1990 Johnson 200hp can't get to WOT

Iceboy149 · #1 07-28-2010, 12:00 AM

Guys any ideas on this? I have a 1990 Johnson 200hp Counter Rotating on my 1983 20' Seacraft SF. Anyway I can get up to about 4400rpms and then a short couple of horn bursts. The horn bursts are intermittent, they are not one of hte four characteristic ones, the constant for fuel restriction, overheating, or low or no oil. They happen sporatically every 5-40 seconds apart but only at WOT.

Now at WOT I only get 4400rpms. As I trim up the engine the rpms slowly get up to about 4800rpms as the load decreases (I guess) as the prop nears the surface of the water.

Here is what I have done and the problem still exists:

New Filters, inline and Fuel Water Seperator.
New Fuel ball
New Plugs
Carbs rebuilt last season and winterized.
New Powerpack, Ignition Coils, and Plug Wires
Switched out VRO2 oil/fuel pump with a spare one from a newer engine.
Dismantled VRO Tank and everything looks to be in good working order.

One mechanic told me that there is a temperature relay somewhere near the top of the head on both sides and to try unplugging each one for the sporatic beep.

He also said that on this motor the high speed jets have been known to work themselves back and they need to be tightened and then have new carb bowl screws that have "tangs" on the end installed....these being a new part from Johnson in order to keep the high speed jets in place and to not back out.

Has anyone ever heard of this? And yes I visually inspected the high speed jets to see if there was any debris in them but did not touch them for fear of disrupting them, so I do not know if they are seated correctly.

Any other ideas as to where the loss in about 600-900 rpms is? I'm doing a spark test on thursday again, perhaps one of the new coils went out already?

THANK YOU for your help!

Fr. Frank · #2 07-28-2010, 12:16 AM

Try a stator test. I had an '88 Johnson 225 that would run great for a little while, then suddenly the horn would bleat twice, and it would drop back to a max of 3800 rpms. Shut it down, let it cool off, and it would turn up to 5200 normal max for a short while, then repeat the offense.

After lots of carb and fuel work, we began checking the electrical. One day, I replaced the stator with a known good one, and the problem disappeared. The old stator tested good. So for giggles the mechanic stuck the old stator in an oven and heated it to 250 degrees. Suddenly it tested bad. Cooled off, it tested good again. Go figure. We found the problem by accident after over $1000 spent searching for the problem cause.

Still no idea why it would bleat the horn twice (which I was told is s'posed to be oil injection pump failure warning) and still run 3800 rpms. If the oil pump failed, it was s'posed to cut back to a max of 900 rpms according to the mechanic. I just figured it was an OMC.

workinpr0gress · #3 08-01-2010, 03:57 PM

Any luck?

Has the timing been done with a test prop, if not then you might want to try.

You can really figure out most electrical issues on those motors with a good multimeter, an omc repair manual, a notepad, & a ton of patience.

pelican · #4 08-01-2010, 04:59 PM

Quote:

Any luck?

Has the timing been done with a test prop, if not then you might want to try.

You can really figure out most electrical issues on those motors with a good multimeter, an omc repair manual, a notepad, & a ton of patience.

true,and not true...dvom's won't read the voltage output on the ignition systems-you're gonna need the correct meter to do that

a series of beeps usually indicate a restricted fuel flow...

here's a few dumb questions:

did this engine ever reach full rpm on the boat ?

compression test,did you do one ?

sounds to me like you threw alot of parts at it,without actually diagnosing anything-that's gonna get expensive-not trying to bust your bubble,but,if you're lacking the proper skills to diagnose a problem,you may wanna send it in and have someone who knows take care of it for you...attempting to diagnose a problem with an outboard on an online message board is a little difficult...

Iceboy149 · #5 08-01-2010, 07:49 PM

I got it. A simple spark plug tester from Pepboys did the trick. it was a brand new coil on the number 2 cylinder. Unbelievable. I just put a spare one on that I had in the garage from when I just replaced all the coils. The thing shot out of the hole and got us up to 40mph at 4900rpms. When I go 5300 now I get a beep every second or two so it must be the oil. I think I can handle that this weekend.

Thanks again for your ideas guys!