intermittent fuel problem

[tom andrews]

Greetings, I have a Nortrac 3500, 30hp. The dozer abruptly shut down and would not restart, of course out in the boonies. I determined the transfer pump was pumping fuel thru the spin filter to the inlet of the injector pump. Nothing coming out of the injection pump. Two days later, I rechecked my process, now I was getting fuel out of injection pump. Hooked up lines to injectors, machine started, bled air and machine is running fine and sitting in shop. How can I check integrity of the injection pump, or am I overlooking something?

 

[Wagtail]

I'd put an inspection camera down into the fuel tank... you could have a biological growth (known as 'algae', but it's not). It'll look like fairy-floss (cotton candy) mixed with phlegm.

A major cause of intermittent diesel fuel problems.

 

[Bob Rooks]

I have personally witnessed diesel bugs bring a 14,000 HP diesel engine to it's knees, and subsequently $125,000 in fuel system repairs. They are very corrosive and can destroy injectors and injector pump plungers and barrels, not to mention steel fuel lines. I use this test kit periodically on my storage tank. https://www.amazon.com/Biobor-HUMBU...eywords=humbug+test+kit&qid=1572051131&sr=8-1 I think the first thing to do is determine if you do have a dose of the "bug" because that will direct the course of action.
Many articles have been written on this topic.
Microbial contamination of diesel fuel - Wikipedia

Here is one of my personal experiences with the slimy sludgy critters (the pink stuff is fuel).

 

[thepumpguysc]

WOW BOB.. I've NEVER seen a tank THAT BAD.!!

Tom, u do have a weird problem.. U prob. need to inspect the fuel AND TANK..
Its weird because u had NO FUEL & then the next day U HAD FUEL..
1 think I should mention.. the supply pump HAS TO pump enough fuel to fill the fuel gallery AND open the overflow valve..{prob. 25psi}
Does your have a hand primer on it..??
IF SO, run the hand primer until u hear it passing fuel thru the checkball return & back to the tank.. THEN try to start it..
IF it continues & your tank is clean.. u can contact me by clicking my screen name on the left hand side of the page.
I hope u find SOMETHING.. Good Luck.

 

[redman135]

There is another less expensive possibility, and that is there is something in the bottom of the tank that gets sucked onto the line line and block it until the sucction stops(engine died) then floats clear and you can restart and it will run perfectly until the obstruction gets sucked uver the fuel line again.
Take wagtails advice and put an inspection camera into the tank so you know one way or the other.

 

[tom andrews]

Thanks to all for the replies. Machine still starts and runs fine now, of course it is sitting in the shop, I'm reluctant to get back out in the timber with it again. But I'll definitely check the tank for obstructions. Maybe the supply pump is pumping, but not enough pressure as the pumpguy mentioned.

 

[Bob Rooks]

Thanks to all for the replies. Machine still starts and runs fine now, of course it is sitting in the shop, I'm reluctant to get back out in the timber with it again. But I'll definitely check the tank for obstructions. Maybe the supply pump is pumping, but not enough pressure as the pumpguy mentioned.

Don't know if I mentioned it before, but I too was stuck in the woods with bug issues once. That prompted me to install a fuel pressure gauge connected to my alarm system. There is a ball-check pressure regulating valve on the injection pump (every diesel engine in the world has some such valve). It maintains a nominal 22 psig fuel pressure in the injection pump fuel cavity and assures the plungers have adequate fuel under all conditions. Some are adjustable, others look like a ball is swaged into the banjo fitting. Corrosion from bugs has been known to cause the spring to fail and to cause pitting of the ball seat, lowering or shutting off the fuel pressure. I personally had to replace the lift pump because the valve seats were so badly pitted that it barely pumped fuel.

 

[Bob Rooks]

As a side note, these machines do not have a primary fuel filter per se, just the screen in the sediment bowl so this must be maintained intact and periodically inspected because they can catch some bugs.













As an over-kill precaution against any further fuel related interruptions to my seat time I installed an electric lift pump.



Note: My Mitsubishi excavator and Yanmar powered skid steer both use an electric lift pump instead of a mechanical one.

 

[tom andrews]

Thanks Bob, that was a ton of info. One can't go wrong with belt and suspenders.

 

[tom andrews]

Thanks Bob, that was a ton of info. One can't go wrong with belt and suspenders.