Need Help.....B&S Intek 21 HP 331800...loss of power and can't keep running

SJCharney · 05-15-2009, 07:49 AM

I am new to the forum and need some help.............

The other day my lawn tractor (Craftsman YTS 4500) loss power and stopped runing. No bang, no warning...............just slowed down and stopped. The enginer cranked but would not start. The oil was low in it, and I added some. BTW, the motor does turn over real easy. It is a B&S 21 HP 540 CC Intek (331800)

A day later, I did an oil change, changed the oil filter, fuel filter, and spark plug. I checked the gap for the plug (which should be .030), drained and the gas and put in fresh gas. I have gas flowing nicely to the carb, and I have spark at the plug.

Here is my issue, I can get the engine to start with diffculty and when it does start, it does not run at full power and stalls out after a few minutes. Then it only starts and runs for 30 seconds and stalls again. I did pull the intake from the block to see if there is gas flowing from the carb and there is. The linkage to the carb is working correctly and the idle adjustment screw and mixture screw is set accordingly.

I am not sure if there is not enough fuel getting into the engine or if the spark is too weak. My next step...which I am thinking about is removingand tearing down the carb to look for any dirt or debris inside.

Any thoughts or comments from the forum? I have built engines over the years as a hobby for cars and this issue has got me perplexed........any input would be great!!!

**octaneman** · 05-15-2009, 10:30 PM

Hello SJCharney

You covered all the bases so far, you should concentrate on the electrical system and focus on the coil and surrounding connections. Use a DVOM and do a continuity test on wires and take a few reading on the stator and any kill switches ( if applicable) if they are open or shorted. Check the spark plug wire to see if it's grounding out anywhere and check the terminals for solid connection. If you got a spark tester handy hook it up and see if the spark has good intensity and arc distance and work from there.

I am curious as to your findings.

Good Luck !

SJCharney · 05-16-2009, 09:25 AM

The electrical system is good and I have strong spark. My issue is in the fuel delivery. I am having issues with the carburetor. The carburetor is a Nikki and what I am told by two different repair shops that they are not the most reliable nor are they worth it to rebuild. I tore down the carburetor anyway and cleaned it out. Once I put the bowl back on the bottom of the carburetor, it dump a lot of fuel into the engine and leaked all over the place. Hence the point I was told. What that said and $45 for an overhaul kit, I just ordered a new carburetor for $85 and I am going to toss the old one. I should have the new carburetor on Wednesday and the tractor back together and running that night...more to come.

SJCharney · 05-20-2009, 08:24 PM

I finally got my tractor to run.

I back tracked my troubleshooting and after determining again that I had strong spark, a newly instaleld carburetor which had plenty of gas in the bowl, and correct timing......the engine still would not start.

I pulled the rocker cover to find that the stud for the intake valve rocker vibrated loose and the rocker loosen, slipping off the valve spring and push rod. I tighten the stud and re-adjusted the intake valve to .0005 of an inch. After that, if fired right up and is running great!!

**octaneman** · 05-21-2009, 06:10 AM

Good job !

05-15-2009, 07:49 AM	#1 (permalink)
SJCharney Registered User Join Date: May 2009 Posts: 6 OS: Vista	Need Help.....B&S Intek 21 HP 331800...loss of power and can't keep running I am new to the forum and need some help............. The other day my lawn tractor (Craftsman YTS 4500) loss power and stopped runing. No bang, no warning...............just slowed down and stopped. The enginer cranked but would not start. The oil was low in it, and I added some. BTW, the motor does turn over real easy. It is a B&S 21 HP 540 CC Intek (331800) A day later, I did an oil change, changed the oil filter, fuel filter, and spark plug. I checked the gap for the plug (which should be .030), drained and the gas and put in fresh gas. I have gas flowing nicely to the carb, and I have spark at the plug. Here is my issue, I can get the engine to start with diffculty and when it does start, it does not run at full power and stalls out after a few minutes. Then it only starts and runs for 30 seconds and stalls again. I did pull the intake from the block to see if there is gas flowing from the carb and there is. The linkage to the carb is working correctly and the idle adjustment screw and mixture screw is set accordingly. I am not sure if there is not enough fuel getting into the engine or if the spark is too weak. My next step...which I am thinking about is removingand tearing down the carb to look for any dirt or debris inside. Any thoughts or comments from the forum? I have built engines over the years as a hobby for cars and this issue has got me perplexed........any input would be great!!! __________________ Thanks, Steve

05-15-2009, 10:30 PM	#2 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 551 OS: WINXP	Re: Need Help.....B&S Intek 21 HP 331800...loss of power and can't keep running Hello SJCharney You covered all the bases so far, you should concentrate on the electrical system and focus on the coil and surrounding connections. Use a DVOM and do a continuity test on wires and take a few reading on the stator and any kill switches ( if applicable) if they are open or shorted. Check the spark plug wire to see if it's grounding out anywhere and check the terminals for solid connection. If you got a spark tester handy hook it up and see if the spark has good intensity and arc distance and work from there. I am curious as to your findings. Good Luck ! Last edited by octaneman; 05-15-2009 at 10:34 PM.

05-16-2009, 09:25 AM	#3 (permalink)
SJCharney Registered User Join Date: May 2009 Posts: 6 OS: Vista	Re: Need Help.....B&S Intek 21 HP 331800...loss of power and can't keep running The electrical system is good and I have strong spark. My issue is in the fuel delivery. I am having issues with the carburetor. The carburetor is a Nikki and what I am told by two different repair shops that they are not the most reliable nor are they worth it to rebuild. I tore down the carburetor anyway and cleaned it out. Once I put the bowl back on the bottom of the carburetor, it dump a lot of fuel into the engine and leaked all over the place. Hence the point I was told. What that said and $45 for an overhaul kit, I just ordered a new carburetor for $85 and I am going to toss the old one. I should have the new carburetor on Wednesday and the tractor back together and running that night...more to come. __________________ Thanks, Steve

05-20-2009, 08:24 PM	#4 (permalink)
SJCharney Registered User Join Date: May 2009 Posts: 6 OS: Vista	Re: Need Help.....B&S Intek 21 HP 331800...loss of power and can't keep running I finally got my tractor to run. I back tracked my troubleshooting and after determining again that I had strong spark, a newly instaleld carburetor which had plenty of gas in the bowl, and correct timing......the engine still would not start. I pulled the rocker cover to find that the stud for the intake valve rocker vibrated loose and the rocker loosen, slipping off the valve spring and push rod. I tighten the stud and re-adjusted the intake valve to .0005 of an inch. After that, if fired right up and is running great!! __________________ Thanks, Steve

05-21-2009, 06:10 AM	#5 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 551 OS: WINXP	Re: Need Help.....B&S Intek 21 HP 331800...loss of power and can't keep running Good job !