1982 Evinrude 70 Surging and Intermittent Spark

[Luke000]

I am finally getting around to starting up my boat for the first time and the engine is running very rough. The engine has good compression (120, 123, 124), freshly rebuilt carbs and It starts up right away. However (and I had this problem when I first purchased the engine but it suddenly went away last year before I put it away) the engine pulses or surges at idle and boggs then dies when you give it throttle. It seems to act like an old hit and miss engine is the best way I can describe it. I checked the spark on all three plus and when it fires I have good spark for a second and the engine speeds up, and then it looses spark for a second and it slows down, then repeats. The only other thing I noticed is when I move the timing base all the way to the rear of the boat the engine looses speed but I get continuous spark and no more surging/pulsing. Any ideas where is a good place to start looking? Also it is a brand new battery and Im getting 13.0v when running (surging) and clean battery connections. No obvious loose or broken wires that I can see now at dusk.

 

[flyingscott]

Did you do a proper link and sync

 

[Luke000]

Did you do a proper link and sync

I have done what I can but the spark cutting out and the engine surging is making the proper job impossible.

 

[emdsapmgr]

Since you are not getting consistent spark, you should consider qualifying both the stator and the timer base. Check out the ignition troubleshooting tips at this website: cdielectronics.com. These guys have some neat tools to qualify both the stator and timer base voltage output when cranking. If both of these check out, then it could be the power pack.

 

[Baylinerchuck]

If it was me I would look at the power pack. There are some checks you can do with a dva meter to prove it out 100%, but most people don't have one since it's a rather specialized tool. You can use a timing light to prove erratic spark timing which would point me to the power pack. if this is the Oem power pack, and at this age motor, it's the first thing I'd replace.

 

[Luke000]

I am going to start testing what I can, but I do not own a DVA meter. Is there a local source that anyone knows that carries one? Or is this something I have to order on the interwebs?

Quick bit of extra info, here is a video of my engine attempting to run, ignore me showing the spark, my camera would not pick up the short bursts.

https://www.youtube.com/watch?v=AcQ0b-iahTY

 

[Luke000]

Well I ordered a new power pack for the boat and went to put her on tonight. Unfortunately not the engine will not even start. It kicks and backfires a few times but that is all it does now with the brand new Sierra power pack. I have very strong spark with the new power pack so I am completely stumped on why the boat wont even start now :grumpy:. I am at a loss, could they have sent me a defective unit? I made sure all of the connections were solid, and I even took it off and reinstalled it three times and no change. between the second and third try I also put the OE power pack back on and the motor started and ran like it did (surging like a hit and miss) before.

help.... :facepalm:

 

[Watermann]

Hey Luke that sure is an odd problem it sounds to me like the motor isn't getting

 

[Patfromny]

Sorry but I'm not super versed on outboards. My experience with my 35 hp evinrude and my many years of muscle car tinkering are what I'm pulling my advice from. It sounds like one of two things. First, have you verified that the firing order on the power pack or packs is correct? You could have the plug wires going to the wrong plugs and firing at the wrong times. With a strong spark, this could cause back firing because the mixture is being ignited when the piston is below the intake bore in the cylinder. A weak spark might not ignite the mixture at all because it is not a compressed mix. I would find top dead center and wire from there. In order to do this, you have to know what cylinder evinrude considers number one. Here is where I don't have the experience to help you. I could help with a Pontiac or Chevy engine. Firing order there is 18436572. One clockwise and the other counter clockwise. That doesn't help you any though. If you have a shop Manuel I would look through it to find firing order and cylinder numbers. It could be 123 from top to bottom but it could also be bottom to top. Maybe one of the OMC experts will chime in on this.

The second thing I would check once firing order has been established is the fuel mixture. I would richen the mix up a 1/4 turn at a time until the engine runs well. I have done this with my old 35. It would run great warm but wouldn't stay running cold. It would run then spit and stall. Drove me nuts because I thought the thing was tuned right due to how well it ran warm. I wound up richening the mixture 3/4 of a turn and it ran great cold and warm. Good luck. Love the boat, great job on everything so far. I'll be back over in the other thread waiting for a sea trial. Lol

 

[Patfromny]

I believe since this engine was bought from an estate sale and never run by you that the firing order could have been screwed up by the last owner and stored because he couldn't figure it out. You have also rebuilt all carbs so there will be a fair amount of fine tuning needed once you get it running. Sincing a tri power set up is one of my not so found memory's.

