I was given an older Honda 7.5 long shaft outboard. The model/serial# is DF75L-1701898. The previous owner said that the engine was hard to start but would run fine after starting except at idle speeds. A couple of questions: Does anyone have any idea what year the motor is and what might be causing the problems described above. He has replaced the fuel pump, filter and fuel lines and spark plugs. No mention of any carb work or replacement of ignition parts. Because the motor was given to me, I have no problem with spending a little money to get it running. It appears to be in great shape except, of course for the running part. Any help would be appreciated. Chuck Turner
Old Honda outboard
- Thread starter Chuck Turner3968
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Experiment
Use the choke partially and see if giving it extra gas at idle helps it or hurts it. Pinch the fuel line - if it is too rich it will rev up as it leans out (before starving and shutting off) Put a bolt in the spark plug wire. See if the spark can jump at least 1/4" from the head of the bolt to the block. do a leakdown check, or have one performed. A leaky set of cylinder rings will make the compression lower than spec. At running speed there is not enough time to allow enough air to leak past the rings to prevent combustion, but at idle and slow speeds that may be the case. (this check is performed by taking an air line at a certain regulated pressure, say 50 psi. You then plumb it into the spark plug hole, with engine at TDC (on combustion stroke if 4 cycle) and see what the cylinder pressure is. Usually anything less than 75-80% of the first pressure indicated you need to refinish the cylinders and replace the rings (and valve seats if 4 cycle)
Use the choke partially and see if giving it extra gas at idle helps it or hurts it. Pinch the fuel line - if it is too rich it will rev up as it leans out (before starving and shutting off) Put a bolt in the spark plug wire. See if the spark can jump at least 1/4" from the head of the bolt to the block. do a leakdown check, or have one performed. A leaky set of cylinder rings will make the compression lower than spec. At running speed there is not enough time to allow enough air to leak past the rings to prevent combustion, but at idle and slow speeds that may be the case. (this check is performed by taking an air line at a certain regulated pressure, say 50 psi. You then plumb it into the spark plug hole, with engine at TDC (on combustion stroke if 4 cycle) and see what the cylinder pressure is. Usually anything less than 75-80% of the first pressure indicated you need to refinish the cylinders and replace the rings (and valve seats if 4 cycle)
Honda Woes
Chuck, I have a 5hp Honda year 2003. When I first got it, it ran badly. Would not idle properly. After much messing around, found the solution was to have the carb bathed in cleaner to remove the varnish buildup inside the fine tubes in the carb. Storing the engine vertically also helped. Also I run the engine dry before putting away. I also replaced the plug, the filter etc. but they were not the problem. The gum inside the carb was the problem. Now everything is fine. Also use fresh gas. Good luck, Pete
Chuck, I have a 5hp Honda year 2003. When I first got it, it ran badly. Would not idle properly. After much messing around, found the solution was to have the carb bathed in cleaner to remove the varnish buildup inside the fine tubes in the carb. Storing the engine vertically also helped. Also I run the engine dry before putting away. I also replaced the plug, the filter etc. but they were not the problem. The gum inside the carb was the problem. Now everything is fine. Also use fresh gas. Good luck, Pete
Sounds like carburator.
The carb is a definite suspect for the condition you describe. If left unused for a period of time the gas may have gummed it up. I would disconnect it and take it apart and clean the housing, its passages and jets with a carb cleaning solution and compressed air. Replace gaskets or if re-using old ones make sure you have no air leaks. Some have adjustment, some don't so it would not hurt to get a manual for the engine. They can usually be found in the net.
The carb is a definite suspect for the condition you describe. If left unused for a period of time the gas may have gummed it up. I would disconnect it and take it apart and clean the housing, its passages and jets with a carb cleaning solution and compressed air. Replace gaskets or if re-using old ones make sure you have no air leaks. Some have adjustment, some don't so it would not hurt to get a manual for the engine. They can usually be found in the net.
Yep, I vote for the carb.
It's a quick, cheap fix if you know where to look. Or send it over. I'll fix it. Of course, if you don't know where to look (or how to tear into a carb) then you are faced with paying someone or replacing it. They don't cost much. I'd price a new one and go from there.
It's a quick, cheap fix if you know where to look. Or send it over. I'll fix it. Of course, if you don't know where to look (or how to tear into a carb) then you are faced with paying someone or replacing it. They don't cost much. I'd price a new one and go from there.
Thanks
Thanks for all the help. I talked with one of the local Honda dealers and he thinks the motor is probably a 1986 or possibly a little older. Luckily, there are still carburetor parts available. I will start there first and see what happens. Chuck Turner
Thanks for all the help. I talked with one of the local Honda dealers and he thinks the motor is probably a 1986 or possibly a little older. Luckily, there are still carburetor parts available. I will start there first and see what happens. Chuck Turner
other ideas beside gas and carb
I have about a 1990 Honda 8 hp and it is also hard to start (I use it at 8600 feet) but runs great once started. Besides the carb and fresh gas advice.. I cludged in a tube so that I can inject starting fluid into the carb with the cover on - and I pretty much do this every time I start the motor. With the starting fluid, starts first or second pull. Also, someone on a different BB suggested filing down (a little) the throttle limit. The throttle limit on the Honda (dont know about newer models) works in both nuetral and reverse so it keeps you from opening the throttle much for starting and it also limits the motor thrust in reverse. Im going to also file this down a little on my motor which will hopefully help with starting.
