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Silver Series LB wont stay running.
#1
T
tlwright21
T
tlwright21
I have a LB model 10304 series 6914509 that I bought new in 1996. It replaced a LB that was purchased in 1973- so you can say I bleed LB green.
Last summer it started giving me trouble starting up. would press primer 2-3x, engine would fire then die. If I continued to press primer over and over again it would eventually come up to speed and run. would take a long time though but once it was warm it would mow with full power. full disclosure-last summer I ended up hitting a bolt on the bottom of a fire hydrant that bent the blade and stopped the engine. Bought a new blade and resumed using but this was when the problem with engine running began. there was no unusual vibration afterwards like a bent shaft, but it took forever for it to get up to speed and starting running on its on without constant priming.
Last week I put in a new plug and cleaned air filter and it started right up and I mowed -no problem. thought I cured it.
This week back to same old problem. Now I think I may have low engine vacuum and it isn't pulling fuel through the reed valve. wonder if I may have damaged shaft seal but not sure and don't know how to ck. Engine will not staying running now unless you prime as fast as you can and then maybe it will run.
So this is what i have done in the last 24 hours. problem did not go away. still wont' run
1. cleaned air filter,
2 cleaned muffler
3 disassembled carburetor, cleaned jet, holder , needle, seat, float with carb cleaner. blew through all openings all clear
4. drained gas tank, checked fuel line,all clear no restrictions
5 took apart primer bulb, checked line, no leaks.
6. checked intake gaskets and float bowl gasket and they are intact
7. carb is getting fuel into bowl. Spilled out when i took apart
8 took off fuel cap and tried to start, made no difference
other than a possible problem with vacuum I'm wondering about the air vane settings or its spring tension. can someone tell me where the position of the air vane is when at full throttle? Im talking about is it in the center of the slot or to the right or left when looking at it from the rear of the mower? when it was running, right before it died, I got down and observed the air vane was all the way to the left. So i think that means the throttle plate is completely closed (full choke???). Is that correct, if not then what do i need to do? Not sure how the air -vane modulates the throttle, does it change position when the engine gets warmer or mowing in heavy grass, like a governor.
HELP Don't want to give up on the mower but its getting close
Last summer it started giving me trouble starting up. would press primer 2-3x, engine would fire then die. If I continued to press primer over and over again it would eventually come up to speed and run. would take a long time though but once it was warm it would mow with full power. full disclosure-last summer I ended up hitting a bolt on the bottom of a fire hydrant that bent the blade and stopped the engine. Bought a new blade and resumed using but this was when the problem with engine running began. there was no unusual vibration afterwards like a bent shaft, but it took forever for it to get up to speed and starting running on its on without constant priming.
Last week I put in a new plug and cleaned air filter and it started right up and I mowed -no problem. thought I cured it.
This week back to same old problem. Now I think I may have low engine vacuum and it isn't pulling fuel through the reed valve. wonder if I may have damaged shaft seal but not sure and don't know how to ck. Engine will not staying running now unless you prime as fast as you can and then maybe it will run.
So this is what i have done in the last 24 hours. problem did not go away. still wont' run
1. cleaned air filter,
2 cleaned muffler
3 disassembled carburetor, cleaned jet, holder , needle, seat, float with carb cleaner. blew through all openings all clear
4. drained gas tank, checked fuel line,all clear no restrictions
5 took apart primer bulb, checked line, no leaks.
6. checked intake gaskets and float bowl gasket and they are intact
7. carb is getting fuel into bowl. Spilled out when i took apart
8 took off fuel cap and tried to start, made no difference
other than a possible problem with vacuum I'm wondering about the air vane settings or its spring tension. can someone tell me where the position of the air vane is when at full throttle? Im talking about is it in the center of the slot or to the right or left when looking at it from the rear of the mower? when it was running, right before it died, I got down and observed the air vane was all the way to the left. So i think that means the throttle plate is completely closed (full choke???). Is that correct, if not then what do i need to do? Not sure how the air -vane modulates the throttle, does it change position when the engine gets warmer or mowing in heavy grass, like a governor.
HELP Don't want to give up on the mower but its getting close
#2
J
jp1961
J
jp1961
Hmmm. Stopping the engine dead after striking an immovable object is not good. Is it possible you cracked the crankcase?
