LACK OF POWER

[daldous]

1986 4.3 omc setting on trailer at home starts right up, idles smooth, reves good in or out of gear. Put it in the water reves good out of gear, put in gear and try to accelerate and bogs, sluggish, sounds like the carb is trying to suck real loud, but no get up and go. Have new rotor, condenser, cap, wires, plugs, fuel pump (had leaky diaphram, fuel in clear tube to carb), new filters,(rebuilt carb three years ago ran great until last year)This year just cleaned carb off of engine blew through all openings with carb cleaner and compressed air(didn't lose any balls, two) set float level reinstalled. checked timing several times, set points with dwell meter, checked wires for proper firing order. No help! Whats next?

 

[vipzach]

Re: LACK OF POWER

Welcome to iboats! It sounds like a fuel problem, jsut blowing out the carb may not have been good enough. Did you check the pickup screen in the tank? How did you know where to set the float?

 

[pvisser]

Re: LACK OF POWER

Check for water in gas, or if your water separator is full of water?

 

[JustMrWill]

Re: LACK OF POWER

This problem has been related to many different things...looks like you have looked at most of them...here is a few more-<br /><br />Fuel related:<br />1. anti-siphon valve (the barbed one coming off the tank) - clogged or spring/ball not operating correctly...clean out or replace.<br /><br />2. tank pick-up tube - screen clogged...tube clogged...if this is the case...you probably got some bad gas and tank should probably be emptied and cleaned.<br /><br />***either one of the above can be tested by diconnecting fuel hose from tank and putting it in a fuel container...be careful if you are doing this on the water...gas spills=fumes=big booms.<br /><br />Ignition:<br />Looks like you have replaced almost everything that I have heard cause this...the only thing I don't see is the coil. May want to make sure you are getting the proper spark.<br /><br />Engine:<br />I have heard someone say that low compression/vacuum leaks can cause simular problems. Do a compression test on all cylinders and make sure they are within specs.<br /><br />I am no expert...actually, I am workign through a simular problem (mine bogs down at about 3/4 throttle) so...most of what I have stated above... I found out from reading many posts here. Good luck.<br /><br />-JMW

 

[daldous]

Re: LACK OF POWER

For float settings I have a omc sterndrive manual, also the repair kit I purchased three years ago has some settings, I went with the manual. Have not taken seats out to get to the tank. will do that now. I had stabil in the gas but the problem started last year now the gas is a year old, topped it off before storing to help prevent condensation. Just now getting back to it. May have to drain and start over? Have not tried a new coil. pulled the new plugs they look like they have a little soot(black, like to rich) but not bad.

 

[daldous]

Re: LACK OF POWER

brain fart on the gas tank check. Remove fuel line from fuel pump,put fuel line into container, put air into the tank air vent about four lbs is enough to open the anti siphon valve. You can also checks the anti siphon valve, try to put air into the fuel line none should go into the tank. No water came out of the fuel line suction tube just steady stream of gas. This makes me thing the screen is not plugged? And no water in tank.

 

[bruceb58]

Re: LACK OF POWER

Having that old gas in there is definitely not helping matters.<br /><br />The gas that came out the vent did not come from the bottom of the tank and that is where the water would be. Any water that you get out that way is probably just condensation in the vent hose.

 

[cobra 3.0]

Re: LACK OF POWER

Fuel pump problems?

 

[daldous]

Re: LACK OF POWER

Thanks for all your suggestions:<br />I didn't find any water in gas tank, no water in carb bowl when I took top off again. Did find a vacuum leak in the intake manifold. There is a hole beside the choke tube, part of the plate that bolts on there. It is a hole for something but not sure what. I took a picture of the carb back in 2003 to make sure I got the linkage back on right, the hole was there then. Boat worked good after carb rebuild then, and the hole was still there. I have pluged the hole and runs alot better need to take it to water to see if it helped. How do I post a picture? Can anyone tell me what this hole is for, not shown in manual.<br />Thanks again guys.

 

[daldous]

Re: LACK OF POWER

Update:<br /> Still Stalls on excelleration and won't go.<br /> Vacuum hole is for air to warm up choke spring. Emtied gas tank put in new gas, checked anti syphon ball and pick up screen, 5.5 lbs gas pressure at Idle, filled 16 oz of gas into container in 20 seconds while engine at idle <br />tried a different known working coil <br />bypassed all switches at coil wiring and hot wired ignition<br />had carb rebuilt by carb shop--still stalls on excel.