Johnson 90hp Outboard - Idles bad and won't go above 2000 RPM

[heffees]

I've got a 1987 Johnson 90 HP Outboard that ran good last year, but so far this year has been nothing but trouble. This is my first boat and of course I’m already having trouble…

Ran good across the lake, but on the way back it just went from 4000 rpm down to 2000 rpm - won't go any higher and won't run w/out the choke arm up. Won’t even start unless the choke arm is up and as soon as I put it all the way down and lock it, the motor stall within seconds. If I do manage to close the bar and lock it and drop it into gear, it idles very rough and won’t go above 2000 rpm under load.

I always add Stabil and mix oil/fuel at 50:1 (VRO Pump removed) - so I don't think it's a fuel problem, but at this point…. I did try running it with a one-gallon can of fresh gas, mixed 50:1, with some Berryman’s B-12 cleaner in it, but it didn’t make a darn bit o’difference.

Before I took it out on this bad inaugural trip, I did some maintenance on it. Here’s what I had done:
** Replaced the broken ignition switch
** Replaced fuel line and bulb from the tank to the motor & put new fitting on at QD
** Installed a new Bass Pro Shops 5/5/5 On-Board Battery Charger
** Put in new Nippon Denso plugs (Autozone didn't have the req'd Champion Plugs)

I have since pulled the Nippon plugs out and the ones on the right side of motor had fuel all inside the insulator and didn't look like they had fired much, if at all.

Checked for spark at plug wires and I don't see anything when I hold the plug wire close to the plug tip and turn ignition over. I don't know what wires to ohm out or anything else - someone mentioned 'Power Packs', of which I think there are two - but I don't know how you test these to see if they are good or are the problem...

If anyone has any ideas what this might be - please let me know. I simply can not afford $75/hour. I'm a mechanic by trade, I just don't have schematics or books for any boat motors.

Please help - I am so desperate to take my daughter out for Sandies on Eagle Mtn and Lake Weatherford!!! I have a great kid with a deep interest in fishing, and I don't want her to loose that!

Like I said, I'm new to the whole outboard motor thing. They're not too difficult to understand, I just can't get the wire colors down.

I simply can't afford $77/hour....

If anyone knows any good websites to buy quality boat parts for cheap, would you please send them? That'll help slow the bleeding from my wallet....

Any other help is always appreciated.

Thanks!

[RUSTY63]

Welcome to the BBC.

From your post I would guess the pack on the starboard side is bad, if you have a DVA meter you can check a few things, do you have one?

[JoshKeller]

I've got a v4 powerpack laying around somewhere. You can use it to try and see if it improves it

[SEAHORSE]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by heffees &raquo;</TD></TR><TR><TD CLASS="quote">. I'm a mechanic by trade, I just don't have schematics or books for any boat motors.
</TD></TR></TABLE>

this link might help you since you have a mechanical background.

http://outboardparts.com/troub...3.htm

[heffees]

I am really sorry about not putting the model and serial numbers yesterday. Here is that information off the ID Tag:

90 Hp Johnson/Outboard Marine Corporation
Mod #: J90TLCUR
Ser #: R 7489430

I do not have a DVA or VOM, I just have a higher-end Craftsman MultiMeter (Digital).

Do I need to buy a DVA or VOM to test these ignition systems, or can I do some more basic checks with a multimeter (Continuity, Ohms, Vdc).

[25xs]

Can you check the spark on all four cylinders and report back? Don't get bitten!

I'm just guessing, but since you just replaced the fuel line, I would start there and double check all those fuel connections. You might be suckin' air in somewhere and the motor is starving for gas. Also, check that all four carb butterflies are funtioning as you move the throttle from neutral to wide open (engine off).

Your Craftsman multimeter will probably accept a DVA adapter ($62.00) and you can become a master on your electical system in one afternoon.
Find CDI/Rapair online and search for "DVA Adapter". This allows your standard multimeter to read really fast pulses of DC and AC voltage and holds the reading on your meter so you can see it (before it disappears).

[heffees]

Well, after listening to all of you good folks and your very insightful troubleshooting experience, I was able to isolate it to a power pack on the right side of the motor (looking from transom to the bow).

The compression was 120 psi on 3 cylinders and 115 on the other.

I swapped the good power pack over from the left side to verify it wasn’t something more like a stator or coil, etc.. and it fired like a champ.

Now I just have to order a new or used power pack to put on my motor and get on the water.

I was wondering if anyone had any ideas about places to buy a new or used power pack for cheap?

The OMC part number on mine is 583110, which I found cross references to a Sierra Part No. of 18-5784. It also has CD4 stamped on both of the power packs. I was told by a gentleman at work that you can just get a Johnson power pack that fits a 2-cylinder motor and it will work on a V-4 like mine. My motor is an ’87 OMC, Part No. J90TLCUR.

Does anyone know if that rumor about any power pack off of a 2-cylinder working on my V4, and/or is there a master cross-reference list somewhere that will show what other part numbers will substitute for my OMC part no. of 583110? I’m having trouble finding the part 583110 part number on websites, and eBay has tons of power packs for sale for 2-cylinders, CD4s, and V4s – just none with the same OMC or Sierra part numbers that I have. Will anything else work? I’m sure it has to be the right voltage, but I don’t know how many volts my current power packs produce…

As always, any and all help is greatly appreciated.