[B]Need help 50hp 1971 evinrude hydro electric.[/B]

[the_one]

I have a 50hp 1971 evinrude outboard motor. I'm currently running into a dilema with the motor. When motor in forward mode at full throttle it doesn't rep up to the maximum rpm(very slow speed). I feel like motor has lost power at forward mode or not enough intake of gas or air. However, when motor is at neutral or reverse mode and at full throttle it reps up to the maximum rpm. Before this dilema, the motor was running great. My assumption is a thermal stat failer. I recently replaced impeller and changed lower gear lube. Please help me solve this issue.

Thank you all.

 

[tashasdaddy]

Re: Need help 50hp 1971 evinrude hydro electric.

i suggest you start with the basic trouble shooting. check compression and spark on both cylinders. pull the spark plug wire and see if the rpms drop. it will run on one cylinder.

 

[the_one]

Re: Need help 50hp 1971 evinrude hydro electric.

i suggest you start with the basic trouble shooting. check compression and spark on both cylinders. pull the spark plug wire and see if the rpms drop. it will run on one cylinder.

I checked the compression and each cylinder at 140 psi but did not test the spark ( no tool). I did as suggested and pull spark plug wire on cylinder one, engine stalled. Did the same test on cylinder two engine still running. Please help with the next step. Thank you.

 

[tashasdaddy]

Re: Need help 50hp 1971 evinrude hydro electric.

i would say, you are not getting spark or fuel to the #2 cylinder, need to check spark. if you have spark, need to clean and rebuild the carb.

 

[jay_merrill]

Re: Need help 50hp 1971 evinrude hydro electric.

The first cylinder that you pulled a wire for is firing, while the second one is not. When operating the engine in neutral, there is no resistence and the motor will "rev up" freely. When in reverse, the throttle travel is limited, so you might not notice a dead cylinder there either.

I don't have a manual for your motor but can point you in the right direction. The 1971 50 hp engine has magneto CD ignition in it. The major components for the ignition system are the stator, the timer base, the powerpack, the coils, and the spark plug wires.

When less than all cylinders (two in your case) have failed to fire, the stator is usually not the culprit. I would suspect a bad sensor coil in the timer base, a bad powerpack, a bad coil, or a bad spark plug wire.

The first thing I would check is to see if the spark plug wire is loose at the coil. These leads screw onto a threaded post in a recessed cup on the coil. They sometimes loosen over time and back off of the post. If this has happened, remove the wire, trim a small amount (no more than the length of the post) and screw back in. You can also put a bead of silicon at the wire/coil junction too.

If this is not an issue, check the boot end of the wire. Original OMC wires have a coil type clip inside of the boot, which makes contact with the plug. The clip connects to the wire by piercing the end of the wire with a "spike" on the end of the clip. This is done before the boot is installed on the wire and if not done correctly, often doesn't stay in place.

Next on my list would be the coil involved. An easy way to check a potentially bad coil is to swap it with another coil that is known to be working. Since you only have one other coil, just swap the two. Be sure to get the leads to the powerpack switched too. If the dead cylinder changes to the one that was previously known to be firing, you will know that you have a bad coil.

There are some simple ohms tests that can be done on a stator and timerbase, but I don't know the correct values for you motor. My guess is that they are the same as my 1972 Johnson 65hp motor, but I can't be sure. You might want to invest in an OEM manual for your motor, which will have this information. I wouldn't bother with generic manuals or web page derived info that is generic, because every one that I have ever seen is wrong for the first "editions" of the magneto CD ignitions.

In the mean time, try the things that I suggested and see what happens. If you don't find the problem, we'll take it from there.

 

[the_one]

Re: Need help 50hp 1971 evinrude hydro electric.

The first cylinder that you pulled a wire for is firing, while the second one is not. When operating the engine in neutral, there is no resistence and the motor will "rev up" freely. When in reverse, the throttle travel is limited, so you might not notice a dead cylinder there either.

I don't have a manual for your motor but can point you in the right direction. The 1971 50 hp engine has magneto CD ignition in it. The major components for the ignition system are the stator, the timer base, the powerpack, the coils, and the spark plug wires.

