84 Merc 200HP - Won't Accelerate Past 3400RPM

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Charlie,

Thanks for the reply. I started in replacing some of the more damaged wires this evening. I have spliced them and soldered the connection and if it hadn't been for the AC service man coming by tonight I'm sure I would have gotten them all replaced this evening.

As for the idle control module, I removed it this evening. I have read a few different places that after removing the idle control module you need to set the WOT timing to 23.5 degrees, but I have yet to find a detailed procedure for doing so.

Again, any help and comments are greatly appreciated.

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Update 6.15.10

I have spliced new wires and soldered the connections where needed to replace the severely damaged wires coming down from the stator.

I'm wanting to give it a water test to see if anything has improved.

Question for the pros: I have removed the idle control module, but have not reset the WOT timing to 23.5 degrees. The timing has not been adjusted. Would it be safe to give the boat a water test and test this engine after simply removing the idle control module?

 

[CharlieB]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Set WOT timing while cranking with the starter.

Remove all the spark plugs to reduce the load on the starter.

Ground all the spark plug wires, rig paper clips, alligator clips, etc., and wires to a good ground(s).

Remove the prop or be VERY CAREFUL of the spinning prop while cranking.

Use a remote starter button to trigger the starter relay/solenoid.

Rig your timing light on #1 plug wire.

Set throttle control to WOT in Forward gear.

Hit the starter button, crank the motor and observe the WOT Timing, adjust as necessary.

WATCH OUT for that prop if you didn't bother to take it off!

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

CharlieB I really do appreciate all the help. I'm going to owe you a case of beer when this is all over

 

[kawidad]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

this may not be the problem but i have a 1986 200 meerc and if i would idle out of the no wake zone with my motor trimmed all the way down it would build up back pressure and when i would gas it to get on plain it would only go to about 3400 rpm because it was building to much back pressure and fouling plugs and it didnt look like they were fouled

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Update 6.21.10

**

I checked the stator leads against the Seloc manual today. Here are the results I obtained.

It should be noted that all of the stator wires were removed and loose while tests were being made to reduce the possibility of interference by other components. If this was an incorrect method of testing, I will retest.

Readings were taken with a bargain-basement digital multimeter but before tests were made readings were taken against known good resistors in my electronics repair bin with accurate results.


Between Blue & Red Stator Leads


Manual Scale | Manual Reading | Observed Scale | Observed Reading

Rx1000 | 4.5-6.2 | 200k (Digital) | 92.0


Between Blue/White & Red/White Stator Leads


Manual Scale | Manual Reading | Observed Scale | Observed Reading

Rx1000 | 5.4-6.2 | 200k (Digital) | 29.5


Between Red Stator Lead & powerhead ground


Manual Scale | Manual Reading | Observed Scale | Observed Reading

Rx1 | 125-175 | 200 (Digital) | 162.6


Between Red/White Stator Lead & powerhead ground

Manual Scale | Manual Reading | Observed Scale | Observed Reading

Rx1000 | 4.5-6.2 | 200 (Digital) | 164.1


I also measured the White/Blue wire to powerhead ground on a 200k scale with a observed value of 28.0

The Blue wire to powerhead ground on 200k scale with observed value of 86.0

The two yellow rectifier wires were taken loose from the rectifier and mesured with red test lead to yellow wire / black to powerhead ground. The top yellow wire was measured on a 200k scale with observed result of 26.0 The lower yellow wire was measured on a 200k scale with observed result of 28.2


The yellow wires (seen in photos above) were brittle and cracked. I cut them as close as I could to the stator without removing the flywheel. I do not currently have a flywheel puller for this engine but will be ordering one as soon as I can find a decent price for a quality tool.

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

post above edited to correct numerical error.

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

*bump*

still hoping someone can give me some advice and information on my stator.

 

[sschefer]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Test your stator or have it tested. Sounds like the high speed coils are shot.

