New Checkie- 150 black max hesitation, carb issue??

[Needafunboat]

Hello All,

I just picked up a nice '81 sportfire with a stock '87 150 XR2 Black Max on it. It has new plugs and Motor starts fine, idles OK (a tad rough/low - but doesn't stall). If you try to get on plane gently, it barely accelerates until you just about hit full throttle, then it kinda clears out and GOES.

I'm guessing this is a carb issue (it's how my KTM 2-stoked behaved when I was playing with a BIG main jet in the carb). Ok, so it's just a little bit different than an OB enigne, but I've never jetted an OB motor...

Motor seems to make good power at full throttle (runs about 64 w/ 23p quicksilver per spedo). It just isn't nearly as progressive as an old '78 Johnson 150 on my parent's boat and will be a little handfull to pull skiers with. I guess it won't be an out of the hole rocket with that prop, but the way it's running it doesn't just feel like pulling a bigger load - it's very on/off.

Any help / direction is greatly appreciated. Thanks!

 

[Acer2428]

Mine had similar symptoms (115 merc) and after testing, found out I had no spark on 2 cyls. Seems like they kick on every once in a while, making accelerating/idling hit-er-miss but would go all out with no problem.

Most likely a carb issue, but check for spark.

 

[Needafunboat]

interesting - no spark...

'hmmm acer - now that you mention it, that could very well be what's going on - idle is rough, reminds me exactly of a V8 car with a big cam in it -lumpy sounding- not like that johnson 150 at all.

What was the solution for you? Thanks!

 

[slickster]

my 115 evinrude same symptoms.ended up beeing fuel pump diaphram.

 

[Acer2428]

Could be so many damn things.

I have yet to find a solution to my problem...lol Thought it was the coil packs, but apparently not.

Buying a donor motor to pull the stator/trigger off of. Hopefully that solves my problem.

 

[kct11]

i bet your johnson was not pulling a 23 pitch prop also. you are asking a lot out of the motor while getting up on plane. buy a cheap stocker or borrow a smaller prop before you beat your self up chasing other things. that thing ran good at any throttle position once on plane. hear me now, and believe me later.....try to gear your bike to run out on the top end, then see how well it works in the tight stuff........same thing here. i am not suggesting the carbs will not need some work, but i doubt it. good luck

 

[Needafunboat]

I agree that a 23p prop is a fair bit, but that johnson had a 21 and was pushing about 500lb more boat and it was much smoother. It's not the speed that it gets on plane - if you hammer it without bogging it, it comes up plenty fast. It's that the motor really feels on - or off. I get the feeling part-throttle response wasn't your #1 priority...

I gradually fed in throttle and nothing happened until like 80%, then it popped up with just a tiny bit of cav. and was gone. When I hit 80%, it did't correspond to it being on plane or anything - it was more of a motor thing. If you don't run it slow, or want to pull a wakeboarder - you might not notice.

You're right though that if you're up on plane and back off - it responds better. Still not super linearly, but it is a 20yr old 2 stroke! May be a combination of factors. Also i've only had a few hours drivin' it so I'm still figuring it out. Anyhow - I'm Lovin' the boat and how easy it is to manuever - SO glad I steered clear of a big fat I/O!! Just trying to get everything dialied in... I'll try to get a 21 and see what that does.

 

[Blizz]

Your boat is not propped for top-end speed with a 23 on it especially on a 17ft 850lb hull. You've got a couple of gremlins check compression, leakdown if you can, spark and the fuel system.

 

[Needafunboat]

Had it out yesterday again with the family. Same thing starting out, have to feed almost full throttle and then it hits and pops right up on plane, but there is a lag and extremely on/off feeling. Once on plane, trimmed about half way, it zings to (indicated) 50-55 fast - too fast to do with the fam on rough water. OK - nothing really new to report, other than a fun day with the fam on Belleville lake - I've been doing some little things to the boat and working a ton so I've yet to dig into the engine.

