Spark issuse solved, now low compression in one cylinder

[CaneCutter79]

I have an ignition problem and I need to determine if it's a coil going bad or failing power pack? See issue below.

My motor ran great last weekend and has been all summer. I got a tune up last fall, new plugs, etc.

This morning, the starter gear failed to disengage and made awfull noises. I fixed that issue and got the starter gear working correctly and when I started the motor up, it would not rev up very high or get on plane. It acted like the fuel mix was wrong and smoked a lot.

My fishing partner sat on the front of the boat trying to help it get on plane because it had no power. I typcially turn 5,000rpm at WOT. I couldn't get past 4,000 this morning.

After fishing for a few hours, I started the motor to head back and the motor ran fine. The boat jumped out of the hole, hit 5,000rpm and ran great like it normally does. About 100yards after hitting 5,000rpm the motor suddenly dropped to 4,500 so I slowed down to turn around and when I did, I couldn't get it back on plane again.

So my partner sat on the front again and we eventually got it on plane again and then it jumped to 5,000rpm. On our way to the dock, the motor dropped to 4,800 for a few seconds and then back to 5,000 again. As my partner was getting the truck/trailer, I ran down the lake by myself and the motor operated correctly. Quick hole shot, 5,000 at WOT.

Now, my boat mechanic says the starter gear and ignition problems are unrelated but I mentioned it anyway just in case.

 

[Rscardina]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I'm no expert but if you are bogging at WOT then high speed jets in the carbs may be getting plugged or blocked by debris or something in your fuel line.

the smoke is usually an idication of rich running. So again carbs and fuel. Unless you have a VRO, in which case the smoke is usually a sign of air leaking in the fuel side.

My recomendations would be to look at fuel seperators first (replace of neded), then decide how old the gas is (replace if needed), then be sure you have good compression, and spark..

After that..then consider carbs kits for the engine..

 

[mikesea]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

What engine HP.My immediate is a coil,possibly a ground to it,or dirty connections on the small wire or the plug wire.A pack will usually drop a whole bank ,either port or starboard,a coil classic RPM drop is 4-500 RPM depending on the HP or 4-6 cyl

 

[Rscardina]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

mikesea...read my post about my mystery prblem...maybe you can help me too..

as far as coils go, yes mike is right on that, but the reason i thought fuel was the intemittent issue (which could be wires too)..but not knowing year, model and hp.. I always look for fuel..

let me know how you made out

 

[jonesg]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Year, HP and model number helps.

Too late now but on the water its easy to troubleshoot by feeling the head temps, if one hole isn't firing it will be cold or a lot cooler to the touch, then you at least know where to look. That coil or that particular carb.

If its a clogging carb you can easily do damage by forcing the issue at WOT.

If its intermittent spark then try running it up to temp on the hose and see if it drops spark to one cyl, feel if all cyls are getting warmed up.

Do a spark test with an adjustable spark tester set to 7/16th inch gap.
Spark has to jump the gap, see directions for spark test in the top secret FAQ files.
http://forums.iboats.com/showthread.php?t=299680

Try spraying pre-mixed fuel into the carb throats.
If it bogs down the carb is ok, if rpm suddenly picks up its starving.

This assumes you can get it to act up on the hose at temp.
Don't rev the snot out of it on the hose, just in case you don't know.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

What was I thinking....I forgot to include the motor specs.

1979 Evinrude V4 85hp Mod.# 85999R

I'm feel pretty sure it's a spark issue and not a feul issue. When I stopped by my mechanics shop on the way home and described what happened, he felt it was probably a coil or power pack.

When I was running on plane at full WOT and then the rpm dropped about 500rpm, then 5-10seconds later increased to normal, my fishing partner and I both aggreed it was an electronic/wire issue.

The fuel in the tank is less about 1 week old and I use Stabil in the tank so it should not be bad fuel. The gas cans are clean also. I cleaned them last summer and the tanks were in great shape with no rust/deposits. The fuel filter is also clean. The tune up last fall cleaned out a lot of carbon and the carb checked OK. The motor has run flawlessly all summer minus a small idle problem. I think the idle is turned down too low. A coil going bad could help exagerate that as well.


