One for the books - first time A4 owner - Pulling Hair!

[Rando1201]

Hello, long story short my A4 is misfiring on cylinder 3:

I initially came to the boat after running great and popped on a new carb gasket. After doing this the boat wouldn't start.

After pulling off the carb ten times, I finally got the float set to not flood.

After doing this, I found that I was getting no spark, but I never touched anything related to spark.

I went down to a local marine parts store and picked up a coil that needs a resistor which I installed. Got spark back, I did notice the coil is getting hot to the touch.

I carefully traced each plug wire, they were all correct.

Now I am getting it to start but with backfiring, and rare starts, dying under a load. So I loosened the distributor and set the timing so the motor ran more smooth.

Pulled the carb off again, cleaned the internals of the main jet, spaced that one. Still not too much of a difference.

Next, I looked at the distributor cap, it was a little loose, had to jimmy rig the screws when it was in my garage. Secured tightened.

I did notice that the brass or bronze plates in the distributor cap were scored, like a small groove in them.

Looking further I noticed that the rotor was broken, there is a small groove that holds the little piece of metal on the top of the rotor, so it does not sit in its seat.

Now the engine runs better than it ever has, I mean it must idle at 100 RPM you can barely hear it.

Still, Pulled the plugs #3 cylinder plug is not showing signs of burning like the others, and a very small backfire in gear tied up at the dock.

Went to west marine, picked up the only wire set they had, it was the wrong plug wire type, but I was able to use one to try to see if the plug wire was the culprit, still no change.

I have electric ignition. My next step was going to be buying a new rotor.

Just posting this here to see if anyone has other thoughts on this.

[Al Schober]

First thought is to check your firing order. Might have a couple of wires switched. Second is to check inside the distributor cap for cracks or tracking - spark for #3 may be going elsewhere. If I think of anything else, I'll be back.

[Rando1201]

First thought is to check your firing order. Might have a couple of wires switched. Second is to check inside the distributor cap for cracks or tracking - spark for #3 may be going elsewhere. If I think of anything else, I'll be back.

Yes, I did that, when I was testing spark I noticed an ark hitting the alternator, but when I plugged the wire back in that went away. Im gonna buy the rotor probably from napa and give that a whirl.

[Dave Neptune]

Do replace the cap and ROTOR as a set. The damage to the rotor may of caused a minor crack in the cap and there could be a carbon trail built up inside the cap. I'd also be sure all of the plug wires are fresh too.

You could of easily killed your coil by leaving the key on while working on the problem, easy to do and seen it many times~~turn the key off each time you have tested something or the engine dies.

What was the problem with the float? The float level has a great deal to do with the air fuel ratio.

Dave Neptune

[W2ET]

Maybe take a look at the engine running in the dark?

Bill

[ronstory]

+1 on Dave N's post. I had spend hours debugging various engines behavior and finally in desperation I replace the cap and rotor, and all the weird problems vanished. My rule now is if I'm debugging 'spark', if the wires test out and plugs look good and I have spark direct off the coil, I just replace the cap and rotor.

Maybe some of the C&Rs still had life left in them, but IMO they are cheap vs. your time... and they do wear out.

Also, a few year back I bought new C&R (due to age) for my land rover (buick motor) and the engine ran worse. I returned them an got another set from a different brand and it worked fine. Asking my mechanic about my observation, the mentioned that there were a 'bad batch' of caps floating around about 6 months ago. We looked at a both "good" one versus a "bad" one and could see zero difference. But one clearly worked and the other did not.

I can now see how religions can start. ;^)

[Sam]

Well my strong suggestion is to match the brands of cap and rotor to at least try to minimize mfg tolerances or "intolerances". These parts are not made in volume, local or even in the quality that they used to be. A few years back I had a die/no start situation on a bridge run. I was being towed by another boat untill I matched the replacement cap & rotor. Can't verify but am told the caps with brass contacts from Standard are better than the caps with aluminum contacts from Napa. If you have the time order from Moyer. Relative to backfiring at the dock sure sounds like a 1243 firing order issue or timing?

[JOHN COOKSON]

R\E #3 SPARK PLUG

Switch the spark plugs around and see if the problem follows the suspect spark plug.

ex TRUE GRIT

Edit: Buy parts from MMI then you will know you are getting correct parts. +1 on replacing the cap and rotor. The gap between the rotor and the contact inside the cap is critical.

[Rando1201]

Update. Im kinda running around so ill post more details. I went to napa and got a new rotor and distributer cap. I went to base auto by my house and he gave me champion plugs and different plug wires. I started the motor and had #3 out and confirmed spark. I tested in and out of gear man it really sounds like a sewing machine at idle.

My #1 and #2 are still getting really hot. Should this be something I should be concerned with?

[Rando1201]

My oil smells like gas, maybe fuel got in there from the carb flooding out. I have an electric pump. Theres a leak by the plate which covers the mechanical fuel pump, can't fix that leak for the life of me. Boat runs pretty great now. But I'm new and I'm a bit of a worry wart. I don't feel comfy with the plugs getting that hot after 1-2 minutes of running. I just don't know. My legs are burnt from. Squatting and my knee cap is so sore I have a little limp.

I'm taking a long sail when I get this figured out. And I'm too deep to just pop an outboard on the back.

[indigo]

Make sure the spark plugs are fully torqued. If too loose, they will not transfer heat to the head properly.

[joe_db]

Re the spark plug wires, when I was running electronic ignition I found them to have a relatively short life and it was usually the coil to distributor wire that failed first. It wasn't sudden either, it would gradually get worse.

[Rando1201]

So... I wired the spark plug wires on the distributor cap 1243, but come to find out the order is 1234 from the distributor cap. Runs great very explosive, but I'm seeing blue smoke, also the plugs were around .025, gapped them to.035

[Rando1201]

I am going to check the timing, manually next, not power time. Blue smoke according to what I'm reading is leftover fuel, and there is a bit of a slick coming out of the back.

Just to fill everyone in, the carb was flooding immensely. which for the love of god I finally fixed. Float adjustment.

There is a leak by the plate that covers up the manual fuel pump. Looks like oil.

Ya know, I really hope I wasn't a major dumbass and ran the motor like this. Previously, I was motoring it out of the marina, it had symptoms like trying to stall when going into gear, and less power than I had anticipated.

Now with the wires wired up as 1234 the power is pretty explosive, I can wind the prop out pretty darn good. All the new tune-up parts probably help with that.

Hoping its my timing, really hoping. I bought the boat last april, burned up a summer becuase the keel was sagging amoung other bone head moves I made.

[Rando1201]

Make sure the spark plugs are fully torqued. If too loose, they will not transfer heat to the head properly.

I did that also re gapped the plugs. The problem was the plug wires. Now blue smoke, not a lot but it's definitely smoking. It doesn't smoke with the plugs wired from the distributor cap 1243, but smokes, and runs great with the wiring 1234