1965 Johnson FD-19 drops RPM randomly

[dpostman21]

Thanks in advance for any advice on this, this form is so helpful I really appreciate it.

I have a 1965 FD-19D 18 HP Johnson that I recently bought and when going down the river at different speeds the RPM drops for a couple seconds then picks back up. Please listen to video in link below to here for yourself (Video is sideways but the audio tells the story).

https://drive.google.com/open?id=0B__F02102-ELZS04c2pCdFoyUGc

I am assuming its fuel related but am unsure. The tank is older, have new gas lines on engine, pressure bulb does not stay stiff (not sure if it should) any advice is greatly appreciated.

 

[racerone]

I did not listen / look at the video.----The way I would go about this is to pull the flywheel.----Inspect coils as they often burn through and short to the magplate.----IF that is too much work then close the gap on the plugs to 0.020" and test run the motor.

 

[dpostman21]

Thanks. I will give that a try.

 

[dpostman21]

Would there be visible marks like burn marks or cracking I should be looking for?

 

[racerone]

Do this test first.---Set up a test device with a 5/16" gap.-----See if spark will snap across that.----Report what you find.---The test device could be as simple as 2 wires stapled to a piece of plywood.--------5/16" gap between the 2 wires and one end in the plug boot and other end fixed to the blck

 

[lindy46]

Sounds like an ignition problem - one cylinder periodically cutting out. May be a failing coil which cuts out when it heats up, or could just be dirty/improperly adjusted points. Time to pull the flywheel. If it's all original, I'd plan on replacing everything, including the wires.

 

[dpostman21]

Thanks for the input, much appreciated. Tracked down coils and condensers. All I could find locally was aftermarket (CDI) coils and (Sierra) condensers. I would prefer to put OEM on it but I will have to order them online.

Points I have zero experience setting (even thought my 67 cutlass has them) my friends dad set them after the rebuild and have not had any issues with them. is cleaning/replacing point a difficult task?

 

[lindy46]

Not too bad a job but if it's your first time, just take your time and do one side at a time. That way, you can have a reference if you get confused. If you're replacing the coils and wires, you must remove the mag plate to get to the underside where the wires are secured. The plate is held on by the two long bolts which run through the coils, and two more bolts which just run through the mag plate. Once those 4 bolts are removed, the mag plate just lifts off. Leave the points alone for now, and remove the coils and wires. Feed some excess wire though the bottom of the mag plate to make it easier to attach the wires to the coils. The wires actually "screw in" to the mounting point on the coils. Once secure, pull the wires back through the hole in the mag plate until the coils are in their proper position. Secure the wires on the bottom of the mag plate, and the re-mount the mag plate. Now address the points. They are held on by one large bolt, and a small "U" clip that holds them onto the mounting post. Try not to lose the "U" clip as some points kits don't supply a new one. I use a magnetic wand to secure them as I pry them off the post. A small eyeglass screwdriver is useful for prying off the clips. There is also another clip which holds the two sections of the points together. Try not to lose those also! Once the old points are off, install the new points. Install the fixed part of the points and lightly tighten the mounting bolt. Slip the other part of the points over the mounting post and at the same time, hold the spring back in the proper position (a little tricky). Re-install the "U" clip to the top of the post, and the other clip over the spring where it contacts the fixed portion of the points. Now adjust the gap. Set the rubbing block to the high point on the cam by turning the crank until the points are at their widest opening - usually corresponds to the flywheel key. Adjust to .022" for new points, using the small adjustment screw to the left of the points. Once adjusted, securely tighten the mounting bolt. Now CLEAN the points thoroughly. Use a points file or some 200 grit wet/dry sandpaper followed by acetone on a piece of business card stock. Re-connect the wires and you're done. Now do the other side!

 

[dpostman21]

Thanks for the detail on this. Great detail. I will update after work is completed.

 

[dpostman21]

****UPDATE*****
I ended up replacing Points, Condensers, Coils, and plugs. Here is where I am at:

Installed parts (had to remove fly wheel a few times) to get everything right. Motor is idling/Starting just fine. I took the boat out a couple weeks ago (before any work) and the motor moved the boat right along. Getting on plane fast and spinning right up, the only issue was the varied RPM at times. When I took the boat out that time I had shorter cables on the Simplex throttle & gear control box. I bought longer ones to route them better in the boat. Since then it appears the boat will not hit top RPM. When in a barrel at home it spins right up but under load on the water it does not get the RPM. I have tried twisting the throttle while Simplex is all the forward (as far as it goes about 2/3rds the way to full throttle) and still does not seem to get the rpm.

