1985 Evinrude 115 hp poor idle and not charging/no tachometer reading

[ronnyr11]

I have 1985 Evinrude 115 with VRO disconnected. Has sat up for years before I purchased. Hard to start then only running on two. Raise high idle and choke occasionally and will rev up to run on all four. At that point I can get in gear and it will perform perfectly, full speed, 3/4, 1/2, 1/4 slow to idle, in gear or not, even for long periods of time. But shut off for a few minutes and have the same problem all over again. Could this be vacuum or fuel leak in VRO fuel pump? I put new plugs, plug wires, and one power pack was replaced before it sat up. It does occasionally not shut off when key is turned off. I have cleaned out tank, filter, and run over 30 gal. of fuel through it with no change. Tachometer works occasionally and I think it charges battery when tach works. Am told this is a $300 part on this oddball year model which is a water cooled voltage regulator. Any hope of finding part cheaper?

 

[emdsapmgr]

Re: 1985 Evinrude 115 hp poor idle and not charging/no tachometer reading

You have a number of issues going on. Regarding not shutting off: could be a bad key switch. Both packs should short to ground when the key switch is turned to "off" -effectively killing spark. Test the switch. Possible that one of your packs is not firing two of the cyls. You can test it by performing a cyl drop test, or checking each plugwire with an inductive timing light, when running. Since that engine has two identical packs, you can swap them and see if the no spark problem moves to the other head. An intermittent/erratic tach could well indicate a problem with the combination rectifier/regulator. Usually the tach problem coincides with battery charging issues. I doubt your engine would run fine at WOT if you had a fuel pump problem..

 

[ronnyr11]

Re: 1985 Evinrude 115 hp poor idle and not charging/no tachometer reading

Thank you! I had not thought of switch. Could it possibly be causing the charging and restarting problem as well? I will test packs, switch and wiring tomorrow. Do packs sometimes not fire at start up then perform perfectly until next start up? I understand this charging system was implemented in 1985 but do rectifiers sometimes work intermittently or would this be a wiring issue? Is there anyplace to buy a rectifier/regulator for this 1985 for less than $300?

 

[racerone]

Re: 1985 Evinrude 115 hp poor idle and not charging/no tachometer reading

You say it performs perfectly when in gear.--Is this on the boat or in gear on a hose??-----------Running a motor like yours at high revs in nuetral or in the driveway is not a good idea.---Have you confirmed that the carburetors are clean ?---Have you done a proper spark test ?----Spark must jump a gap of 7/16" or more to be considered " good " on these motors.

 

[emdsapmgr]

Re: 1985 Evinrude 115 hp poor idle and not charging/no tachometer reading

Usually weak ignition components tend to work when cold. After the engine warms up to normal operating temps is when these weak ignition components tend to fail-or work intermittently. That appears to be the opposite of what you are experiencing. The charging system is separate from the ignition system on that engine. If you've got no spark when cold cranking, it's not the charging system. That charging system has been around for a number of years prior to 85. The expensive (water cooled) combination rectifier/regulator first appeared on the 84 models.

 

[ronnyr11]

Re: 1985 Evinrude 115 hp poor idle and not charging/no tachometer reading

I have not been revving on a hose, all testing on lake, driving the boat. I know you hear form all types on here but I have been rebuilding natural gas and diesel engines for thirty years, and owned boats that long as well. I checked grounds and switch but found no problem. It ran as first described, perfectly once get motion started first time, but noticed it would not idle well or troll well. Outside temp was 50 and water temp. 50. When I turned ignition off left bank stopped firing but right continued to run. I also found that left bank heads were cool (well below operating temp.) and right bank normal temp. (not hot enough to burn finger). I ran boat down the lake and back 10 minutes, shut down and checked temps again and found same results. All four were firing and engine running very strong. I believe I have a open thermostat on the left bank and functioning thermostat on the right. This could be causing the poor idle and difficulty getting up to speed the first time after start up. Next I decided to swap packs which cured the shut off problem. The left bank stopped firing altogether after brief running at high idle in neutral. I am thinking this pack was not shutting off when it was on the right side and then quit altogether after placed on the left. It appears to be original and the pack still working is blue and has been replaced at some point. Boat would no longer plane out since it was running only on right bank. I was out of daylight and didn't have time to change packs back to original positions to check for change. I did compression check again later that night and found all four around 115, my gauge is old but main concern was they were all about same. I am asking for confirmation that this makes sense and next I will change out the old pack and replace stuck thermostat on the left bank. If this is the way these thermostats operate. One for each bank? How difficult are Thermostats to replace?

Usually weak ignition components tend to work when cold. After the engine warms up to normal operating temps is when these weak ignition components tend to fail-or work intermittently. That appears to be the opposite of what you are experiencing. The charging system is separate from the ignition system on that engine. If you've got no spark when cold cranking, it's not the charging system. That charging system has been around for a number of years prior to 85. The expensive (water cooled) combination rectifier/regulator first appeared on the 84 models.

 

[emdsapmgr]

Re: 1985 Evinrude 115 hp poor idle and not charging/no tachometer reading

Probably a good idea to repl the pack. Not unusual for one stat to stick either open or closed. Lucky it stuck open. A cold-running engine will tend to accumulate carbon deposits around the rings more, so you need to get both halves of the engine up to normal operating temps at idle. You will have to pull the stat housing apart, so might as well replace both stats. They are not that expensive. The stats open at 143, so the normal idle temps will vary between 143 and 155. Once you get up on plane, the pressure relief valves in the stat housing open-flooding the powerhead with extra cooling water. Once you get inside the stat housing, check the nylon pressure relief valves to be sure they are not heat-deformed. When the boat is on plane, powerhead temps could be 20 degrees cooler as a result. That's normal. Your 115 is has the bubble back exhaust manifold which creates real access problems to the stat housing. A real skinned-knuckle job for sure. Get a set of 1/4" drive socets and a swivel for the job. You may want to loosen the lower cowling to improve your access to the bolts. Factory flat rates it to remove the powerhead. Most skilled techs don't. I doubt the spark or cooling relate to your idle issues. If it's been a while since the carbs were cleaned, could be that the small idle passages in the upper carb bodys may be restricted by dried fuel gel. This is an idle issue only-usually the main jets supply enough fuel to run ok at WOT. (those carbs do have mid range jets) Compression of 115 is very good for that engine.