MX5100 reduced power

[Doug Bachman]

I have an MX 5100 that’s approximately seven years old. Recently, it has lost power when going up hills or driving at a higher speed.

Any suggestions?

 

[JerryMT]

I have an MX 5100 that’s approximately seven years old. Recently, it has lost power when going up hills or driving at a higher speed.

Any suggestions?

Check the air filter for clogging. The make sure you have adequate fuel delivery to the injector pump (IP). Inadequate fuel delivery is the most common cause of these kind of issues. Crud and bacterial sludge in the fuel tank can restrict the tank outlet, can get into the fuel line, the filter head and the filter. Non-metalic fuel hose can crack and delaminate. If you have a lift pump to pressurize the IP inlet there maybe a screen in there that is clogged. if you have a common rail fuel system, check for adequate flow to the high pressure pump.

 

[loggin]

I have an MX 5100 that’s approximately seven years old. Recently, it has lost power when going up hills or driving at a higher speed.

Any suggestions?

It is hard to try and diagnose without further information. You will have to do some testing to eliminate certain things. Fuel issues like gelling or lack of fuel due to pump. Could also be turbo issues. Hard to say.

First off how many hours on machine? Have filters been changed? Have you inspected fuel condition? Is there any smoke from the exhaust when the condition occurs??

Just some initial things to check.

 

[Doug Bachman]

To respond to both responses.

there are only 358 hours on the tractor

The air filter and fuel filter have been replaced, the fuel filter twice.

after changing the fuel filter and bleeding the air out of the fuel line, the flow at that point appears OK.

past that point, I stuck a line into the fuel line up to the injectors to see if there was anything clogged and didn’t find any clogs however that also did not help.

I do not believe I have a lift pump.

The fuel tank has been treated with some injection cleaners, sea foam and other water elimination treatments.

A sea foam YouTube presentation suggested cleaning out the fuel filter, filling up the fuel filter glass container with seafoam and running it for a couple minutes and turning off the tractor so that the Seafoam could work on cleaning the injectors. This also did not seem to help.

One additional point, when going up a hill and pushing full throttle, it bogs down, but if I back off the accelerator it is better.

I have not taken apart any of the fuel lines pass the bleed line. I think that’s where I need to start investigating.

 

[JerryMT]

The most probable restrictions occur between the tank outlet and the IP pump connections. The reason the bogging goes away when you reduce the throttle is because at that reduced throttle you can supply enough fuel to meet the engine demand.
When were the fuel and air filters changed and what have you done with the tractor work wise, since then? It takes air and fuel to make power so if you've been in dusty conditions you can have a restricted air filter. I mention the air filter for completeness and it's easy to check. Most problems with low power are due to restricted fuel flow.

Changing the fuel filter doesn't help if the restriction is upstream of the filter. It can be at the tank outlet, in the line between the filter, in the passages within the filter head. You need to eliminate these as possible causes. Very rarely will the injector lines themself be clogged and it is rare for the clogs to be downstream of the fuel filter unless the filter is damaged, misaligned, etc.

if you've had water issues, the odds are you have bacterial sludge in the fuel. Fuel biocide will kill the bacteria but the sludge remains to clog the fuel system downstream of the tank proper. Many tanks have small strainers at the outlet that are easily clogged.

Assume nothing until you check the areas I have mentioned.

 

[Doug Bachman]

The most probable restrictions occur between the tank outlet and the IP pump connections. The reason the bogging goes away when you reduce the throttle is because at that reduced throttle you can supply enough fuel to meet the engine demand.
When were the fuel and air filters changed and what have you done with the tractor work wise, since then? It takes air and fuel to make power so if you've been in dusty conditions you can have a restricted air filter. I mention the air filter for completeness and it's easy to check. Most problems with low power are due to restricted fuel flow.

