Fuel supply problem, need advice????

BerettaMan · 03-21-2010, 07:36 AM

20' NR Scout with 150 2 stroke VMAX. Two days ago went to run back up river and was low on power maybe 50%, primer ball felt soft (acted like there was air in the system). Swapped primer ball with kicker and then big motor ran great.

Two days later with brand new primer ball had the same thing happened after sitting on the hook for a few hours. Stopped the boat and pumped the heck out of the ball then the boat ran good. Motor has only 60 hours so I doubt is is a fuel pump problem.

Does anyone have any thoughts on what could be causing this?

Thanks, Jeff

Okie · 03-21-2010, 07:55 AM

Just a long shot but is the gas cap vent open? If there is a vacum in the tank it will cause the problem you have.

Good Luck

goatram · 03-21-2010, 09:00 AM

Might be the Gas With ethanol in it. Check your filter. see if any stuff comes out when you drain it.

BerettaMan · 03-21-2010, 09:03 AM

I always use the marine Stabil stuff, could the Yamaha 10 mic fuel filter be clogged? Its got around 30 hours on it.

goatram · 03-21-2010, 09:25 AM

Takes a couple of minutes to take it off and check. I would check both. I think it will be the big filter that is bypassing the fuel because it is Clogged. Trash is catching on the oneway valves in the bulb

BerettaMan · 03-21-2010, 10:54 AM

Quote:

Originally Posted by goatram

Might be the Gas With ethanol in it. Check your filter. see if any stuff comes out when you drain it.

Just drained the fuel filter and it looked good. A few pieces of debri but thats it. I will install a new filter but I am thinking it is something else.

bluechevyy · 03-21-2010, 11:50 AM

I had a similar thing going on with my boat recently. I had my primer balls sucking flat. I opened the floor and took out the connection to the fuel line an popped out the anti-siphon ball in the fitting and reassembled. Problem gone! This is also what caused my fuel pump on my large motor to fail after only 3 years. Don't need the anti-siphon valve as there is one in the primer bulb also.

Good luck!

BerettaMan · 03-21-2010, 02:30 PM

Quote:

Originally Posted by bluechevyy

I had a similar thing going on with my boat recently. I had my primer balls sucking flat. I opened the floor and took out the connection to the fuel line an popped out the anti-siphon ball in the fitting and reassembled. Problem gone! This is also what caused my fuel pump on my large motor to fail after only 3 years. Don't need the anti-siphon valve as there is one in the primer bulb also.

Good luck!

Thanks for the info. What exactly is the check valve for? Do most built in tanks have one?

MegaByte · 03-21-2010, 02:40 PM

If you are running gas bought from other than a marina, you most likely are a victim of ETHANOL! I will eat the fuel lines, actuallly disintergrate the black rubber fuel bulbs, actually eat the aluminum of a float bowel and do more fuel related damage than you can believe. Call any marine repair place and they will agree. Are you running STABIL or some other additive? If not you should! I had a 25 Johnson and had the same issues as you. The fuel system was totally messed up as a result. You may have other issues, but I am pretty confident its the "Ethanol Syndrome".

trap50 · 03-22-2010, 04:53 AM

My motor had 40 hrs on it. $896 later and no mor E10 in the tank it runs great again. I used stabil all the time. Injectors filters and gas line.