Diesel fuel problems

[Z71]

I did not realize that diesel fuel goes bad in time just like gasoline. It seems to me that old formulation high sulfur diesel did not, at least not for a long time. I had a 5 gallon can of old diesel that sat for 15 years and it still smelled like good diesel fuel 15 year later. Anyway, I let my truck sit for several months and the tank was only about 1/3 full and the fuel inside the tank was probably about a year old. I tried to start it today without any luck, even though the engine cranked strong. Looked inside the fuel tank and the fuel smells like varnish and there was a thick sludge covering the fuel strainer inside the extendible filler neck. This is odd because about four months ago I did not see anything like this and the fuel smelled like normal diesel. And the batteries did not drain at all while the truck sat.

I plan on draining the tank tomorrow and replacing all three fuel filters. What else should I try? Loosen the injectors to see if I get enough fuel flow while cranking?

I need to replace several O-rings in the diesel injection pump too. One is in the hydraulic head, the other in the fuel shut off assembly. Can this be done without removing the pump from the truck?

 

[Scrounger]

The new fuels definitely don’t last like the older blends. I have found that 3 months is the most to expect from gasoline and 9 months for diesel.
I would drain the fuel, replace the filters and see if it starts. If it does then run some injector cleaner/ fuel conditioner for a while. No reason to tear things apart if you don’t have too. If you can remove the parts to access the O-rings with it on the engine go for it.

 

[rustystud]

What he said. I would also start adding a fuel additive like "Pri-D" to your tank.

 

[Floridianson]

Do your fuel and filters thing. Don't mess with the injectors and yes you can replace the O rings without removing the whole injection pump just the Head if you need to do the O rings under it.

 

[gimpyrobb]

Sounds like your fuel shut off might be stuck in the off position. I'd check that first.

 

[Warthog]

http://www.steelsoldiers.com/showthread.php?143476-How-to-remove-the-Fuel-Shutoff-Rod-on-the-IP

 

[Z71]

I drained most of the fuel tank and the walls of the tank and even the drain plug bottom are coated with reddish sludge. I doubt I have an issue with the fuel shut off, but I will check just to make sure. I need to see if the transfer pump is pumping any fuel at all because it intake could be clogged with varnish.

 

[SLOrazorsedge]

I had the same issue with my wrecker this past spring following a cold for us winter. My IP ingested that varnish stuff and the engine sounded like it was losing a rod bearing from the diesel "clacking". I was lucky, I was able to clean the passenger tank by draining and reaching into the tank having removed the basket filter. I dropped a can of carb cleaner into the tank, sprayed the inside out, melted the crap and wiped it clean. I then ran clean fuel with a good diesel injector cleaner throught the engine. My injectors were loaded up and partially plugged. I was lucky and they cleared w/o having to pull the injectors or pump...Now the driver side tank is another matter at 76 gallons and a mid-tank baffle. I still need to r/r that tank to have it boiled or steamed out. The gunk also fouled my driver side fuel sender unit. Besst of luck brother!

 

[Z71]

The fuel shut off is definitely not the problem. I found out to my aggravation that to remove the primary filter, one must apparently remove the alternator to access the upper nut securing the filter canister. When I opened the petcock on that filter, nothing came out, meaning there is probably sludge in there. I pulled one of the secondary fuel filers and it was clean. so hopelfully nothing got too bad past the primary filter.

What's the best chemical to use to clean that varnish gunk off the fuel tank walls and bottom? I also suspect that the intake of the in-tank fuel transfer pump may be completely clogged. he pump runs, I cna definitely hear it, but is it pumping? Which fuel line should I pull loose to check if the primary fuel tank pump is working?

Finally, how do you bleed air out of the system on these trucks? My old diesel Mercedes 300DT has a small hand pump on the injection pump with which you remove the air from the system. No such thing on this truck.

 

[rustystud]

There is no need to bleed out the air in these trucks. The way the fuel system runs it is self purging. As far as cleaning the tank, I have had good luck with lacquer thinner.

 

[M-35A3]

The fuel shut off is definitely not the problem. I found out to my aggravation that to remove the primary filter, one must apparently remove the alternator to access the upper nut securing the filter canister. When I opened the petcock on that filter, nothing came out, meaning there is probably sludge in there. I pulled one of the secondary fuel filers and it was clean. so hopefully nothing got too bad past the primary filter. What's the best chemical to use to clean that varnish gunk off the fuel tank walls and bottom? I also suspect that the intake of the in-tank fuel transfer pump may be completely clogged. he pump runs, I cna definitely hear it, but is it pumping? Which fuel line should I pull loose to check if the primary fuel tank pump is working? .

I am in a similar situation with my deuce as i let fuel set it in for months so i have to change out all the filters (had green fluid with yellow clouds in it when i opened the drain on the primary filter) . Iam not sure if this helps as i am still learning about the m35 but mine dumps fuel back into the tank via the return line so that could be one way to see if the in tank pump is working to some degree . For the clog on the canister try sticking something up into the canister to help dislodge the blockage (while engine is off) to see if it can be freed up but you may have to remove the petcock to get something up there .