Evinrude 25HP Not Starting

[Spyhopper]

Hello all, new to the forum and it's been a few years since I last worked on outboard motors.

I recently purchased a 1985 Evinrude 25HP with electric start (I don't have a battery yet so using the pull start). It is a tiller handle model which I purchased 'as is' and have not seen it run. It was fairly cheap and came with a parts motor.

The problem I am having is that when I pull it over to try starting it, all it will do is 'pop' or backfire out the exhaust, and nothing else. I am thinking this is a good indicator that it is firing at the wrong time. I think the leads going to the coils are wired up correctly as the orange with blue stripe is going to the top coil, and the plain orange is going to the lower coil.

Do you guys think this sounds like a flywheel key issue, or something else? Are there other things I should be checking for? It does have a good strong spark on both cylinders.

 

[oldcatamount]

Re: Evinrude 25HP Not Starting

Be certain the plug wires are going to the right plugs. The top coil will feed the top plug and the bottom will feed the bottom plug. You should do a link and synch as well but check the plug wires first.

 

[Bosunsmate]

Re: Evinrude 25HP Not Starting

As above and then check that fuel is getting to the cylinders/ not too lean

 

[bonzoscott]

Re: Evinrude 25HP Not Starting

Yes, check flywheel key.

 

[Spyhopper]

Re: Evinrude 25HP Not Starting

The coils are going to the correct plugs. I guess tomorrow I will pull off the flywheel and make sure everything is okay under there.

 

[boobie]

Re: Evinrude 25HP Not Starting

Has that flywheel got timing marks on it ??

 

[boobie]

Re: Evinrude 25HP Not Starting

If it does, there's an easy way to check and see if the key is sheared or not without removing the flywheel. Will the spark jump a 7/16" open air gap on a spark tester ??

 

[Spyhopper]

Re: Evinrude 25HP Not Starting

The flywheel does have timing marks. If the top cylinder is number one, it does not line up with the timing marks when at TDC. The pointer is about an inch away from the marks when that cylinder as at TDC.

 

[boobie]

Re: Evinrude 25HP Not Starting

Did you remove the spark plugs and put a screw driver in # 1 cylinder to find absolute top dead center. If the TDC mark on the flywheel doesn't line up with the pointer on the block, the key is most likely sheared.

 

[Spyhopper]

Re: Evinrude 25HP Not Starting

I pulled off the nut for the flywheel today, and the key looks to be properly aligned. Pulled the carb, and it is spotless inside. I then tried starting it again with the same luck as before. Nothing but a pop and some smoke out the exhaust. Any other ideas? Thanks.

 

[racerone]

Re: Evinrude 25HP Not Starting

Was the nut tight ?----Not sure if you can determine a sheared key by " looking at it " you should pull the flywheel.----You must use the proper puller or get a shop to pull it , takes just minutes.---The " pop in the exhaust " does point to a timing issue.----Are the small wires on the coils going to the correct coil.-----Usually the orange / blue is for the top cylinder.

 

[boobie]

Re: Evinrude 25HP Not Starting

Looking underneath the nut will tell you nothing. You have to pull the flywheel to check the full length of the key.

 

[oldboat1]

Re: Evinrude 25HP Not Starting

assuming you have the electricals needed to operate the starter, including a keyswitch or starter button, I would set it up with a fully charged battery and start testing at that point in your test tank. I think you need to get that rascal spinning before you can figure out what you have. Check to see there is oil in the lower unit. Get some fresh gas and oil, and run with a 50:1 mix. Test with the hood removed. Check for water discharge at the exhaust port on the leg, and test the temp. on top of the cylinder with the side of your hand. Assuming you get it running, if it gets too hot to keep your hand there for a few seconds, shut it down and figure on replacing the water pump.

 

[Spyhopper]

Re: Evinrude 25HP Not Starting

I got the motor up and running last night. Turns out it was a blown head gasket. It had blown through in the narrow area between the two cylinders. Replaced the gasket and it fired right up.

 

[nwcove]

Re: Evinrude 25HP Not Starting

did you check to make sure the head was not warped?? if not, the gasket will blow again, probably when you are at your furthest point from the dock.

 

[oldboat1]

Re: Evinrude 25HP Not Starting

hey -- give yourself a pat on the back, Spyhopper. I go in and out of tinkering with outboards, so know what you mean about not working on them for a while (your opening post). nwcove is right, but you probably scraped and cleaned the face of the head thoroughly before replacing the gasket. If you pull the head off again, it would be good to check for warping. I don't routinely do that, but probably should -- so far no failures. I use some OMC gasket sealer when installing the head gasket, and recommend that (again, if you pull the head for some reason -- not sure whether the service manual calls for sealer.) I think I would run the motor now a little in the the barrel to see how it runs. That will tell you what else you need to do. You will need to shut it down right away if it's not cooling, of course, and should replace the pump impeller anyway at some point before use on the boat. Assuming it has a pretty good run now, you can retighten the head bolts, and maybe check compression and plug condition (clean and regap). All good tinkering.

 

[HighTrim]

Re: Evinrude 25HP Not Starting

I don't think I have ever found a head that was perfectly true. I have always had to dress them slightly. It is always low in the center where you found it blown as well, always the last spot to come out when dressing it. I would follow Tims advice so it doesn't fail again.

Here is some pics to help. Be sure to torque the bolts in the proper sequence and torque value as well.

BTW, new shiny head gaskets do not need any sealer at all, it is built in.

 

[Spyhopper]

Re: Evinrude 25HP Not Starting

Thanks everyone for all the input. I cleaned all surfaces with a scotch bright. I then ran a straight edge over the surfaces and it all looked good.