Intermittent power loss

[BuckeyeMike]

I have a 20 hp Briggs and Straton VanGuard motor on a Simplicity 50" Zero Turn radius mower. It has intermittent severe power loss and will blow out black smoke.
I changed the fuel filter, plugs, air filter.Iit ran okay for a short time but it's now back to doing the same thing but more consistent. Does anyone have any idea what could be causing this issue?

 

[mechanic mark]

http://www.briggsandstratton.com/eu/en/support/faqs/adjusting-the-carburetor see if this helps, always start with basic possibilities.

 

[ILENGINE]

What spark plug number and air filter did you install by part number also get us the model number of the engine because there are several parts that look alike but are not interchangeable.

 

[BuckeyeMike]

What spark plug number and air filter did you install by part number also get us the model number of the engine because there are several parts that look alike but are not interchangeable.

I got them from the place where I purchased the mower which is a place that specializes in sales and service of mowers...It did run fine for about 3 hours. :/

 

[ILENGINE]

I got them from the place where I purchased the mower which is a place that specializes in sales and service of mowers...It did run fine for about 3 hours. :/

the reason I asked for that information because it isn't the first time I have seen dealers give the customer the wrong air filter for their engine or spark plugs. On the vanguard there a few models that take a different air filter than the rest, and both have the same dimensions but different filter media, Also the Vanguard is picky as to heat range of spark plugs.

One or both being wrong will cause the symptoms that you are having and will result 3-5 hours after the wrong part is installed.

 

[BuckeyeMike]

Thanks for your input...I will check those items out.

 

[bertsmobile1]

:welcome:

Get inlline spark tester and fit it some where so you can see it while mowing.
You might need to pinch in the contacts a bit so it stays on and hold it up with some cable ties.
Go mow and the instant the engine starts to loose power quickly check the lamp.
If it is flashing faster than the engine is running then you have a fuel problem but if it is flashng intermittedly then you have an ignition problem.
I either case you have halved the work you will need to do.

The other thing is to make sure the oil is full.
Some vanguards have a low oil cut out so wen you are on a bit of a slope and your oil level is on the low side it can drop below the cut out level

 

[BuckeyeMike]

I talked to the dealer and he said the same thing you said...there are 2 types of air filters that will fit but only one will work. I did have the right one. So, I went home and started checking carburetor linkage and I noticed the butterfly choke was only open about 1/4 of the way. I moved the choke lever back and forth several times and it would open all of the way sometimes and only open 1/4 of the way other times which explains why it would work fine sometimes. So I fixed the choke cable and it is now running like a champ. I got the yard mowed before I had to buy goats to keep the grass down.

This looks like a great forum with some very knowledgeable people...thanks for the help.