1984 70hp top cylinder spark seems off

[HighTrim]

Re: 1984 70hp top cylinder spark seems off

Plugs sound normal, fuel delivery likely good due to their semi wet condition, and the recent carb rebuild.

I am leaning towards the PP, but they are expensive, and dont want to see you waste your money without first testing your current one.

Not a problem at all, good luck

 

[emdsapmgr]

Re: 1984 70hp top cylinder spark seems off

What's the compression reading on the top hole compared to the other two?

 

[wavrider]

Re: 1984 70hp top cylinder spark seems off

I think this site also has dva adapters in tools section, or ebay, all around the same price and well worth the money to diagnose ignition problems, cheaper than throwing parts at the engine.

 

[cmuman]

Re: 1984 70hp top cylinder spark seems off

Compression is 115 on all cylinders

 

[cmuman]

Re: 1984 70hp top cylinder spark seems off

Can I just take the powerpack into the marina without the rest of the boat and get it tested?

 

[Chinewalker]

Re: 1984 70hp top cylinder spark seems off

Do you know of anyone else, preferably a buddy, with the same, or simlar motor? Once, I tested my suspect power pack on a cousin's motor that ran well. When his also exhibited the same intermittent spark issue while underway, I knew my pack was bad. At first, I thought I'd try his on mine, but I didn't want to risk blowing his out if my motor had other issues...
- Scott

 

[cmuman]

Re: 1984 70hp top cylinder spark seems off

no one with similar motor. No such luck.

What was your eventual solution with the powerpack?

 

[Chinewalker]

Re: 1984 70hp top cylinder spark seems off

Being that the problem went from my motor to his motor with the power pack, I replaced it with a new one...
- Scott

 

[ezeke]

Re: 1984 70hp top cylinder spark seems off

It would be a lot easier to borrow an inductive timing light and just see if the firing is correct. Have you cleaned all of your wiring connections?

 

[cmuman]

Re: 1984 70hp top cylinder spark seems off

cleaned spark plug connectors. Is the strip of screws with the assorted colored wires part of the power pack. we cleaned one connection there that looked really yucked up.

 

[cmuman]

Re: 1984 70hp top cylinder spark seems off

Is there a degree mark that I should look for on the fly wheel to check for cylinder 1 firing?

 

[cmuman]

Re: 1984 70hp top cylinder spark seems off

I changed to fresh new plugs. Plugged in my timing light. Started the boat up. All cylinders had steady spark. I could get the spark to jump at least 7/16 of an inch. I then took the new plugs out to check the story on fresh plugs and..... the top one was dry. I already had the carburetor apart and cleaned out passages. I also took out the jets and cleaned them. The float seemed ok. When I took the drain plug out of the bowl, gas came out. Put plug back in. Started engine for a sec. Bowl was full again. I didn't put the carb kit on the carb. Everything seemed clean.

I squeezed the primer on the line today while running, and no change.
All compression is at 115.
Spark seems ok now.
Where do I go next?

 

[cmuman]

Re: 1984 70hp top cylinder spark seems off

I'm not the properness guru. Now that I believe this is a fuel issue, should I post a new thread. Just want to follow correct procedure.

Thanks

 

[wavrider]

Re: 1984 70hp top cylinder spark seems off

carb is full of gas, cleaned all jets, the venturi, brass looking tube may be clogged up and not allowing fuel to get up into the carb.

also link n sync is very critical on the carb set up

carb could be sucking air at the butterflies, try spraying some wd-40 around that top carb and se if it makes a difference maybe bad gasket etc etc

you can also put your fingers into the throat of the carb to richen up the fuel air mixture to see if you are getting any gas at all through the venturi you will be able to feel the gas squirt up on the intake stroke, if you are not feeling any gas on your fingers you are not getting fuel to that cylinder

put some pre mix fuel, same as you run in your tank 50:1 into a spray bottle and spray that into your suspected bad carb see if engine rpm's increase.