no fire on top cyl 4hp 1971 evinrude

[outbdnut2]

Resistance reading on coils doesn’t tell the whole story – just like spark plug wires. The insulation somewhere inside may be breaking down and bleeding off your spark. Swap them like has been suggested.
Dave

• This reply was modified 4 years, 9 months ago by outbdnut2.

[crosbyman]

will do but plug wires brand new Belden wire core

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[outbdnut2]

crosbyman wrote:

will do but plug wires brand new Belden wire core

Since plug wires are new, they are probably OK, unless the spark is finding a path where they connect to the coil. dirt or grease on the surface of the coil can neatly conduct spark over the insulation to ground, so inspect that carefully as you swap coils. Most often you can’t see where the spark is going on bad coils due to bad internal insulation letting spark jump to the core laminations.
Dave

[need2fish]

Continuing outbdnut2’s comments — You could try turning the motor over whilst in a blacked out room, to try to catch any leakage.

I have an induction spark plug wire checker. it has a winding and a small neon lamp. Slip it over a spark plug wilre and turn over the motor. It’s not a definitive test, but it could ID a bad wire (and is has to be mettalic wire). Got it at NAPA.

[crosbyman]

guys… everything is new coils .point, . condensers, . mag plate is clean, points are clean & all connections, . using solid wire core 0 ohms boots new …… it just makes no sense

I will swap bottom electricals to the top cyl one piece at a time 🙁 till it fires 🙂 even my old plugs fire ok on the bottom but not on the top cyl.

I tried drill spinning… bottom plug snaps fine top is totally dead even after points ,coil, condenser changed …….

the only common link is the unchanged….brand new Belden wire core plug wire

more tomorrow time permitting ! ( got straddled with an estate executor job which is interfering with my winter hobby 🙂 )

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[crosbyman]

morning update…. bottom cyl fires

top cyl.
points are new & clean ………………………………….no fire
condensers swapped……………………………. .no fire
plug wire & boot replaced with a new one…… no fire
2 different coils……………………………………… .no fire
grounding strap & ring polished degreased… no fire
plug wires loosend up under the mag plate…..no fire (maybe it was crimped…)

to do list………. interchange the coils 🙁 although 2 previous ones did not solve the issue but… I will swap asap …

crows circling above. 🙁 i’ll sleep on it a few days

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[Buccaneer]

Could the points be “grounded” full time for some reason?
Did you do any checks with an ohm meter?

Prepare to be boarded!

[fleetwin]

Grounding strap?? Is this something you added?
Seems like you have swapped everything but the points…I know you said the points are new and clean but there have been a few complaints here about new OEM not opening properly for some reason. Just cuz they are new, doesn’t mean they are any good.
I understand that you “loosened” the plug leads up under the mag plate, but the chance still remains that the wire is shorted or arcing somewhere. Please remember what I said about wire routing by the cylinder head….Cut the new wires a little long until you confirm they are routed correctly and don’t get jammed in the cover latch…

[crosbyman]

ohms tests all good points open and close the ground properly ( tested good on my digital and old style needle meter (Actually a very good old meter with a x1 scale for ohms used by Telco technicians doing Central office relay adjustments when relays were the backbone of the central office)

ground strap is a small thin 3/8 inch stainless bar 2 inches long bolted under the mag plate and it rides on the mag plate ring support underneath …and it does not affect the bottom Cyl… no reason to affect the top cyl… 🙁 I could remove it just to see most oldies I have worked on have no such grounding ..accessory under the mag plate

loose plug wires under the mag plate do not hamper flywheel rotations for now so Ican’t see this as an issue till I find what is wrong 🙁

I am dropping this for a day or two to resync my brain

patience brings joy….it won’t win 🙂

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• This reply was modified 4 years, 9 months ago by crosbyman.

[Mumbles]

Here’s the same mag as on your motor. Pretty basic on top and the only place the plug wire could be worn thru is where the two hold down clamps are on the bottom. The other little strip of metal at the bottom is for grounding.

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