1974 evinrude 70 hp won't rev in the water ???

[Skifferskipper]

Re: 1974 evinrude 70 hp won't rev in the water ???

Check the Stator....

 

[Skifferskipper]

Re: 1974 evinrude 70 hp won't rev in the water ???

If the stator was bad it would be running on battery power and would cause the engine not to have enough power to run the coils under a load.. so check the diods on your stator and make sure they arent running both directions..

 

[Skifferskipper]

Re: 1974 evinrude 70 hp won't rev in the water ???

Does it Kinda Miss a little bit too when your trying to WOT Under load? But still idles pretty good...?

 

[jtexas]

Re: 1974 evinrude 70 hp won't rev in the water ???

For a few years there OMC used a battery-driven CD ignition, but this one is magneto driven. If the stator's bad, you won't get spark on any cylinder.

QL78C is a cooler plug, probably the alternative for racing applications. Expect it to foul more easily and possibly contribute to carbon build up in the cylinders. I'd change 'em at your next opportunity but they're not a likely cause of your present symptoms.

The results of your compression and spark tests are good; I would be inclined to focus on fuel.

I just reread the thread and found something I missed before -- if you pulled core plugs out the carbs, but didn't have any carb kits on hand, what did you plug the holes with?

You also asked about timing:
Your timing at idle is 0? TDC. WOT timing is 19? BTDC, but *DON'T* set it with the motor running on the muffs. It has to be done with the engine fully loaded, like in a test tank with a test wheel. But Joe Reeves has a procedure for setting WOT timing at cranking speed, it's on this forum in the Top Secret Files. You won't find that in any manual.

If you see a foreign substance on top of the powerhead that might be melted epoxy thrown from the flywheel, it's possible that a magnet or two has shifted; that'll throw the timing off. Also if the flywheel key has sheared.

Check the timing pointer alignment first:
[note: Rotating the flywheel CCW turns the water pump impeller vanes backwards, so do it for this procedure only, and as little as possible.]
1. rotate the flywheel (clockwise) until the TDC mark is a approaching the TDC pointer, a few inches away. Insert a piston stop tool into the #1 hole and rotate the flywheel (CW) until it contacts the stop. With a pencil, mark the edge of the flywheel at the TDC pointer.
2. rotate the flywheel (CW) a few inches past TDC, insert the piston stop tool, and rotate the flywheel back (CCW) until it contacts the stop. Mark the edge of the flywheel again, at the TDC pointer. Now rotate the flywheel (CW) a bit, to relax the water pump impeller vanes.
3. draw a straight line between your two marks.
4. draw a straight line from the center of, and perpendicular to, the first line to the edge of the flywheel.
5. if your 2nd line hits the 0? TDC mark embossed on the flywheel, you're done.
..........otherwise,
6. rotate the flywheel (clockwise) until the 0? TDC mark aligns with the TDC pointer.
7. loosen the TDC pointer and slide it over to align with your 2nd line. That should be the correct position, but if you like, repeat from step 1 just to be sure.

 

[Skifferskipper]

Re: 1974 evinrude 70 hp won't rev in the water ???

abc

 

[jtexas]

Re: 1974 evinrude 70 hp won't rev in the water ???

Okay........ Just figured because I have a 1974 Evinrude 3cyl that ive been working on this problem with for about a month now and I rebuilt the carbs and everything your talking about right now then my step dad tested the diods somehow and said replace the stator.. Just used the boat all last weekend.. Sorry for interupting..

ah, I see now...sounds like you're describing the "rectifier"

 

[Jd 1978]

Re: 1974 evinrude 70 hp won't rev in the water ???

Thanks for your input skifferskipper. And jtexas when I drilled out those plugs I reused them with a dab of silicone over my 1/8 inch hole. But the carb kits come with those plugs so I can do away with the silicone. And I will pick up the proper plug thanks. As far as the timing you gave me lots of info. I will need to re read all of it with the motor in front of me for it to make sense. As far as the idle goes it is smooth until you turn it down. Somewhere below maybe a thousand

 

[Jd 1978]

Re: 1974 evinrude 70 hp won't rev in the water ???

It idles smooth until you turn the idle down to under a thousand. Then there is a miss.

 

[Jd 1978]

Re: 1974 evinrude 70 hp won't rev in the water ???

I got my carb rebuild kits yesterday. I am going to try and get that done this weekend and see how it effects the motor. Will keep you posted. Thanks.

