fuel pump/carb problem ?
 

I took my v out yesterday, started and ran well until I got to my fishing spot. I slowed down and the motor (470 I/O) knocked off. After checking it out I found the carb was flooded, storm was brewing off to the north so I rolled up some paper towels and stuffed down the open throat of the carb and dried it out. I clamped the fuel line before the fuel pump to stop the fuel flow,tapped the carb over the float and finally the fuel stopped coming in. This is the second carb Ive rebuilt and put on it. My question is there a pressure relief in the fuel pump? I guess this could cause my problem. It seems the last owner had the same problem ocassionally. After I got it started it ran back to the boat landing ok, but did it again while moving it into loading position.

Re: fuel pump/carb problem ?
 

Don't sound like a fuel pump to me if you are taping the float area and its ok, sounds like a sticky needle value or a bad float?

When you did the rebuilds did you change the floats and all??

Re: fuel pump/carb problem ?
 

I used the same float but it is a poly float and it seemed ok. This is also a different carburator and still getting the same problem once in a whule. Makes me think it might be a pump pressure relief problem. Ill try and borrow my buddies pressure gauge and check my pump pressure . I cleaned both tanks,installed a new spin on filter and rebuilt carb. Maybe it a piece of trash ? Ill check it all out when I get home from work, 7-3 this week.

Re: fuel pump/carb problem ?
 

Poly floats will soak gas up and give problems too. You may also be having a problem with ethanol in your fuel deteriating your fuel lines or swelling the float or needle seat. Check your fuel system for trash first, and then tear the carb down and check the needle and seat as well as the float very closely.

Re: fuel pump/carb problem ?
 

Yea Ferm, I thought about the ethanol too. I was wondering how it would effect floats,needles and other fuel related parts. Thanks , Ill give it all a good check and let yall know what I find. I think ethanol is gonna give alot of us trouble!Maybe Ive got a float level adjustment problem,but this is the first time Ive had problems with this carb since rebuilding. Ive ran the motor about 20 hours since complete rebuild.

Re: fuel pump/carb problem ?
 

which needle and seat did you use, did you use the spring loaded or the weighted, I use the weighted and set teh level a little lower than spec.. I also like to use a thick base gasket to prevent fuel boil in the bowl> mercury even offered a water cooled fuel line for these engines to prevent perculation in the fuel bowl. If you ever happen to run across a rochester 2bbl carb from an 888, or 898 Mercruiser, grab it, it will fix all your carb problems for idle quaality, perculation, vapor lock, and even give it a little hp boost, it takes a little modification though

Re: fuel pump/carb problem ?
 

I didnt get ta check it out yesterday. I used the spring loaded needle, and I think it has a rubber tip for the seat. I set the float to factory settings. Ill check it out today. Maybe the float is bad or set too high. I might have another needle for it in an old carb kit.

Re: fuel pump/carb problem ?
 

I got into it the other day, changed the needle to a weighted needle and reset my float down a little more. It seems to be ok now. Ill give it a good test this week if it cools off. It was 101 in the shade with humidity at 96%. Man its HOT!

You guys are freakin me out with the ethanol thing. What is it REALLY doin to my OB?

ETHANOL has this wonderful cleaning affect. It may sound good at first, but that trash has to go somewhere. It will also swell many rubber fuel lines made prior to the 90's. For the marine industry it is pretty much bad news. HAWAII got sued over it and they now offer ethanol free gas at marinas. CALIFORNIA was sued earlier this year by 3 different people over ethanol problems, and a class action lawsuit was just brought against several of the large oil company's over ethanol and damage it has caused to boat fuel systems and engines.

Ferm,
What should (or can) I do to counteract this? Please tell me I'm not going to have to rebuild at the end of the year.
Paranoid Boat owner,
BigDaddy

Check your fuel lines, make sure they are newer USCG approved hose. Also make sure you have a good fuel water separator filter, and carry at least 2 spare filters. Also check your fuel lines on the engine. I have read that the clear fuel lines will break apart with ethanol fuel. Another are to address is if you have an older V-20(built prior to some time around 90/91), replace your fuel fill and vent lines as they most likely are not E-10 compatible. The POLY tanks are said to be fine, but the aluminum tanks do give issues as the ethanol will clean ALL of the old black crud out of em that has built up over the years(this is where the spare filters come in). Check your filters often and if any crud shows up in your filters keep changing them out until it clears up. You don't want that crud to make it into your engine.

He speaks the truth...take it from me the fuel water filters are your good friend! I just got finished going through the carbs on my '04 outboard.

Yep, keep them fuel filters clean. I change mine 2-3 times a season. Beats cleaning out the carburator. I just changed back to my original rebuilt carb to try to increase my gas milage. I recently ran the Mercarb on my 170 at Oregon inlet with 5 adults and topped out at 42 mph. Burned a little gas but ran great!!
:sun:

CFelton, whatch out for perculation as well, if teh carb gets hot enough, it will boil the gas out of the float bowl, Make sure you use the thick oem type gasket for the carb base when you install it. Mercruiser offered a water cooled fuel line to ease perculation and vapor lock problems on mercarbs. If you can find one, a 2bbl Rochestor off of an old 888 Mercruiser will fix all your carb problems, it takes a little fabrication, but its worth the effort, easier to start, no flooding, idles better, no heat soak problems