it pushes more fuel into the system, but midway will have the opposite effect, pushing fuel out of the system and displacing it with air. The TMs do help if you have one massive stuffed full of cash wallet so you can replace stuff with a "known working unit", but I would prefer a hybrid direction, bred with common sense.
 

WV New Guy

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Dog head yes I did read and print the TM before attempting this and had I believe page 470 to 473 or 3-105 thru3-107 open when I completed the change . I had read here that guys pressurized the systems from the fuel caps guess I was wrong about the air chuck ontop of the canister filter . TM 9-2320-272-24-1 October 1992
 

98G

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From the fuel caps yes, from the filter no.

Some people are lazy and splice a shraeder valve into the fuel cap.

Some people are lazy and just crank it enough to prime (me).

Some people are lazy and squirt it with ether enough to prime. NOT RECOMMENDED!

At this point on your truck, I'd open the bleeder and then try to pressurize the fuel tank. 2-3psi should be quite sufficient. When you have a stream, close it and crank...
 

Suprman

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I thought the air chuck on filter was to allow trapped air out. The 8.3 injection pump will not self prime you have to crack the bleeder. You can crank it instead of pushing the primer pump but the bleeder still has to be open. Too much cranking may kill your starter though.
 

Jbulach

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Bosch P/MW/A pumps do not need bleeding, they will prime just fine w/o cracking lines, removing plugs, etc. Put the throttle off idle and crank it.
I always bleed mine, but never knew or thought to manipulate the throttle. Does it make a difference how you position the throttle? Does it push air through faster at wide open vs just off idle?
 

WillWagner

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WOT works faster, yes you should fill the system with the lift pump primer, but no need to crack lines.
 

98G

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The TM says to crack lines, but my experience has been that it isn't necessary.

Silverstate55 sucked a tank dry in his M931A2 and was getting ready to hop out to crack the line. I asked him to humor me and just switch the tank selector and crank. He did so, and it fired up in 2 cranks of about 8 sec each. Edit to emphasize, it sucked air due to mechanical fault, and not silverstate55 not paying attention.

Once upon a time, some fumbduck (ok,it was me) thought the switch on the dash changed tanks on the M931A2s and flipped the switch when one tank got low. Shortly thereafter, the truck sucked the tank dry and coasted to a stop. A quick call (to gimpyrobb) located the valve beside the seat, and a couple of 10sec cranks was enough to prime and fire up and said fumbduck was back on the road...
 
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silverstate55

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The TM says to crack lines, but my experience has been that it isn't necessary.

Silverstate55 sucked a tank dry in his M931A2 and was getting ready to hop out to crack the line. I asked him to humor me and just switch the tank selector and crank. He did so, and it fired up in 2 cranks of about 8 sec each.

Once upon a time, some fumbduck (ok,it was me) thought the switch on the dash changed tanks on the M931A2s and flipped the switch when one tank got low. Shortly thereafter, the truck sucked the tank dry and coasted to a stop. A quick call (to gimpyrobb) located the valve beside the seat, and a couple of 10sec cranks was enough to prime and fire up and said fumbduck was back on the road...
Compounded by the fact that one tank had the fuel pickup tube lose the solder joint and fall off into the tank, and a faulty tank selector valve....that was an interesting trip!
 

WV New Guy

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Pics of the top of the canister filter with the air chuck . It ran for about a minute today with the air filter removed and some ether after breaking the line and pumping to 100 plus and getting a stream . I also removed and reseated the gasket and o ring on the canister filter just to make sure it was about 1/2 full of fuel . Reseated bled the back of the pump and the line adjacent to the screw n filter . Like I said ran a little then quit . Later tonight I have a friend coming over who's an over the road Diesel engine rebuilder so it should be back up tonight . Thanks for all the pointers ! TMs are good but real world exp. seems to help me better.
 

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doghead

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Your square gasket/seal is not sitting down in the square hole correctly.

That will let air in like it is in the picture.

There should be a bleeder where you have a shrader valve. This could be noticed if you looked at a tm and read the bleeding/fuel filter change procedure.

Thank goodness for the internet.
 
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