Fuel System Problem

[Alaska Dan]

My 1980 TD8-E is acting up. It has eratic RPM's and acts like it is running out of fuel. There is plenty in the tank. It will run at half throttle but revs up then almost dies.

Things I have done:

Checked tank for debris - it is clean
Cleaned air filters with air hose
Changed both fuel filters and filled each before installing new
Traced fuel line back to tank looking for signs of air/fuel leaks - none fouind
Loosened injectors at the pump - good flow

When I took the Final fuel filter off, the "O" ring was broke. A frienbd and I both thought that was the problem but it had no effect.

I'm at a loss..

Dan

 

[Alaska Dan]

I forgot to mention - yesterday it ran for half an hour until I shut it down. But it would rev up then almost die. It repeated this pattern the entire time it ran, except for the first 30 seconds..

Dan

 

[Alaska Dan]

One more thing - when I open the vent screws on top of the filter (both of them) no fuel escapes as it should.

 

[willie59]

Not familiar with the components of your TD8, but two things you need to do. Remove the fuel pipe that comes from your tank and goes to its first component, either filters or lift pump. Remove fuel tank cap, blow compressed air back through fuel supply piping from tank to remove any debris that might be restricting piping. If that doesn't fix your problem, I'm wondering if you have a Bosch type lift pump mounted on the side of the injection pump. I worked on a Case 850 that had that type pump and the plastic poppet under the hand primer pump was sticking, causing it to act like it was running out of fuel because it restricted fuel flow. Installed a new lift pump and fixed the problem.

 

[Alaska Dan]

Yes it is a Bosch. But it doesn't have a hand primer. A local mechanic mentioned that too but there isn't one.

It's at a job site. Getting compressed air isn't really an option.

Thanks

 

[John C.]

There is a in line filter on your machine that looks like the kind you put on your car. If you changed that then your problem is right there.

The filter that comes on the machine has a brass strainer inside instead of the paper type used for gasoline. Any water at all will swell the paper and cause it to shut off fuel flow. I've taken probably half a dozen and cut them apart to show people what they are dealing with. If you still have the old in line filter blow it out in the opposite direction of flow with air pressure. You will probably get lots of junk and it might even be plugged solid. Once you get it clean try it out and see if your problem goes away.

You will have to get the proper filter from the Komatsu dealer.

Good luck!

 

[Alaska Dan]

John,

I have 2 fuel filters side by side on the left side of the engine toward the front. They are above the injector pump. Each looks like a car oil filter except they are smaller in diameter and require a smaller filter wrench. I pulled the floor pans and seat so I could follow the fuel line back to the tank looking for signs of fuel/air leaks in the fittings. Everything looked good and I didn't see a "car type" filter. I assume you mean a small one about 2" long with about an inch and a half to 2" diameter.

I've been told there are screens in the line that act as filters but I am yet to find one.

I hope you are right - that it's something simple. I got a little spooked today when a parts guy said it could be $1300 or $1400 for a new injector pump.

Dan

 

[SterlingR]

The line that comes from the filter to the top of the pump. That "bolt" that holds that line on is hollow. Look inside that "hollow bolt" for a screen.

 

[Alaska Dan]

Mine has a hole drilled through it to allow fuel into the ring but the bolt is not hollow. There is no screen, just the hole.

 

[Alaska Dan]

Dressta1, you are right - the screw is hollow. But there is no screen inside of it. I'll look on the filter housing where the fitting screws on.

 

[D6B_dude]

Does the lift pump function as normal?

 

[swampman]

I had similar problem with my case 850. Turned out, all it was was fuel tank venting problem. Very simple fix, but racked my brain for a few days. Check (after it dies) to see if there is any vacuum when you remove the tank fill cap. If so, then you have a clogged tank vent not allowing fuel to get to the filters, pump, etc. Hopefully, that is the problem.