6500 problem

[cowsmowmygrass]

This is a test I am capable of doing. Than you Harry. I agree with your diagnosis. It MUST still be a fuel flow issue. Your test method seems very indicating of the potential problem. I will report what I find next here.

[cowsmowmygrass]

My experiences with Mahindra tractors has shown that this particular symptom can be caused by at least two separate problems. One is fuel blockage/starvation due to restriction somewhere. Another is the pump timing issue. My observations of each show the smoke puffs with timing problems will be more blue/gray in color while fuel supply problems cause the color to be closer to white. Timing issues usually occur within the first 150 hrs of operation, you must be well beyond that. With the timing problem, the condition most often comes on after the cold start timer goes off(about twenty minutes), and can continue until the engine is switched off and restarted. It will often return after another twenty minutes or so. The blockage problem can occur at any time, so stopping and restarting the engine will have little or no effect. I suspect your problem is supply related, and would suggest you place a pan below the fuel filter assembly and remove the banjo bolt from the outlet fitting( the line leading up to the injection pump) and observe the flow for a minute or so. Since the filter base is mounted low, the fuel will gravity feed at a good rate. It should continue at this rate until the tank empties, and not quickly reduce to a trickle. This may give an indication of where to go next.

First, Harry how do I mark your post as 'sticky' or very useful. Your reminder to approach this problem with logic is refreshing.

Outcome - fuel flows freely up to the hand pump

Details follow
I chose "fuel blockage/starvation due to restriction somewhere" because
1. I remembered the smoke being closer to white than blue/gray
2. My 6500 has about 225 hours
3. stopping and restarting had no effect
So , I did as you suggested
1. "remove the banjo bolt from the outlet fitting( the line leading up to the injection pump) and observe the flow for a minute or so."
Result is a bunch of diesel on my hands making wy wife say 'ooooo yuk' when I come back in to type this. But, then the leaking diesel stopped. After checking that the petcock is open I realized that I still have a fuel blockage problem.
2. Next, I removed the banjo bolt from the inlet fitting. The steady stream of diesel did not stop. OK, got diesel to this point.
So, then I planned to open each bolt between here and the outlet fitting to isolate the blockage.
3. The primaty filter(closest to tank) drain flowed freely
4. The secondary filter(closest to pump) drain flowed freely.
HUH? The blockage is between the secondary filter and the outlet? There isn't any other opening to check between these two points. The only thing between them(sort of) is the hand pump. Asked myself, how can the pump be restrictive?
I opened the pump handle and got a little faster stream from the secondary filter drain.
I operated pump 1 stroke and got a face of diesel. Oh yeah. The outlet banjo bolt is still removed.
So, fuel flows freely up to the hand pump. What is blocking it between beyond here?
Remember earlier I had operated the hand pump when tractor was running but sputtering. The hand pump had a vacuum on it. The upstroke was resistant. The downstroke was not restrictive.
Does the entire filter base have to be removed next? Any precautions to doing this?

[cowsmowmygrass]

https://skydrive.live.com/redir?resi...728B6597E9!294 Here is a video demonstrating the 6500 running with constriced fuel line.

[cowsmowmygrass]

Here ia a picture and diagram of my Mahindra 6500 Fuel Filter Base.
I will be following Harry's suggestions.

MahindraFuelFilterHousing.pdf

[cowsmowmygrass]

Harry in Ky wrote this:
I would proceed as follows: turn off the fuel valve at the tank outlet. Remove primer pump(the whole assembly should unscrew from the filter base). Open the valve a few turns and watch what happens. I would expect fuel to escape at a good rate. I believe this is a Bosch type primer pump, with two check valves involved. Simple theory here; pump plunger is lifted upwards - vacuum is created under it opening the inlet check and fuel flows in. Plunger moves downward - pressure builds, pressurized fuel opens outlet check and fuel flows towards outlet. In your case if the plunger shows resistance to being pulled up, it indicates that the passage through the inlet check and into the pumping chamber is somehow restricted. I think the pump assembly is no more than the plunger unit, and suspect the check valves will be in the filter base below, but I hesitate to say for sure. Once the pump has been removed you should be able to figure that out. I believe the primer pump circuit is merely a parallel circuit to the fuel flow through the filters, and may be between the supply and the primary filter, or between the primary and the secondary filter. I've never had to examine one to know for sure. You may have to remove the entire filter base, but I'd start by removing the filter cans first and looking at the inside of the base with a small hand mirror, and go from there. With both cans off, and the valve opened, you should get plenty of flow. Maybe try leaving the secondary can off and try the hand primer for effect? The problem must be in there somewhere.

[cowsmowmygrass]

https://skydrive.live.com/redir?resi...728B6597E9!294 Here is a video demonstrating the 6500 running with constriced fuel line.

This video was taken a few months ago as soon as I got the Mahindra back from the dealer, Top Flight, after they 'fixed' it. I have not run it with it smoking like this. My weeds are tall. My hay is unstacked. Beginning to get serious around here.

[cowsmowmygrass]

Yes, chronic fuel contamination continues.
Review of highlights for those just joining.
Engine starts, runs fine, accelerate to PTO 540 rpm. Brush hog for 10 minutes and then sputtering and white smoke. See video at
https://skydrive.live.com/?cid=93289...E9%21294&sff=1
1st - suspect fuel flow restriction. Remove the banjo bolt closest to the inlet of the 2-can filter base (left side, beside starter). Fuel should gravity flow at a steady stream non-stop. This is also one option for draining the fuel into a container to empty the tank for cleaning, inspection, etc.
2nd - if fuel is slow or inerrupted, then a blockage occurs between here and tank. Opening the fuel tap at the bottom of tank is only option to further diagnose and repair. Drain tank into fuel container. If not possible, get ready to be covered in diesel and quickly plug the hole with something - I used a wine cork shaped to plug it, though still slightly leaked but I only needed it there a few minutes.
3rd - Remove fuel tap, which will have the in-tank screen attached, with an open-end wrench(I think 15mm)

[cowsmowmygrass]

Observed the in-tank fuel screen. What is clogging it?
Mine is a lot of scuzz out of the tank: brown paste -is it rust?
I removed the filter for further diagnosis. The primary can filter will catch everything, so I surmised to run it for a while without this main restriction.
Ran another 10 minutes, then chronic problem all over again.
Now, I find oatmeal sized rust flakes when I remove fuel tap. What is in the tank?. Drained remaining fuel. Rinsed tank with water and dried thoroughly first time. This all happened again, found rust flakes and brown scum paste. Rinsed tank again. This time with gasoline.
Have followed with 6 iterations of running for 10 minutes until it sputters, remove the fuel tap(still have not reinstalled screen) and unclog banjo bolt.
These events happened over a 3 month period.
Today, the Mahindra is stalled in the pasture. Time to go through it all once again. Poor wife, she hates the lingering smell of diesel on me when I do this. I don't like it either.

What could be contaminating the diesel?
How should the tank be cleaned without removing it?

[DavesTractor]

I'd suggest you pull the tank and clean it. It's a chore, but so is having a recurrent problem. We have found no good way to really get a tank clean without removal. Also check your fuel source for the possibility you are introducing contamination into your tank when filling. People that pump fuel out of 55 gallon drums will often be surprised to find their drum has a bunch of water and rust in it.

[BobG_in_VA]

If you pull the tank, suggest you get in touch with your local radiator type shop...they can clean and coat the inside of the tank so that no further contamination will occur from the tank...this won't help if you have fuel that is somehow contaminated...sorry to hear about your issues...I know thay are a bear to deal with.. BobG in VA