7520 ksb/cold start issue?

A

Ajcook5

New member
Hello everyone, my family has a Mahindra 7520 that we are having issues with. We haven’t had the tractor very long so we don’t know too much about it. It starts up just fine and seems to idle good but when any throttle is given it smokes (blueish white) and seems to be missing. I’ve been trying to do my research but could use some help to figure it out. I’ve read some about cold start system issues with these.

So far we’ve checked fuel filters and made sure the fuel pickup tube was clear. Have not found any air leaks in the lines at this point. I read that the injection pump on these needs to be turned a touch sometimes but the previous owner must have done that as it was already done when I checked.

As far as the cold start system, I’m trying to do my research. I believe there should be 12 volts to the solenoid on startup correct? We don’t have any voltage. Out of curiosity I applied 12 volts with my power probe and the tractor ran great and throttled up great. So I wired a temporary 12 volt jumper from the fuel shut off solenoid to the cold start solenoid and it ran great for about 5 minutes. Then I could hear the cold start solenoid area get really chattery and it started smoking and missing again. It stayed that way with the 12 volt jumper removed as well. Failing solenoid? I’d anyone has any insight, it would be greatly appreciated.

Thanks, Andrew
 
Too many possibilities on that one. Yes, the pump timing can be a factor with that pump, but so can fuel supply. Looks like you have a low mounted fuel tank, no dedicated fuel lift pump, and Mahindra's (patented) fuel lines with sections of rubber fuel hose crimp sealed to sections of steel tubing. Am I right so far? Those lines are well known for air leaks and have been known for causing problems even when new, so if you still have the originals they're going on twenty years old now.

If I were faced with this I think my first move would be to start at the supply line from the tank. Pick up a generic parts house electric fuel pump somewhere. Interrupt that supply line and insert said fuel pump in the circuit with some temporary jumper wires. Get it running and see what if any difference that makes. If the poor running, spit, sputter, smoke problem changes (or disappears) you have at least part of the problem figured out. In fact, if I were doing this I would be looking seriously at mounting the fuel pump permanently. Having done that on many tractors I know it solves a number of problems. For now though, I would just hang it on there and see what changes. If, on the other hand, it's all still the same, then the cold start/ pump timing issue would be next in line to experiment with. There are few tricks to that as well.
 
Fedup said:
Too many possibilities on that one. Yes, the pump timing can be a factor with that pump, but so can fuel supply. Looks like you have a low mounted fuel tank, no dedicated fuel lift pump, and Mahindra's (patented) fuel lines with sections of rubber fuel hose crimp sealed to sections of steel tubing. Am I right so far? Those lines are well known for air leaks and have been known for causing problems even when new, so if you still have the originals they're going on twenty years old now.

If I were faced with this I think my first move would be to start at the supply line from the tank. Pick up a generic parts house electric fuel pump somewhere. Interrupt that supply line and insert said fuel pump in the circuit with some temporary jumper wires. Get it running and see what if any difference that makes. If the poor running, spit, sputter, smoke problem changes (or disappears) you have at least part of the problem figured out. In fact, if I were doing this I would be looking seriously at mounting the fuel pump permanently. Having done that on many tractors I know it solves a number of problems. For now though, I would just hang it on there and see what changes. If, on the other hand, it's all still the same, then the cold start/ pump timing issue would be next in line to experiment with. There are few tricks to that as well.
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Thanks for the reply, I will change out the rubber fuel hose just to be safe but they are definitely not the original ones. You're right though, the tank is mounted low and has metal with rubber sections I have a fuel pump I can temporarily instal when I get a chance and see what happens.

Anyone know how to edit the thread title? I didn't realize I put child instead of cold. ooops.
 
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