first test drive today, got problems.

[sti1471]

I just got a boat from a guy basically for free.

I got a 1983 Mercury 80, thunderbolt ignition

I hooked the motor up to the flush muffs and started the engine and it runs fine. I can rev the motor fine, and when I put it into drive or reverse idle, it works fine.

I got it onto the lake today and turned it on and it ran perfect. I rev it up in neutral and everything is good. However when I shift into gear, the engine kind of "jerks" into gear and the water starts "bubbling" as the prop starts and the boat moves about 4 feet in gear idle, but then it stalls, same for reverse. The engine starts right back up, but when put into gear again it stalls. I tried putting it in drive "idle" and it dies, I tried putting it in drive and then throttle up, and it dies.

It dies slow enough it sounds as though it is choking out. When it is in neutral on the flush muffs, it idles around 2000 RPM, so i adjusted it last night and when I reached the lake it idled at 1000RPM. Since it was dying, I adjusted the "idle stop" until the idle reached 1500RPM and it still died in gear. While it is idling, the engine sounds as though it idles GREAT, but AGAIN, I am a boat noobie. Every now and then it sounds like there is a small "cough" or "sputter" while it is idling in neutral.

I removed the spark plugs last night and all 4 of them had a very small amount of liquid on them that on the rag lookd to be oil/fuel and inside the spark plug hole it smells like gas.


While I was out I noticed something very odd. It will idle for about 5 minutes and die as though it is not getting fuel. so I pumped the primer and it will pump about 1.5 times before it is hard again. After pumping it, the "bulb" stays deflated so i cannot pump it again. I removed the gas tank cap, and then the bulb inflates. This happened several times. it is like it is sucking all the air out of the tank as if it is air tight. I am a noobie to boating, but this does not seem normal. if I remove the gas cap every 3-4 minutes the engine never stall in neutral idle.

Lastly, when I have it out of water on the flush muffs, i shift it into drive idle speed, but right when it is on the verge of shifting into gear, I can hear the motor making a slight "ticking" or "grind" noise that I can feel on the throttle lever, and then pops into gear and the prop turns fine. Same goes for reverse. I just replaced the gear lube, and when filling it up, it only took about 16 fl oz. before it was coming out the vent plug, I would imagine it took more then that, so I thought that sound when going into gear might be low gear oil?

I am going to make adjustment any one suggests, and take it to the lake tomorrow for another test.

Thanks in advance everyone!!!

 

[Coloradolakeboy]

Re: first test drive today, got problems.

I just got a boat from a guy basically for free.

I got a 1983 Mercury 80, thunderbolt ignition

It will idle for about 5 minutes and die as though it is not getting fuel. so I pumped the primer and it will pump about 1.5 times before it is hard again. After pumping it, the "bulb" stays deflated so i cannot pump it again. I removed the gas tank cap, and then the bulb inflates. This happened several times. it is like it is sucking all the air out of the tank as if it is air tight. I am a noobie to boating, but this does not seem normal. if I remove the gas cap every 3-4 minutes the engine never stall in neutral idle.
!

You have a fuel restriction. Is your tank vent open? If you have a vent tube instead, check that is not clooged with mud goggers nests. Your fuel filter or pickup tube screen could be clooged.

 

[CharlieB]

Re: first test drive today, got problems.

You have a number of things to sort out.

As already pointed out, check the fuel tank vent, fuel pickup tube and fitting for any restrictions limiting fuel flow.

Idle mixture may be set too lean, readjust the carb idle mixture screws to best idle speed while on the hose PLUS almost 1/4 turn out (CCW), then rest idle speed to about 1000 RPM. This should get you close enough to get it in gear once out on the water, there you should readjust the idle mixture to best idle while IN Forward gear PLUS almost 1/8 turn out to provide the additional fuel necessary for crisp acceleration. Test acceleration, any hesitation, even the slightest, back out (CCW) each idle mixture screw just the width of the screwdriver blade slot, retest, readjust to perfection.

Shift quickly and fully into gears, do not try to 'ease' it into gear, they are straight cut engagement and solidly drop in, idle speed once in the water should be reset to 750 to 800.

Gearcase oil MUST BE filled from the bottom drain hole, squeeze, or pump in the oil til it begins to come out the fill level. Oil must be filled from the bottom to push out the air, filling from the top usually will NOT fill the case and you will end up running with a very low oil level and can damage the upper bearing, the metal fragments will then soon take out the gear set.