Mercury 2.4 200hp Dies in Gear.

[jbwillis76]

Hello all,

Long time Force owner, new Mercury owner. This may be long so please bear with me. Little history:

Just purchase a 1996 Javelin 4090 TE bass boat, separately purchased a 1986 Mercury 2.4 200hp outboard. The outboard had a new powerhead installed last year and the motor has around 10hrs on it. Installed the motor and went for a test run. Motor had a 23" Laser prop on it. The tach doesn't work and I'm still waiting on the new one to arrive so I don't have any RPM numbers for you. Set the motor 3.25" below pad, with a 6" manual jackplate. Motor ran GREAT and GPS speed was 65.6 MPH.

All was great, brought the boat home and did the following to it:

Changed props to a 25" Tempest Plus and recarpeted the entire boat.

Started the boat on the muffs today and it started and revved up perfectly just as it did before. Took it to the lake and it started and idled fine. Put it in gear and tried to ease into the throttle and it died. Started back up instatly. Put it in gear again and give it any gas and it will die. It would idle in neutral indefinitely. Got it to where it would BARELY go in forward then die like it was running out of gas, but would start back instatly and idle perfectly.

Brought it home and put it back on the muffs and let it idle in gear for about 5-10min with no problems, also revved with no problems. Took it back out to the lake, same problem as before.

Checked and I have spark to each cylinder (just used timing light). All plugs look the same, little oily but normal for a 2 stroke. Checked compression and have 130 on all cylinders.

There is an idle advance?? box on the top of the motor and the red wire coming from it broke at the switchbox and is not connected, the other wire from the advance is still hooked up. I cannot remember if this was hooked up on the first time out on the lake or not. I read to remove the box anyway.

Anyone have any ideas as to why this thing runs and revs perfectly until I put it under a load (in gear) in the lake??

Sorry for the long post, just wanted to be thorough. Thanks for the help, James

 

[j_martin]

Re: Mercury 2.4 200hp Dies in Gear.

That's pretty normal. Idle needs to be set, on the water, in gear at 700 rpm. You need a tachometer, a screwdriver, an end wrench, some flat water, and a life jacket.

It needs to be set on the lake. How deep the leg is in the water, and the propeller all makes a difference.

hope it helps
John

 

[jbwillis76]

Re: Mercury 2.4 200hp Dies in Gear.

It doesn't die instantly. In fact it will idle in gear (doesn't sound great, but does idle). When I give it throttle it dies. If it doesn't die it bogs and doesn't increase in RPM, even at WOT position.

Do you still think it is as simple as a setting idle RPM issue?

Again, I can't think of anything I did differently to the linkage/motor since the first run instead of changing props. I did idle it down some since the first run because it was idled a little too high in gear which caused loading and docking trouble.

Thanks for your help.

 

[j_martin]

Re: Mercury 2.4 200hp Dies in Gear.

It doesn't die instantly. In fact it will idle in gear (doesn't sound great, but does idle). When I give it throttle it dies. If it doesn't die it bogs and doesn't increase in RPM, even at WOT position.

Do you still think it is as simple as a setting idle RPM issue?

Again, I can't think of anything I did differently to the linkage/motor since the first run instead of changing props. I did idle it down some since the first run because it was idled a little too high in gear which caused loading and docking trouble.

Thanks for your help.

The propeller affects the engine load at all speeds, including idle. That's the problem. Without a tachometer you're blind as a bat.

If the module on top that is broken has one red and one yellow wire on it coming from screws, it's the voltage regulator. If it has 2 or more wires going to the switchbox, it's an advance module. In either case, completely disconnect it to avoid trouble. Either one can cause major headaches, but especially if crippled.

BTW, the answer would be the same on Screamandfly.

hope it helps
John

 

[jbwillis76]

Re: Mercury 2.4 200hp Dies in Gear.

Thanks JM. I will disconnect it and do a lync and sync and see what that does for me. I've found that posting at several different places usually gives the fastest answer along with different opinions.

James