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localdj77

312-8 new purchase but now an issue

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Did some diag last night.....idled for about 5 minutes to warm it up.....no hiccups.  Throttled up to maybe 40%, dropped the deck and started mowing.  Ran great for 10 minutes!  lol  Then is slowly died......couldn't restart it.  It's a magnum BTW.  I took a look in the tank and the valve looked pretty clean but had some sediment near it.  I think a tune up is in order.....front to back.  Found out the gear box oil looks pretty bad....gotta change that and the oil!  Needs a makeover!  lol

 

Also realized that the left blade is cutting lower than the right.  Haven't even looked into that but any common issue thoughts would be appreciated.  I'll keep you updated as to what I find!  Thanks for the help!!!

 

Oh yeah, at 40% it sounds like the motor is running very high revs.  How do I know if it's overrevving??? 

 

The good news is - everything about these tractors is easy, especially on your model.

 

If you have a Magnum engine - good!  No tune-up required, only a new spark plug.  No points and condenser, etc., to deal with.

 

Oil change in the rear is easy.  There is a hex plug on the bottom of the tranny, take it out, let it drain and refill.  I want to say you will use 80-90W gear oil.  Check the manual - others will probably chime-in on what is correct, I'm working from memory here - with is dangerous.... ;)

 

The deck rides on the ground - it doesn't hang from the tractor.  Let the lift all the way down and set the height on the deck via the lever on it.  You should get a BEAUTIFUL cut!  If your deck is truly out of line side to side (I've never had to deal with this), I'm sure it can be adjusted.  Down load the manuals for this.  Also, you can adjust the deck front to back height via the jack screw/bolt at the center/rear of the deck.  The front blade tip should be about 1/8 inch lower than the rear tip.

 

As far as a tac for the RPMS, you can get one at harbor freight for not to much $$'s I should think.

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I would really recommend cleaning out the tank, and replacing the fuel lines, so you know you have clean fuel going to the motor.  I had a bunch of water and orange stuff (not sure what it was on the bottom, but did not mix with the gas)  I replaced the shut off valve at the tank, and all of the lines, and put in a filter towards the engine, with a shut off there too.

 

One trick for replacing the line, and feeding it through the middle of the chassis, is to use a drill bit and connect the old, and new fuel line.  The new line will have a curve to it, and won't feed easily.  This will save a bunch of time.  Be sure to get extra spring clips, and note that not all fuel lines have the same OD, I found out the hard way.  Good luck.

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Wow thanks guys....I'm sure it will be a cinch when I have some extra time.  My grass needs mowed like YESTERDAY!  Time to break out the old honda push!  Hopefully for the last time!

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To check fuel pump disconnect line to the carb... get a clean can for the gas... turn the key to the start position and

the pump should be pouring out of the line.

:text-yeahthat:  Quickest way to check for good fuel  supply to carb.  If supply is good, work on carb clean-up. If supply  is bad, remove the line into the fuel pump to check for good supply to pump. If supply is good, replace the pump. If supply to pump is bad, keep working back to the tank till you find the clog.  Could be lines, line filter, tank filter screen, shut-off valve.

 

:twocents-02cents:      :WRS:       

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On the deck cutting crooked:

 

Check that the front bar to the deck is properly latched in on both sides (with the fork up to the alignment bar) to the attachmatic hitch.

 

Second, check the spindles/blades for equal spacers on both sides.

 

Beyond that I am afraid the mower deck is tweaked/bent and very difficult to straighten.

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Ok so I got the carb off and I'm going through the system.....all is going well and we found a couple small issues that need addressed.

 

In the meantime.  I searched for manuals but where can I find things like how to adjust the drive belt and req. deflection?  The belt seems sloppy but maybe it should be that way.  Is there a maintenance manual I can find?  Can any of you help?  Thanks inadvance!

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There is no service manual for the 300-Series that I am aware of. Some of the exported models have service notes throughout the illustrated parts lists. There is a 1978-79 service manual for the B, C and D-Series tractors at the time and your 312-8 is a decendent of the C-121-8-Speed.

