5 hp Briggs Funpower will not idle!

[mutt606]

I got an old 5 hp Briggs engine. 136212-1026-E1

The engine will not idle. This model does not have an idle mixture screw. It has a brass screw called a high altitude jet. Its seated all the way in and has a hole in the tip. See http://bsintek.basco.com/BriggsDocumentDisplay/default.aspx?filename=mssAIN-K_ny7tH217FzoPu on page 14, it says "The idle mixture valve on this engine is not adjustable".

I have the idle speed screw on the throttle plate screwed all the way and it still does not hold the throttle open wide enough to allow it to run.

I have replaced ALL of the gaskets on the carb and tank. I have cleaned out all of the carb including removing the welch plugs and using a tip cleaner to clean all of the ports. Also used carb cleaner to ensure all ports are open and free flowing.

The both intake tubes are clean with no buildup over the screens.

New spark plug.

A bit of history of my pain and suffering. It got the engine and started it up, it ran with a ROUGH idle occasionally stalling out when the throttle was let up. Backfired ALOT when the throttle was let up also. It ran extremely fast and I finally figured out the governor spring was missing. I put a spring on and it still had the exact same symptoms. I read how to adjust the governor (pushed arm down to WOT, and turned governor shaft clockwise and tightened back down), and did that. Now it won't start on idle and when revved up it surges, although it doesn't seem to be going past 3600 (just a guess from the sound, and half throttle plate opening).

I included a few pictures for reference. I am not small engine person, but pretty handy around the house. This engine is causing me a lot of frustration!

 

[Russ2251]

Check valve lash and flywheel key just to eliminate them from source of problem.

 

[jeremybentham]

You mentioned gaskets, but, did you replace the carb diaphragm?

 

[shake this]

I agree with Jeremy, it's less then $5 and trust me, it might be worth every penny. I have the same style engine and had problems keeping it running. Everyone told me to replace the diaphragm. Well after replacing everything else and no change I decided to listen to what was being said. Hell it starts and idles better then my clone.

 

[mutt606]

Yes, I did replace the diaphragm first thing with the other gaskets.

I will pull the flywheel and check the key this evening.

 

[shake this]

You also have a nut on the throttle linkage facing the rear of the engine that you can adjust the idle with. It opens the throttle more as you screw it in, have you tried it? (looks like it might just replace the idle screw you have in your first picture.

You can see it in this picture under the linkage for the choke (something it seems you are missing in your pictures)

I also think you might be missing a screw on the carb just to the right and down a little from the (for lack of a better word) the white circle from your first picture. I'm not sure if this screw is needed but someone with more knowledge might chime in.

 

[mutt606]

I have all screws that secure the carb to the tank and the linkage from the choke and on/off switch assembly to the tank. I removed those so I could take the photos of the governor assembly.

 

[shake this]

What about the screw that is missing from the side of the carb?

I circled it in white for you.

You also have a spring that hooks up to the governor linkage on the backside of the gas tank, do you have it too?

 

[Bluethunder3320]

hmm... i had trouble with governor linkages on a 5hp b&s leafblower. its from '97. anyways, i got it working and it now has an EXTREMELY low idle. it sounds like it is going to die any second but it keeps going blurp... blurp... blurp...

ill have to read the RPM on it this spring.

does your carb make an intense sucking noise?

 

[Nick]

I have the same problems on what I think is the same model engine. I took the easy way out and found a position on the throttle valve that let it run and tide it open in that position (not a very good fix but hey it works). Have you ever had any trouble with it not sparking? Mine just recently stopped sparking and I can't figure out why.

 

[kendelrk]

try a new plug, if it sparks its the spark plug, if it dosent it could be the magneto