24HP V-Twin B&S - Fault driving me CRAZY!

[Neo7]

Hi Gents,

Here's one to test your fault diagnostic skills on lol!

I have a B&S 24HP V-Twin (Model 445677 - Family 6BSXS.7242VF) Which is a horizontal V with dual barrel carburetor.
It start Ok and revs up Ok (a little hesitant) but when idles the anti-stall is always blipping the throttle every second or two. But worst of all it's randomly (every 5 to 20 seconds) missing and backfiring through the exhaust and inlet ports.
In desperation I've checked all of the following is Ok...

• Spark plugs are OK --- But both were sooty (black)
• Both ignition coils OK --- Swapped out with known working ones
• Stays running on either cylinder --- with one HT lead earthed down
• Ground Wire Harness (with two diodes) --- Disconnected but no effect
• Flywheel Shear Key --- Checked in good shape
• Carburetor Solenoid --- Removed and confirmed working
• Carburetor stripped down. Was dead clean inside but still blew out jet with airline.
• Cylinder Compressions are 160/165 PSI
• Inlet and Exhaust Pushrods checked --- all 4 dead straight
• Valve Clearance set ---- as per spec.

Any thoughts or additional things to check guys?

Thanks for your help.
Neo


npwGEEo.jpg

[Boobala]

Check that plastic intake manifold for hairline cracks or loose mounting ........

FORGOT : check your fuel system for water contamination .........

[Boudreaux In Eunice La.]

Yuo mentioned carb stripped down and blew jets out.... That 2 barrel carb is way different than a 1 barrel. They have more stuff to take out..... Did you take out a small gasket made with holes in it and a figure 8 looking gasket... The small gasket with the holes is hidden and is a pain to get to .... You mentioned plugs are black and sooty... That means you are running rich.....

[Neo7]

Thanks Guys.

Ok I'm going to have another stab at that manifold and that Carb today ... I know the figure 8 gasket. Is the "small gasket made with holes" item 150 in this parts diagram?

Carb 2018-09-26_063721.jpg

[Boudreaux In Eunice La.]

No 150 is the that gets plugged up and causes it to run rich...... 1124 is the double figure 8 gasket...... Also the jets in your carb are L and R and have to be put back in exactly as taken out cause that will cause hunting .......

Also the O-rings on the jets get worn out and causes issues too......... You cannot the O-rings from Briggs at all.....They come with new Jets....

If your O rings are worn the jets won't stay in place.................

Let us know Mon Ami ~!~!

[Boobala]

Brought out some vids might be of interest on your carb issue .............

http://outdoorpowerinfo.com/repairs/...-twin_carb.asp

http://outdoorpowerinfo.com/repairs/...twin_carb2.asp

https://www.youtube.com/watch?v=uPWul3T0fRE

https://ruclip.com/video/I_k1ystbSWs...c-engines.html

[Boudreaux In Eunice La.]

Boo Boo..... Taryl has a good one I saw this morning I'll have to find it again... I wasn't finished watching it..... We had to go somewhere real quick and the power went out in our area, soooo the PC was off when I got home...

[Boudreaux In Eunice La.]

I found it here is the link ~!~!

https://youtu.be/emsafzhGLC0

[Neo7]

Ok Engine is running sweet now .... "What was it" I hear you say!..... Well on the backfiring was plain and simple ... My Stupidity ... it was just the Spark Plugs!! ... Like how simple is that! .... Kept assuming they were Ok just because they were firing.
The Idle hunting.... Two of the 4 mounting bolts that go through the 4 corners of the carb were quite loose and the rectangular gasket must have been breathing. Also gave the carb another clean out as instructed.... Now she starts without choke ... Hasn't done that since I first fitted this engine.

Then when I put the cover back on it started running on one cylinder. Turned out one of the two diodes had failed. If you have a soldering iron they so easy to replace. B&S use IN4001 diodes which has to be the most common diode known to man lol! .... can be purchased from any Radio Shack type shop in the world.... I paid 76 cents for 4 diodes!

Anyway thanks for your help and ideas guys... Was so good to see my favorite mower running again


All the best.
Neo

[Boudreaux In Eunice La.]

Well good for you.......... Yep those diodes are cheap..... When I had my radio repair and sales shop at Tiger Truck stop on I-10 down here I used those numbered diodes a lot... I used to order them by the 500 bag from CEI in Ohio .02 cents a piece....

All they are is a reverse polarity diode.. Let current flow one way not the other way... I wish I had a dollar for every radio, car stereo and cb radio I changed those diodes in.....