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casey t
New member
Username: slik24
Post Number: 1
Registered: 11-2009
| | Posted on Monday, November 02, 2009 - 07:10 pm: | 
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i am losing my mind trying to get my grandfathers boat running right again and i hope the guru can help! its a 2003 tohatsu 140 that has never given us any trouble until now! this boat gets ran year round and never sits more than a week at a time since new. original owner. the running issue occurs @ idle up till about 2500 rpm. it seems as if the #4 (bottom) cylinder is loading up with fuel. it will idle great for a few mins then start hiccuping every 10 seconds or so as if its loading up and firing at once. the hotter the motor gets the worse it is. i can get it to run better if i turn the #4 mixture screw in all the way (which is whats making me think its loading up) but it will still do this to the point where i can hardly get the boat off the trailer. hes had it in the shop and they said it was ignition soooo they replaced all four ignition coils, all four pickup coils, and the cd unit. were now close to 1200 dollars into this and still have no luck. ive rebuilt the carbs twice including soaking in an ultrasonic cleaner (im a motorcycle tech, never claimed to be a boat tech but im trying!). after both carb cleans we found nothing out of the ordinary, and all were in sync. this time around i pulled the reeds and all was good on that end. all fuel lines/tank/filter are clean and im pretty sure sure its loading up by looking at the condition of the new plugs(br8hs10) and how quickly #4 gets dark. typically 1 anda half turns out on all mixture screws makes this lady purr like a kitten but lately she purrs with hiccups! ive checked compression and found all 4 to be above 160psi. in my 23 years this old hillbilly has taught me to fix anything and has helped me build some of the fastest bikes in texas but to watch this thing wear us down youd think we just started workin on motors!!!!im at wits end. the fish are biting and we cant leave the dock!! any help would be greatly appreciated. |
Tohatsu Guru
Senior Member
Username: tohatsu_guru
Post Number: 1037
Registered: 06-2007
| | Posted on Monday, November 02, 2009 - 07:39 pm: |
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Absent mechanical, absent fuel, absent ignition you are left with?
Start over
You have replaced all the ignition components(I would advise beating the crap out of the mechanic at the dealership for that one) so assume that was never an issue. The fuel system would normally be the most likely source of the problem with bottom carb or reed set being high on the list of culprits...But, I want you to eliminate one possible mechanical source before you tear back in to the fuel system.
I want you to pull the plugs and the cover off of the flywheel. Then bring each piston up in turn to its closest point to the hole (top dead center). When each piston reaches TDC mark a groove on the flywheel. Then count the spaces between each of the four marks. If they are even, then look at that fuel system. If you are over/under on the marks you have a twisted crank shaft. It's rare, but it can happen if you had a catastrophic stop or went way over on the RPMs. |
casey t
New member
Username: slik24
Post Number: 2
Registered: 11-2009
| | Posted on Tuesday, November 03, 2009 - 10:31 am: |
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Thanks for the quick advice kind sir!! as soon as the day is up im trying that trick! i knew youd give me a new place to search, were tired of chasing our tails. will keep ya updated with the solution. |
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