Weak spark on 1977 Evinrude 75hp -Problem solved!!

BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp

Re: Weak spark on 1977 Evinrude 75hp

Do new coils normally come 'put together' or am I going to have to terminate the wires and install the boots myself?
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

I'm fighting 2 problems now. Water just quit pumping(see my thread on that subject) and weak spark.

Just replaced all 3 coils. Hopefully, I put them together correctly. I exposed the wire, bent it back over the insulation and crimped on a 90 degree plug connector. I did nothing to the other end of the wire...I just screwed the bare wire into the coil stud.

Did a spark test today. Spark jumped 1/2" air gap, but still didn't seem a bright and snappy as my last test when I swapped coils around. It was sunny outside, so maybe I'm mistaken.

Tried to start the motor and it takes quite a bit a cranking to get it to finally start. Doesn't stay running for more than a few seconds though.
I just pulled the plugs and ALL 3 PLUGS are wet and smell like fuel.

Would a bad power pack cause all 3 plugs NOT to fire and/or fire correctly?

I'm frustrated beyond belief right now. Motor ran great the first launch 2 weeks ago and ran WOT for 30 minutes with only a couple small "misses". Now I've got a motor that won't pump water and won't spark. :confused:

It may be coincidence, but the water problem and the "won't start" problems seemed to happen at the same time. Seemed like as soon as I saw the telltale stop peeing water(I was running on muffs), the motor didn't want to start the next time I cranked it over. Motor only ran about 10 secs with no water, so it never got hot or overheated.
 
M

mrcrabs

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Would a bad power pack cause all 3 plugs NOT to fire and/or fire correctly?
Click to expand...
yep, it sure wil.
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

I'm gonna order a new PP in the morning. Is there a difference between the OEM and CDI versions of the PP? Only a $10 dollar diff between them, but was curious if maybe the CDI pack was an improved version of the OEM.

BTW: Is there no diaphragm on my fuel pump? I wanted to order a rebuild kit and there is no diaphragm listed.
http://www.marineengine.com/parts/j...5743S&manufacturer=Evinrude&section=Fuel+Pump
 
M

mrcrabs

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

I'm cheap, Over the years I have replaced several Plastic cased CDI replacement PP with used metel cased OEM power pack because there so many of these engine being parted and I have a buddy in the business and I get them 20-30$ and I have seen alot of junk from CDI and try to spend as little money with them as I can, although I'm pretty sure CDI built the OEM power pack???

The Power pack is the Capacitor source for you capacitive discharge ignition, problems there can have a adverse affect on a coil and I would guess even kill one.

I have a diagram some place of the so called un rebuildable OEM fuel pump
View attachment 139489 here it is.
Someone may know the sierra kit number to use, the one I used before did not have the new hat for the diaphragm but every thing else was there and it worked like a charm....
 
M

mrcrabs

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

It sure is....I didn't even look at it and my memory is short do to advanced age, soon they should let me out of the nursing facility for home visits I hope :eek:
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Decided against ordering a PP until my DVA adapter arrives and I can confirm that it's not the stator or timer base that's the culprit.

Glued 3 spark testers together, so I could check all 3 cyls at once. Spark looks great here and plugs were wet yesterday when I tried to start the motor. Could I be losing the strong spark when the leads are attached to the plugs?:confused:

http://www.youtube.com/watch?v=rjc-E9qwhIQ
 
nwcove

nwcove

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

could be a stupid question , but what plugs are you running?
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Champion J4C. Motor ran great first time out. Second outing it ran well for a minute at WOT then I limped back to the dock.
 
nwcove

nwcove

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

are those the plugs that are spec'd for that motor??? ( my " modern " 1980/1985, cdi motors dont use those, but all my magneto motors do?)
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

mark1961 said:
You should be running Champion L77JC4 or QL77JC4 or equivalent.....gapped at 0.030"

http://continuouswave.com/whaler/reference/BRP_SparkPlugChart2007.pdf

Not J4C.....they are a colder plug and much more likely to foul/misfire and cause hard starting in a motor designed to run on a hotter plug like yours.
Click to expand...

I thought they were one and the same. I could've sworn I checked them online...maybe not. And I've got them gapped at .040.
 
mark1961

mark1961

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

BonairII said:
I thought they were one and the same. I could've sworn I checked them online...maybe not. And I've got them gapped at .040.
Click to expand...

Did you check the link i posted?......definitely not the same.
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

I don't know what the heck I was thinking using the J4C plugs. I'll change them tomorrow.

I'm doubting that the plugs are what's causing my current problems though.

I'm now wondering if I've sheared the flywheel key or something else has thrown the timing off. Of course, as luck would have it...I just returned the cheapo timing light I bought at Harborfreight cause I'm going to order a better timing light(that also does RPM).
 
mark1961

mark1961

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

BonairII said:
I don't know what the heck I was thinking using the J4C plugs. I'll change them tomorrow.

I'm doubting that the plugs are what's causing my current problems though.
Click to expand...

I think its quite possible they are causing you some issues.....on top of the heat range difference, did you know that the J4C are a 3/8" reach plug and the (Q)L77JC4 are 1/2" reach?

You probably dodged a bullet by erring on the side of colder and shorter.....things could have been very different the other way round. :)
 
M

mrcrabs

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

You probably dodged a bullet
Click to expand...
agreed
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Re: Weak spark on 1977 Evinrude 75hp (UPDATE!)

Just did a rudimentary check to see if flywheel key might be sheared. I put a screwdriver in the hole and manually turned the flywheel to get piston at TDC. Timing pointer pointed to TDC, so flywheel key is ok.

DVA adapter will be here tomorrow, so I guess I'll have to wait to do any other tests.

BTW: Mrcrabs, I did end up finding the proper fuel pump kit (part#39313)
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp -New Video posted!

Re: Weak spark on 1977 Evinrude 75hp -New Video posted!

Update:

Changed plugs. One of the Jc4 plugs I had put in was gapped wide for some reason. It didn't look like anything hit the electrode, but it was obviously wrong. Could a weird running condition pulled the electrode on the plug out a bit?:confused:

Anyway, changed to the correct plugs and gapped them to .030. Motor started instantly. The idle is still too high(i need to go over the link and sync again).

I'm STILL having an issue with the new impeller NOT pumping water. :facepalm::mad:

Please check out my thread on that subject, so I can get it fixed and get this darn boat back on the water.
http://forums.iboats.com/showthread.php?t=539664
 
BonairII

BonairII

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Re: Weak spark on 1977 Evinrude 75hp -New Video posted!

Re: Weak spark on 1977 Evinrude 75hp -New Video posted!

Final Update (I hope):

Splashed the boat today to test motor and also try out my new fishfinder.

Motor started easily, idled well, and ran great! :D Apparently, I got the shift rod height correct(using my homemade tool) cause it shifted flawlessly also.

We ran around for about an hour at various throttle settings....and not a single hiccup. Telltale stream was very strong also.

Had my son and myself..12 gallons of gas...tools and fishing tackle onboard, and still got her up to 31mph(in windy/choppy conditions) so that's a speed improvement also.

All that's left is to slap a tach on the motor to make sure it's turning the correct RPM at WOT.
 
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