These models changed so little over the years much of the manual still appied to the last in 2007.

 

You may have a dampener on the clutch idler arm that is supposed to prevent the clutch from being applied too fast causing a wheelie and they can over do it at times. Fairly expensive so many remove it and add the return spring to the left side of the transmission over the brake band that was used before the dampener idea. Will get and IPL added to the library so you can see for yourself.

 

Garry

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Forgot that IE works much better for putting the parts lists together and I'm not using it at the moment so go to

https://lookup3.toro.com/partdex/index.cfm?xCaller=Toro

Use 21-12K804 for a model number and the first page of the parts lists is for Clutch Brake and Speed Control. Item 48 is the spring and it hooks over the clutch rod and a 45 degree cast iron web over the left axle housing. The hole should already be there for the spring.

 

Garry

 

Adding

Don't see where the model number of your tractor has been identified but it has a M12 so it is 1987 or newer. Post all the numbers off the engine data decal including the serial number and will try to find the proper manuals.

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Alright.....I got everything back together and was adjusting the needles and things seemed to be going well......then it died.  Started fresh with the needle adjustment and it still wouldn't start.....at all.....so I dug deeper.  Turns out the fuel was HOT and was not pumping any longer.  Seems it gets hot and shuts off. 

 

What are your guys opinions?  Buy another electric or go back to the factory pump?  The mech pump is still on it but can it be rebuilt???

 

Thanks in advance!

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The Mechanical Pump is nice once rebuilt. The Carburetor is abused from too many tear downs & rebuilds. Invest in a new one if your friend can't get it to work, the Main Jets get moved and they crap out.

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Like the other guy said, the engines are expected to be run at 3600 RPM. The whole system is designed to cool the engine properly at that speed. Cutting grass at 40% of throttle is not a good idea. With that load, you will be generating a lot of heat and no way to dissipate it. Make  sure that there is no debris under the tin surrounding the engine. That will also prevent the engine from cooling properly. That carburetor is very easy to work on. Very few parts. Use your cell phone and take photos as you take it apart. Especially when you remove it from the engine. Sometimes it is confusing when you go to reattach the linkage to the engine. 

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Yeah ok I'm guessing I'll buy a rebuild kit.  I will mow at 3600 RPM but I have to get it running first.  The electric pump is mounted in front of the mech pump so I'm sure its not as susceptible to heat.  The engine isn't getting hot because I'm just idling at this point.....the previous mention of me mowing was before I knew about the RPM requirement and it was only for a couple minutes right after I bought the tractor.  At this point I have only ran at idle after cleaning the carb and it ran great......until the fuel pump pooped out.  I see a rebuild kit on amazon for 40......is that a good deal?  Anything I should watch out for?

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Ok so I found out the kohler part number is 47559 11-s.  My engine number is 471527.  The kit on amazon turns out to be $100.  Is there a cheaper option?  Can't seem to find a good source for the fuel pump.  This is the next step in getting this thing running.  Please help!

 

Also, took a look at the deck issue.  Looks like the left side adjustment wheel is much lower then the right.  There seems to be an adjustment near the wheel.  Is that where you make the left and right match?  Maybe a link for me to reference?

 

Thanks for all your help guys!

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Concentrate on one area, which is getting the engine to run properly. 

 

Take the electric fuel pump off the engine and put back in your shed for when you need to pump out a fuel tank.  It should not be used on a stock tractor as they provide too much pressure for the standard carb.  Once you put it back to factory, with the fuel tank at least 1/4 full, fuel valve open, when you disconnect the supply hose form the mechanical pump, fuel should flow out the hose via gravity, and it should be a decent amount.  If it is, your tank, screen, valve, and hose is functioning correct.  If not, the valve is probably to blame and is often overlooked.

