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Discussion Starter · #1 ·
I have been reading forums for three days and gave gleaned some good info on tractors from you guys yet I'm still at a standstill on this. I have a 13.5 briggs ohv single cylinder nikki carb. Engine model 21B807 type 0326B1 code 090226ZA
Mower was used about ten times and was stored in tool shed for at least eight years, not sure what happened to take it out of use. Tried to start with new fuel, battery and oil change. All the fuel was in the crankcase. When I sprayed it it tried to run and was blowing back through the carb enough to have flames from my carb cleaner.
Took the nikki carb apart and found no fuel and a stuck fuel cutoff solenoid. Replaced the solenoid and cleaned The carb out with brushes, tip cleaner and air hose. It started but only when you choke it even when hot, surges at all speeds and still the popping out of the carb. Have checked for vacuum leak, valve adjustment replaced spark plug and carb. The valves appear to be moving the same distance every time. Oh and I also checked and adjusted the governor. Have driven it under full load with no change.
Im at the end of my limited knowledge and experience. Please help.
 

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To load up the crank case with the fuel...the needle valve is probably stuck open or debris holding it open just enough to cause your problem....was the float ok when you had it apart?...no holes in it allowing it to fill with fuel?
 

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Discussion Starter · #5 ·
The carb is not leaking any longer. I also tried a new carb and a used one I put together from parts I had. That one was off a larger engine and
 

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Discussion Starter · #6 ·
If I Choke the engine, about half choke, it will surge much less and the popping goes almost away. If I suppress the governors movement it runs smoothly
 

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Discussion Starter · #9 ·
To what purpose. I disassembled it cleaned and air tested the valve to make sure it was opening and closing. There is no adjustment to be made to the float assembly. If I hold air to the inlet and raise the float it stops The flow. The three carbs one of which is new should have made a difference. My next thought is fuel delivery to the carb. I have replaced the filter with a new one and there is a shut off valve also, it must have been left on when parked. What about a low presure fuel pump inline ??? Maybe a secondary fuel source. Right now I'm grasping at straws. There has to be something I'm missing

Maybe I was not clear. It's not flooding. It acts like it's running lean from my automotive experience but that is not the same as mower knowledge.
 

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Discussion Starter · #10 ·
I ran a separate fuel source with no restrictions. No change. I'm going to check th he keyway next. Wish me luck.
 

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If you did not remove and clean the emulsion tube, I bet it is riddled with clogs. Most hide behind/above the main jet.
OTOH, given you have gone through 3 carbs, I would be looking at the outlet from the tank.
You can follow the fuel line back from the carb inlet to see if there is a pump inline.
One possibility is that the fuel line has degraded internally. It can look perfect on the outer layer, but be an absolute mess internally. To know, you can replace the lines, or feed from a separate fuel source, with a known good fuel line, and clean tank, filter and outlet.
tom
 

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Discussion Starter · #12 ·
Did that Is in my post put out while you were typing. Lol. No change. I have had a carb with a drilled out main jet that will run a 17 hp rich. No change.
I have a tip cleaner and a carb brush set to do battle with these nikki carbs. Now I'm looking for a replacement carb of another brand. do you know if any exist???
 

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Here is a link that shows Nikki carbs.
Look at the one for Briggs engine and Kohler engines. (or both if you do not see your carb)
Small Engine, Lawn Mower, Snowthrower Troubleshooting, Repairs and Safety

I've used the less than $15 china clone Nikki subs with good results.
It's common for the o-rings around the jet's to leak and also for the emulsion tube to get restricted.
Some of those nikki carbs have o-rings on the emulsion tube.
The o-rings have to have a secure fitt for good sealing.
It's also common for needing a fuel shutoff on the gravity fed carbs.
You need to replace the fuel lines and add a Briggs red fuel filter between the shutoff and the carb.
(red is for gravity fed systems. Do not try to use a clone red filter. they will eventually leak. Use a Briggs red one.
 