Regards
Jeff
Regards
Jeff
#3
T
tlwright21
I guess anything is possible but the engine runs and i was mowing with it after I bent the blade. it started and ran last week with no problem after i changed plug.
the problem that i see now is the air vane is in the complete closed position when the engine fired up yesterday. why I dont' know. nothing was adjusted or changed to cause this. With this being the case the throttle plate is completely closed and that is why there is no fuel getting into the engine. I need for someone that knows LB to tell me where the air vane should be in the slot when it is running.
also quite a while ago the throttle lever on the handle quit doing anything. it was attached to the lever on the carb but when moved didn't do anything to the engine speed, which is all connected to the air vane.
T
tlwright21
Hmmm. Stopping the engine dead after striking an immovable object is not good. Is it possible you cracked the crankcase?
Regards
Jeff
I guess anything is possible but the engine runs and i was mowing with it after I bent the blade. it started and ran last week with no problem after i changed plug.
the problem that i see now is the air vane is in the complete closed position when the engine fired up yesterday. why I dont' know. nothing was adjusted or changed to cause this. With this being the case the throttle plate is completely closed and that is why there is no fuel getting into the engine. I need for someone that knows LB to tell me where the air vane should be in the slot when it is running.
also quite a while ago the throttle lever on the handle quit doing anything. it was attached to the lever on the carb but when moved didn't do anything to the engine speed, which is all connected to the air vane.
#4
unclelee
unclelee
You should be able to see moisture around the crank seal if it is the cause of your problems. It is very possible when you hit the fire hydrant bolt that it damaged the seal.
#5
T
tlwright21
When I took the muffler off the other day I was inspecting the crank shaft seal area and there wasn't anything unusual there. No gas/oil moisture or anything that might look like blow by . I really believe that i have a issue with the air-vane not operating correctly.
I'm going to put back together and hopefully get it to run long enough to maybe manually hold open the air vane from the closed position. maybe install a new spring or fiddle around with the governor collar. I have never touched either in the 21 years I have owned it so I don't know why it would be off now. If that isn't it then i'm done. I'll have a LB for sale for parts.
T
tlwright21
You should be able to see moisture around the crank seal if it is the cause of your problems. It is very possible when you hit the fire hydrant bolt that it damaged the seal.
When I took the muffler off the other day I was inspecting the crank shaft seal area and there wasn't anything unusual there. No gas/oil moisture or anything that might look like blow by . I really believe that i have a issue with the air-vane not operating correctly.
I'm going to put back together and hopefully get it to run long enough to maybe manually hold open the air vane from the closed position. maybe install a new spring or fiddle around with the governor collar. I have never touched either in the 21 years I have owned it so I don't know why it would be off now. If that isn't it then i'm done. I'll have a LB for sale for parts.
#6
L
lewb
L
lewb
Crank out of phase? you will still get good compression but if the piston is not getting the spark at correct time will experience loss of power. There are not a lot of short blocks for this model but that may be your fix if this is your issue.
#7
T
tlwright21
How does a 2 stroke get out of phase? And how do you put it back in phase?
T
tlwright21
Crank out of phase? you will still get good compression but if the piston is not getting the spark at correct time will experience loss of power. There are not a lot of short blocks for this model but that may be your fix if this is your issue.
How does a 2 stroke get out of phase? And how do you put it back in phase?
#8
B
bogdaN
Here some pic,s of carburetor that show u that governor vane should be open.Dan
B
bogdaN
I guess anything is possible but the engine runs and i was mowing with it after I bent the blade. it started and ran last week with no problem after i changed plug.
the problem that i see now is the air vane is in the complete closed position when the engine fired up yesterday. why I dont' know. nothing was adjusted or changed to cause this. With this being the case the throttle plate is completely closed and that is why there is no fuel getting into the engine. I need for someone that knows LB to tell me where the air vane should be in the slot when it is running.
also quite a while ago the throttle lever on the handle quit doing anything. it was attached to the lever on the carb but when moved didn't do anything to the engine speed, which is all connected to the air vane.
Here some pic,s of carburetor that show u that governor vane should be open.Dan
#9
L
lewb
A violent stopping of mower/With a new crank, if you can find one. I would say if you cannot cure issue with carb adjustments your only process of elimination is the crank imho. You can spray carb cleaner or ether/starting fluid under mower while it running to see if you have a damaged seal, there should be no RPM change. If RPM jumps then you have a seal bad. Ebay you can probably find a motor. I have not seen a short block for the 4.75 hp LB.
I had the same mower for probably as long as you did. My son filled with gas when I was out of town, did not know I filled with fresh gas but normally had mixed in can. I bought a duraforce in replacement. You can find them on craiglist readily and you can also get short blocks for around a 100.00 which is crank and cylinder assembly. That is what I did, bought a donor mower for 25.00 and put a new short block in.
L
lewb
How does a 2 stroke get out of phase? And how do you put it back in phase?
