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My motor has been cutting out. I can ride around 4000 rpm on a calm day and it will run just fine. When I increase the rpm I can ride for a few minutes and then it cuts down as if fuel starved. I can then pump the primer bulb and she start running again and then a few minutes later cut back down. I can have someone sit at the back and pump the bulb and she'll run without cutting out. I'm trying to solve this issue. Another thing I have noticed around the same time this happened is that trying to fill the gas tank is a pain. It will take a quarter of a gallon and then the pump cuts off, it takes forever to fill up.

I've been reading a lot online. Here are my thoughts. I may have an issue with my vent. It may be the primer bulb. It could be the anti siphon valve. I could have a hole in one of the fuel lines allowing air in... Or it could be the fuel pump.

Last night I replaced the thru-hull vent connection. I went with an Attwood 90 degree style, which is suppose to get rid of the need for the loop in the vent line. I cut out the extra vent loop and installed the vent line directly to the attwood vent. I am able to blow in the vent and then have the air push back out of the tank. So I don't think the vent is blocked. I'll be on the water this weekend for the NFGFC tourny so I'll see if this helped the problem at all.

Next, I wanted to go ahead and replace the Anti Siphon Valve and the Primer Bulb since they are relatively cheap fixes. Here is something I don't understand. I took off the Anti Siphon Valve and the Primer Bulb. All of my gas lines have 5/8 listed as the size. I took my bulb and valve to West Marine and they do not carry a 5/8 bulb or siphon valve. I've been searching online and I can't seem to find one. I'm now scratching my head, how do I replace these parts when I can't find the size I need. I must be missing something. I even placed my primer bulb up next to the ones at West Marine and I confirmed that the three sizes they did have were all smaller then the bulb I've got. Anyone got any advice on this...?

After I find out how to replace the primer and the anti siphon, if the problem is not fixed, I plan to replace the fuel lines from the engine back to the bulb, bulb to water separator, separator to tank. I can't replace the vent or gas fill line without finding some place to cut a hole in the deck, there is just no access.

THANKS!

Not a mechanic here, but sure sounds like you have a restricted fuel line -- probably caused by ethonal. The vent problem sounds like a second problem, maybe mud dobbers have the screen plugged up? Ethonal basically slowly melts the inside of "None ethonal rated" fuel surfaces -- hoses -tanks- carb parts. As the fuel starts flowing at a higher rate, it's picking all the crap up in the line and closing off the flow!! Just my $.02 ?????????????????

Isolate the problem first, run it on a portable tank with new hose and bulb that way you have totally removed all the variables of the boat's fuel supply system and can also know that it is not an on engine filter or fuel pump issue. Conversely if you still have the problem running off the remote tank then you have an engine side problem. Course I guess you could have both but lets start positive Quick, easy check and not much cost involved especially if you have or can borrow the remote tank.

Some boats have an access plate to the fuel sending unit etc. so you may be able to eyeball the AS valve, and part of the vent hose anyway. Any trash in the filters that might be related to the hose breakdown issue CT mentioned?

If you are getting 4000 rpm consistently with no problems I would think an air leak is pretty much out of the question as it doesn't take much of an air leak to shut the engine totally down (been there done that with a pinhole in my fuel separator).

Age of boat/engine?

I would look at the line and bulb closer. I've heard of a 3/8 and a 5/16 line and bulb, but never a 5/8

I'll take a look at the line again. It can't be 5/8, I cannot find anything online about a 5/8 hose...

Boat and motor are 2009. 2009 Suzuki 115 Four Stroke.

Now that I think about it. A 5/8 line is the size of a water heater hose on a car No way you got a fuel line that size

Rainman wrote:I'll take a look at the line again. It can't be 5/8, I cannot find anything online about a 5/8 hose...

Boat and motor are 2009. 2009 Suzuki 115 Four Stroke.

2009 boat would have ethanol rated fuel lines (A1 rated since it is underdeck) so that probably takes out another potential issue... 5/8" fuel lines are available (see below) but I would think 5/16" is way more likely from the tank to the fuel/water separator... should be marked every foot or so and of course the sizing is id. Boat builder may have used what they had on hand that day or were allowing for rigging a Seven Marine engine so who knows

http://www.defender.com/product3.jsp?pa ... &id=106431

I had this same problem about 6 months ago. My problem ended up being the anti siphon valve that is connected to the fuel pickup tube. It is a 90 degree fitting on the top of my gas tank. Inside this fitting is a pinball that is suppose to float when gas is flowing and fall when it is not. My pinball got stuck at the top due to corrosion. This only allowed a small amount of gas to flow through the motor. I could idle and be half throttle all day but nothing else. I also could use the primer ball to force the fuel through. I tried several things before giving up and finally taking it to Porter's Marine. Mr. Porter himself found this problem and I am very thankful.

Not being able to fill your tank up at the station could be another problem. I am not sure if you have a key largo but, i know they are famous for not taking fuel.

Thanks for all the replies. The lines were 3/8 not 5/8. The 5/8 was the size for the vent hose... I was able to replace the bulb and the anti siphon valve. Ran the boat all day for the NFGFC tournament and it worked great, no more issue! We were able to pull out a 4th place finish. It was a tough day for catching slot fish.