When less than all cylinders (two in your case) have failed to fire, the stator is usually not the culprit. I would suspect a bad sensor coil in the timer base, a bad powerpack, a bad coil, or a bad spark plug wire.

The first thing I would check is to see if the spark plug wire is loose at the coil. These leads screw onto a threaded post in a recessed cup on the coil. They sometimes loosen over time and back off of the post. If this has happened, remove the wire, trim a small amount (no more than the length of the post) and screw back in. You can also put a bead of silicon at the wire/coil junction too.

If this is not an issue, check the boot end of the wire. Original OMC wires have a coil type clip inside of the boot, which makes contact with the plug. The clip connects to the wire by piercing the end of the wire with a "spike" on the end of the clip. This is done before the boot is installed on the wire and if not done correctly, often doesn't stay in place.

Next on my list would be the coil involved. An easy way to check a potentially bad coil is to swap it with another coil that is known to be working. Since you only have one other coil, just swap the two. Be sure to get the leads to the powerpack switched too. If the dead cylinder changes to the one that was previously known to be firing, you will know that you have a bad coil.

There are some simple ohms tests that can be done on a stator and timerbase, but I don't know the correct values for you motor. My guess is that they are the same as my 1972 Johnson 65hp motor, but I can't be sure. You might want to invest in an OEM manual for your motor, which will have this information. I wouldn't bother with generic manuals or web page derived info that is generic, because every one that I have ever seen is wrong for the first "editions" of the magneto CD ignitions.

In the mean time, try the things that I suggested and see what happens. If you don't find the problem, we'll take it from there.

First of all I would like to say thank you very much for all your help (Jay_merrill & Tashasdaddy), I really appreciate it.

Second I'm not a mechanic or have any experience in outboard motor. But I have taken all your suggestions in consideration. Before I follow all your suggestions (Thanks Jay_merrill) I have double checked all connections to ensure none of them are lose. After all connections are checked, I started engine and retested as Tashasdaddy suggested (Thanks Tashasdaddy). I just wanted to verify my results are the same compare to the first. Compression still the same for both cylinder but this is wierd when i pull out the spark plug cable engine of the first cylinder engine still running. I did the same for second cylinder the result are the same. Checked the sparks and it's produced strong spark plugs. I also took this opportunity to rebuild the carburetor just in case it cause the problem. After all this work I started the engine and put in forward with full throttle (engine was not submerged under water, I used the ear muff). Engine sound greats, I thought problem is fixed. So the next day my bro-in-law took it out and the issue still exist. But what he told me was every time engine is in gear (forward mode) with full throttle. Engine tries to speed up but it slips. Therefore, I think the issue is in the lower unit. But I don't know what is the exact issue, worn gears or bearing issues, thrust washers or bearing. I checked all teeth on the propeller everything is in great condition and the drive shaft itself. Please help me pint point the issue and where do I buy OMC tool or do I have to.

Thank you.
Peter.

 

[tx1961whaler]

Re: Need help 50hp 1971 evinrude hydro electric.

First of all, NEVER run the engine at full throttle on muffs or in neutral. That's a quick way to totally destroy it.
It sounds like the propeller hub is spun. The prop is 2 pieces, the inner hub and outer part are pressed together with a rubber bushing in between. You can check to see if the prop is slipping by drawing a line completely across the prop centerline with a magic marker, run the motor in the water, and then check and see if the inner and outer parts still line up.

 

[the_one]

Re: Need help 50hp 1971 evinrude hydro electric.

I did the biggest mistake (stupid), please help.

I hooked up the battery wrong. Positive to negative and negative to positive. What did I burn ? engine won't start. I replaced the fuse but it kept burn out every time i cranked the key.

 

[the_one]

Re: Need help 50hp 1971 evinrude hydro electric.

FYI.

Reverse polarity at the battery will shorted out the following.

rectificer, Diode & lead Assy', ignition selonoid, maybe the power pack and 20amp fuse.