A violent stopping of mower/With a new crank, if you can find one. I would say if you cannot cure issue with carb adjustments your only process of elimination is the crank imho. You can spray carb cleaner or ether/starting fluid under mower while it running to see if you have a damaged seal, there should be no RPM change. If RPM jumps then you have a seal bad. Ebay you can probably find a motor. I have not seen a short block for the 4.75 hp LB.
I had the same mower for probably as long as you did. My son filled with gas when I was out of town, did not know I filled with fresh gas but normally had mixed in can. I bought a duraforce in replacement. You can find them on craiglist readily and you can also get short blocks for around a 100.00 which is crank and cylinder assembly. That is what I did, bought a donor mower for 25.00 and put a new short block in.
#10
L
lewb
The vane is a governor, the more load on engine the more it opens up throttle. Your spring is probably sacked out or something is binding which is why no difference in throttle change rpm. To replace the spring you have to remove the throttle plate/butterfly (looks like a penny) Just use a needle nose and pull it, The spring has a tab the sits in the dial adjuster and the other end goes into throttle. To set it clockwise each click is 25 rpm at full throttle, want 3000 to 3200 rpm. I have done in the past is tie up the safety handle and start mower, you can turn the vane by hand to run throttle up and down. You should be able to do this to see if you can get it to stay running.
L
lewb
When I took the muffler off the other day I was inspecting the crank shaft seal area and there wasn't anything unusual there. No gas/oil moisture or anything that might look like blow by . I really believe that i have a issue with the air-vane not operating correctly.
I'm going to put back together and hopefully get it to run long enough to maybe manually hold open the air vane from the closed position. maybe install a new spring or fiddle around with the governor collar. I have never touched either in the 21 years I have owned it so I don't know why it would be off now. If that isn't it then i'm done. I'll have a LB for sale for parts.
The vane is a governor, the more load on engine the more it opens up throttle. Your spring is probably sacked out or something is binding which is why no difference in throttle change rpm. To replace the spring you have to remove the throttle plate/butterfly (looks like a penny) Just use a needle nose and pull it, The spring has a tab the sits in the dial adjuster and the other end goes into throttle. To set it clockwise each click is 25 rpm at full throttle, want 3000 to 3200 rpm. I have done in the past is tie up the safety handle and start mower, you can turn the vane by hand to run throttle up and down. You should be able to do this to see if you can get it to stay running.
#11
J
jp1961
J
jp1961
Another item to check is the flywheel key. It's possible it was sheared when it stopped.
Regards
Jeff
Regards
Jeff
#12
T
tlwright21
i shot with it starting fluid to keep it running and it did not raise the engine rpm. I'm going to buy a new air vane spring. the air vane was going to the closed position while it was briefly running. i haven't ever touched it, didn't not ever even know what the air vane was or what it did
T
tlwright21
A violent stopping of mower/With a new crank, if you can find one. I would say if you cannot cure issue with carb adjustments your only process of elimination is the crank imho. You can spray carb cleaner or ether/starting fluid under mower while it running to see if you have a damaged seal, there should be no RPM change. If RPM jumps then you have a seal bad. Ebay you can probably find a motor. I have not seen a short block for the 4.75 hp LB.
I had the same mower for probably as long as you did. My son filled with gas when I was out of town, did not know I filled with fresh gas but normally had mixed in can. I bought a duraforce in replacement. You can find them on craiglist readily and you can also get short blocks for around a 100.00 which is crank and cylinder assembly. That is what I did, bought a donor mower for 25.00 and put a new short block in.
i shot with it starting fluid to keep it running and it did not raise the engine rpm. I'm going to buy a new air vane spring. the air vane was going to the closed position while it was briefly running. i haven't ever touched it, didn't not ever even know what the air vane was or what it did
#13
L
lewb
You have to spray underneath or in the deck as mower is running not into the carb intake. X2 on key, have to pull the tank, cover and recoil to see top of flywheel.
L
lewb
i shot with it starting fluid to keep it running and it did not raise the engine rpm. I'm going to buy a new air vane spring. the air vane was going to the closed position while it was briefly running. i haven't ever touched it, didn't not ever even know what the air vane was or what it did
You have to spray underneath or in the deck as mower is running not into the carb intake. X2 on key, have to pull the tank, cover and recoil to see top of flywheel.
#14
T
tlwright21
i started it up with primer/ starting fluid. the air vane was in the closed position while running and trying to die. I manually opened it with my hand while pumping the primer. i managed to keep it running for a minute or so before it died. the motor was running at full rpm and except for the fact it was running out of fuel it was running stong as it always has.
soooo do I spend a $100 and buy a brand new carb. by all appearance there is nothing wrong with this one other than the engine won't run for no known reason.