 

[lonemust]

Re: 1974 evinrude 70 hp won't rev in the water ???

the one thing i see no one has asked, and i had this happen before.. is your water pump working properly.. if the pump is not ppumping the water through the engine it will do what you described in the first post.. I had an old mercury that ran fine in the barrel but on the water it would not run. Impeller in the pump was shot. replaced the water pump and it ran like a raped ape.. just a thought.. i had checked and rechecked everything in the ignition system and fuel system for months.. then got mad and sold the boat and the guy who bought it replaced the water pump and it ran fine.

 

[Jd 1978]

Re: 1974 evinrude 70 hp won't rev in the water ???

Thanks lonemust for the comment. Now that you mention it I don't think I have ever checked the water pump. Will make certain to do that next time on the water. .... I got my carb rebuild kits and got them installed. There were some parts in them kits that I couldn't match up to my carbs ?? I assume the kits were for multiple carbs ?? Also had a chance to drop the boat in the water last weekend and the problem is still there. The carbs were defiantly in need of a good going through cause it idles a whole lot better now. I guess I didn't see how rough the idle was before. Like I said I'm new to boat motors ! But anyway the motor done the same thing. Full throttle and the boat would not pull it's self anywhere. One thing I did notice is when in reverse the motor wanted to pull a whole lot harder than in forward. It was a drastic difference. Never had gave it that much throttle in reverse before so that's why I never knew that happened. Could that have something to do with the water pump ?? Sounds unlikely but I'm nit the expert either. Thanks for the help !

 

[Exotic4x4]

Re: 1974 evinrude 70 hp won't rev in the water ???

My boat had same issues I had a bad power pack. Replaced it ran on all 3 cylinders again. but I would swap your coils around first before u buy any parts see if Ur problems follow that coil if it does then its a bad coil if not get your power pack tested. Also check your kill circuit 90% that's not it but its something to weigh out.

 

[Jd 1978]

Re: 1974 evinrude 70 hp won't rev in the water ???

Thanks red fx4. Where is the power pack ? Is that easily tested ? And I'm not sure what you meant by kill circuit ? Do you mean the key switch circuit ? Thanks for your time.

 

[Exotic4x4]

Re: 1974 evinrude 70 hp won't rev in the water ???

The power pack is located in the right side of Ur motor it says POWERPACK on it has 8? Wires going into it also when my mechanic diagnosed mine hr said the coil will also give the same symptoms when the motor gets warm electronics fail he used a dva? Meter to check ohms or volts not sure exactly on thebprocedure but he pinned mine to my power pack not having enough to feed my coils under load I think is how it went. Anyone else back up this theory with better detail?

 

[Jd 1978]

Re: 1974 evinrude 70 hp won't rev in the water ???

Finally was able to get the boat out on the water this last weekend ! Here is all the things I have done since I took it out last. Put a set of used coils on it also put a new power pack on it. New set of plugs to even though the old ones looked good. Took my timing light with me this time to test for spark under load again. But this time I checked the water pump to see if it was streaming water out of the motor and I couldn't find anywhere it was shooting out. It is supposed to " **** " out right ? Since I couldn't find any water coming out I shut it down and put it back on the trailer. Anybody know where it should be shooting out of ?? I assume the two little holes on the back of the motor ? I could feel puffs of air there but no water. If the water impeller is out I hope I haven't damaged the motor any by getting it hot ?!! It never has felt hot to the touch but then again I never felt it strictly for overheating either. Could a water pump cause these problems without getting the motor hot ?? Or a water impeller I should say. Any help would be appreciated.

 

[BonairII]

Re: 1974 evinrude 70 hp won't rev in the water ???

Maybe your thermostat hadn't opened yet to allow full the water flow. My old '67 Johnson(no 'telltale') won't mist any visible amount of water thru the upper exhaust hole until it's warmed up and the thermostat opens.

 

[Jd 1978]

Re: 1974 evinrude 70 hp won't rev in the water ???

Thanks for the reply bonair II. from the time I backed off the trailer and idled all the way around the dock and then got close to the motor to see it wasn't giving a telltale water stream was prbly around 7-8 minutes. Not really sure on the warming up timeframe but that should have been sufficient I would think to start the telltale stream. I guess next up is a water impeller.

 

[triumph74]

Re: 1974 evinrude 70 hp won't rev in the water ???

ok, finally got the boat back out on the water...... while at WOT running across the lake we shot the fuel mixture into the carbs there was no change unless you squirted several shots in there and then the motor bogged down.... also hooked a timimg light to the spark plug wires and it only came on with the middle cylinder.... that really didnt make sense to me, but i kept changing it around and the timing light only worked on the middle ?? any ideas with that ?

I think I am having the same trouble. I have spark with a hose hooked up, but when I put it in the water it still bogs down. I have not used a timing light out on the water yet. Did you figure out what your problem was?