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During a leisurely ride across Biscayne Bay yesterday I discovered what appears to be a fuel delivery problem with my 1985 60 hp Johnson powered Whaler. The motor ran beautifully as we motored at idle speed through the channel. However, as soon as I opened her up and she began to plane, the motor became sluggish and then dropped power altogether.

Before the day was over several issues became apparent. The most obvious issue involved the fuel hose. Because the motor appeared to be fuel starved, I stopped the boat and unplugged the hose to try and rid it of anything clogging it. I did this several times. After reinstalling the hose the boat would run good for a few moments then lose power again. At one point, after the motor had been running awhile, the bulb on the fuel hose became flat as if the motor had sucked all of the gas out of it. The connections were good.

What component would cause this sort of thing to happen? Could it be a clogged or faulty hose, hose valves, too much oil in the gas, tank float fuel pick up, fuel pump or something else? During the day we also discovered a slight drip from a gas line that was missing a clamp at one of the carburetors. This appeared to be a very slight leak and I am replacing the clamp ASAP. Very little fuel was leaking and I don’t suspect it has anything to do with the performance problem. Am I correct? From time to time I would rev the motor in neutral and it would rev then roughly drop power over and over. This happened several times while cruising under power as well. At one point it almost seemed as if the waves were affecting the performance. But this only occurred a couple of times.

During our run back across the bay, after resting for a couple of hours at Boca Chica, the motor ran better but it still only ran at about 25% of its full power. Any suggestions? The boat is equipped with an under seat twelve gallon gas tank. I am going to add a five gallon auxiliary tank and run the motor with it to see if the problem involves the tank or fuel pick up. This might be an extreme measure to diagnose a simple problem. If anyone is familiar with these issues I would greatly appreciate some advice.

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if the bulb is becoming flat that would indicate that the problem or clog is in or behind the bulb, i once encountered a similar problem with a 4hp johnson, the hose was kinked at the tank fitting, straitened it out and she ran fine.

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I had a similar problem once, it turned out to be that the spring was weak on the fuel line connection hose, try a new, or different fuel hose with new clips (could be the tank "fuel connection" clip too), you might be pulling some "air", or not connecting well to the fuel clip on the motor. The springs get tired in the fuel line, I also noticed that "O.E.M." hoses are heavier and better made than the after market ones. Is the arrow on the bulb facing away from the fuel tank and toward's the engine ??? I ask this because, I accidentally hooked up the fuel line backward's when I 1st got my boat, and it acted much the same way as you descibed your boat's performance recently did. Sound's to me like a bad fuel hose. I would also check the fuel pump diaphragm for pin holes if a new hose does not remedy this (you'll need one anyway). Hope this help's
mw

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...and you may be sucking all the air out of the tank, thus making a vacume. This will cause fuel starvation. Try opening the fuel cap, this should make the bulb re-inflate. That may allow the fuel to flow again. It may be that something has gummed up the vent in the fuel system.

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Your problem is upstream of the Fuel Primer Bulb. First thing to check is the fuel vent. Seems simple, but you'd be surprised how often this happens. Usually, somebody closes it and forgets they did, or doesn't realize it's suppossed to remain open.

If the vent is open, then the next thing to check is the hose between the tank and the primer bulb. Look for kinks (even partial kinks or evidence that the hose has been kinked at some time), or for something causing a collapse in the hose. The reason for this is once there is full flow, a kink or collapse will become a small area of lower pressure and the hose will actually suck itself closed.

If the hose is nice and round for its full run between the tank and the bulb, check the fuel tank pick-up screen. It should be totally clean and free of any debris.

By what you've descibed, one of these three is likely the culprit; something upstream of the primer bulb is restricted.

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I'd be more inclined to say the main fuel hose has deteriorated...your getting more air than fuel...it wouldn't be a bad start to replace the line, bulb(s), clamps...and probably the connectors...they all could be tired after 23 years.

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Don't just start changing parts, as this is the most expensive way to diagnose a problem. If your primer bulb sucks flat, 99% of the time it means that no air is getting to the gas tank. The other 1% of the time a hose is kinked.

Of course, fuel hoses should be replaced periodically, and they do go bad. Usually, however, the failure mode is leaking, not obstructed. Primer bulbs have a simple check-type valve that can go bad, and they also loose their flexibility over time. Go ahead and change your fuel line if you want to, or it needs it, but if your fuel tank vent is closed, the primer bulb will still suck flat.