5.7 indmar carb problem.
 

Hi,
Upon full throttle from stop the boat seems to have only about 60% power. It then after about 5 sec's hits hard with 100%. You then stop and go again and its the exact same thing. Not really hesitated, seems to run fine but, not all there. Then like a switch is turned on, instantly full power.
Now it just doesnt run. Just tried a new dist. cap. new fuel filter. Now I have the carb off getting ready to kit the carb and Ive read about the oil pressure sensor doing something simaliar to others.?
should I start now with the carb. kit?

Was it bad gas by chance? Did you try running some SeaFoam through it? I'm not sure since it won't run now.

sounds like fuel filter (replace) or bad gas. doens't sound like a clogged carb as you wouldn't get it going to 100% but it couldn't hurt

Wow, thanks for the fast reply's.
Thing is it started doing it end of last season. Its had 10 different fill ups since then.
I put carb clean on the visible carb parts. see fuel flowing from carb. checked the diaframs on the carb.
Its funny how it just hits like a switch being flicked.
i'll put another fuel filter in right now.
Does this oil sensor actually effect the engine running if its faulty?
I see a few have thought to be their carbs and then found it to be the problem.
thanks again.

How about plugs and plug wires? I understand the oil and carb things you have seen. However, from your explanation in the first post it seems like you could also have a plug miss firing or one that has fouled out. I had a similar thing your describing happen to my boat this summer and we checked plugs/plug wires before changing the distributor cap(which was our problem). You never know with these complex machines!

So I cleaned out both floats, inlet line, reset the adjustment screws and float levels.
When I pump the throttle I can see fuel squirting out from both sides fine. new fuel filter.
I had put in a new dist. cap. last year and it looks as good as new.
Wont start, checked plugs and all seem to be firing fine.

Your original post makes it sound like the secondaries arent kicking in. They most likely are vacuum, thats where I would start...

secondaries come into play at hard throttle or with heavy load. Should start and idle if the secondaries were completely plugged

Thats why I had said from his first post....

Good point

Spray some starter fluid down the carb and try to start the engine. If it fires up then you know you have a fuel problem. If it doesn't then it is an ignition problem.

Hi, so I did as above and boat fires up right away. I took some fuel from the carb supply fuel line and tried to light it. It would'nt burn.
looked like just water. siphoned fuel from the tank starting at the bottom. Wow, over 4 gallons came out before I started getting gas.
Ive never in 25 yrs of boating had this happen. inspected the tank for cracks, all hoses connected, cap looks ok.
Somehow alot of water got in there or just alot over time. maybe from the station. who knows but now im aware that it happens just never thought this amount could happen.
thanks to you all that helped out.

Are you a surfer?.. Somes guys have had problems on the tank vent being under water when the weight it for surfing..

What carb is this? Verify secondaries are opening. Check initial timing and check that you're getting full advance at a proper RPM. Timing should be ~10* initial and 32*-38* at 2500-3000 RPM, exact specs depend on the engine and distributor but you should be in that ballpark. May be rusty/stuck advance mechanism. Just disassemble, clean, and grease all pivot/contact points. Good to do this every few years anyhow.

I used to have an older dd and when surfing the vent was way to close to the water line. So the exact same thing happened to me. Drain you tank enough to get it out then completely drain it and inspect for leaks and debris when doing this. Change fuel filter again. Then disconnect fuel lines from carb and turn over engine to get all bad gas out of fuel pump. It helps to hook up a temporary supply of good gas so the pump has something to push old gas out with. Hook everything back up and fill up wih real 100% gas and fire it up