Jinma 254 starting problem

[greg_g]

Ok, perhaps my problem is comprehending the size of the fuel and water molecules. Water molecules are almost certainly smaller than diesel fuel molecules (although I doubt the diesel bugs are). If diesel fuel molecules are truly smaller than a millionth of an inch, then it all falls into place. The lubricity donated by sulphur in the fuel (or additive) lubes the cylinder walls. During extended idle periods, gravity takes that fuel down into the sump where it mixes with the lube oil. Over time, the diesel/oil mix must be drained & repleaced. In the case of wet fuel - the water content must be left behind, which in turn may cause the piston to stick to the cylinder wall.

Is that anywhere close?

//greg//

 

[Bob Rooks]

I believe you've got it Greg.

"Diesel Bugs" dead or alive en masse can be seel with the naked eye, not so at the molecular level.

Think of a fuel pump barrel and plunger assembly (I'm from the old school) as a hydraulic spool valve that also turns as it goes back and forth, with tolerances approximately five times closer. The amount of fuel that gets by is almost immeasurable.

 

[psj12]

The lower end of the barrel is sealed from the lube oil sump and drained by a return line. The very small amount of bypassed fuel is returned to the tank. If you do get diesel contamination of the lower end of the pump the seals may have failed.

 

[Ronbo]

Pull the bowl off the bottom of the tank. I bet it is brown. Does the diesel flow freely out of the tank? If not, unscrew the fill cap. Blow air into the hole on the bottom of the tank. It gets plugged with rust deposits. Happens more often if the tank is not full. When the fuel starts flowing, replace the bowl. Do not tighten it up until it is full. Unscrew the plunger on the pump. Grab the ring on the pump and turn it counter clockwise 1/2 turn. Pump the plunger until fuel comes out around the screw with the ring. Tighten the screw with the ring. Push the plunger down and screw tight. Lift compression release and crank. While cranking, turn loose of compression release. It should start. If it doesn't, repeat the compression release thing a few times. When it starts, it will run rough for a little bit and then smooth out.

Start with the simple things guys.

Ron

 

[greg_g]

The lower end of the barrel is sealed from the lube oil sump and drained by a return line. The very small amount of bypassed fuel is returned to the tank. If you do get diesel contamination of the lower end of the pump the seals may have failed.

I'm not pickin' on you purposefully, but this is the 2nd time you mentioned return line in relation to the injection pump. Pretty sure the one you've indentified is just for low pressure fuel (fuel pump output). The high pressure fuel (injection pump output) returns via the injectors.

//greg//