Boat starts out of water but not in it

[t2sunquan]

I have a 1980 200hp OMC that ran, full throttle or idle (planning/cruising on water) for about 30 minutes then all the sudden it just died in the water(it was a very expensive tow), it would not restart but here's the kicker, when i trailered it... it started right up on the second crank. Now today i went to bring it out to the lake and i started it on muffs before i left to warm up the engine, ran fine. I dropped it into the water and it would not run, i checked the carb.. had fuel running down it when i moved the throttle, and spark seemed to be ok. Last month i did a compression check and everything checked out ok, I'm wondering if water is getting into the cylinders while it is the water. It has 35gal of fresh gas mixed with Startron in it too. It just seems like it tries to start then just sputters down and dies while it is in the water regardless of throttle position, I cannot even get it into gear. The carb was also just rebuild a couple weeks ago, along with the fuel lines, fuel filters, and anti-syphon valve, i would imagine fuel pressure is ok as i cranked it over with the hose un-attacted and it sprayed everywhere. I'm pretty much at wits end with this boat.. anyone faced this problem before? or perhaps some insight as to where i look next?

 

[chrisrooter]

Re: Boat starts out of water but not in it

Mis-adjusted fuel float sounds like it could cause those symptoms, you stated you had carb rebuild few weeks ago, did that include a new float? Also where all fuel filters replaced? Also when you stated you had running on muffs that was at idle, with no load. And when you dunked it things changed? What carb are you running?

 

[t2sunquan]

Re: Boat starts out of water but not in it

Carb is a Holley 4160, and yes i bought new floats and the filters are both new(external and carb-side). I believe i diagnosed the problem, upon going down to the marina and just backing up into the water while trailered.. I tried cranking but no go, so after countless minutes of troubleshooting timing, spark, and plugs. I unhooked the under-floor gas tank and ran the hose to a red can with a gal of fresh gas, and to my surprise after a few minutes of cranking the old gas out it fired up and finally ran in the water. I'm wondering if there was water in the tank at the bottom of the fuel pickup and it was sucking that in, or maybe just the angle of the launch ramp with the gas in the tank, either way I'm going to send the tank out to be cleaned and the pick-up checked. In the end, I'm guessing a case of bad gas.. but why it would not run while in water, I may never know.

Though.. last week i was out on Lake Michigan and the waves were very big, I'm wondering if i sucked some water in through the fuel vent. No idea. :fatigue:

 

[chrisrooter]

Re: Boat starts out of water but not in it

Well at least you got some clarity. My grandfather when I was a kid ran a bottle of dry gas with every tank fill up. I think it does not hurt anything but that is some old School thinking. I will tell you I was running an excavator for a small job I had, running great but low on diesel, so loaded up on trailer strapped it down went to fill up diesel from the local station, came back ran for 10 min good, then bogged down hard let off gas and leveled off idle again, could not handle a load, replaced fuel filter no good. Drained all the 25 gal. Of fuel and sample test. Water in fuel. New diesel and perfect again. So water in tank very possible or bad load of fuel. He'll I might start using dry gas myself after this. Might turn out to be very cheap insurance.

 

[t2sunquan]

Re: Boat starts out of water but not in it

the verdict is bad gas. I cleaned the tank out completely and filled with fresh fuel, it runs great now.