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Author Topic:   26-year-old Honda 7.5-HP Hard To Start

Fishmore posted 09-12-2010 01:11 PM ET (US)
I have a 1984 Honda 7.5 hp. Getting it started involves about 10 to 12 pulls on the rope. Once it is started I can shut it down and restart it, usually on the first pull. When running, it runs excellent. I really want this motor to start on the first or second pull. I have installed a new carburetor, replaced spark plugs, and replaced wires. The next thing to go after would be the CDI ignition system which has several parts to it. Because it runs so well once I get it started, I am not sure if I should just take it all apart and clean it all to remove any corrosion or if there is a particular part I should be focusing on or replace. Any ideas?
Tom W Clark posted 09-12-2010 01:14 PM ET (US)
Check to see if the choke is operating correctly.
Fishmore posted 09-12-2010 03:09 PM ET (US)
Yes the choke is operating correctly. Before replacing the carburetor I rebuilt it and went through adjusting the linkages. When I still had the problem I replaced the carburetor and went through all the linkages again. I also replaced all the fuel lines, replaced the impeller, replaced the pull rope, etc. That is why I am now focusing on the ignition components. This is made up of the coil assembly, coil assembly exciter and the coil assembly charger. I was hoping somebody had this problem before and knew which part might be needing replaced or maybe it is just a matter of cleaning up all the connections due to the fact that it runs so good after it is started once.
jimh posted 09-13-2010 08:01 AM ET (US)
To see if you are getting spark on the first pull, put an in-line spark tester in one of the spark plug wire leads to a spark plug. You should be able to easily see the spark jump across the tester.
An electrical problem does not sound like the cause of the hard starting. Typically an electrical problem comes into play after the engine has been running and something gets too hot. Hard starting is more often a problem with the fuel mixture. Most engines need some fuel enrichment for starting.
Most engines have their own starting procedure. Check the owner's manual for the proper procedure. I am serious about this. Many people think they know how to start their outboard, but they don't follow the recommended procedure. This usually leads to hard starting.
brisboats posted 09-13-2010 08:14 AM ET (US)
Your ignition is fine. Is the carb new or just rebuilt? Mix up some premix in a spray bottle and squirt a shot or two into the carb before starting. If it starts easier it is now time to redo that carb rebuild.

Brian
weekendwarrior posted 09-13-2010 09:14 PM ET (US)
Are you pumping the fuel bulb in the gas line to fill the carb before you try to start it? Also if you haven't yet, check the valve clearances. Difficulty starting can be a sign of valves that are too tight. A compression test when cold would show low readings in this case too.
Does it sputter at all with the first several pulls, or just no fire at all until 10 or so pulls? Also once it starts, can you turn it right off and start again easily, or does it need to get warm before starting easily?
Fishmore posted 09-14-2010 12:27 AM ET (US)
The carburetor is new from Honda (supposedly).
Could be the start procedure and I have not checked the spark or compression (that was dumb) but I will check the spark and the compression now.
I have tried a number of variations on the start procedure but maybe there is a trick I don't know. Primer bulb is pumped up solid before I start pulling.
No sputtering until it starts then it starts right up. I can shut it down again quickly and it will restart after that. I do not even have to leave the choke on for very long after I start the motor and it idles down nicely. On my newer model 5 hp Honda I have to leave the choke on for quite a while before she will idle which I attributed to a single cylinder design rather than the 7.5 hp two cylinder design.
One thing of note with this engine is there is a cam on the shifter shaft which prevents you from turning the throttle more than 1/4" if the motor is in neutral or reverse. You can only open the throttle if the motor is in forward gear. I have tried placing the motor in forward gear opening the throttle a few times and then putting it back in neutral prior to starting and that made no difference. I thought about removing that cam but, the motor should work as designed.
Thanks for the ideas (so far).
Fishmore posted 09-14-2010 04:00 AM ET (US)
I have good spark at both plugs but the gap was too small .024 and should be .028 so I reset gap. I found the owners manual and my starting procedure is correct. One interesting item of note is the Owner's manual recommends 92 Octane fuel and I am using 87 Octane. I will have to try a higher Octane fuel.
Fishmore posted 09-14-2010 03:53 PM ET (US)
Okay final post on this subject. Before getting new higher octane fuel I did some more research turns out "87 pump Octane is what Honda considers 91 research octane" therefore 87 Octane fuel is correct for the engine. I went back over the starting instructions and read where I should not use the choke if the ambient temperature is above 68 degrees Fahrenheit. So the only 2 changes I made were increased spark plug gap from .024 to .028 and did not use the choke. Started on the third pull from dead cold.
jimh posted 09-14-2010 11:08 PM ET (US)
Bravo!
PeteB88 posted 09-14-2010 11:13 PM ET (US)
I learned the same lesson to LISTEN to manufacturer's recommendations for octane rating. Good work.
cgodfrey posted 09-15-2010 03:25 PM ET (US)
The use of premium, higher octane fuel seems to be generally discouraged in older engines.
I'm not questioning this consensus, but I'm curious as to why this is- from a mechanical or combustion standpoint.
Squeaked through college Chemistry 101 with a C. Go easy on me.
Chris
JMARTIN posted 09-15-2010 04:41 PM ET (US)
Premium 92 octane fuel burns slower. It is designed for high compression engines.
John

