Mahindra 5500 losing prime

[janderson421]

Good afternoon everyone,

I recently purchased a Mahindra 5500, the tractor will only start and run by bleeding the 4 injectors. Once you crack the lines and bleed the air it starts and runs like a dream, I haven't hooked anything to it to do work with, but it seems to run fine with no lack of power. The problem is, if you kill it, it will immediately lose prime. It will go from running great with no miss to so much air in the system that it has to be bled to crank in a matter of 1 or 2 seconds after being killed. I have changed the fuel filters, but the previous owner said it has been doing this for a while and that he changed fuel filters several times before finally parking it. I bought it after it setting for a year. The other thing the owner mentioned is that when he was trying to fix it that it could set for 5 mins or so before losing prime. So it has gotten a lot worse over the year of setting. In addition to changing the filters, I have checked all the fuel lines and nothing is leaking. I won't say that there might not be a very, very, small leak I missed, but I can't see how a leak that small would cause it to lose prime so fast. Any help would be greatly appreciated.

 

[Harry in Ky]

If the tractor still has the factory fuel lines, I would suggest you start right there. The lines were nothing but problems since the tractors were new. If it still has the braided steel covered hoses, I would carefully cut the crimp sleeves, peel them off and remove the hoses. Replace them all with good quality rubber fuel hose and gear clamps. Once done with that, bleed it out, get it running, and see what effect that has before going any further.

 

[thepumpguysc]

It sounds to me that the feed pump took a dump.??
U should be able to HEAR IT RUNNING when U turn the key to ON, without starting it.

 

[Harry in Ky]

Actually, there is no feed pump. If it had one this problem might not be there. Sometimes the addition of an electric pump can be quite helpful.

 

[thepumpguysc]

I Googled Mahindra 5500 feed pump and it popped right up.,

 

[janderson421]

Thanks for all the help guys. If it is supposed to have a feed pump, I don't know where went. Right now It gravity feeds into the filters, and then the injection pump pulls it from the filters and pushes it into the injectors. I don't have a problem changing the hoses, if that doesnt fix the problem where else should i look? I was thinking at that point the injection pump? Could I add a check valve somewhere that would stop it from losing prime and fix the issue?

 

[Harry in Ky]

Injection pump is the LAST item on the list.

It never had a lift pump. The engineers decided to let the injection pump pull fuel from the tank through the filters. Wasn't a great idea then, and even less so now. Change out the hoses first. You need to do that anyway.

I've added electric fuel pumps to a number of those tractors when I felt it would be helpful. I never had a problem because of it. You may well be at that point now. I put it between the tank outlet and the first filter. Power it with a jumper wire from the injection pump fuel shut off solenoid. Simple, effective, and I've never experienced a problem doing it that way.

 

[RjCorazza]

I agree that the injection pump would be far down on the list for now. As others have mentioned, replacing all soft fuel lines would be my first on the list, followed by adding an electric lift pump. I added a secondary lift pump on 2 of my diesel zero turns when I added lower micron filters. They can be found for $20 or so on eBay or Amazon.

 

[janderson421]

Again thanks for the awesome help, I'll get the lines changed this week. Any suggestions on an electric pump I could get and add between the tank and first filter?

 

[RjCorazza]

Again thanks for the awesome help, I'll get the lines changed this week. Any suggestions on an electric pump I could get and add between the tank and first filter?

Any universal 12v, 3-7 psi pump will work. I have had reliable service from the cheap ones. I believe they also prevent backflow with a one way valve, or the inherent operation of a diaphragm pump.
Not necessarily recommending this particular one, but they are all over ebay and Amazon.