'77 70 HP Evinrude running on one cylendar

[stonesays]

My symptoms started as such: Engine runs great on muffs forwrd and reverse. Stalls with a load on it in the water when put in gear.

I suspect my power pack is shot and would like advise on how to test the voltage from it. Here's the wierd part. I tested the individual plug wires and get about 119 volts from each when cranking engine. Gounded each plug to head and have nice strong spark at each. compression 115 each,(just installed head and water jacket gaskets.) As I pull individual plug wires off while it's at idol I found that the top cylendar is the only one running the engine. (removeing lower two plug wires engine run the same. Remove top wire engine stops.)

So I know the is alot of voltage stored up in that pack and want to respect it and read it properly. What's my next step here guys?

BTW, nieghbor recomended this site to me and I think it's great! Just wish people would post the end results more!
TKS,
Stoney

 

[Joe Reeves]

Re: '77 70 HP Evinrude running on one cylendar

That engine is not running great on the flushette, it only sounds like that to the untrained ear.

Using spark plugs to test the spark is a waste of time. The spark must jump a 7/16" gap on a spark test. You can use a medium philips tip screwdriver in the plug boot wire terminal and hold the shank that distance away from the block if you have no tester.

If you have spark and compression,what is left is the fuel system. The usual problem is clogged carburetors... clean them (all) thoroughly and be sure to manually clean the brass high speed jets that are located in the bottom center portion of the float chambers with a piece of single strand steel wire.

 

[stonesays]

Re: '77 70 HP Evinrude running on one cylendar

true sir, not running great, just running.
I have since swapped coiles from bottom to top (to isolate coil or power pack) and have the same results. with the bottom coil up top it's the only cylender running. so, it's not the coil that is bad. would you lean to the power pack?

Your right on the gap for spark. Thanks for the reminder, I'll re-do that to check up, but pretty confidant that my power pack has gone out. do you know how to check the voltage readings on the power pack? seems I only have power to top cylender even changing the coils around.....

 

[hidef]

Re: '77 70 HP Evinrude running on one cylendar

Follow page 34 in the CDI troubleshooting guide it will help you diagnose your problem. Don't over look disconnecting the voltage regulator.

 

[Joe Reeves]

Re: '77 70 HP Evinrude running on one cylendar

Do the spark test as I mentioned above. If you have a 7/16" spark on all cylinders, that eliminates anything in the ignition system. If this is the case, suspect the clogged carburetors. Don't get hung up on the ignition system until you properly check the spark as that will drive you nuts!

THe fact that you have no power on #2 or #3 while running does not pinpoint that the problem is ignition nor fuel, hence the procedure of trouble shooting..... compression (100 psi+), then spark (7/16" gap), then fuel problems.

 

[stonesays]

Re: '77 70 HP Evinrude running on one cylendar

you were right. spark was nice and blue at 7/16" thanks for the advise. little intimidated in breaking down the three carbs even though I read about alot of the guys doing their own re-builds on here. I have good mechanical skills but it still seems intimidating. I've already sprayyed carb cleaner down the throats and up the float bowl drain plugs so I would guess they should be pulled to be cleaned and at that point should be re-build....

 

[Big Bubba]

Re: '77 70 HP Evinrude running on one cylendar

Yeap, take Joe Reeves advice he knows his stuff and I definitely have his respect as a AWESOME!!! mechanic with alot of outboard knowledge. Yeah, I would clean the carbs really,really, really good and see how it runs. I betcha, it will run really nice after the cleaning. By the way, when was the last time they were cleaned/rebuilt? Let us know how it goes. Yeap, in fact, I actually cranked up my 1983 Johnson, 70 horsepower outboard yesterday on my pontoon boat for the first time and she ran a little rough at first very briefly then cleared up and ran very nice and smoothly and no miss of any kind noted and peed really good. So I am getting anxious of getting my rig out to water for the very first time this year.

 

[Big Bubba]

Re: '77 70 HP Evinrude running on one cylendar

Yeah, the carbs on those outbaords are pretty straight forward. Go to the frequently asked questions above in this forum to see the actual video on how to rebuild a carb pretty easy to do.

 

[Big Bubba]

Re: '77 70 HP Evinrude running on one cylendar

http://forums.iboats.com/showthread.php?t=244013 Here is a good talk about carb cleaning. Click on the link in this thread.

 

[stonesays]

Re: '77 70 HP Evinrude running on one cylendar



You guys were right. Broke down the carbs and found red fiberous material throughout all 3 blocking all ports. Upon breaking down the fuel pump I found the culprit in a total breakdown of the gasket as pictured. I suspect using seafoam caused a breakdown of the gasket. I used it last year trying to fix these issues. Also as you can see the whole thermostat area was melted down due to an overheat 3 years ago causing multiple issues. Your recommendation to look at the carbs was invaluable and correct. Thanks for the help. Stonesays