Mahindra 6530 Inj pump problem

[Jdman]

I know it’s been discussed before problem with these but I’ve got a 6530 that runs perfect for about 10-15 minutes until it gets to temperature and then at about 1500 rpm it’ll miss and blow lots of white/gray fuel smoke. I can turn it off a couple minutes and cool down some and it will run fine till it reaches the temperature again then start missing only at higher rpm. I unplugged the cold start on the side and it reverses it. It will miss at low rpm and run fine when at higher. Is there something sticking in it or is this a timing problem? I took the pump and had it rebuilt and I’ve got the engine set right if they have the pump locked it the right place. I believe this is a T3 engine

 

[Fedup]

So This problem was there before the pump rebuild? Is the problem still there after the rebuild? Just what are you asking for here?

 

[Fedup]

Nice photo by the way.

 

[Jdman]

Same problem before rebuild and after. Is it possible the cold start is causing this or am I looking in the wrong place?

 

[Fedup]

My experience with these tier 3 VE pumps goes back a long way. In most of the cases I've dealt with the spitting, sputtering, smoking, run like crap condition is (or at least very often is) caused by just slightly incorrect pump timing. You put the rebuilt pump back on (or someone did?) in as close a proximity as possible to where it was before. Timing wise that is. Yes/no? Some external marks are visible in the photo and appear to be a close match. Often lock timed pumps don't have such marks.

Here's the point. For some reason I can't explain if the timing is off by just a few degrees it can cause the engine to run as yours does. I've seen it many times, not just on Mahindra engines but New Holland and Cummins engines as well. Maybe more. These pumps use a cold start advance. That's the gadget on the side of the pump with the electric shut off solenoid. Not the solenoid on top, the one one the side right out out front. When power (12 volts) is applied to the coil it opens an internal passage allowing transfer pressure to add a few degrees of advance to the pump's internal timing advance mechanism.

What I have found is if I loosen the mounting nuts and rotate the pump just the width of the mark and tighten it down that change in timing can make the difference. What happens is this. The cold start advance changes the timing when it's engaged. Mahindra uses a timer to control this. Start the engine and the advance is on. After twenty odd minutes the timer shuts off and so does the advance. When the pump timing is right on the edge of being right, the advance on or off will make the difference. That's where the twenty minutes thing comes into play. If it runs right with that on, and then runs ragged with it off you need to advance the pump a degree or two. If it runs right when the system is off, then you need to retard the pump by just a little.

You can experiment to prove or disprove the point. Take the wire off the solenoid. Use a jumper wire and apply battery voltage to the solenoid. You will hear and feel it click on and off. Now start and run the engine for a few minutes at about 3/4 throttle. Apply the 12 volts to the coil and see what happens in regard to how it runs. Is it better with the wire on or with it off? If it makes a noticeable difference then you have some decisions to make.

 

[Jdman]

As far as external marks I put it back where it was to begin with. With the cold start on it runs fine with it off it misses at around 1500 rpm up but runs fine every where before 1500. I marked the gear in relation to the key slot in the pump shaft when I took it off just for a reference when I got it back. I noticed it would’ve been advanced more the way they set it when I got it back so I backed it up some to align with my marks when I removed the pump. Should I have just put it back the way they had it locked when I got it from the pump shop? When all of this started it was colder than normal for us for several weeks below freezing and fuel froze or gelled and quit running. After a few days of warmer weather finally got it back running but really hasn’t been the same since. Would it have been possible if the fuel froze or jelled could it have slip timing since it doesn’t have a key way? I’m wondering now since they had it locked in a more advanced than it was when I took it off. If that is even possible to happen?

 

[Jdman]

I took the pump back off and I was wrong it’s been awhile since I started this project. It does have a key way in the gear and pump. So why does the pump have a way to lock it down if it uses a key way?

 

[Jdman]

I also looked at mahindras parts break down if it’s correct it doesn’t show a key in the shaft. Is it supposed to use one? I can’t remember if it did when I took it off the first time they installed a new one at the pump shot.

 

[Fedup]

My experience is most lock timed pumps do not use a key. Are the external marks factory or your marks put in place before you pulled the pump? If there are no factory marks I will usually make my own before pulling a pump. Just a reference point for myself later when things like this happen.

That said, where are you now? pump off or on? Engine running or no? When you put the pump on (with the key in place) is there room in the slots for the mounting studs to rotate the pump both ways?

 

[Jdman]

That’s one of my problems I don’t remember it having a key they stuck a new one in it anyway. The marks are factory. I’ve got the pump off right now and I tried before removing it to rotate it both ways to see if that would help but if it did it wasn’t a big change not enough to say it helped anything. I was debating on taking it back and letting them lock the pump again and try installing it without the key and see what it does. With the flywheel pinned and where they had the pump locked it wasn’t close enough to put the pump on without loosening the pump locking bolt and turning it some to get the key ways to line up. I just can’t remember it having that key in it. I need to start taking pictures of everything because on it they took a long time getting it rebuilt had to order something for it around Christmas time then everything shut down for a few weeks. I’ve even called a dealer and they can’t tell me if it’s supposed to have that key or not ether.

 

[Fedup]

If the pump shop installed a key that's not a good sign. They should know better than that.

Sorry for all the questions, but you had this problem to start with, had the pump rebuilt, and still have the problem? What did they tell you was wrong with the pump? I'm wondering if you paid for a rebuild you didn't need. I have my doubts the pump was/is the problem. Once you unlocked the stop bolt to install the pump (key or no key) you stepped in it. I would recommend you take it back to them and have them time it again before putting it back on. Your choice, but that's what I would do.

Once it's back up and running, I would start playing with timing and dealing with the cold start advance as needed. I have a few ideas relating to that but until it's running again there's no point in going there yet.

 

[Jdman]

It runs exactly the same as before I had it rebuilt. They said there was something with timing advance. I’m not sure if they were talking about the cold start or something else inside but that’s what the long wait was over what ever they ordered. I’ll take it and have it retimed but would you try it without the key in it this time after they time it?

 

[Fedup]

Yes. If the engine is set/timed for pump installation, the pump is locked, mount it up and go. If possible set it so the slots give you room on both sides, tighten it down and see what happens. Then we go from there.