Annoying Honda Problem,

kellaig · Jan 2, 2003

Hi there, I have a 40 Hp Honda current model that performs excellent except if the motor has been turned off for a while ( say 20 minutes). When i turn it on again the motor runs rough, coughs and splutters for at least a minute and if I put it into gear too quickly sometimes it will stall. Any suggestions appreciated. Regards Kellaig

steelespike · Jan 2, 2003

Re: Annoying Honda Problem,

Just a guess.Maybe the gas is siphoning back into the tank.Have you tried squeezing the primer bulb before restarting. Have you checked with your dealer to see if this is a recurring problem on these motors. Your discription sound like a lean condition.

DJ · Jan 3, 2003

Re: Annoying Honda Problem,

kellaig, I'm with Steelspike. I suspect the fuel primer bulb. It should remain hard. If not, it's probably leaking internally.

radsrh · Jan 3, 2003

Re: Annoying Honda Problem,

If this is a current model then you should have a full 3 year warranty, take it to the dealer and let them take care of it for free.

Trevor · Jan 3, 2003

Re: Annoying Honda Problem,

how long do you leave the motor befor you try and start it. it sounds like your gas is draining back in to the tank. when you try and start the motor check the bulb and then giv it some choke to get it going from experiance they like to be choked when first starting if they cool off to much or its cold out they require an abnormal amount of choke some times you have to click the choke on several times to get the motor running smooth. the motor has an automatic chock that comes on only when you lift the fast idel lever all the way up.

Skinnywater · Jan 3, 2003

Re: Annoying Honda Problem,

Your manuel (page 57)calls for a valve adjustment as well as having the carburators syncronised at 20 hours. This is a critical breakin adjustment service. While the carburators were not far from spec's., the valves sure needed attention on my current year BF50. Tight valves and carb adjustments cause starting problems. If you haven't had the 20 hr.service it would be the most obvious. I don't think the engine fuel pump would allow siphoning back to the tank. In addition, the siphon wouldn't occur through 3 closed needle valves. Initial starts would draw on 3 full float bowls. Checking the fuel filter (under cowl,lower rear, white plastic)for fuel contamination/debris would be an easy second step. If you need more info on your BF40 in the way of service manuels, special tools and personal experience just ask.

hondon · Jan 3, 2003

Re: Annoying Honda Problem,

Jeez, I was just about to post,but I couldn't have said it any better myself.I will go on too add that if you are not useing a water separator,PLEASE, get one.These carbs employ tiny tiny jets and passages.Water contamination can really blow the weekend and be costly.

kellaig · Jan 3, 2003

Re: Annoying Honda Problem,

thanks Guys, The problem i have only occurs when ther motor has been warmed up after trolling and running about for several hours. If you stop for a short time the motor starts first kick and idles excellent. If you stop for about 20 minutes or longer the motor starts first kick but runs rough for at least a minute. It is a tiller steer model and sometimes when I put it into gear to qucikly it will stall. The way I get around this is to let the motor idle at high revs for at least 30 seconds until I can't notice any miss or cough. After this short time i can run the motor and it runs excellent . Is this normal for the Honda. i have tried pumping the primer bulb before I start it but to no avail. i have tried using the choke but It doesn't like it because I'm guessing that the motor is already hot. This machine has had its 20 hr service. Regards Kellaig

Skinnywater · Jan 4, 2003

Re: Annoying Honda Problem,

It certainly isn't normal. It would be most useful to other Honda owners on this list if you let us know what the actual problem is, once it's found. Again, I'd pull the filter out and back blow the contents into a clean container. This will be a good indication on weather you'll have a bill to pay or a warranty claim.

hondon · Jan 4, 2003

Re: Annoying Honda Problem,

Hard start warm usually indicates a tight exhaust valve.When was the last time you had those valves adjusted?They are due after the first 20 hours of use, and reccomended anually after that.

