Fuel pump issues D4 6U1141

I had a hard time starting one of my D4s yesterday. I had a stuck plunger on #1 again; freed it up and gave it some liberal spray lube. I rarely start this machine to use, WHY is the plunger sticking? Bad fuel? I ask this, as I also had other machines which I use regularly that refused to start.

This particular unit also had fuel escape after I removed the access panel. I will inspect it and look for seepage.

I do not have anything going into the crankcase. Have I lost the 2 seals for the pump/governor or? It seems to be a never ending thing here. Too many machines, so little time.

Hi JM,

modern diesel fuel has less sulphur and less lubrication ability and is hard on plunger type injection pumps.

Some 4x4 forums recommend adding a dose of modern two stroke engine oil to the fuel to stop the sticking and wear.

Recommended Ratios & Amounts:

• General Lube (Older Engines): 1:200 ratio (approx. 250-400ml for a 50-70L tank).

• Example 50L Tank: ~250ml 2-stroke oil.

• Example 70L Tank: ~300-400ml 2-stroke oil

Your experience may vary.

Machines with worn plungers and barrel bores can by-pass fuel when static for a long time--check the drain tube that should drain the lifter and pump cavity of the fuel injection pump. On D2/4's there are 2 or 3 tubes down below the injection pump filter tower at about the same level as the sump/crankcase parting line that mud daubers love to clog up.

Cheers,

Eddie B.

Thank you Eddie B., I will take a look today while I am close by. What is your thought regarding the use of ATF, Marvel's Mystery Oil besides 2 stroke oil? This one for sure has not been started in over 6 months, and honestly never ever noticed anything come from the weep tubes, so there is a good chance they could be plugged up. I might have to swap the ditcher attachment for the toolbar blade, so I can spread some crushed rock here. Good excuse to stretch its legs.

I really appreciate your wisdom. Thank you again, JM.

Hi JM,

ATF will both lubricate and eat rust, we do not get Marvel Mystery Oil down here so I have no experience of this product.

Cheers,

Eddie B.

Hi, JM.

One 'trick' that I have used for a LONG time is to add the 2-stroke oil into the tank BEFORE filling the tank. If the tank hazza dipstick, 'kalkillate' the amount of 2-stroke oil that you need for the amount of fuel that you will be putting into it, add the 2-stroke oil and then let the incoming fuel do the mixing for you.

Many, MANY moons ago, back in 1971, I discovered that Australian BP pre-mixed 2-stroke fuel was the ONLY one on the market at that time in which the 2-stroke oil would not separate from the gasoline in the mix if left standing for a while - dunno if the same still applies.

Just my 0.02.

they don't make zoom any more. that went out in the early 90s/late 80s. i can just remember servos having the bowsers for it. you can still get sthil motomix though pre mixed premium unleaded at 50 to 1 ratio.

what we use is flash-lube diesel conditioner 50ml to 50 litres. works well adds that lubricity back and has a slight cleaning effect too.

we also use flash-lube valve saver for our old petrol engines too since modern fuel is unleaded.