Johnson Ocean Runner 90 HP V4 Idle Issue

Long time reader with a motor that is haunting me!

I'm helping a friend get his Whaler going for the first time after sitting a good 5 or so years and it has a 1995 Johnson 90 HP Ocean Runner on the back that's in good shape. Model J90SLEOC. The problem I have after going through it and starting for the first time is that it will start and run but if left alone will stall/die off after no more than 10-15 seconds.

The compression checked out great and so did the spark. This engine has the plastic carbs and all the funky timing linkages with the "Covered" flywheel. I rebuilt all the carbs and the carb bodies of which came out really nice. All carb bowls have been sealed where those "BB's" are as those leaked like crazy and 2 had fallen out. Fuel system is now "Tight" and has no leaks with all new gaskets throughout. Replaced the water pump, gear oil and thermostats as well as a thorough go over with a fine tooth comb.

What I have found is if I can start it and quickly run back to the engine and move the timing lever which protrudes out of the top most shroud over to about midway it will idle all day long! As soon as you let go, the engine will die by itself in about 10-15 seconds. I followed the book to check the timing but of course I do not have the special tools to analyze the system. This is where I have left it and frustrated in about December. Now it's getting to be boating time and I want this done so I do not have it in my head!

Any and all advice is greatly appreciated, thanks in advance!

We need numbers what are the compression numbers and do all plug wires jump a gap of at least 7/16 inch open air gap test? Exactly how are you adjusting the slow needles plus you need to check engine sync between ignition timing and throttle opening every time you pull the carbs. Did you install new carb gaskets? Ignition timing and max timing advance should be good unless you messed with them.

You are sure " bb's" had fallen out ?---Any pictures if where they fell out ?

kimcrwbr1 said:

We need numbers what are the compression numbers and do all plug wires jump a gap of at least 7/16 inch open air gap test? Exactly how are you adjusting the slow needles plus you need to check engine sync between ignition timing and throttle opening every time you pull the carbs. Did you install new carb gaskets? Ignition timing and max timing advance should be good unless you messed with them.

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Compression:
1 - 146
2 - 139
3 - 146
4 - 131

Spark was good on my tester and just holding the plugs up to the block, was a sharp smack sound and bright blue, I know it'd jump a gap that big, I do not own one of those types of open air testers. Seems I should invest finally.

I rebuilt the carbs and had the throttle bodies off, sonic cleaned everything and preset the low speed needles at 1.5 turns, my general start point with all of them. I followed the manual on re-synching the carbs like I always do anytime I remove them and this one was a little trickier than the typical 2 barrel carb engines (I like those better!). It came out well and I re-checked my work at least 2-3 times and everything came out the way it's supposed to. All new gaskets throughout is the only way to do it. I did not mess with any timing, just re-synched the carbs once all installed with new gaskets.

That is the ficht ignition system I`m pretty sure Racer will give you better guideance. When the engine stalls are the plugs wet with fuel? Having to add air sounds like it is burning too rich, have you tried messing with the slow needles?

kimcrwbr1 said:

That is the ficht ignition system I`m pretty sure Racer will give you better guideance. When the engine stalls are the plugs wet with fuel? Having to add air sounds like it is burning too rich, have you tried messing with the slow needles?

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That is not a FICHT motor. FICHT is a direct fuel injection system not an ignition system and did not show up on evinrudes until 1998 OP has carbs. I believe your motor has the OIS ignition system there have been several updates to the sensor, you will want to change that especially after sitting for 5 yrs. What have you done with the fuel system that has also been sitting for 5 yrs and are you running fresh gas. You make no mention of the fuel pump or tank are the lines degraded.

The little "bb's" were on the bowls of the carbs, forget which side exactly and I flushed some new fuel in and it just drained right out of the carbs. 2 were completely missing and the other 2 were leaking, owner stated he would get it to run but not till an hour of screwing around with it and warming up. His words to me. Sorry no pics.

Yes this engine has the OIS Ignition system on it with the optical sensor. I watched a couple YouTube videos on replacing that, pretty straight forward. I just do not have a way to test it with the Ignition analyzer tool, don't have that either. Would the sensor be the direct cause of the engine not idling when I do not hold the timing arm over? It will always start it seems with a quick prime then run for no more than 10-15 seconds before dying. It just starts to slow and then cuts out, every time, but if you hold that timing lever over manually, it'll run all day. I totally went through the fuel system, rebuilt everything including all new lines. Tank to engine line is new and hard plumped, no connector on engine side, VRO disconnected and running premix and pump puts out plenty of volume. There isn't a leak anywhere, I've checked and pumped it full with the primer till pretty hard and it's tight. The mixture screws I installed pre-set to 1.5 turns out which is where I always start as a base point then once running move from there. I have not played with them at all because it doesn't stay running. Only thing I did try was opening them to 2 and 2.5 turns respectively to see if that was causing the stall but it did not eliminate that issue.

Anything I'm missing or need to check? I'm hoping someone will just chime in and say replace the optical sensor and let her go or some adjustment! Thanks for the replies!

Have you tried adjusting the idle stop screw? Engine idle is controlled by ignition timing in most cases. Has the idle stop been messed with? Or possibly a link or bushing is worn causing ignition timing to be too far retarded. It sounds like a mechanical issue to me?

It wouldn't matter if I adjusted that or not by how far over I have to hold the timing lever to keep it running. When I do hold it over, it runs amazing, just mind boggling it won't hold as soon as you let go of the timing lever.

Where is that adjustment located anyways? (Motor is not at my house and it was in December that I was working on it) I'll have to see if I have the book with me and find it.

Carb needles are about 5 turns out from a light seat...

So if that's the case, then the engine is starving of fuel when at idle after starting? That's what I get out of that if the needles on the throttle plates are supposed to open 5 turns. Of course yes a light seat! Just had to re-turn a very buggered up antique carb needle that had quite the groove.