kellaig · Jan 4, 2003

Re: Annoying Honda Problem,

Thanks Hondon, I am a little confused. I don't have any trouble starting this tiller model even when it is hot, cold or sitting in drydock for weeks. It starts first kick even without choke. The problem I have is when it is started after being hot and sitting for a while it runs rough even in neutral. when I decrease the revs to place the motor in gear sometimes it will stall. The way I get around this problem is by placing it in gear at higher revs than I would normally do. could this problem be caused by the exhaust valves. Thanks for your time Regards Kellaig

kellaig · Jan 5, 2003

Re: Annoying Honda Problem,

Hi there, i have had the valves lloked at and they seemed fine. took boat out today - stinking hot 35 Celsius. motor performed excellent except when turned off for a while. It would fire first kick at base revs but begin to run rough and when i would put it into gear to move it would stall. Any other suggestions Regards Kellaig

Bear · Jan 6, 2003

Re: Annoying Honda Problem,

kellaig, Sorry to hear about your problems. I have a problem following what you have and have not done so far. From your profile I can follow all your posts, but can you please give us all information. I think all you can tell us will help you and us. -Where do you live? Altitude, fuel quality, octane temperature, thermostat etc. -What kind of boat is this Honda 40 on? You had a 30 hp earlier and made a post about 3.5 meters (11,5 ft) of fuel line and a mix of Mercury and Honda fuel line. Is that what you are using today too? Your Post about fuel line -What have you done so far? A valve check. The 20hrs service. Adjusted idle rpms (Hondon said earlier 950 +/- 50 rpms in neutral after a good warm up.) Primed with bulb (engine warm after it sat for 20 minutes). New spark plugs? (What about the old ones, same colour all three?) If I get this you have two problems. -Stalling at idle warm or cold -Hard to start after 20 minutes You have had these problems since day one (May 2002)? My suggestion is to try a new fuel tank, new fuel line, bulb, fuel connectors. Everything from cas cap to the fuel connector at the engine. Standard length! You do do use the plasic portable tank do you? I don't know if there was a Honda Service Bulletin about leaking fuel connectors, fuel pickups in the tank or what it was. Maybe just a rumour. Let us help you kellaig. But tell us what you know.

kellaig · Jan 6, 2003

Re: Annoying Honda Problem,

Bear, This is a 40 HP tiller Honda 2002 model. It has had it 20 hrs servuice as well as a complete check of the carbies, valves etc 3 weeks ago. It has new plugs and everything has been checked. It is a different motor to the 30 Honda and fuel line. It is sitting on the back of a 4.0 metre aluminium boat and I run the normal unleaded fuel we have here with a RON of 91. i live in Australia and I don't have a problem starting this motor at anytime. It fires first kick. When i use this motor on a colder day and troll or to kids around on a tube it idles excellent and it doesn't run rough after sitting for a while. Yesterday I tooke the boat out again. It was 35 degrees celsius. It started first kick from cold and idled excellent.As it got hotter the idle got rougher. The cowling was extremely hot. If I would pull up to a snag in the river and fish for a while and turn the motor back on it would start first kick but run rough. If I tried to put it in gear it would stall. If I managed to put it into gear and give it a burst the motor would settle down a bit. In general this machines performs much better on colder days so I think that the fuel mix may become too rich on hot days causing these problems. When it has been sitting for a while thwe motor gets hotter so air temp under cowling is hotter so maybe not enough air to fuel mix. What do you think- if I adjust the fuel mix when it is hot will this cause problems when it is cold. Regards Kellaig

