I have a John Deere SST18 with a "18hp" B&S Vanguard. It has run fantastic from 2001 until recently. It runs fine, but blows black smoke for about 20 minutes. Then it falls on its face power wise. I take it in the garage, clean the plugs and it's fine again, but only for 20 minutes. A mechanic told me he thought the coils were probably getting worn out and I should replace them. I did and it ran great...for 20 minutes. Is it time for a new carburetor or is there something else I should check first? I am perfectly capable of throwing parts on a machine, but as far as rebuilding a carb, it's not gonna happen. I can put a new one on for less than I can pay someone to rebuild it
Briggs and Stratton Vanguard fouling plugs
- Thread starter nateisaac
- Start date
Sounds like it's not getting enough air and running rich. Just had this happen to one of my machines. I thought it was a plugged air filter which will cause the symptom you describe but in my case the choke wasn't opening up properly. So I suggest you clean/replace your air filter and check to make sure your choke isn't sticking shut at all before venturing deeper into your carb.
Two things to check on that engine. One make sure you have the correct heat range plug that is called for in that engine. The other is make sure you have the correct air filter. Briggs has two air filters that look the same but have different filtration rates. Makes sure you don't have the 394018 air filter in the engine that requires the 692519 air filter. It will cause rich running after about the first couple hours of operation after replacement in some cases.
The choke is not sticking shut. I did have the wrong air filter, but it's been in there all summer. Of course, nobody local stocks the correct filter. I have the correct filter ordered, it should be here Tuesday.
In the meantime, does anyone know the proper spark plugs for this unit? I have found specs for Champion RC12YC and RC14YC. When this whole thing started, I put E3.20's in it, they cross over to replace both the Champion plugs. I picked up a set of RC12YC's and put them in, but I can't seem to get home in time to take it out for a test.
In the meantime, does anyone know the proper spark plugs for this unit? I have found specs for Champion RC12YC and RC14YC. When this whole thing started, I put E3.20's in it, they cross over to replace both the Champion plugs. I picked up a set of RC12YC's and put them in, but I can't seem to get home in time to take it out for a test.
Some of the engines call for the RC12YC and others call for the RC14YC. I have personally seen RC12YC plugs cause what appears to be a rich run in the Vanguard enignes, and foul plugs, that instantly cleared up when switched to the RY14YC The RC14YC is a hotter plug than the RC12YC and when I was using Champion plugs always put the 14's in the Vanguards.
Thank you so much for the help.
I put the RC12YC plugs I bought in. It ran great for about 30 minutes this time, then fell on its face. The new plugs were fouled so I cleaned them and put them back in. It still ran like crap. I spent the next 6 hours mowing with my L130. Haven't touched the SST18 since. I couldn't find any RC14YC plugs local, so they are ordered and should be here Friday.
One thing I forgot to mention is that when the machine starts acting up, it won't steer. I read somewhere that the steering runs off vacuum. Could this whole thing be traced to a vacuum leak somewhere? I haven't checked for a leak yet, but will if anyone thinks it's worth while.
I put the RC12YC plugs I bought in. It ran great for about 30 minutes this time, then fell on its face. The new plugs were fouled so I cleaned them and put them back in. It still ran like crap. I spent the next 6 hours mowing with my L130. Haven't touched the SST18 since. I couldn't find any RC14YC plugs local, so they are ordered and should be here Friday.
One thing I forgot to mention is that when the machine starts acting up, it won't steer. I read somewhere that the steering runs off vacuum. Could this whole thing be traced to a vacuum leak somewhere? I haven't checked for a leak yet, but will if anyone thinks it's worth while.
It appears that it was the air filter. The new filter showed up yesterday. I mowed for about 45 minutes and had no problems. It got dark so I parked it. Don't feel like doing anything tonight. The hotter plugs will be here Friday. The real test will be Saturday.