My Mitsubishi 372 won't start.

   / My Mitsubishi 372 won't start. #1  

Soots

Member
Joined
Oct 29, 2012
Messages
46
Location
Inverness, Florida
Tractor
mt372
Some of you might remember me from a few months ago, when I was talking about the fuel getting into the crankcase. Well I pulled the injector pump and had it rebuilt. $239.00 went out to sea during that time. Now I am back, I replaced the pump. filled the tank with Diesel, put Oil in till it reached the full mark, about 3 quarts. Tracked the fuel in the lines up to the injectors, starting at the filter and bleeding the air. It still won't start. small faint puffs of pale blue smoke from exhaust, but it won't start. One question I have, is there a safety switch or control preventing the starting?
 
   / My Mitsubishi 372 won't start. #2  
It sounds like you have verified fuel is reaching the injectors. There is no additional safety switch or control apart from the throttle on your tractor. Make sure it is at full throttle. You can depress the foot throttle to make sure you have the hand throttle set in the correct position.

Have you made sure the glow plugs work?

All of this assumes that the injection pump was installed correctly timed. Remember, the engine works by using the pump to spray fuel into the cylinder at a certain time in the compression stroke. There is no fuel in the cylinder's compression stroke until the injection pump fires. If the application of fuel into the cylinder occurs at the wrong time, the engine will not run. Have you installed the pump correctly?
 
   / My Mitsubishi 372 won't start.
  • Thread Starter
#3  
I was told I only need to put the pump in. the rollers on the bottom of the pump take care of the timing. no need to put the engine at TDC. sounded strange to me but he said he was sure. He was the pump rebuilder. the weather is mild in central florida so I don't think the glow plugs are an issue.(only guessing here). the throttle is a stick as i move it i can hear the pump working.
 
   / My Mitsubishi 372 won't start. #4  
I am 99% sure that is not the case that you can put the injector pump in without it being in time. I would call Valley Power Products, as they are a Mitsubishi tractor dealer, and ask them.
 
   / My Mitsubishi 372 won't start.
  • Thread Starter
#5  
I will do that. What state and city are Valley power in?
 
   / My Mitsubishi 372 won't start. #6  
Isolate your experimentation, and work simple to hard, and cheap to expensive.

If you are certain the pump is moving to full throttle, this first step is done.

Glow plugs are easy to test, and you can attach a jumper wire to make sure they work. Even in warmer weather, my relabeled Beaver (A Satoh ST1440) won't start without the glow plugs.

I don't have a service manual for the Beaver, but my Yanmar service manual has instructions for setting the pump timing. I wouldn't use these numbers, but the procedures are probably very similar.

"Beginning if injection should occur at 23-25 degrees before top dead center....attach a tube to number one outlet of fuel pump (for Yanmars, this is the cylinder nearest the flywheel) then rotate engine in normal direction until fuel stops flowing out of the tube. This is the beginning of injection and should occur as mark on crankshaft pulley aligns with notch..."

It goes on to explain that adding shims will ****** the injection timing, and subtracting them will advance the timing of the injector pulse. I don't know if the Mitsubishi engine has similar timing notches or not, but it is worth a look. In rebuilding the pump it is possible the timing was altered enough so it won't quite start.

My Yanmar manual says the shims are 0.1mm thick, and alter timing 1 degree each. That is a tiny increment, and well within the realm of being altered by a rebuild in my estimation. Point being, if your glow plugs check out and it is moving fuel, you need to verify the timing is correct on the pump, too, then move to the injectors and compression testing.
 
   / My Mitsubishi 372 won't start.
  • Thread Starter
#7  
284, everything you say makes perfect sense and i'm going to work in that direction. It sounds like i might have changed the timing in the pump, if it was set to TDC. I'll keep that in mind. One thing that concerns me is that when I bled the fuel from the lines the pulse of the fuel was steady and constant. that is squirt, squirt, squirt, squirt, squirt, with no break in rhythm, or any that i could detect. I'll check for that. the fuel line makes a "T" at the injector for the return line. could the injector pump send a constant flow of fuel, and with an internal valve of some sort to control the feed of fuel to the firing chamber? I'll be going over there this afternoon. and will check on that. Easy to hard, I'm still looking for the Easy part. It is a labor of love. I've never been a mechanic, but i'm finding that I'm looking forward to doing this, it makes me feel good. I'm doing something that is important to no one but me, it'll be a great accomplishment for me.
 
   / My Mitsubishi 372 won't start. #8  
sounds like pump timing to me too
 
   / My Mitsubishi 372 won't start.
  • Thread Starter
#9  
With everybody's help and advice we have the problem solved, almost. On this tractor the injector pump has a roller on each plunger that rides on a cam for each plunger, thus squirting the fuel at the proper time. as the cam is the timing. So after checking again that all the air is bled, and the pump is working proper, it still wouldn't start. The only thing missing now is Compression. I am on the hunt for a compression tester. I found some at auto parts stores, I even brought a glow plug to make sure the tester would fit proper.Can't find one that fits the glow plug hole. Tomorrow i'll take the injector out, it is bigger threaded hole. might find a rental at Advanced Auto Parts that will fit. With the crank case and upper rocker arm area having been flooded with Diesel, from the bad injector pump, and washing away all the GOO that keeps most engines running, I have little doubt that there will be no compression. I think I'm going to be sick.
 
   / My Mitsubishi 372 won't start. #10  
Did you check the glow plugs for proper operation?
 
 
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