Changing the fuel filter doesn't help if the restriction is upstream of the filter. It can be at the tank outlet, in the line between the filter, in the passages within the filter head. You need to eliminate these as possible causes. Very rarely will the injector lines themself be clogged and it is rare for the clogs to be downstream of the fuel filter unless the filter is damaged, misaligned, etc.

if you've had water issues, the odds are you have bacterial sludge in the fuel. Fuel biocide will kill the bacteria but the sludge remains to clog the fuel system downstream of the tank proper. Many tanks have small strainers at the outlet that are easily clogged.

Assume nothing until you check the areas I have mentioned.

thank you! I will check these items.

air filter and fuel filter remain cleaned, so I do not believe the issue is with them.

 

[North Idaho Wolfman]

One additional point, when going up a hill and pushing full throttle, it bogs down, but if I back off the accelerator it is better.

Is this tractor an HST?

Do the RPMS drop when going uphill and how much of a drop?

 

[lugbolt]

It has a lift pump. #090 on the "fuel injection pump" grid.

You will have to do a flow test. Take the line off of the inlet side of the lift pump. Put that line into a jar or bucket. It should free flow and fill a quart jar in a hurry, especially considering that the tank is above the engine so it gravity feeds quite well. If that's ok, move on. If not, you have junk in the filter, bowl fittings, or in the tank. Yes check the bowl fittings particularly around where the lines go onto the bowl itself (elbow fitting)-junk tends to plug them.

If flow is ok there put the line back on the inlet side of the lift pump. Then take the line that runs from the lift pump to the injection pump. Put that line into a jar or bucket. I like to make a nurse tank with fresh filtered diesel, to feed the injection pump. Then start the engine with the nurse tank attached and watch the fuel flow from the lift pump. If it's good, it will fill the jar very quickly. If it start off good and then peters out to a trickle, and your free flow from the tank through the filters to the lift pump is fine, then your lift pump may be failing-although that's quite rare. Normally if they fail, the diaphragm fails internally and fuel leaks into the engine crankcase, and the #1 complaint is that the engine oil is way over filled.

Start with that and see what happens.

 

[Doug Bachman]

Is this tractor an HST?

Do the RPMS drop when going uphill and how much of a drop?

Yes and when it bogs down the RPMS drop off, but not by much

 

[Doug Bachman]

It has a lift pump. #090 on the "fuel injection pump" grid.

You will have to do a flow test. Take the line off of the inlet side of the lift pump. Put that line into a jar or bucket. It should free flow and fill a quart jar in a hurry, especially considering that the tank is above the engine so it gravity feeds quite well. If that's ok, move on. If not, you have junk in the filter, bowl fittings, or in the tank. Yes check the bowl fittings particularly around where the lines go onto the bowl itself (elbow fitting)-junk tends to plug them.

If flow is ok there put the line back on the inlet side of the lift pump. Then take the line that runs from the lift pump to the injection pump. Put that line into a jar or bucket. I like to make a nurse tank with fresh filtered diesel, to feed the injection pump. Then start the engine with the nurse tank attached and watch the fuel flow from the lift pump. If it's good, it will fill the jar very quickly. If it start off good and then peters out to a trickle, and your free flow from the tank through the filters to the lift pump is fine, then your lift pump may be failing-although that's quite rare. Normally if they fail, the diaphragm fails internally and fuel leaks into the engine crankcase, and the #1 complaint is that the engine oil is way over filled.

Start with that and see what happens.

Will do. Thanks!

 

[loggin]

As lugbolt wrote you do have a lift pump and it can fail internally. Check your engine oil level because it can leak into the crankcase!!!

 

[North Idaho Wolfman]

Yes and when it bogs down the RPMS drop off, but not by much

You don't have a Fuel / Engine problem!

You are either asking to much of it in the wrong range or you have a hydraulic or clutch issue.
When was the last time the HST filter, hydraulic filter and fluid was changed?
Have you checked the clutch pedal linkage adjustment?

 

[Doug Bachman]

You don't have a Fuel / Engine problem!

You are either asking to much of it in the wrong range or you have a hydraulic or clutch issue.
When was the last time the HST filter, hydraulic filter and fluid was changed?
Have you checked the clutch pedal linkage adjustment?

Filters have been changed per the manual.
Hydraulic fluid will be changed at 400 hours, as per manual.