I think my outboard was running on one cylinder

[Molska]

Hi, i'm trouble shooting here so:

I think my outboard a 1980 25hp evinrude was runnng on one cylinder but i don't know for sure.

If it was how might it run?

Now my problem was when i was going full speed on the lake the motor died down to trolling speed and won't plain out and if i give anymore gas it starts to shutter sounding and feeling like its starving for fuel.

Now i changed the plugs cause both were just black and when i started and idled my engine i pulled one plug cap and the motor idled down and was still running i put the cap back and pulled the other and the engine stopped. Now is this a correct test or am i completely off base here?

Could it be anything else?

 

[Bob_VT]

Re: I think my outboard was running on one cylinder

Yes you are on the right track. I use an inductive timing light to verify the spark. You need to do more troubleshooting.

 

[mucduc]

Re: I think my outboard was running on one cylinder

hey
I have the same problem that you are having but i think i fixed it last night. my 1985 50hp would be going full throttle then die down, then full throttle, then die down, and so on until it would just shut off. so i did the same test as you and found that when i pulled my top cylinder spark plug wire nothing would really happen, but when i pulled my bottom wire the motor would shut off. so i pulled the bottom(good) spark plug and wire and moved them to the top cylinder and top coil. there was spark. so i then moved the top plug and wire and moved it to the bottom and there was spark. so the only thing that i could think of was that there was a loose connection between the top coil and spark plug wire.

I guess that is a long way of saying that you may just have a loose connection. hopefully that is what my problem was, i will be checking that today when i get a new battery.

I now have spark in both top and bottom after removing the wires and putting them back on both the plug and coil, if i wasnt clear in my above text

 

[jtexas]

Re: I think my outboard was running on one cylinder

"If it was how might it run?" exactly like you would expect...less than half it's normal power.

Is this a 1-carb or 2-carb motor?

Back to basics. Three things she needs to run: compression, spark, fuel. If she gets all 3, she runs; if she don't, she don't.

Compression test. PSI should be about the same on both (within 7% or so).

Spark test (not a "spark plug" test): use an inline spark tester (couple bucks at autozone), set the gap for 7/16", clip it to the engine block, attach the plug leads (one at a time) and look for a strong blue spark while cranking. If it can't jump a half-inch gap in the open air without a spark plug, it's not firing in the hole under heat & compression.

Report your results.

 

[Molska]

Re: I think my outboard was running on one cylinder

Do i still need to perform a spark test if i changed the spark plugs and the coils?

Oh my engine is a one carb engine. And i just reolized that my spark plugs were not gaped properly. How much of an impact will that have on my engine or how much damage.

Although i didn't have the plugs gapped properly i did take out the motor earlier this week and no change.

 

[Rick.]

Re: I think my outboard was running on one cylinder

Yes you need to verify that you have spark. New plugs is good but won't matter if you don't have spark. Plugs gaped to .030 . Improperly gaped won't hurt anything in the short run. OMC two cylinder engines run remarkably smooth on one cylinder. The noticeable symptom is a lack of power. Best of luck. Rick.

 

[jtexas]

Re: I think my outboard was running on one cylinder

Do i still need to perform a spark test if i changed the spark plugs and the coils?

You replaced a couple out of a half-dozen ignition components, so there's still a few things there that could be robbing you of spark in one cylinder.

Or it might be bad compression, or fuel delivery. Luckily, you don't have to guess. Do the spark test and compression tests.

Make sure there's no water or debris in the fuel tank, the tank vent is open & clear, the gasoline is fresh, and the fuel line holds pressure.


Best not to run it like it is...if it's starved for fuel, then it's not getting enough oil.

 

[Molska]

Re: I think my outboard was running on one cylinder

Okay heres whats going on:

1) did compression test and both cylinders are firing the top was 111 psi and the bottom 110psi

2) Did a spark test and electricuted my self both times but there is spark.

3) change my impeller cause it felt like it was over heating

4) Did a cab kit and a marine mechanic checked it over after i did it and it wouldn't start. He rest my float and checked it over and it seemed fine, but it still won't start.

5) Bought a new gas can and hose and new fuel mixed perfectly.

i never had a problem starting with moe that 2-3 pulls before carb kit now nothing. Oh and now is sounds a little different like its not even igniting or wants to fire. and there is spark.

So new spark plugs gapped properly, new coils, new impeller, carb kit done and checked, new gas tank and hose and new fuel mixed properly.

What the hell could it be now?

