no fire with plugs in 1975 Evinrude 85hp

[thellcon]

1975 Evinrude 85hp ran good last season, this year with the spark plugs in I see no spark with the plugs out I get a strong 1/2" blue flame from all 4 coils. The battery is new and fully charged the engine is spinning well over the required 300 rpm minimum. I removed the flywheel and see no leakage of the stator or corrosion on the flywheel surface. All ignition components on this motor are the originals from 1975 (except spark plugs). I did a low ohms test across the sensor leads at the powerpack and 2 to 4 reads 7.8 and 9 to 12 reads 7.6. (I do not have a neon tester) Where to from here? Should the timer base be replaced and if so what is the degree of dificulty in replacing it and getting it set right.

 

[Joe Reeves]

Re: no fire with plugs in 1975 Evinrude 85hp

Many engines of that dsign, for some reason, when testing for spark, show no spark when the spark plugs are installed. This is the reason for having the plugs removed when testing.

You don't mention whether the engine starts/runs or not but I assume it will not start.

The fact that the spark will jump that 7/16" or 1/2" gap with a strong blue spark indicates that all is well. However, FYI, replacing the timer base is simply a parts replacement project that does not require and adjusting.

I would suspect that somewhere in the starter circuit, you are experiencing a voltage drop. Check all of the related cables for hot spots after cranking the engine for 10 or 15 seconds as it's possible for any cable to develop a internal corrosive problem.... the highest degree of heat would reveal the problem area.

Remove and check the cable terminal ends to make sure that they are secured properly to the cables. Remove and clean thoroughly all of the cable ends and their related seating areas, including the battery terminals themselves, then tighten all connections with a wrench or pliers... no finger tightening of wing nuts if they exist.

Hopefully you'll find a problem within the above mentioned areas. If the starter should become quite hot when cranking within a short amount of cranking time, ir's quite possible that it may be failing but usually this type problem is due to a voltage drop.

 

[thellcon]

Re: no fire with plugs in 1975 Evinrude 85hp

Joe, forget to mention that after eliminating the 1st stage choke warm up function and cleaning the carbs I cannot get the motor to run or even fire that is how I found the spark dilema. I read on another site that if the engine has good spark with the plugs out but no spark wth the plugs in it is a sign of a defective timer base?

 

[Joe Reeves]

Re: no fire with plugs in 1975 Evinrude 85hp

No, that's not a sign of a defective timer base. Is that electric choke operating as it should?

 

[thellcon]

Re: no fire with plugs in 1975 Evinrude 85hp

Joe, I eliminated the warm up stage of the choke by combining the two purplewires as per an old service bulletin the motor was taking a long time to get over the warm up stage with excessive smoking due to an over rich condition at start up.

Please check out this link and tell me what you think about the defective timer base is http://www.boatpartstore.com/page30.asp (see item #1 under 4 cylinder engines)

The electric choke is now working fine although only when the switch is activated for full choke.

Why would I only have spark with the plugs removed?

I checked the starting system and don't see any problems.

This engine sat for over 20 years, but over the last 4 it has been working fine, the compresion is 135, 135, 132, 135

 

[ezeke]

Re: no fire with plugs in 1975 Evinrude 85hp

The engine needs to turn 300RPM to generate good spark. The reason that you take the plugs out is that it is easier on the starter with no load. If you see spark with the plugs out, the ignition system is usually not the problem.

 

[Joe Reeves]

Re: no fire with plugs in 1975 Evinrude 85hp

Re-read my reply above pertaining to the cables and cable ends.

 

[thellcon]

Re: no fire with plugs in 1975 Evinrude 85hp

Thanks for all of your help on this project I now believe I might be ready for the lake before the ice is off. I wonder what everyone did before Joe Reeves got a computer.

Okay here is were the engine sits as of now, I checked all wire cables and terminals all seemed good.

