1977 Johnson 85HP, manual tilt/trim on 18' Larson open runabout.
Ran this thing down stream today for a mile or so before getting to the open water, free of the no wake zone. Went to hit the gas, outboard powered up just fine for a few seconds, then just as I was getting on plane it died.
Hmm, this is not good right there in the channel with 30 foot Scarabs flying around
. It took several tries to get it started again. Once it caught, same thing all over again, get above 2500-3000 RPM, it runs strong then dies.
So the weird thing I've noticed this season but not paid much attention to is that the primer bulb in the fuel line *never gets hard*. You can squeeze that thing until next Tuesday and it never firms up like the OE bulb did.
Keeping this in mind (and mind you, I'm still floating out there in the channel with two kids and a wife wondering if we're going to make it back) I took the fuel line connector off the engine and squeezed...nothing came out. Yes, the built-in tank was full to the tippy top!
Next, using my Leatherman tool I removed the fuel connector (engine side) and squeezed. At first, nothing, but then I heard/felt something in the bulb "click" and the next squeeze I got some fuel. Connected everything back up, squeezed the bulb -- it still didn't get hard -- started the engine. Still wouldn't run at full power, but I was able to idle back to the dock and pull it out of the water without incident.
So, my theory is that there's something wrong with the check valve(s) in the primer bulb that is cutting the fuel off. The tank was taken out of the boat last season and cleaned up -- I had dropped something in it when changing the fuel gauge sending unit. No signs of rust forming, and the pick-up was clear. I'm guessing that the fuel pump is able to draw enough fuel in through the check valves to keep it running at an idle, but when big fuel demands come up the bulb shuts the flow down and the pump can't refill the carburetors fast enough. When it dies, it feels just like it has run out of gas. It's hard to explain, but my sense is that it isn't ignition.
Anyone seen anything like this before? The carbs were rebuilt a couple of seasons ago and only saw about 10 uses since then. The boat has had some trouble this year with stalling, but it has also run fine at open throttle for extended periods, so I'm pretty sure I don't have an ignition problem. The fuel lines under the motor cover were all replaced with stuff that can handle the ethanol in today's gas at the same time the carbs were rebuilt...basically the only thing I didn't do was change the fuel pump.
The trouble is it's hard to know if I have it cured before I take the 20 mile trip out on the water. It runs fine on the muffs. Should I do both the fuel pump as well as the hose/primer bulb?
Ran this thing down stream today for a mile or so before getting to the open water, free of the no wake zone. Went to hit the gas, outboard powered up just fine for a few seconds, then just as I was getting on plane it died.
Hmm, this is not good right there in the channel with 30 foot Scarabs flying around
. It took several tries to get it started again. Once it caught, same thing all over again, get above 2500-3000 RPM, it runs strong then dies.So the weird thing I've noticed this season but not paid much attention to is that the primer bulb in the fuel line *never gets hard*. You can squeeze that thing until next Tuesday and it never firms up like the OE bulb did.
Keeping this in mind (and mind you, I'm still floating out there in the channel with two kids and a wife wondering if we're going to make it back) I took the fuel line connector off the engine and squeezed...nothing came out. Yes, the built-in tank was full to the tippy top!
Next, using my Leatherman tool I removed the fuel connector (engine side) and squeezed. At first, nothing, but then I heard/felt something in the bulb "click" and the next squeeze I got some fuel. Connected everything back up, squeezed the bulb -- it still didn't get hard -- started the engine. Still wouldn't run at full power, but I was able to idle back to the dock and pull it out of the water without incident.
So, my theory is that there's something wrong with the check valve(s) in the primer bulb that is cutting the fuel off. The tank was taken out of the boat last season and cleaned up -- I had dropped something in it when changing the fuel gauge sending unit. No signs of rust forming, and the pick-up was clear. I'm guessing that the fuel pump is able to draw enough fuel in through the check valves to keep it running at an idle, but when big fuel demands come up the bulb shuts the flow down and the pump can't refill the carburetors fast enough. When it dies, it feels just like it has run out of gas. It's hard to explain, but my sense is that it isn't ignition.
Anyone seen anything like this before? The carbs were rebuilt a couple of seasons ago and only saw about 10 uses since then. The boat has had some trouble this year with stalling, but it has also run fine at open throttle for extended periods, so I'm pretty sure I don't have an ignition problem. The fuel lines under the motor cover were all replaced with stuff that can handle the ethanol in today's gas at the same time the carbs were rebuilt...basically the only thing I didn't do was change the fuel pump.
The trouble is it's hard to know if I have it cured before I take the 20 mile trip out on the water. It runs fine on the muffs. Should I do both the fuel pump as well as the hose/primer bulb?
