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706 Gas dies out past half throttle.


RandyIN
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   Just refreshed a 63 706 Gas. Clean tank, clean fuel, new fuel line, rebuilt carb, and new ignition. Timing and fuel  flow is great.

   Starts and Runs great. When you try to Rev it up past half throttle, the Governor appears to shut it down and it dies.

Any ideas?

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I would double check the fuel flow and also make sure air cleaner isn't clogged up with mouse nest or some other obstruction.  At least to start with. 

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Rev it up and yank the choke when it starts to die. That will tell you a lot about what is wrong. If the choke will save it from quitting, the fuel supply most likely good and the problem is in the carb. If the choke doesn’t help at all or very little or only briefly, then carb bowl is running dry = fuel supply problem. I would not rule out a fuel supply problem. I use a customer’s 706 gas to pull my Rowse rake (pulls the guts out of that tractor on a hill!) and that 706 has more than once given trouble because the fuel outlet of the tank was somewhat obstructed. Fuel would run out of the line but if the tank outlet is unobstructed  it should gush out. 

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1 hour ago, Moodnacreek said:

Many people have taken their carburetors apart when the problem was in the gas tank at the inlet to the sediment bowl.

I will check that first.

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On 5/13/2021 at 7:06 PM, RandyIN said:

   Just refreshed a 63 706 Gas. Clean tank, clean fuel, new fuel line, rebuilt carb, and new ignition. Timing and fuel  flow is great.

   Starts and Runs great. When you try to Rev it up past half throttle, the Governor appears to shut it down and it dies.

Any ideas?

Double checked the air cleaner and fuel flow today and it was all was good. When it stated to die, I shot some starter fluid in the air cleaner and it revved up. Still think it's in the Carb????

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On 5/13/2021 at 8:32 PM, RandyIN said:

I will double check fuel flow, then I will take the Carb apart.

Thx

Double checked the air cleaner and fuel flow today and it was all was good. When it stated to die, I shot some starter fluid in the air cleaner and it revved up. Still think it's in the Carb????

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9 hours ago, RandyIN said:

Double checked the air cleaner and fuel flow today and it was all was good. When it stated to die, I shot some starter fluid in the air cleaner and it revved up. Still think it's in the Carb????

Yes, unless you are completely misreading the fuel flow.

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Last winter a guy buying hay from me had similar problems. He thought fuel flow was good too till he beat his head against a wall for 2 weeks. Finally rechecked fuel flow and it looked like plenty.......for about 5 seconds then it tapered off severely.  Make sure you let it flow into a container long enough to account for a partial blockage. 

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If fuel will keep it running that pretty much rules out spark or timing. I would [maybe you have] run the throttle in one hand and the choke in the other and try to get it to run fast. What ever part of the carb runs high speed is suspect.

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  • 2 weeks later...

   Hello everyone, this is where I am at now. 1. Timing good, 2. Fuel Flow Good, 3. Carburetor Good, 4. Starts and runs like a top until you get up past half throttle, then the Governor shuts it down. It can be running fine, then I bump the Governor,  causing it to spit and sputter. Am I looking at rebuilding  the governor? Is there any way to test it?

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Don't believe it's the governor at all. If you watch throttle linkage as it dies. You will see throttle go to wide open not closed. Don't know what else you're reading wrong but sure sounds like not enough main fuel to me. It could be electrcal. A spare plug with a wide gap laying on the frame rail will either prove or eliminate that.

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10 hours ago, snoshoe said:

Don't believe it's the governor at all. If you watch throttle linkage as it dies. You will see throttle go to wide open not closed. Don't know what else you're reading wrong but sure sounds like not enough main fuel to me. It could be electrical. A spare plug with a wide gap laying on the frame rail will either prove or eliminate that.

Runs smooth as silk up to a point just past half throttle, starts spittering (my word), the Governor opens up the throttle then it dies. I have good fuel flow, and carb appears ok. How would I verify it is getting enough main fuel. As far as a spare plug with a wide gap goes, run it that way, with one cylinder dead, and push it up to the failure point???

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5 hours ago, Duntongw said:

No idea how this is setup, but it's not something dumb like it's missing the tension spring off of the throttle linkage?

Brand new spring. I keep wanting to think it is a fuel problem, because I can shoot either in the air cleaner and it fires back up. But to describe it when it dies, its like unplugging it. 

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Have you played with the high speed adjustment on the carb?

 

sounds like it might just need adjusting................

If you jam the governor so it can't interfere what happens?

 

 

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56 minutes ago, RandyIN said:

Runs smooth as silk up to a point just past half throttle, starts spittering (my word), the Governor opens up the throttle then it dies. I have good fuel flow, and carb appears ok. How would I verify it is getting enough main fuel. As far as a spare plug with a wide gap goes, run it that way, with one cylinder dead, and push it up to the failure point???

Well you just told us it's not the governor. As far as the plug on frame. Yes that is exactly what you do. Does it lose spark as it dies or does it spark right up until it stops turning? The fuel gets a little more complicated. Have you done as others have said. Verified running fuel level in bowl with clear tubing in drain plug? Run with solenoid removed? Removed discharge nozzle and verified acceleration well is clean? Verified main jet size with gauge wire or number drill? Careful do not enlarge.

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Reread this this morning. Forget about the plug on the frame. You've already proven the problem is fuel. Also you were not told in this thread about checking fuel level in bowl with clear tubing or running without solenoid. My mistake. I have to ask. Is this the IH carb?

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One thing I do with all the sediment bowls is drill them out on both inlet and outlet.  I also make sure there is no screen in tank or extension into tank.  I want the water or sediment to settle into the bowl not bottom of the tank.  I have seen a few severely rusted tanks from water that was trapped and had no way to escape.

I expect if it is a fuel delivery problem as using the procedure proscribed by Gearclash using the choke to recover it, usually 1/4 choke allows that extra signal across the venturi.  If already confirmed no vacuum leaks and spark is good, timing set, I found with the Ethanol fuel you can run a bit more timing, I can't verify this will work with everyone.  With all that correct, I think your main jet needs a slight reaming for whatever reason especially with Ethanol fuel, I would start .002 at a time until the stumble is gone.

Scott

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Randy, make sure you do the thing with the spark plug on the frame rail.

 I have a 340 industrial that did exactly as you said, I cleaned out the fuel lines, carb jets, sediment bowl, tank screen , all of it.

 Still had the same problem, much more than 1/2 throttle, and it quit.

 threw some new sparkplugs in it,problem solved (or so I thought).

 A few days later, same thing.

 Long story, short version:

New plugs worked until they got some soot on them, cleaned the plugs, worked again.

 Got suspicious of the ignition coil, replaced that, no problems since.

 I believe what was happening is the spark was not strong enough.

So when the throttle opened up, and the cylinder pressure became too high, the spark would not jump the gap.

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Have you simply tried draining the fuel and putting 5 gallon of 98 octane (or even Av-gas) in and see what happens?   Without blaming "ethanol", none of these engines were designed to run on 87 - seen some weird things caused by poor modern fuel.

Since I started using premium only, my little gas engines (pumps/pressure washer/etc) have been WAY easier to start and run better too.  

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