Bear · Jan 6, 2003

Re: Annoying Honda Problem,

Okay Kellaig. Now we know a little more. 35 degrees Celsius? Up here it has been -19 today. This summer we had a heat wave for 8-10 weeks. Temperatures around 30. Then back to normal 22-25. Okay I'm getting there. I have had Hondas 45-50 hp since 1991 and never had any problems at all. So I'm no Honda expert at all. What came to my mind was vapor lock . I searched this section and found other members suggesting that as a possible cause. But it never was. Check this: "What may be happening is that the fuel in the bowl,carb or fuel line is becoming overheated, almost boiling=vapor lock or no solid fuel,after you let engine sit awhile, fuel returns to liquid state and engine will re-start.I learned that from Bombardier hotline, my 99 Johnson 60hp does it(won't immediately restart after running it for awhile) You'll need to reroute fuel line or have dealer check for TSB's on that engine for a fix." What do you think? My fuel line isn't exposed to the sun all the way, but my primer bulb is. No problem last summer. Starts immediately even after a 10, 20, 30 minute break. I was also thinking, as 35 degrees is quite normal where you live, why your dealer didn't suggest this as one possibility? Check with him. My suggestion is to reroute the fuel line, cover the bulb, remove the cowling next time. Let some breeze in there. Don't drop it in deep water $$$$... So, you have the plastic tank too? Mine is like a ballon if I close the vent screw when I take a breake for a swim and a beer. Also if I stop for fuel (cold fuel) a hot day. Better not fill to the top. Fuel expands when it gets warmer. I guess you knew all that. But the teenagers at the marina doesn't. So I have to tell them four times a week

Long post - short message: vapor lock. Any other suggestions anyone? Good luck!

Regards, Bear

BillP · Jan 6, 2003

Re: Annoying Honda Problem,

This is a long shot...but my 50 4 stroke Mariner will idle rough when the plug gap is to big. It shows up only when warm. My thoughts are the reason it doesn't show when cold is because the auto choke has the revs up at idle and masks the symptom. My idle was a tad low too and after setting it up 75 more rpms the rough idle disappeared even with a too large plug gap. I found a big improvement in plug life when I changed from NGK to Champion...I couldn't believe how fast the NGKs just quit firing. I never had a 2 stroke eat plugs like this 4 stroke (and they aren't burning too hot or cold). Maybe your problem is too low idle setting and/or incorrect plug gap.

Troy_from _Oz · Jan 6, 2003

Re: Annoying Honda Problem,

kellaig, I have had a similar problem with my 'old' merc and posted here a while back - 'Merc650 restarting problem' One of the things suggested was the idle mixture being too lean - -which when hot leans out even further hence causing the problem you describe?? It sounds exactly like the problem i have been having. Motor starts flawlessly except when left to sit once being run for a while. I think steelespike also touched on this in the very first reply to your post. I have only had my boat out once since making a fine adjustment to the mixture setting but It seems to have worked so far. Too early to say for sure for my case but it might be worth a try for you too. Try a small adjustment to begin with and remember where the original setting was (and to take tools to reset it while you are out if you make it worse

). best of luck - troy

Skinnywater · Jan 7, 2003

Re: Annoying Honda Problem,

All summer long I was on the river in all different situations. It was a common day to start looking for shade in 105F. The only time day in and day out that I had to lift the Choke/high idle lever was at the boat ramp first thing in the AM. I never got the slightest roughness or hesitation in all of my motors 91 hours. So you obviously have a malfunction. Since your service and valve adjustment was done. And you've checked you fuel system for debris/contamination, it's now possible you have an electrical problem. Based on your explanations, here's what is sensible to me. It's possible I suppose that a single carburator on a hot start will exibit a lean condition. However, the lean condition won't come and go. If a jet or passage is plugged it will likely stay plugged. It definately won't plug on a hot start then unplug 2 minutes later then replug during a hotsoak. If you have a vapor lock you'll have a very extended crank time. The configuration of your Honda's secondary ignition system is pretty hard to diagnose for the layman. About the best you can do is remove the cowl after a hotsoak. Start the motor and listen for arcing in the secondary. Another way is to run continuety checks on the secondary wires while inspecting for carbon tracking. At this point it is extremely possible you have a single ignition coil that is shorting internally during your hotsoak and is breaking down. Again please and by all means let us know what is found to be the actual cause.

Annoying Honda Problem,

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