 

Once you verify that fuel can make it to the fuel pump, disconnect the outlet hose preferable from the carb, while cranking the engine over, it should pulse a good amount of fuel out the hose.  If you are brave, try to put your finger over the hose and see if the pump can build a slight pressure.  If flow is bad, or will not build pressure, replace the entire mechanical pump, they are not able to be rebuilt as the magnums used plastic body pumps.  Again skip the electric, they are great for people running aftermarket carbs, or for the pulling folks, but are not needed on a daily worker.

 

If the fuel pump is getting too hot, this can be tricky, there should be a nice paper gasket between the block and pump body, not just silicone. 

 

Once you rule out that fuel is getting to the carburetor but it still will not run, download the kohler magnum manual and completely take apart and reclean + inspect.

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My guess would be the fuel being hot was the result of the electric pump continuing to run while pressure was high, that may have caused a vapor lock. If you can find a good 1965 or earlier mechanical fuel pump they have a priming lever on the botom of them, pump it a couple of times before starting and it will fire up faster after sitting for a week. I have them on everything I own that has a pump; find them on ebay now and then.

 

Good luck.

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I found a model specific pump for $50 and it should be here tomorrow.  I just want to go back to stock.  I think the electric pump was causing more issues than it was worth.  When I jacked with it a couple days ago it wouldn't even fill the fuel filter.....I'm going to start there.....I'll let you know the results!!!

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I have a Toro wheel Horse 312-8. I bought it new in 1992. It has been a work horse and I really love it, 23 years with no trouble except some minor repairs. Last summer it started stalling once it got hot. Took it to the shop and they said it needed the carb. to be adjusted. It worked the rest of the summer with no problems. It worked all early spring with out a hitch, until about a month ago when it started stalling once it got hot. I took it back to the shop this time they said it needed an ignition module they replaced the module spark plug, and fuel filter(which I had all ready replaced. After $185 I got it home and it was still doing the same thing. Since I have replaced the carb. with a brand new one, and checked the fuel pump. When I started it up it purred like a kitten. I mowed for about fifteen minutes and it started stalling again. I am at a loss at this point don't know where to go from here. Anyone have any thoughts?

 

Toro Wheel Horse 312-8

Engine Magnum M12S

Spec 471527

Build 1992

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:WRS:   Birdog9999, I had the same type of problem once, the vent in the gas cap was bad, new cap, problem solved. Hope this will work for you.  :text-welcomeconfetti:

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i had a similar problem with a 88 or 89 312-A with a kohler mag on it. tried a new magneto on it and that didn't work finally talked to my dad's old dealer and he told me that a valve was getting tight when it heated up. he reamed the valve guide out and cleaned the valve up and it runs good now. mine would run good till it got hot, the cooler the out side temp was the less problems i would have. it would just loose rpm and just before it died it would back fire and come back to life. not sure if this is your problem but its an idea to at least look at. good luck

 

 

 

eric j  

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Ok so after buying a new fuel pump more than a month ago I finally got time to put it on.  Well, I should have pulled the old one off before buying another one.  I installed the new one and it wouldn't pump.  A side note....I moved the filter to before the pump.....nothing was being pumped into the filter.  So I decide to pull off the line and make sure fuel was actually coming from the tank.  It was with no issue so I hooked up the old pump and started to actuate it with my hand.  It shot fuel probably 4 feet!  It looks like the old pump was not the reason the previous owner went to an electric version.  Bottom line......what the heck can I do to get this thing running!  Is the fuel pump lobe the issue?  I'm not tearing the engine apart to fix it if so.  If electric is the next step.....any suggestions?  I need this thing to be running already.  Ya know?

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Yu can buy an electric fuel pump from Auto Zone made for small engines. It is low pressure and will work fine for your application. There are several sellers on EBay selling low pressure pumps as well. When you hook it up do not run it in line with your old one. Are you sure that the gas cap is not plugged up.

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Yeah pretty sure.  Seemed like the old electric pump got super hot and thats what killed it.  Would it do that if the cap was bad???

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Can't say one way or the other but if the cap is not able to ventilate the tank, gas will not flow.

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So I'm ok to assume that if I take the cap off and it pumps fine......thats my issue.  Right?  Could I drill a hole in it as well???

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