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1988 88hp Evinrude hard start and rough idle

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Ben A

New member
Hi, first post here. I've been searching and reading a lot but looking for some advice. I have a 1988 88 HP Evinrude on a boat that I've had for about two years. I've had a hard start/rough idle problem for some time now. The engine performs well at WOT, but it takes some cranking to get it to start and will not idle well.

I've verified the timing pointer, the carb plates are in sync, and set the cam follower pickup. There seems to be a lot of play in the throttle cable linkage, as well as the spark advance rod where it connects to thing under the flywheel. There also seems to be a lot of play in the throttle lever. All this play makes my timing readings not precise when checking the cam follower pickup timing. I ordered a new bushing kit for the spark advance rod, so that may help. When checking the cam follower pickup timing, I can get it as low as about 6 degrees before the engine will stall. More advance keeps the engine running. The idle adjustment screw has to be fully in to offer enough ignition advance for the engine to idle.

I did not check the max spark advance timing but will try soon, but not sure it will help this problem. The spark advance rod on the 1988 does not have a thumbwheel but rather 3 positions on the retainer that attaches to the throttle lever.

Plug 1 looked pretty fouled when I pulled it to check TDC today. I'm running the Champion plugs recommended for the engine.

I replaced the water/fuel filter and it didn't seem to help. I always run ethanol free 93 octane, premixed with OMC oil at 50:1.

With the front plate off, I stuck my hand (with a latex glove on) over each of the two inlets. It seemed like the top was creating more vacuum than the bottom, so much so that I wonder if it is even running on all four cylinders.

Admittedly, I'm a novice to outboard engines but I am very familiar around a car engine. I could really use some guidance as to what to do next. Compression test? Decarb? Plugs? I got a factory service manual in the mail today and will continue to read through it. Any help is appreciated. Thanks!
 
With "all" spark plugs removed, what is the compression psi of all individual cylinders?
The spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it?

The 7/16" gap is important.

(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1


You're probably aware of the numbering but if not, standing in back of the engine, facing the spark plugs, the cylinders are numbered as:

2....1
4....3
 
Thanks for the response Joe. I just did the compression test. The factory service manual says to warm it up to operating temps...I did the test with the engine cold from not running since yesterday but can do it again with it warmed up. Let me know if this matters.

Concerning results though:

Cyl 1 - 90psi
Cyl 3 - 80psi
Cyl 2 - 105psi
Cyl 4 - 100psi

I checked the spark with a tester set at 7/16". I got decent spark from 1, 3, and 2. Could not get 4 to spark but believe it is a bad wire. There was rust on connection from the boot to the plug and corrision on the other connection from the boot to the ignition component. I'll track down some new wires and plugs and see if that helps. Plugs were last changed 2 years ago I think, not long after I got the boat. I do recall gapping them to .30. I took a picture of all 4 plugs and can post it if that helps.

Any other thoughts?

Thanks

Ben
 
If that compression reading holds true, there is 20 psi between cylinders #3 and #4 which indicates a problem. Before going any further, I'd strongly suggest removing the cylinder heads for an inspection of the head gaskets, the sealing surfaces, and the top of the pistons along with the cylinder walls.

I suspect that this difference in compression is the base of your problem if it holds true in a second checking.
 
Thanks Joe. Do you think bringing the engine up to operating temp then rechecking the compression may yield different test results?
 
joereeves said:
It's not likely but worth a try to see what those readings are.
Click to expand...

I'll check again soon. After thinking more about not getting spark on 4 and the corroded wire, I called around to see if I could get a local set. The only thing I could get was one similar wire. I put new plugs in and the new wire after cleaning the bad contact on the coil, and she fired right up. But, then it started bogging and I could hear a loud tapping, definitely some ignition arcing. I thought it was the new wire so cleaned up the old one and put it on. Same thing. Stared at it for a while to see what could be causing the arc. I noticed that the plug wire from coil 4 was right up against the wire going to the coil from the harness. I rotated it around so there was no contact, starts and idles solid again.


Seems like I still have some bigger issues to test for. Will redo compression test and if still 20psi off then a leakdown test.

Thanks for the help, Joe!
 
Possibly a little something that may be of help in the future.

(Replacing Regular Spark Plug Wires)
(J. Reeves)


If you also need the spark plug boots and the spring terminals that connect to the spark plugs, purchase them from your local dealership (OMC Part #581027). This includes one boot and one spring connector. Price is about $3.25ea.


Purchase whatever amount of spark plug wire you need. Be sure to purchase the kind that has a steel (or copper) twisted wire leading through the center of it....... not the carbon type plug wire that many automobiles now use.


Using your old plug wire, cut the new wire to a length about 3/4" to 1" longer. If you have no old plug wire, just make sure that the wire is longer than you'll need as you can trim the other end later.


The rubber boot, spark plug end.... With the wire cut to the length required, trim back 1/4" insulation again but do not solder tint the wires. Simply fan out the wires and fold them back against the insulation, cutting the excess off as explained above. Holding the spring wire terminal, estimate where the prong should be inserted so that the spring will be flush against the exposed wire. Hold the spring terminal away from the wires end (sideways) and insert the prong into the insulation and into the center wire, then swing the spring terminal in front of the exposed wire portion (makes a tight fit for continuity purposes). Spraying the inner portion of the boot where the wire will insert with a small amount of WD40 makes the installation of the wire a easy project.


Now, the other end that slides into the magneto coil... Look into the awaiting hole of the coil and you will see a somewhat threaded tapered prong. Double check to make sure that the wire is cut to the length required (better slightly longer than shorter), trim back 1/4" insulation again but do not solder tint the wires. Simply fan out the wires and fold them back against the insulation, cutting the excess off as explained above, then simply slide the wire into the coil so that the inner wire core of the wire is impaled by the tapered prong within the coil. That's it.... you're done.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
********************
 
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