Mercury 200 acting up......again

[.44mag]

S/N: OG724176

Yesterday my son took the boat out. Said he had to "saw" the steering wheel back and forth to get on plane. As the worecon he let his buddy drive and he would sit 9n the front deck to get the boat on plane. They took the cowl off and found the bolts holding the low pressure or pulse fuel pump were loose and fuel was leaking out. They tightened every thing up but still had planing issues and said it wouldn't g even t over 4500 rpms. Today since I was off I rebuilt the low pressure pump, I noticed that two plug wires were knocked loose from the cdms. I put them back on. 0umped the bulb and fired it up on the muffs all seemed fine. Took it to the lake to run it and went about 300 yards cranking the steering wheel back and forth before it would plane out. It was only getting to 2500 rpms. It finally broke over and would only reach 5000 rpms. I did replace the stator a few weeks ago, but only the stator as all else tested fine at the time. The main fuel line/bulb and fuel filter were replaced a month ago.

Compression is 119 to 120 on all six cylinders. Do I look into the fuel system more or the electrical side now?

[JOE54]

spark on all 6 , plug fouling ?????

[.44mag]

20210707_140042.jpg starboard/right side. Top plug on left.
20210707_135951.jpg left/port
Probably wouldn't hurt to replace them. Did find one cdm not firing replaced it.

[JOE54]

you fixed it

[EuropeanAM]

Make sure that all cylinders are now firing, as often it is not the CDM you "think" is the culprit (it can actually be one that IS firing in many cases).

That being said- this engine came with ADI ignition (coils). Might have had a transplanted CDM ignition system or powerhead at some point, though.

[.44mag]

Make sure that all cylinders are now firing, as often it is not the CDM you "think" is the culprit (it can actually be one that IS firing in many cases).

That being said- this engine came with ADI ignition (coils). Might have had a transplanted CDM ignition system or powerhead at some point, though.

Put my spark gap tester on all six, set at 7/16th gap good spark as far as I can tell. The original power head was OG129892 I bought this one to replace it when the number 1 rod bearing let go. Also when I went to get a new fuel filter the guy behind the counter said that my power head was supposed to be carbureted but it is efi. So what would the timing spec be set at for idle and wot? I don't like this cdm stuff have contemplated on swapping the original electronics onto this.

[JOE54]

Make sure that all cylinders are now firing, as often it is not the CDM you "think" is the culprit (it can actually be one that IS firing in many cases).

That being said- this engine came with ADI ignition (coils). Might have had a transplanted CDM ignition system or powerhead at some point, though.

+1 grnd path fault in another cdm can cause this

[.44mag]

+1 grnd path fault in another cdm can cause this

Will look at the grounds and cdm's Friday when I get off work, maybe Saturday when I have all day. I'm guessing there would be an arc path if the cdm itself is arcing to ground? Oh any idea which other cdm may affect the number two cdm?

[EuropeanAM]

CDM ignition has two "banks"- 1-2-3, 4-5-6 as I recall. As such the return ground path for #2 is 4, 5 or 6. When stop circuit diodes fail/short weird things start happening.

REALLY simple though... and IMHO a more reliable system since the stator pretty much works, or doesn't.

If you have spark on all 6 now, you should be good to go on the CDM's.

Recommend 4 ATDC for idle timing (spec is 0-9 ATDC), CRANKING speed WOT timing would be 24 BTDC (which results in 18 BTDC @ WOT RPM's).

[.44mag]

Ok thanks

[.44mag]

CDM ignition has two "banks"- 1-2-3, 4-5-6 as I recall. As such the return ground path for #2 is 4, 5 or 6. When stop circuit diodes fail/short weird things start happening.

REALLY simple though... and IMHO a more reliable system since the stator pretty much works, or doesn't.

If you have spark on all 6 now, you should be good to go on the CDM's.

Recommend 4 ATDC for idle timing (spec is 0-9 ATDC), CRANKING speed WOT timing would be 24 BTDC (which results in 18 BTDC @ WOT RPM's).

Between work and rain I haven't been able to do any thing. The spark plugs I was sold are NGK BPZ8HS are these correct? I have the next seven days off when I get off in the morning and plan on and plan on checking the timing an what not.

[JOE54]

BPZ8HS-10 for cdm ign

[.44mag]

BPZ8HS-10 for cdm ign

Yes they have -10 on them

[leonreno]

10 just means the gap is per set for the motor, you should check the gap anyway, you can buy them without the -10 a gap them yourself.

-10 is 1.0 mm which is .04 inches, that’s the preset gap.

[EuropeanAM]

10 just means the gap is per set for the motor, you should check the gap anyway, you can buy them without the -10 a gap them yourself.

-10 is 1.0 mm which is .04 inches, that’s the preset gap.

AKA: .040" GAP

[.44mag]

Set the gap at .040. Ran the boat this morning, well tried. If I floored it to get on plane it would just bog out. Yes trimmed all the way down. If I eased in to it the bow would lift then it would bog out and fall. Found a wire on the solenoid loose tightened it up. Rechecked grounds and put back in the water. It seemed it idled a little better but would only reach 2000 rpms even if I eased in to it. What to check next.

[JOE54]

need fuel psi test under acceleration

[.44mag]

Ok will have to rent a fuel pressure gauge.

[.44mag]

Wow couldn't find a pressure guage any where today, just my luck. Did find that the fuel pump in the vst is running for 20 to 25 seconds key 9n engine off. That's to long isn't it?

[JOE54]

no sir