Help a newbie with a Johnson 150 faststrike

[Rugger]

Hi, I'm fairly new to the wonderful world of bass boats (even if mine technically is a walleye boat) and trying to learn as much as possible but still VERY green.

I'm running a '98 150 Faststrike on a 1995 Hydrasports 171 no jackplate.

Got it two falls ago and in our climate only run it from about May to Oct. so this is the second season.

At the end of last season, I could swear that one day the sound of my engine changed and my rpm's went up and my speed went down.

I'm fairly sure I was running around 6000rpm and it went up to 6500-6700 and my speed went from about 58 mph to 55 ish???

I was running a rapture 16 pitch prop, other than the change in rpm's the engine was sounding fine and smooth to my ignorant ear.

Winterized it and this summer the rpm's were still high (no one could tell me why). So to get them down I started looking for a new prop. Found a guy willing to let me test as many props as I wanted to find what I was looking for after about 8 I decided on a Renegade Bass 25 pitch which on the test runs gave me 5-6 mph faster and knocked off about 400-500 rpm running about 6100-6200.

This result was without the weed/exhaust ring and the thrust washer borrowed from a hub kit. Took a few weeks to get the right washer meanwhile I ran the old prop with the old results.
Put the new prop on and all was well for 2-3 trips then the same thing happened, rpm's went up and I was running 6700 rpm again but speed did not change...
I still did not have a weed ring because the ring suggested for renegad bass does not fit into the gearcase of my 150... (I'm the second owner don't know if it was changed).

Day 2 of a tourney on beautiful lake of bays Ontario, running full out in a good chop Fuel starvation alarm goes off, and engine goes into what I now am told is "slow mode". Sounded bad, got off the water.

Running it later on land saw that the new primer bulb I just installed was faulty and collapsing under the pressure and cutting off the flow. Replaced bulb, still some fuel problems, removed the anti siphon valve to find it was not a valve and had some aluminum filings stuck in it. Cleaned out and replaces with valve.

So there were two problems looks like.... fuel restriction (fixed) and engine went into "slow mode" because rpm's went to high maybe because of getting some air in the choppy water....

My main concern is Why the H am I suddenly running 500 ish rpms higher than I was last month with the same set up?????
What can I do about it????
Is there a weed/exhaust ring that will fit my setup? will it help?

Thanks in advance for any advice, I'm totally stymied...

p.s all of the repairs theories and several test runs were done with a well trained, experienced and certified mechanic.

Rugger.


Modified by Rugger at 7:58 AM 10/4/2008

[t-bone]

I would say you have a Tach problem or a reg/rectifier problem. First signs of a charging problem seems to be a tach misbehaving. That engine won't live too long at those RPM's if the Tach is right. What is the dia. of your case? My 96 Faststrike case is 4 5/8", has the weed ring. The V4 gearcases are 4 1/8" in dia.

[LIQUID NIRVANA]

Please post your Model number.

If you are running at the RPM (6500 - 6700) & if you are running a 16" prop then I am amazed the motor is still running at all. The motor develops its full horsepower at 5000 RPM & has a max RPM of 5500rpm.
================================================== ===

[Lockjaw]

I didn't think those engines had the limiter set that high. It should be about 6k or so. Big loopers had a 6700 rpm limiter.

You don't need a weedring unless the prop blows out.

You probably need a power pack or a new tach. A 16 in prop is to small unless you have the engine on a very heavy boat.

[Rugger]

I apologize, I saw that requirement but I'm about 2.5 hours from my boat. Next time I'm up I'll check the model #. The diameter of the gearcase is 4 3/8 (this is the internal diameter of the opening). To get the tapered end of the weed ring in I would really have to jam it in there it would be a very tight fit, I would have to force it. (no one up here that I have talked to has ever installed an exhaust ring) The side with the two sets of dogs or clips slides into the prop hub right?

If I were to jam the other side into the gear case there would be a lot of friction...

Interesting you should mention a tachometer problem. When I hit the trim switch it interferes with the tach. While trimming the needle jumps down (lower rpm) about 700-1000 rpm and quivers till I get off of the switch and then it's steady.

How would I go about checking the accuracy of the tachometer?

If it were really running at that rpm would it not overheat a bit?
Two of the things we checked was the paint on the block and the sparkplugs and both looked good...

Really appreciate the input thanks for the help!
Rugger.


Modified by Rugger at 10:16 AM 10/3/2008

[t-bone]

Sounds like you have the right case. The side with the clips goes into the gearcase not the prop. The prop hub should be just smaller than the weed ring. How is your hole shot, if you're blowing out bad you need the ring. Running with or without the ring affects holeshot only, you will not gain or lose anything on top end. Do you use wing nuts on the battery? Replace them with stainless lock nuts. Check the pole position on the back of the tach, I think it should be set at #6.

[Lockjaw]

I have never had a blow out problem with a gade. A little slip is ok, but if it won't plane over, or it takes forever with the tach sitting around 5k rpms, then you need it.

I would just get anothe tach and see if it helps. I have never had a tach issue from wing nuts on the battery. Usually if the tach doesn't work at all, you need a new regulator.

[Rugger]

The battery is 2 months old with regular nuts well tightened.

Ha ha ha I was trying to put it in backwars Told you I was green :)
When I put the clips into the gearcase, they don't catch anything, the ring is quite loose.
Is it supposed to just rattle around?

#6? I hope I'll be able to see what you mean next time I'm up there.

So basically you guys are saying there's no way I'm running 6700 rpm?

Seemed strange that going from a 16" three blade to a 25" four would make such a small difference in rpm.

[ChampioNman]

I would think that a 19 pitch Renegade would work fine on your hull, That should bring the RPM into normal level and keep you with the desired punch and hole shot you need for your boat. You sure it isn't a 2004 and not a 2005? Look at the last two digits of the HID number that will tell you what the year is.

[Rugger]

Sorry I'm an ijiot!

That was a bit of a typo it's a 1995 hydra sports 171

[Rugger]

Just got the model and serial #'s

Model# J150GLECD
Serial# G045010BG

Hope that helps.

[Lockjaw]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rugger &raquo;</TD></TR><TR><TD CLASS="quote">So basically you guys are saying there's no way I'm running 6700 rpm?

</TD></TR></TABLE>

Pretty much. I think you can disable the rev limiter, but then you loose the SLOW and QUICKSTART features.

[ChampioNman]

Is this a CC or a bass boat? Reason I ask is you are on the great lakes and spinning a 16" rapture. That leads me to think it's a center console. I would have my tach checked against a known good tach and verify your speeds via a hand held GPS. Speedo's are notorious for being off.

[Rugger]

Here she is:



Technically she's a walleye boat.

[Rugger]

I was running a 16" rapture, now I'm running a 25" renegade bass.

[ChampioNman]

And your RPM's with the gade are?

[Rugger]

When I first tested out the prop I was runnig 6100 6200 now magically it's back up to 6700...

And it was with the gade that I had limiter kick in for the first time ever... The only other factor was that the engine was being starved of fuel at the same time... I don't know if this would have anything to do with it...

Sorry, I know it was a long first post but I included all of that information in my original post...

[ChampioNman]

Yeah I know but your boat was a 2005 in the first post too.

[Rugger]

Ah So

[Rugger]

Any idea why changing from a 16" to a 25" made a small difference in rpm that disappeared shortly after.
And why the limiter only kicked in after I was running a prop with a steeper pitch?

The only thing I could think of was that I didn't have the weed ring on but sounds like that should not have made a difference at WOT...