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Discussion Starter · #14 ·
I broke out the carb dip and soaked the carb I'm rebuilding for half hour. Washed thoroughly and blew it clear with the air hose. Will try it tomorrow. also ordered a non nikki replacement 791886. Fits a 13.5 Briggs but is on a different mower. We will see. I plan to try the dipped carb first and finish up with the non nikki one. Will let you know how it turns out.
Btw I spent long time brushing those tubes with soap and water. They are the craziest carb I've seen on a briggs
 

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I broke out the carb dip and soaked the carb I'm rebuilding for half hour. Washed thoroughly and blew it clear with the air hose. Will try it tomorrow. also ordered a non nikki replacement 791886. Fits a 13.5 Briggs but is on a different mower. We will see. I plan to try the dipped carb first and finish up with the non nikki one. Will let you know how it turns out.
Btw I spent long time brushing those tubes with soap and water. They are the craziest carb I've seen on a briggs
You are correct about the fineky Nikki's. They also act up on the Kohlers.
You have to keep a heads up on those Nikki's about the o-rings and the upper sealing gasket type sealing. Any little bit of non-secure rubber sealing places will upset them and cause your issues.
(and some of them have some itty bitty o-rings that are not in the kits (but available at outrageous prices by themselves) and I've had to sometimes take three or 4 Nikki carbs and make one because the o-rings I needed were not in the kit and do not be surprised if a re-build kit you have is just not quite correct for the Nikki you have.
You have to also really keep a heads up on some of them Nikki's, the jets will just fall out on the floor when you are inspecting with the bowl off and you won't notice until you get the jaw dropper look, where did it go.
Also make sure you do not have any intake air leak.

They will last longer if you run non-ethanol gas.
All of the China Clone carb bowls, will usually generate lots of rust inside the bowl in a years time even using non-ethanol gas.

Sometimes if you have a Nikki carb that has been running great and you notice it starts slightly surging slightly you can let the engine cool and then loosen the anti-back fire solenoid and drain the bowl and it will run ok.
When just little bit of water gets in the bottom of the bowl most all of the small engines carbs starts getting sickly. If you cannot drain the carb's bowl just pull the rubber fuel line off the carb, block off the incoming fuel supply and fill a 1 ft section of a elevated gravity fed rubber fuel line with alcohol or carb cleaner (using a small funnel) and run the engine until it quits and refill. May have to do this more than once.
You will be surprised at how just draining the carb's bowl when one first starts getting sick will cure the carb instead of completely pulling the carb and completely removing the bowl.
 

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I swapped a 14.0 Briggs OHV onto a ariens rider that had a 19hp intek on it. The 14hp was running lean so I swapped the carb from the 19hp on and it ran perfectly. For whatever reason it wanted a lot of fuel. So I wouldn't rule out a lean condition yet. How does the plug look? That will tell you definitively if what your mixture is.
 

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I've got a Briggs 16.5 I/C (I Can't) doing this exact thing. I've chased the problem till I'm blue in the face. Brand new carb, same result. Do these things have a compression release? I'm wondering if it's stuck, or maybe the cam is damaged?
 

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I've got a Briggs 16.5 I/C (I Can't) doing this exact thing. I've chased the problem till I'm blue in the face. Brand new carb, same result. Do these things have a compression release? I'm wondering if it's stuck, or maybe the cam is damaged?
Check the flywheel key, magneto air gap and spark plug gap. Install a new spark plug.
Do a leak down test.
 

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I just fixed this exact issue on my Husqvarna rider with the 20 hp briggs. Would run beeter on choke than not. The 20 hp does have a fuel pump.

What I did:

Ran 3 tanks of Seafoam treated gas through it.
Changed the platsic manifold out to a meatal one.
Changed the fuel pump, seems like the one on a lot of briggs is a real common, pretty much generic, pump. Got mine at Advance auto.
Checked the valve rocker gaps. I did find one exhaust valve at .014, way out of spec, supposed to be .004 - .006.
I removed the top plate of the carb, and the solenoid, flushed it liberally with carb/choke cleaner. My soleniod comes off of the bottom/side, not straight off the bottom, but I was still able to shoot some cleaner into the tube. (After this step it started running normal again)
New plugs.
It ran like new after this, I ran anoter tank treated with seafoam.

This is a 20hp V win Intek.

Someone told me just yeaterday that the higher percentage of ethanol on gas can cause problems in small engines.

IMG_2152.JPG IMG_2165.JPG IMG_2159.JPG IMG_2161.JPG Solenoid Valve.jpg
 
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