1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

[nate_camille]

I was given an old 1964 Evinrude 18 HP (Serial 18042) by my dad. He got it from an old friend of his. The motor sat on an engine stand for about 10 years. I went through the motor completely and did the following:

1) Replaced seals and impeller in lower unit. Replaced lower unit gear oil. Old oil looked fairly good, but it was sitting for a long time, so for good measure changed it anyway. Didn't see any water or milkly color in old oil. Gears all look great.
2) Took carb completely apart and cleaned. Used rebuild kit to replace everything expect the float (which still looked good). I set low speed mixture screw at one turn out to start.
3) Checked spark plugs and cleaned them up. They looked like new almost.
4) Put a little oil in cylinders before cranking engine over.
5) Cranked engine to verify good spark on both cylinders. Everything looked good.
6) Cranked engine and it started on first pull.
7) Water pump is working well

I had the engine out on a lake, so I let it warm up for a bit but it kept acting like a cylinder was misfiring (engine would jolt a little) with RPM's on the low end. As long as I kept the RPM's up towards the upper end it ran fine. If I let the RPM's down, it would start acting like it was misfiring and then die if I didn't give it gas.

I did put it in forward and give it some gas and it was running fine. Slowly brought up RPM's and let the engine run for about 5 min at about 1/2 speed. Then slowly raised it up to top speed and it was running great. But as soon as I bring it down to low idle, it acts up again.

Not sure what to look for as the culprit at this point.

 

[HighTrim]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Did you inspect the ignition? Are the coils original? IF so, they are NFG and need to be replaced. Now would be a good time to go over the rest of the ignition system as well.

Start the low speed needle at 1.5 turns out from seated, the high at 3/4 then tune from there. Check out the FAQS for info on this.

 

[kfa4303]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

+1. If the coils haven't been serviced/changed, they could be causing the intermittent firing. The stock coils had a 100% failure rate over time. Thankfully, the replacement coils will last forever and only cost about $20 each. Tweaking the carb a bit will help too. Here are some great links to help you give the old girl a tune up from top to bottom.

Maintaining Johnson E & FD Serie

1964 Evinrude 18403 18 hp Outboard Motor Parts

 

[nate_camille]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

+1. If the coils haven't been serviced/changed, they could be causing the intermittent firing. The stock coils had a 100% failure rate over time. Thankfully, the replacement coils will last forever and only cost about $20 each. Tweaking the carb a bit will help too. Here are some great links to help you give the old girl a tune up from top to bottom.

Maintaining Johnson E & FD Serie

1964 Evinrude 18403 18 hp Outboard Motor Parts

Thanks for the info. I will go take a look at those ignition components and let you know what I find.

 

[kfa4303]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Here's another great link for rebuilding the ignition with lots of pics. It's for a slightly different model, but all of the steps are the same for your motor. You can get coils right here at iboats and/or at your local NAPA auto parts which also carry Sierra replacement parts.


Woops! Here it is.....

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm

 

[nate_camille]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Hi,

Thanks for the info so far. I ordered the parts for the ignition system and have a puller to get the flywheel off. I am having a problem, though, getting the screws out of the top of the flywheel inspection cover. There are 3 close to the center that I need out to connect the puller bolts to and there is also one screw on the outside edge of the cover near the outer edge of the flywheel. None of them initially wanted to break loose. They are all flat head screws and it is making it difficult to remove them. I put WD40 on all the screws and let soak overnight. One of the inner screws came loose but the others are still refusing to budge. I've tried hitting the screwdriver with a hammer while turning it, and that didn't work. I've tried another penetrating fluid for a few days and still no luck. Any ideas out there on how to get these screws out? Also, the one larger screw on the outer portion of the inspection cover - what is it connected to? If I get the inner 3 screws out can I pull the flywheel with the inspection cover still held on by the outer screw?

