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14.5 Briggs Won't Idle Down


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06-12-05, 08:47 AM   #1  
Floridacruiser
14.5 Briggs Won't Idle Down

Purchased a used mower last week. Briggs 14.5 hp...Model #287707...Type 1272-E1...Code 98050623. Here's what it does. Put it on choke and it fires right up. Slip throttle back to max run and it runs and mows perfectly. No loading up or bogging down. Pull throttle down to idle or shut off and nothing happens. The engine speed doesn't change at all. I can shut it off by choking or turning the key off.

When it is RUNNING the governor arm is completely forward with alot of spring tension and the throttle plate is completely closed. If you push the governor arm to the rear, it opens the throttle plate and the engine speeds up. How can it run with the throttle plate completely closed???? The screws are tight in the throttle plate.

When it is NOT RUNNING and the throttle lever is put at max speed....the throttle plate is wide open and the governor rod is to the rear with heavy spring tension. If you slip the throttle lever down to off..the throttle plate closes fully and the governor rod is fully forward with very little spring tension.

WHAT BLOWS MY MIND.........HOW CAN IT RUN AND MOW SO GOOD WITH THE THROTTLE PLATE COMPLETELY CLOSED???????????????

What do you need to check the RPM on this 4-Cycle? Will a car tach work and where do I hook it? All comments and suggestions appreciated.

 
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06-12-05, 11:06 PM   #2  
The only accurate way I know of to tach this engine is with a vibratach or small engine tach.

Are you certain you're looking at the throttle plate and not the choke plate? Could the idle speed screw be set to high? I don't see how the engine can run that fast with the throttle palte completely closed. Unless there's a large vacuum leak between the carb and engine, it can't run that fast with the palte closed. It's not possible because the engine needs a fair amount of air to run at high rpms. If the choke is closed, and the carb was restricted, it could very well run fast with the choke plate completely closed. (it has holes to allow air to enter).


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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06-13-05, 03:43 AM   #3  
Floridacruiser
14.5 Brigs Won't Idle

Thank you for the reply. Yes....I'm looking at the throttle plate and it is completely closed and the choke with the holes is wide open when it is running. Is the idle screw the one that touches the throttle plate? If so, it is backed off enough for the throttle plate to be completely closed. How can I check for a vacuum leak without pulling the carb off and checking gaskets. On a car we squirted oil around the intake to check for leaks.

Would there be any damage to the engine if I run it like it is? It runs and mows great!!!!! Have a great day.

 
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06-13-05, 07:49 PM   #4  
Floridacruiser
Cheese...Please Read

Didn't know if you would check my post on 14.5 Briggs Won't Idle so I made a new post. If you read my old post on that subject, I answered all your questions.

I picked up a set of gaskets for the carb and manifold to engine. Wouldn't you know it....he gave me a regular gasket instead of an "O" Ring. 1998 models and newer use the "O" Ring. I'm going back to the shop tomorrow and get the right part.

MY QUESTION: When I took out the old "O" Ring it had some red sealer on it. Do I need to put some type of sealer on the new one? If so, what do I use?

I'll let you know how I make out after I get the new "O" Ring and install and fire it up.

Thanks for your help and God Bless............Keep Looking Up!!!!!

Ron
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06-13-05, 11:33 PM   #5  
Hello Ron,

I merged this new thread with the old one to maintain continuity of the discussion.

You don't have to worry about any kind of sealer. In fact, it seems like the new o ring comes with the red stuff on it already if I remember right.

BUT...if it is in fact the throttle that is closed and not the choke, then the gasket/o-ring isn't the problem. At the moment, I still can't think of any possible way the engine can run fast with the throttle all the way closed unless the throttle is distorted and not actually sealing the throat of the carb off (allowing air past the butterfly valve).


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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06-14-05, 01:23 PM   #6  
Floridacruiser
14.5 Briggs Won't Idle

Cheese: I talked to my local shop and they agree with you on the gasket not being the problem. They think the previous owner tinkered with the linkage and the governor for some reason and got it to run.

I put it back together and mowed the lawn. The engine sounds great and the mower does the job. I'm going to just keep mowing until something serious happens and it goes to the boneyard. It seems another problem is developing....The motor is running fine but the mower is slowing down going up hills. Top speed is not as fast when I first purchased the mower about 3 weeks ago. It has a Peerless Hydro...205-024-C. Serial #205-024C82888105.

Is there a way to check....add....or change the oil? Is their any adjustments on this transmission?