 

[oldcatamount]

Re: I think my outboard was running on one cylinder

Sounds to me like you may have an electrical short somewhere. You have done all of the other possiblities. An electrical short can be intermittant, may work for the first few pulls and then nothing. something may be loose (connection) or broken (wire) that is not obvious at first. The problem is, to find a short like that is difficult. Be patient (if you can), when you do find the trouble spot, please let us know.

 

[Al-53]

Re: I think my outboard was running on one cylinder

check all the wires....early '80 motors had a crappy wire system..they crack and corrode inside..it happened to my motor also....I replaced a few wires already...also make sure grounds are clean.....check the wire ends also...they fray and break on the connectors....

Al

 

[jtexas]

Re: I think my outboard was running on one cylinder

If you electrocuted yourself, then you might be using the "spark-plug-held-to-the-engine-block" method of checking for spark.

This is a good way to tell if there is no-spark, but not so good for testing the quality of the spark.

You might see a spark outside the cylinder, which then fails when it gets inside the combustion chamber because the compressed air and fuel is more resistance than atmospheric air.

This is the reason for using an inline tester clipped to the block in place of the spark plug. The 7/16" gap in the open air is enough resistance to tell if there's enough electricity there to fire in the hole.

Not saying you *don't* have spark...just saying, you haven't confirmed it.

If I'm mistaken, and you used the method described above, then please disregard this entire post.

 

[minkota]

Re: I think my outboard was running on one cylinder

i never had a problem starting with moe that 2-3 pulls before carb kit now nothing. Oh and now is sounds a little different like its not even igniting or wants to fire. and there is spark.

Is the Kill/Lanyard disconnected or bad?

 

[Molska]

Re: I think my outboard was running on one cylinder

Okay so i tested the spark using an inline spark tester and both plugs have a strong spark.

Now when i did my carb kit i noticed that my old needle and seat were different. The new kit came with a spring that goes on the needle and float. where my old set up didn't have a spring.

I do find when i flip my carb upside down to check the flot gap the float doesn't drop smoothly kind of gets struck half way through. Its not as free moving as the last.

So should i remove the spring and put the old needle back which is in fine condition? And the old needle didn't accomadate for a spring so its not lostor broken.

could this be a potential problem maybe not enough gas?

 

[Molska]

Re: I think my outboard was running on one cylinder

Okay I got my engine started. I squirted some gas into the carb and BOOM it fired.


BUT

now it sounds like its miss firing, the spark plugs get wet all the time and they go black. Also the engine won't restart unless i pull the chock all the time. it also won't continue to idle unless it increase the throttle. So what should i look for? and or do?

 

[bktheking]

Re: I think my outboard was running on one cylinder

Sounds like the carb service made it worse, take it apart and check it out , a stuck float will make it run too rich. When you did the kit did you remove all the plugs and clean it out completely? The spring in the new kits is actually a standard now in all float carbs of that style, it aids in pulling the needle down.

 

[BigB9000]

Re: I think my outboard was running on one cylinder

I had this same problem. Posted here, got the same answers.

I went through everything, 18 times trying to figure out my top cylinder problem. Turned out the Reed (or leaf) Valve was stuck closed. Completely cutting off fuel to that (top) cylinder.

Does one spark plug look more used than the other?

 

[Molska]

Re: I think my outboard was running on one cylinder

Ya i took out all the plugs and cleaned it out real good and had it checked by the mechanic, but the float did seem to get stuck when i checked it. Do i just play around with it till it drops free and easy?

And yes kind of both plugs get black right away after start up i clean them right after before starting again, but the top plug is the one that gets more wet that the bottom.

where is the reed and or leaf valve and how did you fix the problem?

Good feed back thanks everyone keep it comin

 

[BigB9000]

Re: I think my outboard was running on one cylinder

Its wet, thus, probably not the leaf plate.

Back to spark. put your ear close to the spark plug, and slowly rotate the flywheel. See if you hear any 'hissing' sounds.

 

[Molska]

Re: I think my outboard was running on one cylinder

Okay so i'll do all of that, but before i did the carb kit i never had these problems should i look the carb over again, which i'm thinking is the case of all this bull@#*& not starting or idling properly.

I am almost leaning to power pack problem for my initial problem as for the fuel
should i readjust my float once more and see where that gets me?

Oh and if i have to start with my choke all the time what does that mean?

 

[bktheking]

Re: I think my outboard was running on one cylinder

You are getting consistant spark, powerpack I would think is ok. If you have to start with choke everytime the carb isn't right. I had a 9.9 here I put a carb kit in 2 weeks ago. I'd start it cold with the choke closed, I could walk over to it 10 minutes later after being off and pull the cord to fire it right up, no choke needed. Take is apart and recheck everything for proper float height , binding and cleanliness.