Need help with Evinrude 30hp misfire

Storm27m

Cadet
Joined
Apr 30, 2008
Messages
7
Hello all. This is my first post on iboats as I came across the forums while searching for answers for an outboard problem I am having. I will start by saying that I am not very familiar with outboards as this is the first boat I?ve owned, so my knowledge is limited. I?ve done quite a bit of reading on this forum and others, but I?m not really sure what to do next.

Background: Motor is a 1993 Evinrude 30hp tiller (E30TEL, Ser# G03246215), electric start. I bought this motor on a jon boat in Feb, ran it briefly (in barrel) before purchase, didn't notice anything wrong. I've been out of town for a while and been working on the boat itself and haven?t had it out on the lake yet. Since I finished the work on the boat, I changed the lower unit fluid and replaced screw seals (very clean, but don?t know how old), gave the engine a once over looking (for loose bolts, wear, etc), and started it up. I ran the motor (with motor flusher for water) and noticed an intermittent misfire at idle and higher rpms. Not too much smoke during idle, a puff of smoke with the misfire, and a lot of smoke when throttling up. After the misfire, the engine drops in rpms for a second or two before coming back up. After listening closely on the left side of the motor (looking from rear), I hear an intermittent click that coincides with the misfire, but I hear it more often than the misfires. With each click, there?s a slight jerk to the motor. I?ve got a good flow of water out of the ?pee-hole?. The first time I ran the motor at home, some grayish, gas-smelling foam came out of the exhaust, but it cleared up pretty fast and hasn?t returned.

With help from another forum, I had a few things to check for. I checked for spark on both cylinders and spark seemed fine on both cylinders. I?m planning on checking with a spark tester because I didn?t really know what I was doing the first time. I?ll also see if I can borrow a compression tester, but I haven?t done compression tests yet. The fuel mixture was old, so I replaced that with new fuel and purged the fuel line. I also replaced both spark plugs. One of the old plugs had some black carbon, but looked dry. The other was black and a little wet/oily. Both old plugs were gapped at around .037 (.030 according to manual). Bought the new plugs at local marine shop that were supposed to be pre-gapped but also measured .037. Re-gapped both to .030 and installed. Engine ran better for less than a minute before beginning the same intermittent misfire. I haven?t pulled the new plugs to look at them yet. I checked the coils for cracks and didn?t see any, but I will check again. All wiring looked good.

Another thing I noticed while running the engine was that the water coming from engine never got really warm. It was warmer than the hose water, but still cool to touch. When revving the engine to higher rpm, water got noticeably warmer, but still only luke warm. I don?t know if that is normal or not

I am hoping someone can give me some advice on what to do or look at next before I give up and take it to the local marine shop (I want to go fishing!). Money is tight and I?d prefer to keep the motor out of the shop if at all possible. If it would help, I can try to take some video of the engine running and post it on Youtube or something. Sorry for the long post, but I?ve tried to be as descriptive as possible. If you need any other info, please let me know. I appreciate any advice you can give. Thanks.
 

Harker

Chief Petty Officer
Joined
Sep 21, 2003
Messages
452
Re: Need help with Evinrude 30hp misfire

Since it starts and runs, I would do a decarb on it then take and run it on the lake. Don't throttle up on muffs or you could really mess it up. Get a can of Sea Foam and do a decarb. When a motor is running on muffs there can be a lot of little noises....little bloopy misfires aren't that uncommon for a 2 stroke. Take it to the lake and run it for a while and see what it does.
 

Storm27m

Cadet
Joined
Apr 30, 2008
Messages
7
Re: Need help with Evinrude 30hp misfire

Thanks for the info. I did not know that it was bad to throttle up on muffs. I wasn't going too high, so hopefully I didn't damage anything. I won't be able to get to the lake until this weekend at the earliest, but I'll give it a go.

Anyone else want to chime in?
 

Storm27m

Cadet
Joined
Apr 30, 2008
Messages
7
Re: Need help with Evinrude 30hp misfire

I was able to check the compression this evening. Both cylinders were very close to 100psi. I also bought a spark tester and both sparks would jump nearly 1/2" with a bright blue spark. After removing the new plugs that I put in earlier in the week, the top plug was wet and oily with no carbon deposits. The bottom plug was dry with a light coat of carbon. After all procedures, I cleaned and replaced the plugs.

On another note, the misfire and click/knock didn't begin until after a few minutes of running. It seemed like it started when the engine was warmed up.
 
Joined
Apr 24, 2008
Messages
23
Re: Need help with Evinrude 30hp misfire

sounds like a cracked coil dead short ! run engine at nite or in dark garage look around coil arching to engine plug wires coming from coils to plugs look for arching also. Let the engine warm up keep looking from cold until engine gets to operating temp HOPE IT HELPS
 

Storm27m

Cadet
Joined
Apr 30, 2008
Messages
7
Re: Need help with Evinrude 30hp misfire

Well, I decide to go ahead and rebuild the carb. I don't know when it was done last on the motor, so I figured what the heck, I'll learn something in the process. The rebuild was a piece of cake. The hardest part was getting the carb off, which also required removal of the starter. The rebuild kit was only about $18 with the new float. Add a few bucks for some B-12 carb cleaner and the repair cost me about $21......not too bad.

The carb was pretty dirty. There were several chunks of debris in a few places, but little fuel varnish. Some chunks were so large, I don't know where how they got in? Since I found so much debris, I also removed and cleaned all fuel lines. I re-assembled, adjust the carb and linkage per the manual, and the results.......

Not wanting to jinx myself, but I think my problem is solved! I let the engine run on the flushers for about 10 minutes and didn't have a single misfire. The engine knock & twitch was also gone. The next test is to get out on the water and give her a good run and try to fine tune the carb. I'll probably do a decarb also.

I learned a lot about outboards these last few weeks and doing the work myself has given me a better understanding of how they work and need to be maintained. Thanks for all the advice.
 
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