 

[Will Bark]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

You can try a mixture of 50/50 Acetone and auto transmission oil to soak those screws and if that fails you may have to apply heat to them but wait for one of the gurus to chime in on that suggestion as too much heat might damage something. Good luck

 

[geoffwga1]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Hi,

Thanks for the info so far. I ordered the parts for the ignition system and have a puller to get the flywheel off. I am having a problem, though, getting the screws out of the top of the flywheel inspection cover. There are 3 close to the center that I need out to connect the puller bolts to and there is also one screw on the outside edge of the cover near the outer edge of the flywheel. None of them initially wanted to break loose. They are all flat head screws and it is making it difficult to remove them. I put WD40 on all the screws and let soak overnight. One of the inner screws came loose but the others are still refusing to budge. I've tried hitting the screwdriver with a hammer while turning it, and that didn't work. I've tried another penetrating fluid for a few days and still no luck. Any ideas out there on how to get these screws out? Also, the one larger screw on the outer portion of the inspection cover - what is it connected to? If I get the inner 3 screws out can I pull the flywheel with the inspection cover still held on by the outer screw?

Get a proper impact screwdriver,they are less than $10 at Harbour Freight.After I got mine I wondered how i ever managed without it.

 

[geoffwga1]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Yes

 

[Crosbyman]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Have you cleaned the fuel's low speed circuit in the carb ?

you need to remove the aluminm plug on top of the carb to acccess 3 small holes that drip fuel in the carb . Engine may be starving for fuel if the upper carb chamber is crudded up.

you need to drill a hole in the dimesize plug, pop it out clean that chamber and reseal the chamber with the spare plug in the carb kit

put some clear nail polish over the plug to seal it ( after punching it in a bit to set in its rim joint)

 

[nate_camille]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Yeah, I cleaned out that area real well and replaced the cap from the carb rebuild kit. Carb shouldn't be an issue at this point, unless it plugged up after I rebuilt it.

 

[nate_camille]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

Changed out points and condensers along with both coils. Had an issue with one of the coils, though. After putting the flywheel back on loose, I spun it around to make sure it wasn't contacting anything. As it turns out, one of the 2 coils was sticking out about 1/16 of inch farther than the one I took off. This caused the flywheel to contact the coil. I ended up taking one of the old coils and putting it back on until I figure out why the new coil was larger than it was supposed to be. The other new coil worked fine and fit normally. Regardless, I put everything back together and checked the spark and it looked good. Took it out to the lake this weekend and it is running well. The motor pushes my 14ft boat at a nice speed. Thanks for the insight on the motor while I was working through this one.

 

[HighTrim]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

The coils are adjustable. That is so that you can adjust the air gap between the coil lamination and the magnet. You set the edge of the lamination flush with the mounting boss if you don't have a coil locating ring.

 

[bonzoscott]

Re: 1964 18 HP Evinrude Fastwin - Runs well at high speed but not at idle

If both new coils are identical, they should fit. They should come flush to the outer edge of the mounting boss on the mag plate that they rest on. However, I'm curious about the folks saying they need replaced. Generally, a faulty coil will fire ok at low RPM but fail at high RPM. You said it runs great at speed. If the old ones are original and cracked, probably good to replace them, but I'm not sure that was/is the problem. Not familiar with that motor but the link and sync maybe outta sync.

 

[Mr. BOB H.]

If the slow speed needle valve does not allow slow speed adjustment the carborator body orifice for the slow idle needle jet has a bushing that seats the needle valve and the bushing is loose in the orifice. The bushing not being secure will not allow slow speed adjustment. I used silicone to secure the bushing in my slow idle orifice body but it was tricky. I used silicone sparingly on the od of the bushing only and marked the needle valve to know when the needle valve is only seating the bushing and not pulling the bushing out of the orifice. Let cure 24hrs. Its working for a few years now. I'm looking for another three point for my old 18 evinrude.

 

[nwcove]

old thread MR.BOB.