In nuetral in the barrel this thing spins up nicely???


Do I have a cable issue? Something else???

thanks in advance you all have been a huge help.

 

[lindy46]

Disconnect the cables, have someone up front to steer, and work the controls at the motor. See if it achieves full RPM's. If it does, the cables are not adjusted properly.

 

[dpostman21]

Thanks for the advice. I looked into the tiller handle and it appears to be misaligned with the gears. its off on alignment. I thought about taking it off but kind of like having it on there in case a cable issue. I need to figure out how to align the gears on the tiller handle. Right now its of about a third. The when tiller is turned all the way down its past the start positing getting into fast.

 

[lindy46]

So is the tiller handle preventing the motor from going to full throttle when using the remote controls?

 

[dpostman21]

yes it was/is misaligned. so when I turn the handle all the way it was only two thirds on the actual control to the motor. the tiller gear goes to end (flipping almost all the way over before the control to the motor reaches full throttle.

 

[dpostman21]

essentially looks like the tiller handle throttle is way off alignment. I disconnected cable. looking at the tiller when turned to idle or stop the throttle aligns with just shy beyond start.

 

[lindy46]

Hard to picture without seeing it. You probably have to take it off to re-align things. With the tiller folded up, look at the gears from underneath. There are two "wide" teeth which should come together side-to-side when aligned properly. Does that make sense? The wide tooth on the tiller should set to the right of the wide tooth on the motor. I'd temporarily remove the tiller and see if the remote throttle cable properly operates the throttle.

 

[oldboat1]

Will offer up another opinion. I don't think that hiccup at high rpms is related to the tiller handle/throttle issue. IMO, it's probably an ignition or carb issue -- don't know exactly how the high speed mix works on that model (adjustable or fixed), but -- if adjustable -- sounds like vibration might be causing fluctuations in the setting.

And there's always potential prop issues (slipping hub) or l.u. issues (worn shift dog -- doesn't quite sound like that to me, though).

 

[dpostman21]

After some looking into it I have watched it closely, it appears there is an issue with the square tube that runs up to the top of the motor not moving when the throttle is turned move about 1/2" before the square tube turns. there is a lot of play. See picture below.

https://drive.google.com/open?id=0B_...lJhRHJybHFtNEk

 

[AlTn]

detach the square tube < lever control pin or vertical shaft > by removing the stainless steel clip that joins it to the armature plate arm and the 2 screws that hold the collar at the top of the shaft...the shaft will pull straight up and out of the gear now...you should have a pin that has 2 wings that slide into the slot on the vertical control shaft gear...not uncommon for one or both of those "wings" to shear off and the vertical shaft is no longer in sync with the tiller

 

[oldboat1]

Be careful with that stainless clip that AITn mentions, and it can break. I haven't had one of the little wings break in that vertical control lever, but don't see it in your picture. It's a separate piece that fits into the vertical shaft, so if broken or missing you might be able to replace it or jigger something up -- should fit in that slot in throttle control gear to move the vertical control lever with the gear as AITn indicates. On some models there is also a tiny spring to stabilize the vertical shaft (presumably) -- think it often ends up on the shop floor. Your assembly must be working somehow, though, or the throttle control gear wouldn't move the throttle (which more often happens, btw, when the stainless clip breaks or comes off). Maybe it's jammed in place, and dislocated.

I'm not sure how that idle stop screw would work on yours, as pictured. There is normally a plastic idle adjustment screw and spring (not to be confused with the carb mixture screw). On yours, it looks like there is no idle stop set (throttle is in fully closed position). It also looks to me like the throttle control gear is positioned correctly at the motor. It's possible the throttle control pinion on the tiller handle isn't assembled correctly, and you need to remove the the tiller assembly to reinstall it. You might check out the assembly here: http://epc.brp.com/Index.aspx?lang=E&s1=f4cc6171-0e08-46b6-a3e4-c7620e47826f (1968 and up, but should be the same -- look in the lower unit diagram for the tiller handle assembly.) On some models, tilting the tiller handle to it's full up (and back) position is supposed to release the gear -- might try it on yours.** Think, though, you probably need to remove it and reassemble.

**(not sure, but maybe you can tilt the tiller fully up and to the rear, then turn the grip clockwise(?) without engaging the throttle control gear. That might relocate the pinion in the correct position. Just a thought.)