One last symptom from this morning. When I first began starting the motor, it had trouble turning over with a freshly charged battery. Never happend before. It sounded more like lack of fire on one cylinder because it would fire on 2 or 3 and slow down on the 4th. Like a "na-na-naah-na-na-naah-na-na-naah-na-na-nah" sound. Forgive my description but its the best I can do. The motor doesn't normally sound that way. Its typically an even "na-na-na-na-na-na" sound. Granted, it only did it that one time when the motor was cold. Once I had it started and warmed up later, it hasn't done it since. It did to this too me last weekend though as I was loading the boat after it ran perfect all morning long.

Also last weekend, I lost 100rpm after the motor was good and warm but I though it was due to the headwind on smooth water. I did suspect it was a tiny bit slower RPM though.

Now I'm leaning towards it being a coil. If it was an entire bank, the coil would iscolate to one cylinder. Thanks for the explantion on that, it makes sense.

 

[F_R]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Without delay, check to see if it is getting water in a cylinder. That will do serious damage if it is. It would also explain the 1st time startup cranking problem--water is causing rust in the cylinder.

Also, don't ignore possibility of a bad spark plug. Simple stuff first.

Powr Pack would be the LAST thing I would suspect.

 

[mrcj001]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

No fire or Intermittent on One Cylinder:

1.Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 150V or more. If the reading is low on one cylinder, disconnect the orange wire from the ignition coil for that cylinder and reconnect it to a load resistor. Retest. If the reading is now good, the ignition coil is likely bad. A continued low reading indicates a bad power pack.

No fire or Intermittent on One Bank:

1.Check the timer bases resistance from the #1 sensor wire to the #3 sensor wire and from the #2 sensor wire to the #4 sensor wire. Reading should be 10-20 ohms on each set.
2.Check the DVA output from the timer base. A reading of at least 0.5V or more from the #1 sensor wire to the #3 sensor wire and from the #2 sensor wire to the #4 sensor wire (while connected to the pack) is needed to fire the pack. If the output is low, you may try to reset the air gap between the timer base sensor and the triggering magnet using a sensor gap gauge or use the procedure outlined in #6 above.
3.Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 150V or more. If the reading is low on one cylinder, disconnect the orange wire from the ignition coil for that cylinder and reconnect it to a load resistor. Retest. If the reading is now good, the ignition coil is likely bad. A continued low reading indicates a bad power pack.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

No fire or Intermittent on One Cylinder:

1.Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 150V or more. If the reading is low on one cylinder, disconnect the orange wire from the ignition coil for that cylinder and reconnect it to a load resistor. Retest. If the reading is now good, the ignition coil is likely bad. A continued low reading indicates a bad power pack.

No fire or Intermittent on One Bank:

1.Check the timer bases resistance from the #1 sensor wire to the #3 sensor wire and from the #2 sensor wire to the #4 sensor wire. Reading should be 10-20 ohms on each set.
2.Check the DVA output from the timer base. A reading of at least 0.5V or more from the #1 sensor wire to the #3 sensor wire and from the #2 sensor wire to the #4 sensor wire (while connected to the pack) is needed to fire the pack. If the output is low, you may try to reset the air gap between the timer base sensor and the triggering magnet using a sensor gap gauge or use the procedure outlined in #6 above.
3.Check the DVA output on the orange wires from the power pack while connected to the ignition coils. You should have a reading of at least 150V or more. If the reading is low on one cylinder, disconnect the orange wire from the ignition coil for that cylinder and reconnect it to a load resistor. Retest. If the reading is now good, the ignition coil is likely bad. A continued low reading indicates a bad power pack.

A) I have not DVA adapter (had to Google what DVA is)
B) I'm not that advance of a mechanic, more of a shade-tree variety if that much
C) Anybody got any pictures on how to do any of this?

And
D) How do I check to see if water is getting into the cylinder? (pictures are also helpful)


Thanks to all, I appreciate the feedback/input very much. I have "0" money to take it to my mechanic or else I would. I'm just trying to start with a few simply things like spark plugs first and I have a new coil already. Just need to figure out if which one of the coils may/maynot be bad.

I figure, I have a new coil, if I can find the bad one and swap it out, I'm back on the water and without spending money. (which makes the wife extatic)

 

[jonesg]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Water intrusion will clean a spark plug, if 3 are black and one looks steam cleaned thats the sign.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Water intrusion will clean a spark plug, if 3 are black and one looks steam cleaned thats the sign.