 

[StarTed]

Since I have a similar but slightly older motor I'll be curious about how you solve this problem should I experience a similar one when it's time to start mine up.

The only question I have, could a wire get rubbed when moving the throttle and temporarily ground out? Since the problems are different with 2 different power packs that doesn't seem likely.

Hope it's something simple and doesn't cost you any more.

 

[Luke000]

I do not believe that the firing order was screwed up by the PO or that the mixture is that bad that the engine will not run, as I have had the engine running great at one point last year before I put it away for the winter, I was having a similar problem last year when I first purchased it and then suddenly while running it, everything seemed to catch and it ran great so the firing order could not have been wrong at that point. Once I pulled it out of storage it went back to the intermittent spark problem and now this. Also with the old power pack the engine would at least start and stay running so I cant imagine that the mixture is so bad that with the new power pack it wont even begin to start, even with a little ether.

Does the power pack control the firing order? Is it possible that a wire was crossed in the new power pack and now the firing order is wrong? If so that might explain the problem.

 

[emdsapmgr]

The power pack has coded wires that go to the coils so that you don't get them crossed. All three of the wires coming from the power pack should be a tan color with a stripe. The top plug wire should have a blue stripe (ski). The bottom plug wire should have a green stripe ( grass) The middle wire has a purple stripe. The plain tan wire is part of the overheat system. Easy to miss the color code on these packs.

 

[Watermann]

My last post cut off some text for some reason.

I was going to say that it sounds like your motor isn't getting the proper the proper firing order hence the sound it's making, almost like it's running backwards. Either the order is messed up or the timing is way off. Have you checked the timing just to be sure?

 

[Patfromny]

The way the motor was running sounded as if it was missing at least one cylinder. Check the wires as emd suggests. Make sure all plugs are getting spark after that. TIming could definitely be the problem. I couldn't speak to how to time it but you could have the plugs firing too late or too soon.

 

[sargedog1]

you can rule out a fueling issue with short burst of carb cleaner be careful I do mean a very short burst as there isn't any oil and the rod can get dried easy as all get out. So very small burst to see if she responds to that very small burst down the carb. If it is fuel related it will instantly respond.
a search of google for peak voltage meter schematic can allow you to build an adapter with just a project box, cheap o leads and banana sockets, a cap, a resistor, and diode of the correct values. cheapest I've seen one for sale is $100

 

[racerone]

There are no mixture adjusting needles on these carburetors !-----Might be worth checking the flywheel key.---Not a lot of coins involved in that check.-----Do not overlook the fact that when motor does not spin fast enuff rhere will be no spark.-----So inspect / test your battery / cables and starter motor.

 

[Patfromny]

I'm guessing sargedog means ether and not carb cleaner. Carb cleaner will shut the engine off. I wouldn't recommend ether either. Maybe a small squeeze bottle with your gas mix in it. He is recommending you spray a bit of fuel into the carbs and see if it picks up in rpm. The same can be accomplished by richening the idle circuit screw and seeing if it runs better. Do one thing at a time is my advice. Check the spark in each cylinder, check that the wires are where they should be, check all ground wires, check your timing, then start looking at fuel.

 

[racerone]

There is no " idle mixture screw " on this motor.

 

[Patfromny]

So there is no adjustments you can make to the carb? That sounds nuts. I guess I would check base gaskets and the like. Sorry Racer, I thought you were asking if there were screws. Lol. That would be the first carb I have ever heard of that you cannot adjust. How do you go from hot to cold weather without adjusting the mix? Weird. It sounds like a spark issue anyway. If not, check the fuel pump and for leaky gaskets. You could spray some fuel into the carb but that would just tell you you need more fuel without the ability to give it more apperently.