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Pertronix burning sparkplugs

S

stoner

Contributing Member
"Hi. I bought a pertronix kit

"Hi. I bought a pertronix kit for my omc (ford) 2,3L marine engine. Why does the ignitorII and flamethrowerII 0.6ohm. coil burn my cylinder #2 spark plug? I thought is was working good but when we drove about 20 min.s it burned the plug. I changed the plug and run about 30 min.s and then the plug was burned again.30 min.s and again. What`s causing this problem. When the plug is burned it`s like it`s dropping voltage once in awhile (stumbles). It`s a crap to dock the boat when it`s stalling at lower rpms.because of the stumbling."
 
"I would give that cylinder a

"I would give that cylinder a "Leak down test". A spark plug will only use as much as it's rating. So you can put up a lot of voltage and if everything is right, it will keep going. Would suspect a valve or vacuum leak.

Is the plug comming out white / melted/ black/ or lots of carbon?"
 
"The cylinder head has only ap

"The cylinder head has only approx 10h. on it after the rebuild. The plug comes out white, the other still working plugs are little black.
Just came to my mind that I`ve read on the pertronix site that I can`t use copper spark plug wires, I have supression cables so that would be ok. The plugs I`m using is recommended plugs for my engine Champion RS12YC but they are copper plugs, could that be the problem?"
 
I agree with william g moore

I agree with william g moore

only 1 cylinder doing it? 3 are fine. It's not likely the ignition then. but Double check the firing order.
If the timing and firing order are correct I would suspect a lean condition due to incorrect valve adjustment on that cylinder.
 
I pressure tested the cylinder

I pressure tested the cylinders today and came up with approx. 160 Psi. on every cylinder. Tryed to mess with the idle mixture screws and got it working little better(but still a stuble now and then). I showed the plug to my no1. spare parts dealer and he told me that it`s running lean and told to check pressure because of any valve failure. The valves can`t be adjusted at all on this engine. The carb is rebuilt 1 1/2 years ago. On higher rpm. the engine seems to run good but driving at 1000-1500 rpm. the engine stumbles. Any more ideas?
 
have you done a vacuum test li

have you done a vacuum test like cheif has suggested? your spark plug has to be overheating to look the way you described. So either that cylinder is running lean or not cooling properly futher investigation into the engine may be needed
 
How do I do a vacuum test? Sra

How do I do a vacuum test? Sray some gas on the carb. and have the fire department behind me???
 
"Thanks for the ideas, I`m goi

"Thanks for the ideas, I`m going to buy or borrow an vacuum meter and try to test with that."
 
"click on the link i and mike

"click on the link i and mike posted. read and re-read it, it shows the gauge, and what each problem will look like and please post the result so we can help you.

good luck !"
 
I tested it today and connecte

I tested it today and connected the vacuumgauge to the intake manifold. At idle the gauge indicates 0.5bar/ 7.25psi and when pushing it to wot it is approx. 0 and then going to 0.9bar/ 13.05psi and then to 0.5bar/ 7.25psi at idle. I can`t find out what`s the correct pressure. The link you sent to me/ web page where I can find out what trouble I`m having don`t say what type of pressue the reading on that gauge is.
 
"'Forget' about the ac

"'Forget' about the actual pressure reading, and concentrate about how the gauge (needle) behaves under different scenarios. Then go through the different possibilities on the web link and see if You may find a behavior that fits your engine."
 
"Maybe the pressure is shown &

"Maybe the pressure is shown (on that web site) in inch of mercury? If the reading is right, the needle stays almost at the 0.5bar all the time just a little bit of shaking like the scenario3 with high power engines but not that much of shaking. When the engine stumbles the reading goes rapid down to 0.4bar and rapid up to 0.5 after the stumble. So it`s like scenario1/normal eccept for that stumble. When pushing the throttle the needle goes to zero then down to appox 0.9bar and back to 0.5bar, like scenario2.
Do anyone have any ideas?"
 
"I have a converter but I don`

"I have a converter but I don`t know what type of pressure is on that gauge on that web site how to read vacuum gauge.
Are the readings good or bad, do I have a problem?"
 
"Now I found it. The gauge is

"Now I found it. The gauge is showing the pressure in inch of mercury. So that 0.5bar=14.75, 0.4bar= 11.81, 0.9bar=26.57."
 
"The readings seems ok. The mo

"The readings seems ok. The most important is that You do not have too much flickering or pulsing, but rather stable. Being a marine engine it is considered a bit 'tuned up' compared to a std car engine, which night explain the slightly low idle vacuum. If possible, keep the meter on and do a run 'under load'. That may reveal if You have a hanging valve that occurs after some time running."
 
"I think the engine could have

"I think the engine could have bad piston rings but i don`t think it would stumble like the issue is now, what do you think? I use 95 octane unleaded gas in it or 98 octane, whatever is available at the marine fuel station. The timing is set to 10 btdc. I`ll try to set it to 12-13 tomorrow and see how it affects the engine. But could a retarded timing cause this stumble? If it doesn`t help I`ll pull the carb. for some cleaning. Do you have any advises for cleaning a carb. properly?"
 
"is the plug white, like brand

"is the plug white, like brand new white? maybe its not firing when it stumbles. If brand new white, measure the spark plug wire with an ohm meter. hold the test leads to both ends of the spark plug wire and shake it. It could be broken inside and working sometimes & not other times. Depending upon the brand, it could range from 3000 to 5000 ohms for each foot of its length. you could also measure one of the 'working' plug leads to see what 'normal' is for that brand."
 
"I measured the spark plug wir

"I measured the spark plug wires and they were all about the same but not broken.
When I connected the ohm meter to battery- and a wire that was connected to + the ohm meter "beeped" (got ohm reading). I took the + wire off the battery terminal and it was still "beeping". Tryed at the fuse holder under the dash (+ and -) and it "beeped". It stopped "beeping" at the fuse holder when I disconnected the main plug between engine and dash. But still "beeping" at battery or engine. I disconnected the coil, esa and the diode fix but still "beeping". The ohm reading at battery- and the disconnected battery+ wire was 25ohm. Should it be this way? Or is there any other device that give ohm readings between - and + eccept the coil?
This is/ I`m getting weird."
 
Niklas...I don't understan

Niklas...I don't understand this line

When I connected the ohm meter to battery- and a wire that was connected to + the ohm meter "beeped" (got ohm reading).

It almost sounds to me like you put an ohm meter across the battery???
 
"Ohm meter - wire to battery t

"Ohm meter - wire to battery terminal-, ohm meter + to any wire connected to the + side with the main +wire disconnected from battery terminal+.
I made it sure I don`t take a reading across the battery by disconnecting the +wire from battery terminal."
 
I asked a professional electri

I asked a professional electrican and he told me it`s normal that the ohm meter beeps when connected like I did.
But I`m still having this stumble problem with the engine.
 
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