75hp 4 cylinder plug wires arcing!!

[Mercs and such]

On my 75hp 4cylinder 1984 merc, (observed at night), plug wire # 3 & #4 seemed to be making contact with the throttle arm and discharging along the whole length of the wire and then discharging completely around the outside of the sparkplug without supplying spark to cylinder 3,4 However, it runs in idle on #1,2 cylinders. When i put a load on it in forward in the water, it dies almost instantly

any suggestions? diagnosed CDI ignition and have taken kill wire off of switchbox, new stator, and trigger.

 

[achris]

Re: 75hp 4 cylinder plug wires arcing!!

Replace the plug leads.....

And all the spark plugs while you're at it (unless your useless mechanic has already done it... Like I believe that!! )

Chris....

 

[Mercs and such]

Re: 75hp 4 cylinder plug wires arcing!!

I tell you what achris, its one thing after another!! I fixed the problem with the mechanic and raised a fit and walked out of there with nothing more than a few get the f*@% out of here!

Now, i have noticed that the top carb is wet ( receiving fuel) however, the bottom carb is dry as a rock i then squeezed the bulb as far as it would go and pulled the line and gas spewed out without any going into the bottom carb After replacing the #3,4 cyl. plugs (ones with gaps, not flat) When i sprayed some gas into the bottom carb, it seemed to gain rpms rapidly, burn it off in a big cloud of blue smoke and then drop in rpms when it was burned off.

So, i then neoprene painted the plug wires and then let it volcanize and then applied electrical tape to it. It worked!! no more misfire at high rpm pickup point!

but, i'm still stuck with the carb that gets no fuel and only runs on top 2 cyl. for idle only.

what's the best suggestion??? i need to get that carb flowing that will fix all the problems

 

[achris]

Re: 75hp 4 cylinder plug wires arcing!!

Hi,

I think I need a bit of a baseline here...

Tell me what you took the engine to the mechanic for... Then tell me what he told you he did (should be on the invoice).

Also you should put NGK BUHW-2 plugs in... Those engines are designed to run on plugs that don't have a heat range (surface gap).... The results with a 'normal' electrode gap plug could be 'unfortunate'.

Obviously you need to find out why bottom carbs not getting fuel... Pull the carb and check it out...

Chris..........
Glad you fixed the leaky leads.

 

[Mercs and such]

Re: 75hp 4 cylinder plug wires arcing!!

Hi,

Tell me what you took the engine to the mechanic for... Then tell me what he told you he did (should be on the invoice).

Also you should put NGK BUHW-2 plugs in... Those engines are designed to run on plugs that don't have a heat range (surface gap).... The results with a 'normal' electrode gap plug could be 'unfortunate'.



thanks ok so i took the engine to get the timing set on it because it was way off. Furthermore, i had it to figure out why it was not getting spark.

on the invoice, all it says is labor, and stator

obviously, they had to link & sync the engine when timing, they claim the switchbox was bad however it was just a bad ground. I think they weaseled a stator out of me because it seemed fine before just a matter of taking the kill wire off switchbox to restore spark. Anyways, whatever now i have a fresh stator and i have a great feeling that i payed more for labor than the part isn't that lovely? i will use the ngk plugs there on the top 2 right now i was just using the gap ones because they get spark to inside of plug without grounding. but now i just want the motor running and i think it all boils down to the carb not being timed i don't know for sure though

 

[achris]

Re: 75hp 4 cylinder plug wires arcing!!

thanks ok so i took the engine to get the timing set on it because it was way off.

How do you know the timing was 'off'?

Furthermore, i had it to figure out why it was not getting spark.

Was that before you took it to the mechanic or after it came back?

on the invoice, all it says is labor, and stator

Did you ask for the old stator back? Even though you paid for a new one, you still own the old one and if he throw it away, he shouldn't have, it's still yours.

obviously, they had to link & sync the engine when timing,

No. Changing a stator won't upset the timing.

they claim the switchbox was bad however it was just a bad ground.

Seen that before

I think they weaseled a stator out of me because it seemed fine before just a matter of taking the kill wire off switchbox to restore spark. Anyways, whatever now i have a fresh stator and i have a great feeling that i payed more for labor than the part isn't that lovely? i will use the ngk plugs there on the top 2 right now i was just using the gap ones because they get spark to inside of plug without grounding. but now i just want the motor running and i think it all boils down to the carb not being timed i don't know for sure though

I think you need to get the service manual for your engine (NOT clymer or seloc, they are good as hand wipes and that's about all), get the genuine Merc manual.... Part #90-861344. It'll cost you $81 but will pay for itself very quickly (www.mercruiserparts.com/partsByNumber.asp)

Chris....

 

[Mercs and such]

Re: 75hp 4 cylinder plug wires arcing!!

sounds good i have the clymer manuel and i will try to figure it out. I do still have my old stator so i did keep that and there was no spark when i left it with the mechanic. the piston was not at TDC when the flywheel was put on.

i will look into that manuel a bit pricy but hey, how can i say that when i wasted $200 on something i could have done myself

 

[achris]

Re: 75hp 4 cylinder plug wires arcing!!

Hi again Merc....

I think may be you have the wrong concept of how the ignition timing on an outboard it handled....

Most people understand a car (4 stroke) ignition and carb systems... You set the initial timing (usually around 8 BTDC) and the weights in the dissy handle the advance curve, or the engine management computer for later engines. Once the initial timing is set you adjust the carb mixtures and idle speed... With me so far?

An outboard sets the idle speed with the timing, not the carbs.

An outboard is a bit ars-a-bout... First we set the carbs up... we make sure they are fully closed and (for multi carb engines) opening together at exactly the same time. Next we check (and adjust if necessary) the timing pointer on the engine flywheel. Then we set the MAXIMUM advance on the timing. This is done by removing the spark plugs, opening the throttle to maximum, cranking the engine and checking the timing position... Then we set the primary pickup point. This is where the carbs get picked up as the timing is advanced when advancing the throttle. Once all that is set, we adjust the idle speed by retarding the timing, usually to a few degrees ATDC. Lastly we adjust the carb mixtures and reset the idle speed (by adjusting the retarding of the timing) if necessary...

Just on adjusting mixtures... adjust them on the rich side. Get the engine sounding right, then richen the mixture screws 1/8 turn more. The reason for this is that with no accelerator pump in the carbs the engine will bog/stall on acceleration... If that does happen, you know the mixtures need richening a little...

Hope this helps you (and explains why I was curious as to why you thought the timing was off).

Chris............

 

[Mercs and such]

Re: 75hp 4 cylinder plug wires arcing!!

achris, ok it sounds about right! i get the whole timing thing now and i noticed the plugs were very wet or i believe fouled I need to adjust the idle mixture screw on the carb but before i do any of that i need a new float/inlet needle kit because the other float is saturated after that, the carb should get fuel and she will be running fine.

thanks!

il keep you updated!