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I have had this happen twice in the past week...I will be running at about half throttle for about 10 minutes or so and when I hit some medium waves, the engine starts starving for fuel. The last time it happened, I noticed that the primer bulb on the fuel line was completely collapsed and I had to loosen the water drain on the fuel/water separator to let air in to allow it to pop back to normal. Any ideas?

-chris

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I assume you are runningn on an internal tank, I'd check the vent on the tank, bugs etc can cause tank not to vent properly.

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It is an internal tank...the only vent I am aware of is right below the filler cap on the side of the boat. I will check that and see if it has become an insect condo.

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how old is that primer bulb? for that matter, how old are your fuel lines? I would start by replacing the primer bulb.

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The primer bulb is in its second season and the fuel lines are new as of this year. The fuel filler tube and the vent are the only "old" lines running to the tank. The tank is aluminum too if that matters.

thanks

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Ok, here is an update on the issue. I cleaned the vent screen on the side of the hull and went out this evening and ran for about an hour at mid throttle with no problems. I then slowed down and idled through a harbor with no problems. When I throttled back up leaving the harbor, it was running good for about 5 minutes and then it began to starve for fuel and collapse the primer bulb. As soon as it began I tried opening the fuel filler cap but it didn't seem to help at all. The primer bulb remained collapsed but the engine sputtered along but didnt stall. I then loosened the drain plug on the fuel/water separator and the bulb immediately popped back into shape and it ran fine for about a minute and then stalled out completely.

I am guessing that letting the air in through the fuel/water separator caused the fuel line to lose its prime and it lost the fuel. I have a new primer bulb coming tomorrow that I am going to try because when I went to reprime the fuel, I had to squeeze the bulb about 20 times before fuel started to fill the bulb.

All of this is new this year but so is the fuel/water separator. Are there issues with where these should be mounted, etc. Just thinking that its the one variable that changed since last year.

I am hoping that its not an obstruction in the pickup tube but if it is, what are my options? The tank is aluminum and upon inspection inside, it looks very clean.

Any help on this would be greatly appreciated.

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And this is on your Evinrude?

Are you using 3/8" marine fuel line?

Did you replace the fuel line from the tank itself to the new fuel/water separator?

This may sound dumb but do you have the correct direction of the fuel from the fuel/water separator to the engine?
This usually shows arrows for the direction the fuel should go...

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This is on my 1979 Evinrude 150. I ran a new fuel line from the top of the tank to the fuel/water separator...so the whole fuel line is basically new. The primer bulb assembly was new last year...I'm replacing the bulb just to rule out a defective check valve.

I checked the arrows on the fuel/water separator and unless I am reading it wrong, I have that hooked up correctly. However, I am going to try and find the installation instructions and re-read them just in case. Its a Moeller Clear Bowl Water Separator...it has 2 inlets and 2 outlets...I used the plugs they provided for the one side since its a single engine setup.

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And it is all 3/8" fuel line?

-> IN
OUT -> (to engine)

I know these sound dumb but you do need to double check it.

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Oops...yes it is all 3/8" fuel line and I've got the in arrow coming from the tank and the out arrow going to the primer bulb assembly and then to the engine.

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OK... That's good.

I would think if you still have problems, you might try disconnecting the fuel/water separator and using a straight fitting between the hoses and try it without the fuel water separator. (only temporary)
Just to see if something is wrong with the fuel/water separator.

Or try an external tank.
I have an external 6 gallon tank I use for such purposes.

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I was thinking the same thing...I had installed it because I got water in the tank last fall but I've got all of that removed so I'll try a barbed fitting between the two and see what happens. One thing I failed to mention is that the new fuel line is longer than the old one by about a foot. Not sure if that matters but its worth mentioning.

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It sounds like the fuel pick-up in the tank is getting clogged or blocked from debris particles that may be moving around in the belly tank as the fuel is being sucked in. Only other thing could be a blockage in the fuel filter itself. I assume the engine fuel pump is good?

You might want to remove the fuel pickup, and shine a light in to see if there is a lot of crud in the tank.

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If the bulb is collapsing, then the problem is most likely upstream. It sounds like either a clogged fuel filter, clogged fuel line between tank and filter, or clogged intake screen. Try the small fuel tank to positively identify the problem as up stream of the bulb.

Also, next time the bulb collapses, pull the fuel line to the tank off at the filter and blow back into the tank. You may be able to clear the crud or confirm the obstruction is up steam of the filter.

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I had ths same thing happen to me a few weeks back. My fuel tank is on the deck though. I changed out my fuel cap to one that had a better air vent. That stopped the bulb from collapsing. My fuel hoses and bulb are new. If there is a way to check your fuel tank vent, that may be the problem as mentioned above. Good Luck.

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I have struggled with this same problem. I just re-hosed my entire boat including carb lines. I used clear fuel line for the carbs and the line to the vacuum switch. I fired off the engine after the install and I noticed that the fuel to the vacuum switch would flow to the switch during prime then fall, leaving air for about three inches above the main fuel line at the "t". Should this component be acting more like a one way valve to purge all air? What does it do? the engine runs on the muffs yet I haven't taken it to the water yet.

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Sure sounds like a clogged fuel filter.

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Also, guys running a 5/16" fuel line from the filter to the engine don't need to change over to 3/8." A 150 hp can get all the fuel it can possibly burn through a 5/16" line.

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Blackduck,

That is not what my Evinrude Owners Manual states....


Coop has an Evinrude 150 which is why I mentioned 3/8" fuel line.
So he wouldn't be changing over, that is what it should have.