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Ben Sidaway
Member
Username: ben
Post Number: 22
Registered: 05-2005
| | Posted on Thursday, June 15, 2006 - 07:30 pm: | 
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My Zenith 61 series carb floods as soon as I turn my fuel pump on. Moments after turning the ignition, gas pours out of the air intake. I have cleaned and replaced the throat valve and needle several times. I have even put an inline fuel filter between the fuel pump and carb to cut out any dirt. I now have the fuel filtered in 4 places, the main fuel filter, an added inline fuel filter between this main filter and the pump, a filter in the pump and one between the pump and the carb, so I doubt that dirt is clogging the needle. I did find that one of the floats had sprung a leak so I thought that must be the problem. I have just replaced the floats but I still get fuel coming out of the air intake. The engine won’t start of course until I turn off the fuel valve and pump most of the fuel out of the carb. What’s the next step, I’m thinking I should bend the floats down a bit. The manual says the top of the float should be 9/64 from the gasket when upside down. How critical is this measurement? By how much should I bend the floats down? The needle seems to work, as when the carb is upside down I can’t blow into the bowl through the fuel inlet port. Is there something I’m missing? The engine ran beautifully before I started to commission the boat for the season. I cleaned out the carb since I was having dirt from the tank getting into the fuel last season. Lesson…if it ain’t broke don’t fix it. Any help would be appreciated. |
Richard A. Day Jr.
Senior Member
Username: richardday
Post Number: 338
Registered: 11-2003
| | Posted on Thursday, June 15, 2006 - 08:46 pm: |
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I would take the carburetor off the engine. Remove the fitting connecting the fuel line to the carb. Remove the float and valve that it controls. blow compressed air through the valve seat both from the supply and the bowl side. You need a small tube extension on the air line that permits the air to flush back out the dirt etc. in the area above the valve seat. That works best as it makes sure the dirt is vented back out of the inlet. I would check the valve to make sure it is not pitted or deformed. Seems to me you have something that is keeping the valve from seating. I have had the same problem and I found a lot of residule trash deep in the inlet area above the inlet valve seat. It only takes a tiny piece of trash to keep the valve from seating. |
Brent
Visitor
| | Posted on Thursday, June 15, 2006 - 09:49 pm: |
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I wonder...could this kind of behavior be explained if the shim between the carb & head was missing or angled the wrong way?
You say that it worked fine before you started commissioning...has the angle of the boat changed (e.g., is it in the water now)?
Just a thought... |
Ben Sidaway
Member
Username: ben
Post Number: 23
Registered: 05-2005
| | Posted on Thursday, June 15, 2006 - 11:58 pm: |
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Thanks for the advice folks. I did try putting the wedge/shim on both ways in case I had forgotten which way it went, made no difference. I presume the thick end goes forward since the engine tilts backwards slightly for the prop shaft. I have had the carb off and in pieces probably 20 times in the last few days. I have taken all the ports out and have blasted it with a can aerosol of carb cleaner numerous times in and out of every vent and port. I have used 3 or 4 different throats and needle valves all to no avail. Tip, even with a clean throat and new needle the needle sometimes did not drop with gravity. Moyer Marine (great service, got a new float overnight) recommend polishing the throat with a hard wood stick. I used a chopstick. Still flooded, very exasperating. The solution I found tonight was to bend the floats down. The float I got from Moyer sat about 9/32 above the gasket when upside down, the manual states 9/64 as the distance. So ignoring all that, I bent the floats down to 13/32 (tip, use needle nosed pliers, don’t pull or push on the floats, I think I broke the weld on the top of my old float in doing so when I stupidly tied to make my old float conform to the manual specs). Anyway, now the carb doesn’t flood, engine starts first time and runs beautifully. I don’t know if I got lucky with 13/32 or any gap over 9/32 might have worked. |
len
Visitor
| | Posted on Friday, March 07, 2008 - 06:20 pm: |
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I have just purchased a boat with a Palmer/ c-60 engine with zenith up draft carb. Is there any advice out there as to how the adjust the carb. I see only two adjustment on the carb, one down by the bowl and one up by the chock plate. Thanks. |
Richard A. Day Jr.
Senior Member
Username: richardday
Post Number: 568
Registered: 11-2003
| | Posted on Friday, March 07, 2008 - 08:43 pm: |
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Try the factory setting for the Zenith 61 carburetor. It cannot be too far off to get you running. The small set screw on the top is the idle adjustment. Open one turn. The bottom needle valve adjustment to start try open 2 1/2 turns. open the throttle about 1/4 max. You don't want to race the engine. Slow the engine down to idle speed keep in mind you want the intake manifold warm to the touch before you can do much in the way of fine tuning. Turn the idle adjusting screw right and left until you get the best slow operation with the reverse gear in nuetral. Turning the idle adjustment clockwise (in) makes the mixture richer. Turning the idle adjustment out makes the mixture leaner.
To adjust the needle valve set the throttle about 1/4 but don't race the engine. Turn the needle valve clockwise until the engine noticably slows. Turn the needle valve out until the engine noticably run smoother at the throttle setting. Once you are away from the dock and the engine is under load you can fine tune the needle setting further. Its setting can have a big impact on your fuel consumption and engine performance so be careful not to have it too rich. Just keep in mind the engine needs to be up to operating temperature before any serious adjustments should be made. Be careful not to screw either the idle or needle valve in so hard you ring the points. If you do it will be difficult to make any meaningful sdjustments after that. |
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