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1986 90hp Timing

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fclementsjr

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I have an 86 Johnson 90 HP V4 (J90TLCDC) that I bought with the boat last year. Since I don't know how long it has been since it had any TLC I am working on it over the winter (Rebuilding the carbs, fuel pump, & water pump). I have the water pump installed and in order to get to the shift linkage, i had to remove the carbs (Fun time). I figured that while I have the carbs off, I might as well rebuild them and the fuel pump.
Before I get back on the water, I want to set the timing. Last year, I could never get the RPM's over 4600 even with a 17" pitch prop (Least pitch recommended as far as I understand). It reached 4400 RPMs with the 21" pitch prop (Not much difference). I plan on setting the timing 4 degrees low while cranking (I did this on my old Mercury 60 and it worked perfect).
Before I get into it this (Or next) weekend (stored indoors over the winter), I have a couple of questions:

1. Will this same timing method work on the Johnson 90"
2. Could anything else be causing the RPM's to not want to go up to the recommended range (5200-5400 I believe). It is on a 1985 Bass Master 160V - 16' Long, 72" Beam). It doesn't seem to be lacking power as it comes right out of the hole quickly. The compression is good (Checked before I bought but cannot remember the number (CRS disease)
3. On the fuel pump, EVERYWHERE I look, this motor only comes with the VRO fuel pump. Mine has the typical Johnson "house" shaped fuel pump mounted to the engine beside the carbs. I had to order a rebuild kit for an 1988 90 HP to get the correct kit. Any ideas as to why?

THANX in advance for any and ALL help!!!
 
Do you have spark on all the cylinders? Is the link and sync done correctly? Are the carbs opening all the way to 90 deg? Is your tach reading correctly? Is the stator advancing to the rubber stop? Is the rubber stop on the screw? High speed jets in the carb are clean? Somebody has converted your motor to a premix fuel pump from an 88 hp motor. Is the pulse limiter for the vr o still being used?
 
OK, Answers as follows:
1. Thought about the tach but just want to make sure the timing is correct.
2. Yes, spark on all cylinders.
3. I am going to check the sync when I put the carbs back on. When I got it, I had to make adjustments to get the throttles wide open & am not sure it was all correct.
4. Yes, once I adjusted them last year.
5. Once I make sure everything is correct, I can check the tach.
6. I am not sure about the rubber stop. This works on a slotted cam. I do remember that the guide that rides in the slot was not all the way to the end so it could be out of adjustment.
7. Once I rebuild the carbs, that should take care of the high speed jet if it is clogged.
8. To be perfectly honest, I am not sure are talking about on the pulse limiter. I looked at all the exploded view of my engine and could not find anything called a pulse limiter. I am familiar with a rev limiter that works off the rotation of the crank shaft to limit the RPM's but am not familiar with what a pulse limiter does or is.

THANX AGAIN for your help!!!
 
Visually inspect the ID of the four (4) high speed jets (1ea way in back of the drain screws). I make a practice of carefully cleaning them with a piece of single strand steel wire as solvent just doesn't do that job properly.

There is no "Rubber Stop" full spark advance screw on that 90hp slotted throttle/spark advance setup.

A pulse limiter pertains to the power-pack's internal circuitry... some have it, some don't.

Positioning the throttle butterflies..... back the cam away so that it IS NOT touching the throttle cam roller... Adjust the linkage between the carburetors so that there is no tension on either butterfly... you DO NOT want one closed and the other sightly open, BUT by the same token will open or close both when either is engaged...

Now, adjust the throttle cam roller so that the butterflies just start to open when the scribe mark of the cam is dead center with the roller.

Check that at full throttle (Engine NOT running)... the throttle butterflies should be perfectly horizontal.
 
joereeves: THANX for the info. When I am able to get back to the storage warehouse, and put the carbs back on, I will try to sync it. As far as the syncing goes should the butterflies just begin to open when the engine is put in gear (to keep it from stalling) by adjusting the cables?
When I clean carbs, I do the same thing.
Is there a way to determine if mine is equipped with a pulse limiter? Could this be affecting the WOT RPM's?
 
And I thought the " pulse limiter " had to do with protecting the VRO pump from exploding due to high air flow / back fire in the crankcase !
 
racerone said:
And I thought the " pulse limiter " had to do with protecting the VRO pump from exploding due to high air flow / back fire in the crankcase !
Click to expand...

And you are correct of course Racer. Now everybody knows why I keep you around. :cool: Sometime I don't know where my head's at! I was of course thinking of the rpm limiter circuit of various power-packs. Appreciate the heads up.
 
fclementsjr said:
joereeves: As far as the syncing goes should the butterflies just begin to open when the engine is put in gear (to keep it from stalling) by adjusting the cables?...... Is there a way to determine if mine is equipped with a pulse limiter? Could this be affecting the WOT RPM's?
Click to expand...

If the engine is running as it should at a proper idle rpm, it shouldn't stall... cross that bridge when you get to it.

The pulse limiter/rpm limiter mention..... I goofed on that one. See "Racer's" correction along with my reply to him above.
 
THANX for the clarification. You had me a little confused. So, could this have anything to do with limiting rev's if whoever did the fuel pump conversion did something goofy? Where can I find it? Or, would it have been part of the old pump/mixer that was removed? Or, is it nothing more than a check/pressure valve attached to the engine block?
When I put everything back together, I am going to make sure is is done correctly.
I never did get an answer about setting the timing while cranking. Will this work on my engine?
One other thing I forget to mention. When I am idling along (Especially when I am fishing an idle only lake), I will get a hesitation in the motor at a consistent RPM. I don't want to call it a miss because it is more like the engine gets a big gulp of fuel. It does not do it once a get the RPM's above 1,000 +/-. I am thinking that once I clean the carbs, set the timing, & get everything straight, it should be taken care of... I HOPE?
THANX AGAIN!!!
 
If your pump is PROPERLY mounted on the intake manifold then the pulse limiter can be removed and that pulse port plugged.----The pulse limiter is NOT a check valve.---It is a flow fuse.----What are the actual compression numbers !----And does spark jump a gap of 3/8" or more on all leads , yes or no ??---Important to answer the last question.----And 17" pitch is NOT the least pitch you can find for this motor !
 
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