64 Johnson 40hp rds-26r backfiring

[joepcdr]

Guys I seek your wisdom in helping me trying to resolve my issue with this motor. Last fall the motor died on me in the middle of Glen Elder lake. At the time the only way I could get it running somewhat again. Was to basically have it at full throttle and even then it didn't run for very long.

Since then I've replaced the fuel pump, rebuilt the carburetor, and converted it to electronic ignition. Only sign of life I got out of it is backfiring that sounds like a shotgun going off. Which is what it was doing after I go it home from the lake the day it had died. So nothing really has changed.

I have tested for spark and compression in both cylinders and all seems well and normal.

The one thing that I've noticed today is that it seems that I can squeeze and squeeze that fuel bulb and it doesn't seem to build up pressure. I'm not sure if this is related to the backfiring or just another issue in its own self. But I thought I'd mention it.

 

[racerone]

The loud back firing usually means that plug wires are on wrong cylinder.---------Modules are available to replace the points on these.---The fuel bulb must go hard so look into that.---------Bad bulb / air leaking in .-------Ckeck pick-up inside the tank.

 

[joepcdr]

The loud back firing usually means that plug wires are on wrong cylinder.---------Modules are available to replace the points on these.---The fuel bulb must go hard so look into that.---------Bad bulb / air leaking in .-------Ckeck pick-up inside the tank.

You know I read that having plugs wires on backwards could cause loud backfiring. But it started doing that before I made the swap out form points to electronic. Now I did prior to rebuilding the carb swap the plug wires around as that was suggested on another post. But I haven't tried it since the rebuild of the carb was complete. If I get a chance this evening I'll try swapping again and see what kind of results I get.

 

[joepcdr]

Guys I seek your wisdom in helping me trying to resolve my issue with this motor. Last fall the motor died on me in the middle of Glen Elder lake. At the time the only way I could get it running somewhat again. Was to basically have it at full throttle and even then it didn't run for very long.

Since then I've replaced the fuel pump, rebuilt the carburetor, and converted it to electronic ignition. Only sign of life I got out of it is backfiring that sounds like a shotgun going off. Which is what it was doing after I go it home from the lake the day it had died. So nothing really has changed.

I have tested for spark and compression in both cylinders and all seems well and normal.

The one thing that I've noticed today is that it seems that I can squeeze and squeeze that fuel bulb and it doesn't seem to build up pressure. I'm not sure if this is related to the backfiring or just another issue in its own self. But I thought I'd mention it.

I got home this evening and swapped the plug wires. On a good note we no longer seem to have backfiring. Bad note is it still isn't running.

 

[joepcdr]

Do you have a timing light? It is possible the backfiring blew out the upper crankshaft seal? Check to see if it is time?
http://www.ebay.com/itm/JOHNSON-EVI...LIP-/371336934220?hash=item567567f34c&vxp=mtr
On the outer edge of the plate is two sets of marks 180 degrees out for each cylinder. Shine the light there asy tyou tunr the motor over and the single line on the flywheel has to be somewhere inbetween those two mark. Is the air gap for the ignition coils to the flywheel magnet correct? If you can wiggle the points plate up and down that will throw the timing way off also. If fuel is not gushing out the carb it could be a leaky fuel pump diaphram or just bad check valves in the primer bulb. Is the arrow on the primer pointing toward the motor?

I don't have a timing light. However I do have a pdf copy of a really old repair manual for this motor. According to it and I quote. "Timing is NOT adjustable with a flywheel magneto system. The timing is controlled by the point setting. The correct point setting for ALL engines covered in thismanual is 0.020". The fuel and ignition systems MUST be carefully synchronized to achieve maximum performance from the engine. In simple terms, synchronization is timing the carburetion to the ignition. This means, as the throttle is advanced to increase engine rpm, the carburetor and ignition systems are both advanced equally and at the same rate. Therefore, any time the fuel system or the ignition system is serviced to replace a faulty part, or any adjustments are made for any reason, the engine synchronization must be carefully checked and verified. Before making any adjustments with the synchronization, the ignition system should be thoroughly checked according to the procedures outlined in this chapter and the fuel checked according to the procedures outlined in Chapter 4."

Since the manual doesn't mention anything about using a timing light I guess that is where I draw the confusion. I know for sure that it shouldn't be a leaky fuel pump diaphram as I just put in a brand new pump not no more than a month ago. I do have fuel coming out the carb when I got the choke on. It's not a lot, but its enough. I can tell you whomever serviced this motor in its years past didn't take very good care of it. They beat the crap out of the flywheel and I does have a warp to it. However that's never prevented it from running before.

 

[joepcdr]

http://www.ebay.com/itm/580412-5804...73A-/221127447484?hash=item337c3913bc&vxp=mtr
http://www.ebay.com/itm/Omc-Key-307480-/161707463705?hash=item25a6841419&vxp=mtr
Put on a new flywheel and key torque the flywheel nut to 105 foot lbs torque and check the timing with a light. While you have the flywheel off adjust the sync and link according to your old manual and check the upper crankshaft seal is fully seated down and in good shape. Your symptoms scream flywheel key it is possible the taper on the crankshaft is what is causing the flywheel to wobble. Clean up both the flywheel and crank so the flywheel sits nice and flat and put in a new shear key. I cannot stress enough to get the torque value on the flywheel nut correct It must be 105 ft lbs or you will shear another key.

As luck may have it I located a Evinrude motor of the same year and horsepower of my Johnson this week. It sounds like the motor hasn't been ran for a while. But for the price the guy is asking for it I'd be dumb not to go pick it up this weekend if its still available. If I understood my research on the johnson and evinrude motors a lot of the parts are interchangeable. Can anybody confirm this for me?