 

[dirtdiver]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Is it a Rochester Carb? they're known for warping, That would let it suck air in. Check then points, and under the plate that the points sit on is the mech advance, if those are sticking it will cause you a lot of head ache. Good news is thats a smiple fix.

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Is it a Rochester Carb? they're known for warping, That would let it suck air in. Check then points, and under the plate that the points sit on is the mech advance, if those are sticking it will cause you a lot of head ache. Good news is thats a smiple fix.

Thanks for the reply, but I think my engine runs a different type of ignition system. Unless I'm wrong, there's no points to check on this:

Type III Ignition - Thunderbolt Flywheel CD (One Coil Per Cylinder)


I guess I'm pretty much at a standstill until I can get the flywheel pulled and make a visual inspection of the stator. I'm leaning towards the high side of the stator being bad, but despite numerous searches I haven't been able to come up with a description of the wire colors for the stator.

I know that the two yellows are for the charging circuit to the rectifier, but the blue, blue/white, red, red/white are still a mystery to me. If someone could enlighten me on the functions of those, I believe I would have a better understanding of how my engine works.

 

[j_martin]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Red, blue, and ground are one tapped charge coil. R/W, B/W, and ground are the other tapped charge coil.

Here's the bible on troubleshooting.

http://www.cdielectronics.com/downloads/troubleshooting guide/Mercury 6 Cylinder.pdf

hope it helps
john

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

John,

Thanks for the reply. I will be doing some reading tomorrow.

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Ok. The flywheel removal tool finally arrived today and with a little help from my Dad I was able to get the flywheel removed and the stator pulled.

I took the stator to my electronics repair room and used a higher quality analog meter to check the stator resistances as described at CDI's Troubleshooting Guide

The red wires are within spec of an OEM stator.

The blue wires are WAY out of spec.

Instead of reading 5000-7000 ohms, one blue wire is reading nearly 200,000 ohms and the other is reading in the neighborhood of 15,000 ohms.

The Stator is model number: 398-5454A6 and I have found the CDI replacement here at iboats for a very reasonable price.

Before I purchase the new stator, I was wondering if any of the experts here have any other suggestions on testing this stator.

Like most of the mercury stators I have read about, this one is encased in a hard plastic shell which would appear to make repairing and/or inspecting the individual coils impossible.

Thanks again and I do appreciate all those who have taken the time to lend me a hand with this problem.

 

[CharlieB]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

wcsd106
I sent you a PM

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

wcsd106
I sent you a PM

I'll be watching for it. It hasn't shown up yet.

 

[j_martin]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Yer stator would drop 3 cylinders for sure at high rpm, so replace it.

hope it helps
John

 

[tswest]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

I have a 150 84 merc and it would do the same thing. Ran great but WOT was only 3600 rpm's. Idled fine and started great. Smoked very little. My advice would be check your compression. I had 110 on 5 cylinders and zero on the number one. I got lucky because I have found no damage that can't be fixed. I would check it before I spent anymore time chasing problems.

 

[wcsd106]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Update: Installed New CDI Stator - Now NO Spark

My new stator arrived from Iboats yesterday and I have finally had a chance to get it installed. The new stator tested good on my ohm meter, and I have gotten it hooked up just like the old one was.

Now I am having a problem of not getting spark. I have pulled all of the spark plugs except for the #1 cylinder and have grounded each of the plug wires to engine ground. (I was going to check the timing)

I remembered hearing once that if the stator was installed one hole off you would not see spark, so I pulled the flywheel again and turned the stator 1 hole clockwise. Still no spark.

Before I replaced the stator, I had spark, I was just having a problem at higher rpm.

I tried calling CDI, but they are closed until Tuesday in observance of Independence Day.

Anyone have any ideas? Thank You.

 

[asm_]

Re: 84 Merc 200HP - Won't Accelerate Past 3400RPM

Someone correct me if I'm wrong. but doesn't those motor is capable of running without stator connected? I know my 74 Thunderbolt can run off the battery power.

B