LA 105 - fuel in airbox

[jchester404]

Hi

I was given a LA 105 from my neighbor when he moved. He had it outside uncovered for 2 years. I did all the minor tune-up work last summer and it ran just fine throughout the whole summer. Started right up and idled great. This year I did the same thing (oil change, spark plug, fuel filter, fresh gas) and it about 30 seconds after trying to start it I could smell and see gas in the air box. I let it sit for 30min and was able to start it up, however it idled poorly. I figured it was a carb issue so I took the carb off and cleaned the bowl, float, and inside the carb. I couldn't locate the jets so I didn't do too much aside from spraying carb clean on everything. There was some minor debris in the bowl.

All said and done, once I put everything back together it started right up and idled perfectly. Shut if off to put all my tools away and wouldn't start up again and gas was again present in the air box.

Two things: 1. I failed to clean the float needle as I was too cautious messing with the carb. If advised I'll go back and do so. 2. What I found interesting when I first took the bowl apart was there was quite of bit of gas that poured out from the bowl when I removed the solenoid. Is that normal? Does this indicate a dirty float needle and/or the float becoming stuck?

Sorry for the long-winded post and thank you for any help!

 

[Kish318420]

Possible 2 problems, the fuel shutoff solenoid doesn't appear to shutoff the fuel when turned off. The solenoid usually sets between the fuel bowl and the channel in the carb to the jets. Next the float and inlet valve need to be checked, it should be closing when bowl is full, and opening up depending on the draw of the engine, a little when idling, and full open (the calibration when adjusting the float usually sets this). You've got some work ahead to clean and check the float/inlet valve calibration. Get the TM and the engine service manual, it will have the proceedures.

 

[jchester404]

Thanks for replying.

Would a faulty solenoid explain the fuel in the bowl after shut off or is having gas in the bowl after shut off normal? I'll pull it apart again tomorrow and give the float a nice cleaning. Is there a way to test the solenoid?

Also what is 'TM'? I'll have to find a service manual on the internet as my neighbor didn't have one.

 

[jgayman]

It's normal. I've removed the shutoff solenoid from several carbs and fuel always pours out. The shutoff solenoid just prevents gas from being sucked through the carb and into the compression chamber during the few engine revolutions during shutdown to prevent backfires due to unburnt fuel getting in the muffler. The bowl is always going to be full of fuel and that is what leaks out when you remove the solenoid.

 

[jchester404]

Got it. I found the manual for the LA 105 online, but it's not showing the inlet valve calibration procedure. I'll search for the Briggs and Stratton manual possibly? Unfortunately, Youtube and the like are not showing any results for this procedure as well.

 

[Richard001]

Got it. I found the manual for the LA 105 online, but it's not showing the inlet valve calibration procedure. I'll search for the Briggs and Stratton manual possibly? Unfortunately, Youtube and the like are not showing any results for this procedure as well.

OK you got me on that one. What is a "inlet valve calibration" I've been working on small engines for the last 20 years. Haven't heard about that one.

Richard

 

[s219]

Any chance you had overfilled the gas tank?

 

[Kish318420]

You have a B&S 31 vertical shaft engine (19 HP), get the complete model number from the engine and go to the B&S web site go to manuals and put in the engine model number. Now since this is spec'd by deere you will have to approximate as close to the full number by not quite the complete number. This is because it would cost deere a manual sell of the CTM (Component Technical Manual) $$$. But goes how to check the fuel solenoid shutoff valve, servicing either the nikki or walboro carb on it

 

[tomplum]

The solenoid is not the cause of the carb overflowing. Block the fuel pipe all you want and as the bowl is vented- the fuel travels up into the venturi as it overflows. Just put on a new OEM carb and be done with it.

 

[jchester404]

OK you got me on that one. What is a "inlet valve calibration" I've been working on small engines for the last 20 years. Haven't heard about that one.

Richard

The second poster in this thread had suggested it. I found that I have a Nikki carburetor and I read that there isn't much calibration that needs to be done with the Nikki, what kind of calibration I would do on a carb I wouldn't know yet. I suppose inlet valve calibration isn't a thing?

As of now I ordered a new needle and float bowl gasket. I should be able to get that in there today or tomorrow. I'll report back here with the update in case anyone in the future has a similar problem. I appreciate everyone's help.

 

[Kish318420]

That's because of the nikki carb on the Onan has a few pages on calibrating (measurements) the float/inlet valve any time you replace the inlet valve (rubber tip develops a ridge overtime) or the valve seat (which screws into the base). It is set to get the right travel and pressure (closing the inlet to the bowl). But carbs do go through engineering changes that are mandated by the government or the bean counters over the years. So things do change, including the style of carb for vertical shaft versus horizontal shaft engines.

In regards to manuals:

Understand that Deere, with the engine deals, require the manufacture not to offer the exact manual on-line. This is so the owner will have to buy it from Deere if they want to have the exact manual for the engine service/repair. Same thing with the parts catalog (PC)

That is why I stated getting the TM and the CTM which will have that info.

 

[jgayman]

The second poster in this thread had suggested it. I found that I have a Nikki carburetor and I read that there isn't much calibration that needs to be done with the Nikki, what kind of calibration I would do on a carb I wouldn't know yet. I suppose inlet valve calibration isn't a thing?

One problem is that the float hinge (the part that holds the seat) is made of plastic. So unlike the old days where you simply bent a little metal lip to set the float height, you now have no way to easily adjust it. I have seen folks who heat up the part with a heat gun and then bend the plastic but you have to be very careful. If you happen to have a Chinesium carb rebuild kit the parts can be hit and miss and you can end up worse than when you started.

 

[jchester404]

SOLVED.

I changed the float bowl gasket, valve needle, and main jet and it started right up and idled fine. No more leakage into the airbox. The gasket, and especially the o-ring, inside the float bowl had basically disintegrated. The main jet had corrosion and the o-ring to that was almost non-existent.

If anyone is having a similar issue the part numbers are:

B & S 698781 - Gasket/O-ring
B & S 696136 - Valve Needle
B & S 699733 - Main Jet

I ordered the gasket and needle off of Amazon and received genuine parts from Briggs and Stratton. However, I decided to order a Nikki "Carburetor Overhaul" that also included the listed gasket and needle as well since it was only $11.00 and I wanted to change the gasket between the carb and engine block anyway. I recommend ordering the float gasket and needle separate as I did because the float gasket from the "carburetor overhaul" was poor. I did use the main jet and it's working fine.

Hope this helps anyone in the future and I appreciated everyone's help.

 

[beenthere]

Thanks for the update on the fix. Good to know you are up and running again.