I have about a 1990 Honda 8 hp and it is also hard to start (I use it at 8600 feet) but runs great once started. Besides the carb and fresh gas advice.. I cludged in a tube so that I can inject starting fluid into the carb with the cover on - and I pretty much do this every time I start the motor. With the starting fluid, starts first or second pull. Also, someone on a different BB suggested filing down (a little) the throttle limit. The throttle limit on the Honda (dont know about newer models) works in both nuetral and reverse so it keeps you from opening the throttle much for starting and it also limits the motor thrust in reverse. Im going to also file this down a little on my motor which will hopefully help with starting.
Starting fluid
Walt, The previous owner also used starting fluid and said even that didn't seem to help. It was still difficult to start. Don't know what that means. Chuck
Walt, The previous owner also used starting fluid and said even that didn't seem to help. It was still difficult to start. Don't know what that means. Chuck
FIRST CHECK THE GAS TANK, HOSE & FITTINGS
A FRIEND WITH THE SAME MOTOR HAD THE SAME PROBLEMS. HE FOUND THE PROBLEM WAS THE TANK, HOSE AND FITTINGS. HE TRIED EVERYTHING ALREADY MENTIONED FIRST. HOPE THIS HELPS AND GOOD LUCK.
A FRIEND WITH THE SAME MOTOR HAD THE SAME PROBLEMS. HE FOUND THE PROBLEM WAS THE TANK, HOSE AND FITTINGS. HE TRIED EVERYTHING ALREADY MENTIONED FIRST. HOPE THIS HELPS AND GOOD LUCK.
Ours had a quarter size hole
in th exhaust pipe inside the shaft. It was a bear to start. So, if the carb idea doesn't work, check that. i haven't heard of it as a "normal" older Honda problem, but it did happen to us. Took four different mechanics, the first three didn't bother enough to find it.
in th exhaust pipe inside the shaft. It was a bear to start. So, if the carb idea doesn't work, check that. i haven't heard of it as a "normal" older Honda problem, but it did happen to us. Took four different mechanics, the first three didn't bother enough to find it.
another vote for the carb
My '98 had a very similar problem last year after starting to use the new ethanol mixed gas. Had to have the carb rebuilt. The shop said the carb was filthy. It ran like a champ for the rest of the season. This spring, same thing started happening, I started using some carb cleaner in the fuel and it has cleared up. Try using some stp or gumout carb cleaner in the gas and let the engine run for a while and see what happens. Manny
My '98 had a very similar problem last year after starting to use the new ethanol mixed gas. Had to have the carb rebuilt. The shop said the carb was filthy. It ran like a champ for the rest of the season. This spring, same thing started happening, I started using some carb cleaner in the fuel and it has cleared up. Try using some stp or gumout carb cleaner in the gas and let the engine run for a while and see what happens. Manny
fuel bulb
i had some problems with starting my 2000 honda 5 hp. turned out to be the bulb on the fuel line from the portable tank. there is a check valve inside the bulb that apparently was bad. if you haven't changed it, you may try it first. part is only about $6.
i had some problems with starting my 2000 honda 5 hp. turned out to be the bulb on the fuel line from the portable tank. there is a check valve inside the bulb that apparently was bad. if you haven't changed it, you may try it first. part is only about $6.
Chuck, I'd add a vote for a carb issue as well.
I have an early eighties BF100 (10 hp, 2 cyl.) that gets finicky at idle. It'll start getting hard to start and will not idle. An excellent mechanic claims and makes sense that the idle jets on these guys are tiny and gets (too) easily clogged with goop or the tiniest bit of trash. A good carb cleanout has been the fix.
I have an early eighties BF100 (10 hp, 2 cyl.) that gets finicky at idle. It'll start getting hard to start and will not idle. An excellent mechanic claims and makes sense that the idle jets on these guys are tiny and gets (too) easily clogged with goop or the tiniest bit of trash. A good carb cleanout has been the fix.
Similar problem
I am in the midst of a similar problem with my Honda 50. Idle is rough,some black soot,plugs are black.And this is on a 2006 motor withe few hours. I spoke to a local longtime Honda dealer and he identified the problem immediately. The ethanol in the fuel is the issue. This fuel has a tendency to break down quickly,and it absorbs moisture easily. Start using Sta-bil or some similar fuel stabilizer,and if possible,add a water seperator in the line. I am also running a fuel system cleaner until the problem is resolved.It seems that the carbed Honda motors are particularly sensitive to this problem,and he has been deluged with similar calls.
I am in the midst of a similar problem with my Honda 50. Idle is rough,some black soot,plugs are black.And this is on a 2006 motor withe few hours. I spoke to a local longtime Honda dealer and he identified the problem immediately. The ethanol in the fuel is the issue. This fuel has a tendency to break down quickly,and it absorbs moisture easily. Start using Sta-bil or some similar fuel stabilizer,and if possible,add a water seperator in the line. I am also running a fuel system cleaner until the problem is resolved.It seems that the carbed Honda motors are particularly sensitive to this problem,and he has been deluged with similar calls.
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