Intermitant fuel starvation?

[GLLinMO]

I have had what seems to be a fuel starvation issue occur a couple times in the last couple of month. Occurs after tractor has been running for 20 minutes +, when the engine is turning say 1800 rpm or more. Engine will lose power, and revs will drop. Eventually it will quit running. Will start up, but again, acts like it's not getting enough fuel and dies.

After the first occurrence I noticed fuel leaking around the fuel filter bowl. I then took it out and cleaned it. Got a new O-ring and filter. Dealer thought maybe air was being sucked into the fuel system. After that, it ran well, although I had not used it much since then. Yesterday, when doing some dirt work, I had the same fuel starvation pop up again.

Tractor is a 10 year old L3400 HST. It only gets used about 10 hours a year. so it's a low hour unit - probably too low.

Any thoughts? Thanks all for any input.

Gary

 

[moship]

Just a thought to consider...

Since you don't use your tractor often the fuel isn't being turned over too often. Diesl fuel is hydroscopic meaning it will absorb moisture. This moisture can cause algae to form in the fuel that will look like slime. The slime can cause restriction at the tank outlet and thus fuel delivery problems.

I've experienced this on my tractor with very similar symptoms as yours.

Confirmed the contamination by disconnecting the hose to the fuel filter and allowing the fuel to drain into a clean white bucket. Light colored bucket makes it easy to see contaminants. In my case the fuel would barely come out and some of the slime could be seen in the fuel. After confirming the problem, proceeded with removing the fuel tank and cleaning.

Fuel treatments are available for this problem.

Again, I'm not saying this is your problem, but it is something to consider given how you use your tractor.

Good luck and keep us posted on what you find.

 

[Jerry/MT]

I have had what seems to be a fuel starvation issue occur a couple times in the last couple of month. Occurs after tractor has been running for 20 minutes +, when the engine is turning say 1800 rpm or more. Engine will lose power, and revs will drop. Eventually it will quit running. Will start up, but again, acts like it's not getting enough fuel and dies.

After the first occurrence I noticed fuel leaking around the fuel filter bowl. I then took it out and cleaned it. Got a new O-ring and filter. Dealer thought maybe air was being sucked into the fuel system. After that, it ran well, although I had not used it much since then. Yesterday, when doing some dirt work, I had the same fuel starvation pop up again.

Tractor is a 10 year old L3400 HST. It only gets used about 10 hours a year. so it's a low hour unit - probably too low.

Any thoughts? Thanks all for any input.

Gary

Having the engine run down like this is usually caused by a blockage in the fuel system and in your case, something is most likely clogging the strainer at the fuel tank outlet. Water condensing in the tank together with bacteria (not algae- they are plants) that live at the fuel water interface can cause a snotty looking crud to form in the tank. This is common for diesel powered machines that are not used much and the problem is exacerbated in humid climates. To better manage the water condensate, try to keep the tank full. Biocides are available to reduce the possibility of this occurring but fuel management will also help reduce it. For now, you will probably have to rain the tank and get the crud out.

 

[firemech]

Curiously just took my 7 year old L3400 HST into my local kubota dealer yesterday for the exact same symtoms. My machine is used daily though and is fueled from a tank that is filled approx once per month. Not experiencing any issues with my 2320, U25 or F250 pickup so I don't think it's in the fuel. Same as GLLinMO my tractor might run for days then quits exactly as stated above. Changed the fuel filter (though the old one was changed as part of the maintenance schedule in May) the old one looked like new when cut open. Though it seems like runs out of fuel; I have not had to prime it at all to get it to restart. Don't think it's the fuel shut solenoid as it doesn't shut off immediately like does when you turn of the key. Will definitely be following this thread. My tractor just turned 1200 hrs. FYI

 

[Fallon]

Open the fuel cap after it has issues. If you hear air getting sucked in, the tank inflating or that fixes the issue, it's a vent issue.

 

[GLLinMO]

Crud in the fuel tank definitely seems not only a logical cause of the symptoms, but highly likely give the low rate of fuel usage. I'll drain the tank - and try to remove if it not a major task to make sure I get it properly cleaned. Removing the tank cap was one of the first things I did - wasn't clogged. With my business travel schedule - I won't get to this for a couple of weeks.

 

[moship]

Thanks for clarifying it's not algae. I read several places where they referred to it as algae, but never researched to verify the accuracy.

I found this info from a fuel place, so hopefully it is accurate.

Anyone that uses diesel fuel, whether it’s for a backup generator or for a yacht, has heard of the term diesel “algae” and variations thereof. This “algae,” also known as diesel bug, diesel bacteria, and so on, is one of the leading causes of clogged fuel filters and damaged injectors. We know it’s a problem, but what is this “algae” and how did it get there? How can one prevent diesel “algae” from building up in a tank? Why are we quoting “algae?” There’s a good reason for that.

It isn’t really algae...
Let’s clear this up immediately. Diesel “algae” is not algae. It is actually a bloom of microbial growth within the fuel tank. This misnomer received its name because of its appearance, not because of what it truly is. Algae requires sunlight to grow – something fuel shouldn’t be exposed to within a fuel tank (if it is, you’ve got a huge problem).

Where diesel “algae” comes from...

There is one simple rule when it comes to microbial growth in a diesel fuel tank – it cannot exist without the presence of water. There are a number of ways water can enter a tank. Dry rotted seals, corroded orifices, and moist/humid air entering the tank on filling or inspection are the most common ways water is introduced.

Aside from the damaging side effects water can have on an engine, its components, and the tank, free water found at the bottom of a tank is a breeding ground for microbial growth. The microbes live between the water and the fuel, feeding off of the fuel while living in the water. As the bloom grows, it binds with other forms of fuel contamination, such as particulate, rust, and dirt, to form sludge. As if that wasn’t bad enough, the bloom has an acidic byproduct, promoting tank corrosion.

Here's a link as there is more info and how to prevent it... Mythbusters - The Truth about Fuel "Algae" | Fuel Filtration Systems - Fuel Transfer Systems - Day Tanks - Fuel Additives - Fuel Sampling & Testing

 

[kthompson]

I have similar issue and it turned out to be a wasp in my fuel tank and as fuel was being pulled out the tank it would be sucked over the outlet. When the tractor set the suction would loosen and it would float off. Took a while to spot it due to the color. Do agree to drain the tank.

 

[brain55]

I have replaced more fuel lift pumps than I can count on this series of tractor. The easiest way to tell is to tee a pressure gauge in the fuel line between the lift pump and the injection pump. A good pump will be in the 3-4 psi range, the bad pumps I usually saw had 1 psi or less and many were pulling a vacuum.

Brian

 

[JRobyn]

My experience was IDENTICAL to Moship's. I was successful at removing the "algae-like substance" by slowly draining as much fuel as possible out of the tank using a few feet of fuel hose to drain into a clean bucket. Then applied air pressure to the tank to blast out the remaining fuel and floating "substance". No crazy pressure, just a hand around the filler neck with an air nozzle. A rinse or two with a couple of pints of clean, new diesel satisfied me that it was sufficiently clean. Changed the fuel filter after the next tank. No problems since (but I DID change fuel suppliers!).