I checked all the plugs. Both top plugs were cleaner than the two bottom ones. Not steam cleaned though. The bottom plugs were really dirty and lots of carbon buildup with only moderate buildup on the top ones.

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I checked all the plugs. Both top plugs were cleaner than the two bottom ones. Not steam cleaned though. The bottom plugs were really dirty and lots of carbon buildup with only moderate buildup on the top ones.

A trip to Autozone should find you new plugs for $2 each, be sure to gap them to specs. They also sell an adjustable spark tester for $7 (part 25069) might show a weak coil. Set on 7/16" the spark should be strong and blue. Look for the weak one, testing one at a time on a hose with motor warmed up. Try not to get shocked, it's a bit of a jolt. No bare feet standing in the water, bigger jolt.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

A trip to Autozone should find you new plugs for $2 each, be sure to gap them to specs. They also sell an adjustable spark tester for $7 (part 25069) might show a weak coil. Set on 7/16" the spark should be strong and blue. Look for the weak one, testing one at a time on a hose with motor warmed up. Try not to get shocked, it's a bit of a jolt. No bare feet standing in the water, bigger jolt.

I'll give this a try. New plugs are cheap enough. From what I'm reading and researching in other threads, I may have multiple issues. I know I need a carb kit, I'll replace all the coils at one time (the ones that are on it are probably original-no joke), and check for water in the cylinders.

Can someone explain how water gets into the cylinders anyway?

 

[Rscardina]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

head gasket leaking would do it.. i would think compression test might shoe that though..

 

[F_R]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Head gasket
Exhaust cover gasket or warped exhaust covers.
Corroded (holed) exhaust area.
Warped heads (has it ever been overheated?)

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

head gasket leaking would do it.. i would think compression test might shoe that though..

Now that you mention it, there is a leak from the very bottom of the motor up towards the carb. It just started last fall when I got the tune-up. I was putting it off for an overhaul.

The motor started fine today but I didn't test anything. I'll take it out again soon and test it. I'll test the spark also.

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I'll give this a try. New plugs are cheap enough. From what I'm reading and researching in other threads, I may have multiple issues. I know I need a carb kit, I'll replace all the coils at one time (the ones that are on it are probably original-no joke), and check for water in the cylinders.

Can someone explain how water gets into the cylinders anyway?

The water that keeps the motor cool leaks by a gasket and get in the cylinders and/or crankcase. Leaks come from corrosion in most cases. Overheating can warp things, crack things and worse.

The next easy test is for compression, OMC says within 15psi or 20psi of each other, depending on year. I have seen motors run for years with more variance than that. A compression tester can be had for under $10. Crank with no ignition. A poor compression test result will lead to a leak down test, a bit more complicated. A good result will eliminate suspect cylinder damage. Compression can sometimes be improved by decarbing, Sea Foam can produce good results. Your lower spark plugs point to possible carboned up cylinder heads and piston tops.

You can also remove heads to see what things look like inside, not only carbon but water jacket corrosion. Not hard to do, as long as bolt threads are not corroded to the aluminum block. Do not break them off, if you do $$. PB Blaster, hammer tap, more PB, tap, soak overnight, repeat. If that doesn't work seek help, do not break them off. Replace head gasket when you re-install heads.

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

If you know you need a carb kit, do it before you run it anymore.
Clogged jets starve motor of fuel, oil and therefor motor life.
At least do this: http://forums.iboats.com/showthread.php?t=423578
Some people don't agree with cleaning but it is better than doing nothing and costs very little to do.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I?ve owned the boat for about a year now. The former owners do not remember having a carb kit put in, much less a tune-up. They only operated it 2-3 times a year so it actually has low hours for it?s age. The drawback is, with only 2-3 times a year, that?s a lot of carbonation. When I had the tune-up done last year, the mechanic said it was badly carbonated and cleaned twice with de-carb cleaner through the motor.

That?s why I feel I need to go ahead and do the carb kit. As preventative maintenance, not fuel problems. The boat has run great for over a year and really strong until this last trip.

As for compression, it tested at 125-130psi on each cylinder last fall. That could have changed by now but I?m hoping the compression is still great.

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Carburetors only need rebuilding when they leak, get gummed up to a point where cleaning won't clear them out or are worn out. Air leaks can sometimes be cured by simply tightening down screws and bolts.