T
tlwright21
The vane is a governor, the more load on engine the more it opens up throttle. Your spring is probably sacked out or something is binding which is why no difference in throttle change rpm. To replace the spring you have to remove the throttle plate/butterfly (looks like a penny) Just use a needle nose and pull it, The spring has a tab the sits in the dial adjuster and the other end goes into throttle. To set it clockwise each click is 25 rpm at full throttle, want 3000 to 3200 rpm. I have done in the past is tie up the safety handle and start mower, you can turn the vane by hand to run throttle up and down. You should be able to do this to see if you can get it to stay running.
i started it up with primer/ starting fluid. the air vane was in the closed position while running and trying to die. I manually opened it with my hand while pumping the primer. i managed to keep it running for a minute or so before it died. the motor was running at full rpm and except for the fact it was running out of fuel it was running stong as it always has.
soooo do I spend a $100 and buy a brand new carb. by all appearance there is nothing wrong with this one other than the engine won't run for no known reason.
#15
L
lewb
L
lewb
They are simple carbs, as long as the float is set right and the needle is working correctly so the carb is not flooding (leaking gas when not running) or preventing enough gas into bowl, it should run. The throttle plate can wear into plastic (should be very little play in throttle plate) causing it to stick. Does the vane move back and forth with out sticking? You can warp the front of the carb where it attaches to the motor intake, you should be able to make your own gasket if that is the case. The jets main and idle could be plugged, but they are easy to clean and should last for several years.
Before buying a new carb or finding one on ebay I would inspect the flywheel key. If you manually open the throttle and it still did not rev up something has to be up with the motor. Could also be damaged reeds. They are in the case behind the carb. They should be tight against the opening no gap.
Before buying a new carb or finding one on ebay I would inspect the flywheel key. If you manually open the throttle and it still did not rev up something has to be up with the motor. Could also be damaged reeds. They are in the case behind the carb. They should be tight against the opening no gap.
#16
T
tlwright21
call me a LB mechanic. I removed the strainer screen inside the carb. doesn't appear plugged but wanted to remove the possibility it was choking the jet. Also cranked in about 6 clicks on the governor collar and the motor fired and ran and sat there running. Yahooo. I'm going to buy a new screen for the heck of it. Really believe that the spring is weak and couldn't hold itself open against the flywheel wind. so i think it is fixed. just needed more spring pressure applied on the air vane. guess I could buy another spring also and change it out.
T
tlwright21
They are simple carbs, as long as the float is set right and the needle is working correctly so the carb is not flooding (leaking gas when not running) or preventing enough gas into bowl, it should run. The throttle plate can wear into plastic (should be very little play in throttle plate) causing it to stick. Does the vane move back and forth with out sticking? You can warp the front of the carb where it attaches to the motor intake, you should be able to make your own gasket if that is the case. The jets main and idle could be plugged, but they are easy to clean and should last for several years.
Before buying a new carb or finding one on ebay I would inspect the flywheel key. If you manually open the throttle and it still did not rev up something has to be up with the motor. Could also be damaged reeds. They are in the case behind the carb. They should be tight against the opening no gap.
call me a LB mechanic. I removed the strainer screen inside the carb. doesn't appear plugged but wanted to remove the possibility it was choking the jet. Also cranked in about 6 clicks on the governor collar and the motor fired and ran and sat there running. Yahooo. I'm going to buy a new screen for the heck of it. Really believe that the spring is weak and couldn't hold itself open against the flywheel wind. so i think it is fixed. just needed more spring pressure applied on the air vane. guess I could buy another spring also and change it out.
#17
L
lewb
The springs are cheap and might be able to find one locally at a toro/LB dealer. The tab can work itself out of the notch thus loosing tension, I know when you replace the spring you have to be careful so it stays in place.
L
lewb
call me a LB mechanic. I removed the strainer screen inside the carb. doesn't appear plugged but wanted to remove the possibility it was choking the jet. Also cranked in about 6 clicks on the governor collar and the motor fired and ran and sat there running. Yahooo. I'm going to buy a new screen for the heck of it. Really believe that the spring is weak and couldn't hold itself open against the flywheel wind. so i think it is fixed. just needed more spring pressure applied on the air vane. guess I could buy another spring also and change it out.
The springs are cheap and might be able to find one locally at a toro/LB dealer. The tab can work itself out of the notch thus loosing tension, I know when you replace the spring you have to be careful so it stays in place.