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B100 Only Starts Full Choke and only runs Full Throttle? Help!!

jduck1

Contributing Member
I picked up a Honda B100-1203497. I have it in a barrel with new gas. At first I can only get it to start if I use starting fluid. The motor has to be full choked and once started has to be full choked and high idle. Even at that it will only run for 20-30 seconds and then dies out. If I try to slowly push the choke in it will die or if I reduce the throttle it will die. I did pull the carb and shot carb cleaner all inside. Since then it does start a little easier but still does the same thing and will not idle. Any help would be appreciated on what to try first in getting this motor ready for this summer.
Thanks in advance,
Jeff
 
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These carburetors are notorious for plugging up.----Very small passage ways plug up easily when fuel of today is left sitting in the carburetor.-----Small passages means small.--It has been documented on websites that folks need to pull the carburetor off 3 or 4 times to get them properly cleaned.
 
Thanks. I was hoping the first response was to tryingcleaning the carb again or something that was definitely not a big issue. Iwill give it a try again and be a little more diligent in getting into all thenooks and crannies.
 
Partial success. My carb does not have the #7 screw and according to the description #7 is only on models produce after mine. I pulled the carb and ran an entire can of cleaner through it along with blowing it out with air. Pulled the float and jets and ran cleaner through everything I could stick the nozzle into. I removed the main jet, float, and idle screw. Guessed on where to return the idle screw and put the carb back on. Couple pulls with no starting fluid and fired right up with choke. Pushed the choke in and ran a little high so I turned down the throttle adjusting screw and played with the idle set until it idled as low as it could without stalling. Noticed not much wate rpeeing out so I took the air and blew it out and got steady water flow. Fired up the motor again and ran for about 10 min at idle in the barrel. Even shifted into gear and ran idle up and down a couple times and all was well. Then it just died. I was able to get it started back up but would only idle at a higher speed again. I was still able to get it started without any starting fluid.Played with the idle adjustment and couldn’t get it to idle like previously. I did notice that while it was running I had some water misting out of 1 of the 2 exhaust holes that are on the upper shaft above main exhaust port that is out of the water and the water flow reduced pressure a bit once it ran for 5-6 minutes.

Do I just need to keep pulling and cleaning the carb?

Should I replace the fuel lines and add a inline fuelfilter before the carb?

At what point do I look into a rebuild or purchasing anew carb?

How do you set the idle and throttle screw as a starting point and then the procedure of getting it set?

Thanks again for getting me running J
 
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On outboard motors I see the term " rebuilt " the carburetor all the time.----I just prefer to say that they should be cleaned and kept clean by running the fuel out when boat is taken out of the water.
 
Today I again started the motor up and it ran good for about 1 min then started to die. I squeezed the fuel bulb and it kept running. About every minute it would start to die and then a couple pumps and it kept running. Fuel pump, stuck float,????
 
Sounds like you have an air leak in your fuel delivery line. Or, the gas tank vent valve is partially plugged and when the engine has been running for a while, it creates a partial vacuum in the tank and starves the engine for fuel. If the line and bulb is old, I would simply replace both and clean the gas tank vent. Also, empty your tank and look in the bottom carefully to see if there is corrosion or delamination taking place. This will allow small little pieces to get up into the line and "gum up" the works.

STOP USING ETHER!! If that is what you are calling "starting fluid" It will eventually damage the engine no matter how careful you are. It is an EXPLOSIVE compound and the engine was NEVER intended to burn that as fuel. Used enough times, the engine will eventually seem to get "dependent" on it to start. Mechanics call engines like this "ether babies".

Good luck.
 
The tank is the new plastic honda tank with a brand new bulb. It runs my Honda 8hp with no issues last week all day of use. I will double check everything on it tonight. I only used starting fluid before I cleaned the carb and have not had to use it since. Thanks for the help and will keep updating until I get this thing licked.

On the fuel pump I noticed you can purchase just the diaphram or the entire pump. Either way better than the other?

Thanks again,
Jeff
 
I would think the diaphragm alone would solve any pump issue you might have as long as the housing isn't cracked but you might want to wait for Mike to weigh in on that since he's the guy with the most experience here.
 
I have never rebuilt one. I have only had a couple that failed and I just grabbed a used one off of a blown up engine, since the customer was in a hurry.

Before ordering any gaskets, take it apart and see if you see anything apparent. Then just order the parts you need. It will not be any worse than it is now.

Make sure you take pictures as you take it apart and do it on a surface the will catch any springs, etc that jump out on you.

If the plunger is damaged or if a hard part is sufficiently damaged, t might be best just order a new pump.

Mike
 
It looks like the fuel pump on my 8hp is the same one. Going to swap it out and see if thats the issue. Another experiment tonight :)
 
Put the fuel pump from my 8hp onto the 10hp. Problem solved. Ran with no issues and was able to idle down to a purr and never died.Took the bad pump and tore it apart. Thing is missing the small springs where the fuel inlet is also missing. Looks like the guy I got it from messed with it and lost some springs. Looks like the diaphragm is solid. Looks like the small spring is only available in a $26 kit.
Thanks for all your help!!!!

Jeff
 
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