Thanks for your time...............Ron

 
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06-15-05, 12:08 AM   #7  
Check the belt tension on the tranny belt. Otherwise, there is a plug under the fan on top of the tranny (black rubber plug). This is the only place you can add fluid that I'm aware of.


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06-15-05, 12:12 PM   #8  
Floridacruiser
Hydro Not Pulling

Cheese: Thanks for all your time and input. I checked the belt and it was really stretched. I assume it was the original belt when the mower was purchased in 1999. I tightened it up to make sure that was the problem with the Hydro not pulling. That was the problem!!!! It is pulling fine now after I tightened it up. I'll pick up a new belt next time I'm by the shop.

Thanks again and have a great day!!!! Keep looking UP!!!!

Ron

 
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06-15-05, 11:49 PM   #9  
Great! Glad we could help.

I just had a thought on the engine speed issue....if the air-fuel mixture screw (if equipped) fell out and there was just a hole where it used to be, it could theoretically run fairly well at a good speed even with the throttle closed. Worth a check?


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06-23-05, 11:26 AM   #10  
Floridacruiser
14.5 Briggs Won't Idle Down

Hey Cheeze: While looking at the Briggs & Stratton page on the Illustrated parts list for Model Series 287700...Type Numbers...0026-1290 (mine is a Type 1272) I seen on Page #5 Item 996, it shows a Shield-Carburetor and Screw. Mine doesn't have that part!!!! It screws to the plastic housing that holds the air filter. Looked at my neighbors 14.5 briggs and it has this shield and screw. Apparently the previous owner took it off for some reason.

Could this missing part allow excessive air for it to run with the throttle plate completely closed? The throttle plate is closed and the governor arm is fully forward with heavy spring tension when the motor is running. It runs and mows great but won't idle or shut down. The air fuel mix screw is in place.

Thanks................Ron


Last edited by Floridacruiser; 06-23-05 at 11:28 AM. Reason: Adding additional info
 
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06-24-05, 07:48 AM   #11  
Azis
The shield does little more than get in the way actually. Your engine is NOT supposed to shut down when u move the throttle to the full "SLOW" position, it should idle. The only way it should shut down is with the key or if a saftey switch is activated.
When you are observing the throttle valve in the closed position while it is running, is this at full throttle? Observe the throttle valve with the engine at the same RPM you mow with. If indeed somehow u have a magical condition allowing air in other than through the throat, you should not run the engine!!! You could be running extremely lean or at least, improper fuel/air mixture which can be fatal.
When u move the throttle control from full to slow, does the throttle valve on the carb move with it running? Not running?
Possible I missed it but I do not see where u mention what type of "Mower/tractor" we are talking about....?????

 
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06-24-05, 10:05 AM   #12  
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14.5 Won't Idle Down

AZIS: It is on a 1999 Murray 42" cut with an automatic trasmission. I think all previous posts by me tell what is happening when the mower is running and not running.

The throttle valve is fully closed when it is at full throttle and running. If you try to idle down it does not change the position of the throttle plate or the RPM. If it is not running....the throttle valve works exactly as designed. The minute you start it............its slams shut with the governor rod fully forward with spring pressure. It runs and mows perfect. Pulled the plug after mowing and it looks normal.

Thanks for your interest!!!!

 
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06-24-05, 10:51 AM   #13  
Azis
Do you have a Nikki or Walbro Carb...?

 
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06-24-05, 11:29 AM   #14  
Azis
Posted By: Floridacruiser While looking at the Briggs & Stratton page on the Illustrated parts list for Model Series 287700...Type Numbers...0026-1290 (mine is a Type 1272) I seen on Page #5 Item 996, it shows a Shield-Carburetor and Screw. Mine doesn't have that part!!!! It screws to the plastic housing that holds the air filter. Looked at my neighbors 14.5 briggs and it has this shield and screw. Apparently the previous owner took it off for some reason.

Could this missing part allow excessive air for it to run with the throttle plate completely closed? The throttle plate is closed and the governor arm is fully forward with heavy spring tension when the motor is running. It runs and mows great but won't idle or shut down. The air fuel mix screw is in place.

Thanks................Ron
I was thinking of an external heat shield previously. This should not affect operation. It would be a good idea to have it as it most likely is used to support the air filter and housing as well as help seal any gaskets. The engine should run and the carb able to be adjusted with the entire filter assy removed. Slight adjustments may be needed for optimum with filter in place.

 
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06-24-05, 02:53 PM   #15  
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14.5 Briggs Won't Idle Down

AZIS: The carb is a Walbro. How can it run with the throttle plate completely closed at max throttle? Where's the air coming from? It runs and mows great!!!! BLOWS MY MIND!!!!!