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Author	Topic: 26-year-old Honda 7.5-HP Hard To Start
Fishmore	posted 09-12-2010 01:11 PM ET (US) I have a 1984 Honda 7.5 hp. Getting it started involves about 10 to 12 pulls on the rope. Once it is started I can shut it down and restart it, usually on the first pull. When running, it runs excellent. I really want this motor to start on the first or second pull. I have installed a new carburetor, replaced spark plugs, and replaced wires. The next thing to go after would be the CDI ignition system which has several parts to it. Because it runs so well once I get it started, I am not sure if I should just take it all apart and clean it all to remove any corrosion or if there is a particular part I should be focusing on or replace. Any ideas?
Tom W Clark	posted 09-12-2010 01:14 PM ET (US) Check to see if the choke is operating correctly.
Fishmore	posted 09-12-2010 03:09 PM ET (US) Yes the choke is operating correctly. Before replacing the carburetor I rebuilt it and went through adjusting the linkages. When I still had the problem I replaced the carburetor and went through all the linkages again. I also replaced all the fuel lines, replaced the impeller, replaced the pull rope, etc. That is why I am now focusing on the ignition components. This is made up of the coil assembly, coil assembly exciter and the coil assembly charger. I was hoping somebody had this problem before and knew which part might be needing replaced or maybe it is just a matter of cleaning up all the connections due to the fact that it runs so good after it is started once.
jimh	posted 09-13-2010 08:01 AM ET (US) To see if you are getting spark on the first pull, put an in-line spark tester in one of the spark plug wire leads to a spark plug. You should be able to easily see the spark jump across the tester. An electrical problem does not sound like the cause of the hard starting. Typically an electrical problem comes into play after the engine has been running and something gets too hot. Hard starting is more often a problem with the fuel mixture. Most engines need some fuel enrichment for starting. Most engines have their own starting procedure. Check the owner's manual for the proper procedure. I am serious about this. Many people think they know how to start their outboard, but they don't follow the recommended procedure. This usually leads to hard starting.
brisboats	posted 09-13-2010 08:14 AM ET (US) Your ignition is fine. Is the carb new or just rebuilt? Mix up some premix in a spray bottle and squirt a shot or two into the carb before starting. If it starts easier it is now time to redo that carb rebuild. Brian
weekendwarrior	posted 09-13-2010 09:14 PM ET (US) Are you pumping the fuel bulb in the gas line to fill the carb before you try to start it? Also if you haven't yet, check the valve clearances. Difficulty starting can be a sign of valves that are too tight. A compression test when cold would show low readings in this case too. Does it sputter at all with the first several pulls, or just no fire at all until 10 or so pulls? Also once it starts, can you turn it right off and start again easily, or does it need to get warm before starting easily?
Fishmore	posted 09-14-2010 12:27 AM ET (US) The carburetor is new from Honda (supposedly). Could be the start procedure and I have not checked the spark or compression (that was dumb) but I will check the spark and the compression now. I have tried a number of variations on the start procedure but maybe there is a trick I don't know. Primer bulb is pumped up solid before I start pulling. No sputtering until it starts then it starts right up. I can shut it down again quickly and it will restart after that. I do not even have to leave the choke on for very long after I start the motor and it idles down nicely. On my newer model 5 hp Honda I have to leave the choke on for quite a while before she will idle which I attributed to a single cylinder design rather than the 7.5 hp two cylinder design. One thing of note with this engine is there is a cam on the shifter shaft which prevents you from turning the throttle more than 1/4" if the motor is in neutral or reverse. You can only open the throttle if the motor is in forward gear. I have tried placing the motor in forward gear opening the throttle a few times and then putting it back in neutral prior to starting and that made no difference. I thought about removing that cam but, the motor should work as designed. Thanks for the ideas (so far).
Fishmore	posted 09-14-2010 04:00 AM ET (US) I have good spark at both plugs but the gap was too small .024 and should be .028 so I reset gap. I found the owners manual and my starting procedure is correct. One interesting item of note is the Owner's manual recommends 92 Octane fuel and I am using 87 Octane. I will have to try a higher Octane fuel.
Fishmore	posted 09-14-2010 03:53 PM ET (US) Okay final post on this subject. Before getting new higher octane fuel I did some more research turns out "87 pump Octane is what Honda considers 91 research octane" therefore 87 Octane fuel is correct for the engine. I went back over the starting instructions and read where I should not use the choke if the ambient temperature is above 68 degrees Fahrenheit. So the only 2 changes I made were increased spark plug gap from .024 to .028 and did not use the choke. Started on the third pull from dead cold.
jimh	posted 09-14-2010 11:08 PM ET (US) Bravo!
PeteB88	posted 09-14-2010 11:13 PM ET (US) I learned the same lesson to LISTEN to manufacturer's recommendations for octane rating. Good work.
cgodfrey	posted 09-15-2010 03:25 PM ET (US) The use of premium, higher octane fuel seems to be generally discouraged in older engines. I'm not questioning this consensus, but I'm curious as to why this is- from a mechanical or combustion standpoint. Squeaked through college Chemistry 101 with a C. Go easy on me. Chris
JMARTIN	posted 09-15-2010 04:41 PM ET (US) Premium 92 octane fuel burns slower. It is designed for high compression engines. John