Hard Starting Yamaha F40

[CrestlinerDuckBoat]

Hello Everyone, I bought a boat with a 2000 Yamaha F40MLHY on it. Pull start, and manual tilt/trim. anyways, it was late October when I bought it and of course it was nice and warm when I met the old owner at the lake for a test drive. It fired right up on the first pull and purred like a kitten. the next weekend I went out duck hunting with the boat and it was pretty cold, around 5 degrees and I couldn't get the motor to start, after pulling about 30-40 times it finally popped a few times then came to life after a few more pulls. it ran great after that for the rest of the day, even after we sat for a few hours it fired right back up. but it did the same thing the next morning at the landing, needing a ton of pulls to get it running. I was frustrated, so I ran the motor out of fuel and put it away for the winter. Now I'm trying to get it going this spring and its still doing the same thing, even with the temps being in the 60's its very hard to start. I thought it was just a cold weather issue, but now I'm thinking I have other problems. The old owner told me to engage the prime start I need to open the throttle all the way up, 3 to 4 times. Is that correct? also, should I be checking the prime start solenoid? if so, what's the correct procedure for that? Thanks for your help everyone!!!

 

[rejesterd]

The old owner told me to engage the prime start I need to open the throttle all the way up, 3 to 4 times. Is that correct?

No. The Prime Start system is basically just a wax plunger that gets heated, and slowly expands until it closes the fuel enrichment valve (which cuts off the extra fuel that gets added to the mixture when the valve is open).

However, pumping the throttle a few times quickly will probably help, because that triggers the acceleration pump. So when you open the throttle quickly, it will result in some extra priming action.

But if it takes 40 tries, I would suspect there's a leak somewhere. So I would start by inspecting (and maybe replacing) the primer bulb, the fuel joint, and the hoses that go from the fuel tank to the engine.