1984 mercury 115hp cuts off at full throttle. ..fuel pump???

[Thomas coe]

Took the boat out after work was cruising OK and when I hit full throttle it got onto a plane then it just feel right on her face so when I checked the bulb it felt like there was no gas pumped it up and she started when I hit the gas didn't want to get up and go but when I pumps the bulb when it was going it seemed like it picked back up. Does this sound like a fuel pump issue?

 

[Dekker500]

Yes, it does sound like the pump, especially since you can keep the system going by manually priming it.

You might first want to do a visual inspection of the fuel line first (starting simple) to make sure there is no leak, especially in the section between the bulb and the engine. As the engine sips up the fuel, an air leak would interfere with the small vacuum needed to draw up fuel.

 

[Thomas coe]

Ha I can see some leaking lines already got a pump kit coming and I'm gonna go ahead and replace all fuel lines and bulb. Just gonna replace everything associated with the fuel I think that's a start. And if I get carb rebuild kits do I have to sync the carbs too. Not familiar on how to do that. And the fuel tank I don't think is vented because when you unscrew it to put fuel in it let's pressure out or I don't know what I'm talking about. Thanks for the help. I just got the boat and trying to understand and get rid of all the querks!

 

[444]

Your tank should be vented, there's no good reason for a sealed tank. I would check to see if there is vent, capped or plugged. If not, add a vented cap or tank vent. If the tank was the problem though, your primer bulb would get sucked collapsed.

Any time you take a carb off, you want to do a link and sync on all. It's an easy procedure to do, but there are several steps. If you don't already have a service manual for your engine, get one, the steps will be in there. I suggest a paper copy instead of digital.

 

[Thomas coe]

The bulb is not collapse. Might just buy a new tank then