1974 9.9 spark problem KIT NUMBER????

[dew2]

The motor is a Johnson 9.9 mod#10E74S The bottom cylinder isnt fireing at low RPMs, it does fire when I increase the RPMs.
I changed the coils same problem.I have gone through it two times, Points,New plugs do help but eventually it gets back to not fireing on the botton hole.
Neighbor has a 1975 9.9 says his low #2 spark plug fouls out often, he carries extra plugs for this reason.Trolling he replaces the #2 plug at least 1 time a day.
Suggestions??? when I put in new plugs it purrs but after 5 min it starts missing and only the #1 plug is fireing at low RPMs.
Compression 96 &93,Points at.20 plugs set .30 kitted the carb.Its that #2 hole not firing?

 

[bktheking]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

What plugs are you running in your 9.9?

 

[Daviet]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

A couple of thoughts.
Use an inductive timing light, the kind that clamps over the plug wire, and see if you actually loose spark on #2 cylinder when it acts up.
I beleave your engine uses a pulse type fuel pump, is it driven off of #2 cylinder? Maybe you have a defective diaphram in the pump allowing fuel the be sucked into #2 cylinder flooding it at low speeds and then at high speed it clears itself out.

 

[Monte1961]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

Neighbor and you take your stuff to the same place for repairs? humm: let me think?

 

[dew2]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

Plug is what is listed UL4J Champ. Monte we have our wives do this while supervise

Daviet Thanks! I did get the timing light out,Tomorrow for that.I was thinking about the fuel pump driven off the #2 cyl Just need that advice because I'm not sure if it would cause a problem.That also will be under scrutiny Tomorrow Thanks Guys, You too Monte huggs and kisses

 

[Monte1961]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

Ok well best of luck to you guys, and were here for you if ya need us! Happy Boating!

 

[bktheking]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

There has been reported success that switching to NGK B6HS will eliminate your fowling issues, this particular ignition system is known to be weak from the factory.

 

[dew2]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

Thanks bktheking I am in town tomorrow and i will get them,Do you feel I should check the fuel pump first?
Anyone know the fuelpump rebuild kit number All I fined is the whole assembly which is #0387027

 

[bktheking]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

Run the motor, pull the pump and check for fuel on the backside pulse hole. If it's leaking you'll see fuel. The kits are a PITA, buy the whole assembly. I don't think it's the pump, I think it's the igition system as has been pointed out in the past.

 

[AlTn]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

if you still have the original sparkplug wires and boots, I'd suggest at least pulling the wire and coil from the boot, trimming the wire back 1/4 to 1/2in. and reinstalling the coil end and boot...wd40 makes the removal easier...that last bit or the plug wire on both the sparkplug end and ignition coil end really get corroded over the years

 

[dew2]

Re: 1974 9.9 spark problem

Re: 1974 9.9 spark problem

if you still have the original sparkplug wires and boots, I'd suggest at least pulling the wire and coil from the boot, trimming the wire back 1/4 to 1/2in. and reinstalling the coil end and boot...wd40 makes the removal easier...that last bit or the plug wire on both the sparkplug end and ignition coil end really get corroded over the years

Will Do Thanks off to town