jvstratman
Cadet
- Joined
- Jul 31, 2004
- Messages
- 7
I purchased this engine new from local dealer in 2003. It always displayed rough idle from the beginning. The dealer informed me that it wasn't uncommon for this OB and I accepted his explanation.
A separate issue that it had (and still does) is sometimes (most times actually) the indicator light will stay lit until I stop/re-start the engine. Yes - It runs very rough (limits RPM) until I get rid of the light. I brought that to his attention and he claimed to have changed something but, the problem still exists. I should have persisted but, I learned to deal with it and thought it wasn't a big deal.
In 2005 the timing pulley bolt unscrewed itself @ WOT which caused the engine to shut down. I managed to figure out that the hash marks probably needed aligned to get it running again. The first attemp was 180 deg out and then it fired up and I was back in business.
I'm not certain if the vibration began after the timing belt incident or if it's been getting progressivly worse over time. The prop is like new and I think it's safe to rule it out.
The carb is immaculate. Soaked and blown out w/ compressed air. I always un-plug and run out fuel near dock.
The compression on each cyclinder is 165 PSI.
The fuel tank, bulb, hoses all work perfect on my Tohatsu 20 HP 4 Stroke so I ruled them out.
Spark plugs are new NGK's
The valve gaps (cold) are in spec.
BTW, the reason i'm focusing on the 18 HP is because the 20 HP runs so smooth. I'm on a mission to make the 18 run as smoothly as the 20.
Another part that was just recently replaced (by me) was the Auto-By-Starter. Mine was stuck in the extended position.
I'm starting to believe the timing is off. It sounds like a John Deere @ 900 RPM but the plugs are dry and not burnt.
Can a faulty CD unit cause severe rough idle and vibration?
Could I have damaged a valve when the timing belt came off @ WOT? If so, why does the compression check out?
I purchased the Service Manual for the new 20 HP and assumed that all of the timing alignment marks coincide for the 18 HP.
What would happen if I tried the 2013 MFS20CEFL CD unit on the 2003 MFS18B2? The part numberes are the same execpt for the 3 digit prefixs and the 20 HP went back to a manual choke so there would be extra wires. Also, I think the charging system is little stronger on the 20. I hate to shell out the $$ for a CD unit on a misguided hunch but I don't want to fry my new one either.
I'm hoping someone can point me in the right direction with some troubleshooting tips that I've overlooked or not thought of.
Thanks for your time and a great forum.
A separate issue that it had (and still does) is sometimes (most times actually) the indicator light will stay lit until I stop/re-start the engine. Yes - It runs very rough (limits RPM) until I get rid of the light. I brought that to his attention and he claimed to have changed something but, the problem still exists. I should have persisted but, I learned to deal with it and thought it wasn't a big deal.
In 2005 the timing pulley bolt unscrewed itself @ WOT which caused the engine to shut down. I managed to figure out that the hash marks probably needed aligned to get it running again. The first attemp was 180 deg out and then it fired up and I was back in business.
I'm not certain if the vibration began after the timing belt incident or if it's been getting progressivly worse over time. The prop is like new and I think it's safe to rule it out.
The carb is immaculate. Soaked and blown out w/ compressed air. I always un-plug and run out fuel near dock.
The compression on each cyclinder is 165 PSI.
The fuel tank, bulb, hoses all work perfect on my Tohatsu 20 HP 4 Stroke so I ruled them out.
Spark plugs are new NGK's
The valve gaps (cold) are in spec.
BTW, the reason i'm focusing on the 18 HP is because the 20 HP runs so smooth. I'm on a mission to make the 18 run as smoothly as the 20.
Another part that was just recently replaced (by me) was the Auto-By-Starter. Mine was stuck in the extended position.
I'm starting to believe the timing is off. It sounds like a John Deere @ 900 RPM but the plugs are dry and not burnt.
Can a faulty CD unit cause severe rough idle and vibration?
Could I have damaged a valve when the timing belt came off @ WOT? If so, why does the compression check out?
I purchased the Service Manual for the new 20 HP and assumed that all of the timing alignment marks coincide for the 18 HP.
What would happen if I tried the 2013 MFS20CEFL CD unit on the 2003 MFS18B2? The part numberes are the same execpt for the 3 digit prefixs and the 20 HP went back to a manual choke so there would be extra wires. Also, I think the charging system is little stronger on the 20. I hate to shell out the $$ for a CD unit on a misguided hunch but I don't want to fry my new one either.
I'm hoping someone can point me in the right direction with some troubleshooting tips that I've overlooked or not thought of.
Thanks for your time and a great forum.
