Merc 200 Idle Trouble

[Shameful1]

Does anyone have any ideas as to what the trouble might be??

I was out in my Eliminator on Friday and it was running great all day. I headed back to the marina around 4 pm and the motor started to idle high ( it would not come down under 1300 - 1400 rpm. So I idled out a ways and wacked the foot throttle and it ran great on top end but still would not idle right. It's a stock 1986 Merc 200 with a 1992 power head. I have removed the oil injection.

(I changed the throttle cable the weekend before, but the motor ran great for two days before this started)

So I opend the cowl and tried to adjust the idle, thinking the new cable might have stretched and needed adjusting. Nothing worked, in fact it got worse as I ran up and down the lake. Now it won't idle at all under about 2500 rpm, it still runs OK on top end (I can get it started in gear and keep it going and it seems to be fine at high rpm's)

I was thinking possibly the stator, I believe it has a high speed side (above 2000 - 2500 rpm?) and a low side (from 0 to about 2500 rpm?)
Chasing an electrical problem really sucks, I hate to just buy and replace parts at random, Has anyone ever experienced anything like this before?? Any help would be great. I don't think it's fuel or carburation, it came on all of a sudden.

Thanks, Steve

[WATERWINGS]

I had a switch box go bad on a motor I had just rebuilt, and it would shoot the R's to the moon when I cranked it.

After thinking that I had an air/intake leak, (and pulling it apart a couple of times) I was told to change BOTH switch boxes, and the problem was gone.

Don't know why BOTH, but I had a bunch laying around, so thats what I did, and it worked.

I think I switched the stator a time or two also, (thinking like you), with no change.

[MadTing]

Check the pickup timing screw. If the lock nut is slack, the screw will backout and advance the timing. Also check that the trottle linkage is not broken from the trigger assembly.

[WATERWINGS]

good ones.

[rock]

MadTing is right on. Make sure all timing screws are tight. Make sure trigger is able to move freely. I doubt trigger linkage has broken free from throttle or you would not have full throttle operation Check to be sure carb linkage is cool. Just got a motor from a board member that he said ran good and found stator had broken free from top bearing housing and was binding the trigger. It would not idle below 1500 because of this. Those are probably the most likely problems. Short of that be prepared to pull some hair out. Hate chasing electrical gremlins. Good luck.
Rock

[rock]

Make sure your throttle plates are closing. Seen a chunk of insulation from cover come loose once and got caught on throttle plate.Good luck
Rock

[Shameful1]

Thanks for the info, I will check everything you guys have suggested. Called my friend who owns the marina and ran the problem by him, he thinks it's possible that I have lost my fuel pump, or at least the diaphram for the low speed psi. Any thoughts.

Thanks again, Steve

[MadTing]

If the fuel pump diaphragm is bad you will get one cylinder running rich, and fuel mixed with exhaust draining through the gearcase. Plumb a pressure gauge between the fuel pump and carburetor and check the pressure. Should be about 2psi at idle.

[opti]

You need to replace both switchboxes because the bia circuit in switchboxes which controls the timing has failed and has advanced the idle timing OPTI

[WATERWINGS]

But if ONE goes bad, how does it affect the other?

If you replace the bad one wont that solve the problem?:confused:

[31Cigarette]

Shameful1,

I just went through a similar situation with my 87 Merc. 220 efi.

It started out stalling when I would bring the throttle back to an idle. If I would push the throtle up as I shifted into gear it would run as long as I kept the throtle reved up.
The following day when I was getting ready to leave the dock it would not start.

I got out my shop manual and followed the procedure to test the stator useing a multi meter and found no reading on two of the leads.

With some questions answered by members here I ordered the new stator and a flywheel removal tool and changed it myself.
It was easier then I thought it would be and the motor runs great.

Not sure if it is the same as your problem but worth a try testing with a meter.

Cordell

[31Cigarette]

I am getting this information out of my service manual for models
V-135 Thru V-225
With serial numbers. United States 5464486 and up

STATOR TEST

Two types of stator assemblies are used on V-6 models.

Type 1 stator assembly is without a black ground wire, and the stator is grounded directly to engine thru the stator mounting plate.

Type 2 stator assembly has a black ground wire, and the stator is grounded to engine thru the black ground wire.

IMPORTANT: STATOR MUST BE GROUNDED TO ENGINE.

1. Remove 2 screws and lift outer switch box from inner switch box. Refer to switch box9es0 removal and instalation, following.
( this is all it says under switch box removal....... Remove 2 screws and lift switch boxes from engine. (retain round metal spacers) 2. disconnect wires from switch box.)

2. To test, disconnect blue/white and red/white stator leads from outer switchbox and blue and red stator leads from inner switchbox.

3. Use an ohmmeter and perform the following test.

Between Blue and Red Stator Leads
Resistance (Ohms) ***5400-6200
Scale Reading (x_____) ***5.4-6.2 (RX1000)

Between Blue/White and Red/White Stator Leads
***5400-6200
***5.4-6.2 (Rx1000)

*Between Red Stator Lead and Engine Ground
**125-175
**125-175 (Rx1)

*Between Red/White Stator Lead and Engine Ground
**125-175
**125-175 **(Rx1)



*If stator assembly has a black ground wire, make sure that black wire is grounded to engine.

**Stators with PN 398-5454A34 stamped on stator should indicate 65-75 ohms.

***Stator with PN 398-5454A34 stamped on stator should indicate 4450-4650 ohms.

4. If meter readings are other than specified, replace stator assembly. Refer to stator assembly removal and installation.

CAUTION...SWITCH BOXES MUST BE GROUNDED TO ENGINE BEFORE CRANKING ENGINE, OR SWITCH BOXES WILL BE DAMAGED.


I hope this will help you find you problem.
Cordell