I took off the flywheel again and noticed a small amount of tarnish on the timer base sensors I dressed them with an emory cloth and put it back together I checked the spark with a tester and it readily jumped the 7/16 gap on all 4 I closed it up and it fired and started immedietly.

This boat sat untouched in a boathouse for over 20 years

To date I have cleaned both carbs, replaced all fuel lines under the cowl, replaced main fuel line and bulb, replaced fuel pump, replaced impeller, eliminated warm up stage of electric choke, replaced battery

While I was at it I followed the instructions on this site for installing a tell tale it turned out to be very easy and works well (I have the engine in a barrel).

Now the engine runs and idles very smoothly (I do not have a tach but it seems to be running at sufficent rpm for low idle) after idling a short time the engine will suddenly cough slightly and shut off, I hit the key and it starts right back up then after a while it will happen again. Where to from here? would this be timing? or carbs out of sync? I tried to do a link and sync but addmitedly have never done it before.

 

[Joe Reeves]

Re: no fire with plugs in 1975 Evinrude 85hp

Hopefully you torqued that flywheel nut to 105 foot pounds. Anything less will result in a sheared flywheel key.

The running, coughing, spitting back of sorts, is usually caused by slightly fouled carburetors that result in a lean running condition. Could also be a lack of fuel due to a fuel/air leak in the fuel line somewhere, failing fuel pump, something of that nature.

If no fuel/air leak exists, and this condition ceases to exist while pumping the fuel primer bulb, I would suspect the fuel pump.

 

[thellcon]

Re: no fire with plugs in 1975 Evinrude 85hp

Joe, yes I tourqedthe flywheel with a dial wrench to 105

I will try pumping the bulb tomorrow and let you know

 

[thellcon]

Re: no fire with plugs in 1975 Evinrude 85hp

All hose connections are tight, problem continues even when continuosly pumping the bulb. I removed the air cover and the port side lower cylinder is backfiring through the carb once every 15 to 20 seconds only when at idle, engine speed is good. Would this lead me to a lightly clogged low speed orfice as these are not adjustable?

 

[ezeke]

Re: no fire with plugs in 1975 Evinrude 85hp

If it is coming back through the carburetor throat, a reed is not closed.

 

[Joe Reeves]

Re: no fire with plugs in 1975 Evinrude 85hp

Spitting back, sounding like a mild backfire, indicates a carbureor slow speed restricted jet..... something causing a lean carburetor scenario.

Blowing fuel out the carburetor throat with each downward thrust of the piston indicates a reed (leaf valce) problem.

 

[thellcon]

Re: no fire with plugs in 1975 Evinrude 85hp

Okay here's the latest update:
started engine, held a white business card outside of throats to see if there was any blowback, there was none.

removed both carbs and carefully rechecked, all passages and jets are clear.

looking down into bottom of read boxes noticed an accumulation of oil at bottom of intake outde of the reeds, all reeds appeared tightly closed.

removed starter solenoid, starter, and intake manifold

turned off garage lights, held a flashlight to backside of reed boxes:

2 reads slightly open on lower port side, 1 read open the thickness of a business card on lower starboard side. My manual says .010 is ok. These are too much

Should I go for 2 new stock reed boxes, used, or Boysen

 

[thellcon]

Re: no fire with plugs in 1975 Evinrude 85hp

I bought 1 used reed block from TC outboard and put everything back together now I need to do a link & sync. Last week I read a post about a 75 Johnson that said to set pick up timing you should use the bottom mark on the throttle cam, my manual says to idle the motor up until the timing is at 4 degrees, kill the engine with the idle where it is and adjust the cam link so that the top mark aligns with the throttle cam, a friend of mine told me to use the middle line marked start. (The manual I have is somewhat generic and covers all v4 models and has been incorrect on details like this in the past.) Which mark is correct for setting the timing pick-up top, middle or bottom?

 

[HighTrim]

Re: no fire with plugs in 1975 Evinrude 85hp

I do believe it is the top mark as indicated by your manual.