 

[joepcdr]

As luck may have it I located a Evinrude motor of the same year and horsepower of my Johnson this week. It sounds like the motor hasn't been ran for a while. But for the price the guy is asking for it I'd be dumb not to go pick it up this weekend if its still available. If I understood my research on the johnson and evinrude motors a lot of the parts are interchangeable. Can anybody confirm this for me?

Here's kind of an update on the motor I went to pick up last weekend. The motor is a 66 40hp Lark 8 with electric shift. I got it home and on a stand and grabbed a wrench to see if it would turn and it wouldn't. Removed the plugs shined a light down and I can see where it looked to be carbon froze. I sprayed some PB Penetrating oil in it and let it sit for a few days. I got it to come loose and it actually turns freely now and it doesn't appear that I scored they cylinder walls. I don't know how that can be but it is. I did a compression check and its running between 85 and 90 on both cylinders. Which is actually better than what my Johnson has. My Johnson was only getting about 75 on both cylinders.

The bad news this engine has no spark at all. The starter is fairly weak. It won't turn the engine over very well with the plugs in. The generator itself is a little stiff as well. I've done my testing with the belt off so I know for sure the starter is weak. I haven't looked at the condition of the lower unit yet. But I find myself now in a conundrum and could use some advise.

My conundrum is I now don't know which engine I should try to fix. Ideally I would like to get them both running, but its deciding on which one I should fix first. My Johnson has spark but backfires all the hell and won't attempt to run and has a warped flywheel, rebuilt carburetor and a new fuel pump. It also looks like its had several people work on it over the years.
The Evinrude looks like it hasn't had nobody touch it, has good flywheel and doesn't appear to have any leaky gaskets at least for the moment.
So for now I need to decide who's Peter and who's Paul so I can rob Peter to Pay Paul.

Any opinion would be appreciated.

 

[joepcdr]

Here's kind of an update on the motor I went to pick up last weekend. The motor is a 66 40hp Lark 8 with electric shift. I got it home and on a stand and grabbed a wrench to see if it would turn and it wouldn't. Removed the plugs shined a light down and I can see where it looked to be carbon froze. I sprayed some PB Penetrating oil in it and let it sit for a few days. I got it to come loose and it actually turns freely now and it doesn't appear that I scored they cylinder walls. I don't know how that can be but it is. I did a compression check and its running between 85 and 90 on both cylinders. Which is actually better than what my Johnson has. My Johnson was only getting about 75 on both cylinders.

The bad news this engine has no spark at all. The starter is fairly weak. It won't turn the engine over very well with the plugs in. The generator itself is a little stiff as well. I've done my testing with the belt off so I know for sure the starter is weak. I haven't looked at the condition of the lower unit yet. But I find myself now in a conundrum and could use some advise.

My conundrum is I now don't know which engine I should try to fix. Ideally I would like to get them both running, but its deciding on which one I should fix first. My Johnson has spark but backfires all the hell and won't attempt to run and has a warped flywheel, rebuilt carburetor and a new fuel pump. It also looks like its had several people work on it over the years.
The Evinrude looks like it hasn't had nobody touch it, has good flywheel and doesn't appear to have any leaky gaskets at least for the moment.
So for now I need to decide who's Peter and who's Paul so I can rob Peter to Pay Paul.

Any opinion would be appreciated.

Had a epiphany this evening. I now think I know why my Johnson won't start. I think you guys are right with timing being the issue. When I coverted it to electric ignition I remember thinking how is the motor going to be timed. According to the instructions it would just fire as the magnets on the flywheel came around to the coils. I happened to keep up my research and found some instances where points are still required. This actually makes sense and is what I think I need to do.

 

[joepcdr]

Also you need to install the plug wires into the coils and push the boots up tight then install the coils there should be a matal band on the top plug wire make sure it goes to the correct coil!

So it sounds like you might be in favor of getting the lark running first?

 

[joepcdr]

The lark is a little more difficult from your description. I would put the plate off of the lark on to the other motor.
http://www.ebay.com/itm/Ignition-Co...477-/331556480714?hash=item4d324e66ca&vxp=mtr
The coils and tune up parts are cheap and it sounds like you have issues with the generator as you need it running good for the gearbox. Also I would go to the auto part store and borrow a compression tester and compare results with yours. They normally just ask for a deposit. Once you get it running good give it a good decarb and see if the numbers come up?

OK here's the deal I finely had time to tear into both engines this evening and this is what I find. On my Johnson, at some point of me trying to get it started since converting it to electric ignition I sheared the pin. Which actually lead to another discovery! At some point in that motors life it must of ate through a few of them. Because the crank shaft is just ate up and gouged pretty deeply in spots. It looks like somebody tried to fix it with JB Weld at one point. When I first was working on the motor I thought it was odd to see a little bit of the stuff and never thought more of it until today when it was all falling out of the holes and gouges.

So over to the evinrude I go and it's crank is gouged up to but not nearly as bad as that of my johnson. Problem is thought I think it's cam lobe has worn down. Turning the engine I can't get it to open either of the points. I tried making some adjustments to no avail.

So here is my redneck game plan if you will. Since the JB Weld held up all these years in the Johnson. I'm going to repack and refill the holes and gouges in the crank with the JB Weld and sand it to shape. Replace the electric ignition I put in with points and condenser and put things together and see if she runs. If she does take off and run I'm just going to have to remember that I'm going to have to take it easy on her and not run her at full speed and not hit the prop on anything in shallow water.

Then going forward I'll get the power head off the evinrude and tear it down and do a complete rebuild over the fall and winter months. In the spring if things go my way do a engine swap and start rebuilding the johnson.