Mahindra Losing Power - Continued

RedDawg · Nov 15, 2023

I posted a few months ago about a 2012 Mahindra 5010 with 690 hours on it losing power. It starts and idles fine but if you put it under any load, including even running it down the road in 2nd gear with nothing attached, it bogs down like it is not getting fuel. That thread is here.

A synopsis is that at first I thought it was the low pressure fuel pump since it wasn't keeping the fuel bowl full. I replaced that and it didn't fix it. Then I figured out the gasket behind the fuel (Off-On-Air) selector on the fuel filter assembly was bad. It was allowing air into the system when it was only supposed to allow fuel, hence the air getting into the fuel filter bowl. You can't buy just that gasket, I made one which was pretty intricate. That didn't work. So I bought the entire fuel filter assembly (ouch) and that also didn't fix it. As part of my efforts I've had the fuel tank off and washed out, all lines are free, air filter has been replaced, the original fuel pump is back on and fuel flows back in the return line like it's supposed to when the tractor is running. You can see that here. Completely fresh fuel. There is no smoke of any kind. There is no moisture or leaking around any injector lines or connections. It will start, idle and run (while sitting the shop) at PTO speeds all day but run up the RPM's and put it under any load and it bogs down.

Before I take this to the Mahindra dealer for really expensive diagnosis and repair, what am I missing? Where else should I look? Thanks.

Harry in Ky · Nov 15, 2023

Mahindra's parts diagrams look like they were done by a first grader with blunt crayons. Just curious, but since doing all this work and parts replacements, have you solved the problem of keeping the filter bowl full of fuel while the "bogging down" is occurring?

cathy liebchen · Nov 15, 2023

Mahindra is known for mysterious problems difficult to figure out

terraformer · Nov 15, 2023

On my 3510 was having a similar problem and it was the a valve that goes to a return line for bleeding. I was able to fix it by disassembling the valve and putting a new small oring. Air was leaking around the valve stem.

https://www.tractorbynet.com/forums/attachments/20230706_113939-jpg.809683/

The valve has round knob, near the upper third of the pic. The booster pump is below it. During the diagnostic process I replaced the fuel lines from the tank to the motor and back.

Earlier I could never get the glass mahindra filter to quit leaking, so replaced it with a VW diesel filter. Something that I have done to other diesels.

It wouldn't hurt to put in a clear pvc tubing between the booster pump and injection pump.

CL: I would say that everything is mysterious until you understand it.

Best wishes on your repair.

RedDawg · Nov 16, 2023

Harry in Ky said:
Mahindra's parts diagrams look like they were done by a first grader with blunt crayons. Just curious, but since doing all this work and parts replacements, have you solved the problem of keeping the filter bowl full of fuel while the "bogging down" is occurring?

Yes, the bowl stays full now but the bogging down continues.

Williy · Nov 16, 2023

IMHO leads me to think that it has to do something with the
fuel system. A cracked fuel line really causes problems and
sometimes not easy to see where it is. Age and heat are not
rubber tubing friends. If it was stopping and then starting again would believe to be electrical problem.

willy

RedDawg · Nov 19, 2023

terraformer said:
On my 3510 was having a similar problem and it was the a valve that goes to a return line for bleeding. I was able to fix it by disassembling the valve and putting a new small oring. Air was leaking around the valve stem.

https://www.tractorbynet.com/forums/attachments/20230706_113939-jpg.809683/

The valve has round knob, near the upper third of the pic. The booster pump is below it. During the diagnostic process I replaced the fuel lines from the tank to the motor and back.

Earlier I could never get the glass mahindra filter to quit leaking, so replaced it with a VW diesel filter. Something that I have done to other diesels.

It wouldn't hurt to put in a clear pvc tubing between the booster pump and injection pump.

CL: I would say that everything is mysterious until you understand it.

Best wishes on your repair.

Sorry for the long delay, was traveling and hunting.

I don't have that same setup for where the fuel comes in - between the booster pump and the injection pump. Mine looks like this. Mine's a lot less complicated than yours. I crack this 17mm to bleed the system. I did pull the line between the booster pump and injection pump. The end on the booster pump looked suspicious so I trimmed abut 1/2" off and reclamped it. I've followed the lines from this injector pump fitting all the way to the final fitting where the return line goes back to the tank. The final rubber return line hose was leaking and I replaced that - no change.

I agree it feels like it is still pulling air somewhere but it has to be after the fuel filter assembly as it is staying fuel and acting properly now. Thanks for the help.

RedDawg · Nov 19, 2023

Williy said:
IMHO leads me to think that it has to do something with the
fuel system. A cracked fuel line really causes problems and
sometimes not easy to see where it is. Age and heat are not
rubber tubing friends. If it was stopping and then starting again would believe to be electrical problem.

willy

I agree, it does act like it's pulling air. Initially it was the filter and that gasket behind the selector switch. But that has not been replaced. So, it is post-filter and I haven't found it yet. But still looking. Thanks.

Dman1981 · Nov 19, 2023

Run auxillary
Fuel direct
To fuel pump see what happens. does it sit for
Prolonged periods? Listen to injectors. Do they sound the same. At
Idle have you cracked injector
Lines to see if engine does same on all. governor could be sticking
Put some Techron in fuel
Let idle at 1500 for an hour see what happens
Make sure kill cable is released all the way. Little things cause headaches