bobcat 873 looses power after 15 minutes

[873]

i have a 96 bobcat 873.motor has been completely remaned by a deutz dealer.problem is that after about 15 minutes of operating under full power the engine starts to lose power .example if i was loading my truck with sand from a pile the machine would seem to die down as if it was in a lower throttle position. even if i was lowering the boom and tilting the bucket at same time there is considerable change in engine rpms. checked engine and hydraulic temp with infared and not overheatig. engine is 170 degrees hydraulic is 105 degrees, has new fuel pump and lines. any help would be appreciated thanks.

 

[Rich M-37]

873, When was the fuel filter changed last?. When the engine dies is the primer bulb sucked flat? If it is, the small filter in the tank may be plugged. Open up right side acess cover, it is a rubber grommet on top of the center of the tank, pry it up gently there is a long pickup tube on the end is the filter. Rich M-37

 

[Tazza]

873, When was the fuel filter changed last?. When the engine dies is the primer bulb sucked flat? If it is, the small filter in the tank may be plugged. Open up right side acess cover, it is a rubber grommet on top of the center of the tank, pry it up gently there is a long pickup tube on the end is the filter. Rich M-37

I have to agree, sounds like a fuel restriction. You may need to change the filter in the fuel tank too, you may have crud in there that is sticking to the pickup tube filter.

 

[Ausmarty]

I had that exact problem, I took the fuel line off the bulb and there was no fuel comming out so I blew up the fuel line with an air gun which blew the crud out of the tank filter, ran fine after that I you try this at least you will know if it's that

 

[Websterspower]

I had that exact problem, I took the fuel line off the bulb and there was no fuel comming out so I blew up the fuel line with an air gun which blew the crud out of the tank filter, ran fine after that I you try this at least you will know if it's that

Isn't there a check valve on the filter in the tank?.... I would not blow air through the line as this would blow off that filter. Run a section of new hose to an Aux tank to rule out pickup tube/tank filter instead.

 

[mrfixitpaul]

Isn't there a check valve on the filter in the tank?.... I would not blow air through the line as this would blow off that filter. Run a section of new hose to an Aux tank to rule out pickup tube/tank filter instead.

There is also a screen on the fuel pump that may need cleaning. I believe it has a phillips head screw holding it in place, about 1 1/2" diameter.

 

[873]

There is also a screen on the fuel pump that may need cleaning. I believe it has a phillips head screw holding it in place, about 1 1/2" diameter.

thanks guys for your suggestions. fuel filter was changed yesterday.i did remove the filter in the tank and ther is no dirt plugging it,but i did clean it and the check valve does work.i even did a vacuum check on the new fuel line where it goes into the inlet side of the fuel pump and there is no vacuum leaks either. i do not have a primer if that makes any difference.

 

[Ausmarty]

thanks guys for your suggestions. fuel filter was changed yesterday.i did remove the filter in the tank and ther is no dirt plugging it,but i did clean it and the check valve does work.i even did a vacuum check on the new fuel line where it goes into the inlet side of the fuel pump and there is no vacuum leaks either. i do not have a primer if that makes any difference.

If you don't have a bulb you won't be able to bleed the system of air

 

[Chipperhead]

Don't know if this is relevant on an 873, but my old 743 had the exact same problem. Tuned out to be the routing of the fuel line. After the line came out of the top of the tank, it ran in a channel, across the top of the body. When the cab was lowered it was pinching the fuel line. The pinch was along the length of the line. Not like a crimp in the hose. I never figured out why it would run sometimes, then die out. Not run at all at other times. I re-routed the fuel line about 2 years ago and it hasn't missed a beat since. Hope this is helpful.

 

[Tazza]

Don't know if this is relevant on an 873, but my old 743 had the exact same problem. Tuned out to be the routing of the fuel line. After the line came out of the top of the tank, it ran in a channel, across the top of the body. When the cab was lowered it was pinching the fuel line. The pinch was along the length of the line. Not like a crimp in the hose. I never figured out why it would run sometimes, then die out. Not run at all at other times. I re-routed the fuel line about 2 years ago and it hasn't missed a beat since. Hope this is helpful.

There is a check valve in the screen on the puckup tube, but you can still prime it without it.
Chipperhead - thats pretty bad luck that something so simple caused so many issues. There should be a channel in the back of the fuel tank for the hoses to run, they won't punch there. It seems the previous owner modified it, and did it wrong.

 

[873]

still having problem with 873 loosing power. replace all fuel lines again and did away with screen in tank.removed valve cover and double checked valve clearance , even checked on timing belt,(have pins to check position) every thing seems to be in specs. called deutz dealer who rebuilt engine and asked him. he said to check lift pump pressure. pump pressure is 8 psi at idle and 8 psi at 2500 rpm under load , but engine still looses power. could there maybe a problem with hydraulic system some where? light does come on for high temp or restriction in filters but goes out after running about 5 minutes. i did change filters but added lucas hydraulic oil to system .could it be that this is causing the problem,being to thick? i have new filters coming tomorrow ,i will change them and all new hydraulic fluid again.i am runnig out of ideas . ps dealer also told me it could be injector pumps.but if so why do i have lots of power when cold? need help thanks.

 

[Tazza]

still having problem with 873 loosing power. replace all fuel lines again and did away with screen in tank.removed valve cover and double checked valve clearance , even checked on timing belt,(have pins to check position) every thing seems to be in specs. called deutz dealer who rebuilt engine and asked him. he said to check lift pump pressure. pump pressure is 8 psi at idle and 8 psi at 2500 rpm under load , but engine still looses power. could there maybe a problem with hydraulic system some where? light does come on for high temp or restriction in filters but goes out after running about 5 minutes. i did change filters but added lucas hydraulic oil to system .could it be that this is causing the problem,being to thick? i have new filters coming tomorrow ,i will change them and all new hydraulic fluid again.i am runnig out of ideas . ps dealer also told me it could be injector pumps.but if so why do i have lots of power when cold? need help thanks.

I can't see the hydraulic pumps being the issue. If it starts to smoke, then it shows its under high load. As the oil gets warmer it will thin out, so easier to pump.
It could be the injecotr pump i guess... Just seems weird.... I wouldn't expect it to do it after warming up, things move easier when warm/hot.

 

[Fishfiles]

I can't see the hydraulic pumps being the issue. If it starts to smoke, then it shows its under high load. As the oil gets warmer it will thin out, so easier to pump.
It could be the injecotr pump i guess... Just seems weird.... I wouldn't expect it to do it after warming up, things move easier when warm/hot.

I think I would do a quick check by running the machine on a gallon jug of fuel tied to the motor with tie wire add a hose on the inlet side of the bulb and put it in the jug , this will eliminate a fuel blockage in the 90 degree fitting on top the pickup tube , or a fuel line getting smashed under the oil pan cause the motor mounts are bad , also make sure it has the right fuel fill cap , the wrong cap might be causing a vaccumm , also I would try and run a hose from the return tubes into the jug as some diesels will do that if the return is clogged , John Deere is bad for that -----------also wonder if it could be the turbo getting hot and locking up ------if that all failed , I would compression test the engine , maybe the rebuilder didn't do a good job