 
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06-24-05, 03:26 PM   #16  
Azis
On the back side of the govenor bracket assy, there is a rack and pinion cam affair, there should be a short tuff lookin spring hooked to it in some manner with the other end hooked to a stubby "T" looking tab. Check for any signs that it has been tweaked or damaged. This tab is the speed adjustment. If it appears to have been adjusted (tweaked), then it may need to be set up and adjusted.

Also what happens if you eeeezzzzeee off on the throttle just a bit...? bit more...?
Also what kind of speed is it running...good and fast, loud...sound like a racer or a tractor? What are you mowing to put a load on it?

 
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06-24-05, 03:48 PM   #17  
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14.4 Briggs Won't Idle Down

Azis: The governor spring (heavy) is hooked up properly. I checked it with my neighbors Briggs 14.5 just like mine. If you eeezzzze off on the throttle lever on the dash.....nothing happens. The engine speed stays the same. If you reach down on the carb and manually open the throttle plate, the engine gains speed. If you eeezzze more it will run faster and faster. It would be the same as reaching in and pushing back on the governor rod....the engine speeds up. Release it and the throttle plate goes completely closed and the engine is running at normal max speed.

As far as sound.....it sounds great!!! It's not overrevving. It sounds just like my 12 hp Briggs. I'm mowing regular grass and it doesn't bog down or any change in the rpms. The spark plug looks normal!!!! It's not running lean or rich....it's just like it is suppossed to be.

Check my first post on this problem and it will explain everthing that is happening with this problem.

Thanks for your time!!!!!


Last edited by Floridacruiser; 06-24-05 at 03:51 PM. Reason: Adding more information
 
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06-24-05, 03:48 PM   #18  
Azis
Posted By: Floridacruiser Is the idle screw the one that touches the throttle plate? If so, it is backed off enough for the throttle plate to be completely closed.
If the cam on the end of the throttle shaft is in contact with this screw, the throttle valve is not completely closed. Back the screw out until the cam does NOT contact it and note...

 
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06-24-05, 03:56 PM   #19  
Floridacruiser
Azis: I have backed the idle screw completely out and the throttle plate is completely closed. This is where I'm running it. If you turn the screw in, and it contacts the cam and keep turning it in, the engine will speed up. Back the screw out completely until the throttle plate is completely closed and it runs just like I have explained in previous posts.

Thanks.........

 
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06-24-05, 04:04 PM   #20  
Azis
Posted By: Floridacruiser When it is NOT RUNNING and the throttle lever is put at max speed....the throttle plate is wide open and the governor rod is to the rear with heavy spring tension. If you slip the throttle lever down to off..the throttle plate closes fully and the governor rod is fully forward with very little spring tension.
While I do not know of any governor rpm adjustments with the engine not running...this does not sound correct. I think there should be enuff spring tension at all times to keep the throttle plate at or just near full open even with the throttle set at slow.
If your idle speed screw is set to a point that allows the engine to run at a operable speed, then your governor is not controling engine rpm.

 
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06-24-05, 09:44 PM   #21  
The thing is, the governor IS trying to slow the engine down. It is closing the throttle all the way. I believe the problem is a mis-fitted throttle plate that does not seal the throat of the carb well. Possibly damaged, bent, scratched, or whatever. It should fit so tightly with the idle screw backed out that you shouldn't be able to see light past it.


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07-08-13, 04:22 PM   #22  
fixed mine with similar problem - throttle butterfly screws

i know this is an old thread but it has helped me to fix my 17hp Briggs ohv with a walbro carb. i had the same symptoms, the engine would run full speed only with no adjustment and ran great but i was worried it wouldn't idle down. also the governor was pushed all the way forward it was very difficult to move it while running and when i did there was no change in speed. after reading the threads i finally with doubt removed the carb completely from the air filter assembly and the intake tube. all the gaskets looked great but after removing the carb itself i found that the butterfly valve for the throttle had fallen off and the throttle was wide open ( full on permanently ). i realized that the 2 small screws had fallen out and gone through the engine. ( i read now that this is a common problem ). i took the extra step and removed the head to check the piston and cylinder for damage but luckily all was ok. cleaned the carbon off the piston replaced with new head gasket and found 2 screws to replace the throttle butterfly. also i used some locktite carefully not to let any run down the throttle shaft and reassembled. it was an easy fix but drove me crazy to solve as this would never be something i would have checked as it ran so well. hope this helps others. good luck

 
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