dajohnson53
Lieutenant Commander
- Joined
- Apr 28, 2004
- Messages
- 1,627
Hi: I did what I think was a thorough cleaning of my carb and it didn't seem to help much. Here's the facts:<br /><br />Merc 110 (9.8 hp), 1974. I bought it cheap last year and it ran OK, but not great - a little hard to start, tended to die at low idle. The only adjustment on this carb is the low idle rich/lean screw which would have no effect unless screwed in completely, at which point the idle seemed to even out a little.<br /><br />This weekend I disassembled and soaked all big and little parts in carb. cleaner for about 12 hours or more (1 gallon can with wire basket). Removed parts, and blew out every orifice I could find with air (small can; I don't have compressed air). <br /><br />Replaced all gaskets and fuel pump parts (diaphragm, gaskets). I didn't "rebuild" the carb because the rebuild kit costs $60 - local source as well as on-line price! However, in looking at the various small parts, I could not see any visible wear or defects. Especially the low idle needle - it looked perfect. <br /><br />Only glitch was that one of the small parts is a plastic venturi with two wings that fit into slots in the main throat. Unfortunately, I broke one of those wings off. Fortunately, I cleaned the parts up, dried off and repaired with a tiny amount of JB weld (with toothpick), and it seemed as strong as new and no intrusion into the actual venturi orifice. I really don't think this repair is affecting the function of the carb.<br /><br />Also cleaned tank pick up and the integral fuel filter screen was cleaned and blown out along with all the metal parts. I haven't actually replaced the fuel line and bulb from the portable tank, but they seem to work fine.<br /><br />So, I got it all back together and ran it in the tank. It seems that the starting and idling is again OK, maybe a "little" better than before, but not a huge difference. The low idle screw again does not affect anything until it's screwed completely in (not torqued in hard, just gently screwed in). When in the full-in position, the idle does seem to be better but not great.<br /><br />I know with an old 2 stroke, the thing isn't going to idle like a sewing machine, and it is working OK for what I need, but it seems rougher and noisier than a friend's similar Merc of the same era. <br /><br />The main things that have me thinking are the fact that the low speed adjustment doesn't have any effect full out to nearly full in - it's only at full in that any change is noticed. Also, it's hard for me to get it to idle at a low enough speed to smootly shift gears - it doesn't grind, but really sounds a little too high idle to me - but if I lower it the idle to where I think it should be, it tends to die (again, this is in a tank, not on a hose).<br /><br />I have no problem with re-cleaning the carb and will probably do it on general principles, because with the learning curve, it will be a very simple job the second time. Do you think that even though the small parts look perfect, there might be some defect that I just can't see (with my reading glasses on!)?<br /><br />Thanks in advance for any help you can give.<br /><br />Any other advice?
<br /><br />Ran it yesterday for about 45 minutes pushing my big boat upstream at WOT and below WOT for about 25 minutes. Then I returned down stream at idle and/or trolling speed. Engine was smooth and trouble free. Stopped it a couple of times to see how it would re-start: first pull every time.<br /><br />Final 15-20 minutes were at very low speed because I wanted to see what the plugs looked like after this. Plugs looked perfect - moist with fuel, but no black crap. Some light brown toasting beginning to show.<br /><br />Thanks to all the advice given over the past couple of months.