I'll start with spark and fuel system. I really doubt the compression is low on a boat that runs like that. Curt said they were all even so I'm sure that's fine.

Thanks for the input.

 

[kct11]

how did moving that bolt down 1 position work for you? did it change the bow lift any?

 

[Needafunboat]

Yeah - it helped alot with the bow rise and the cavitation. I don't think I need to move that jackplate at all now. I haven't done any high speed turns (family cruises), but it pulls the bow down in rough water a bit more too and reduces the bounce.

The boat is a blast - like I said from about 30-50, it just flies, even trimmed 1/2 way. - I guess you know that though. Just have to clean up the part throttle issue and I think it will pull a skier just fine with the 23P. It would do it fine now, just have to hit full throttle and back off real quick.

Bilge pump stopped working - you can hear a faint click from the rear of teh boat - and once it actually started for a second. Kinda a pain to pull the tank, but I guess I should do it. Any ideas on it? It was LOUD when it kicked on that once time on so I guess it's about shot. Will be good to get a look back there - maybe even replace some of that floor.

Off topic - as I was pulling it out - some guy starts asing me about the boat and says how nice it is and how he as an exciter up north. Not often you get that on a $2700 boat! Kinda cool. I put an new winch on (that one scared me) and got all the safety stuff so I've got a bit more into it now, but that's all a given.

Oh yeah - forgot the GPS AGAIN!!! 2 kids, new boat stuff, I guess it's OK. Maybe on Sat...

 

[kct11]

that pump is super quiet, put your ear up to the drain to see if you can hear it running..........that is what i had to do. do you think there is more drag while getting up on plane now with the bow down more? dose it feel lazier then the test ride i took you on? that may be putting even more of a load on it at the low speed of getting on plane. i hate to beat a dead horse, but try a different prop. a lot of people have 2 props, 1 for sking, and one for speed.

 

[Acer2428]

If you're pulling the bilge pump, pump an a float switch on the new one.

It's like $15 at Wal-Mart. Remove your old switch and replace it with a 3-position switch. You can wire it for an off-auto-on function.

Just leave it on auto and when water gets back there, the thing floats and turns on the pump....pretty easy.

 

[Needafunboat]

Acer, Curt,

First thanks for all the help on this!

Planing - it definately comes out of the water better with way less cavitation with the trim way down. Like I said, as soon as that motor clears out - it's on plane real fast. Just takes a second to clear it out. A quick WOT causes it to bog but a slow transition to WOT works pretty well. It's fine for riding around, just will be a handful to pull a skier up that way - Ithink it's going to be a reasonably easy fix.

Something is telling me it's a fuel issue - carb or pump. If I'd stop typing and go open up those carbs, we'd know!


Bilge pump - I ran the pump last time I was out right before I pulled out - no water out of the hose. Pulled the plug and there was like 1 or 2 gallons in there. I can't hear a thing, even with the seat off and my head tucked back there. Fuse is OK, but I'm going to check the wires before I pull the tank to make sure it's getting current when it's on.

Acer - I like the on/off/auto deal w/ a float. Will do if I have to replace.

 

[Acer2428]

I can draw you up a wiring diagram if you need it for the on-off-auto, but the switch should come with said diagram.

I had a similar problem int hat no water was coming out. Turned out to be a clogged hose! This was on an older I/O boat though, so grease, oil, etc from the engine bay were getting pushed through. Most kits come with CRAPPY corrigated plumbing which makes it easy for stuff to get in there and is pretty ineffecient, making hte pump work harder.

When I went to replace the bilge pump system on my old boat, here's what I did (and I would reccomend doing the same if you're getting 2 gals in the boat).

1. On-Off-Auto toggle switch (Top Gun covers for looks)
2. Lots of wire
3. 500g gal/hr bilge pump
4. 900 gal/hr bilge pump
5. Auto float switch
6. On-Off toggle switch
7. Smooth plastic tubing
8. New thru-hull fitting

Run the smaller pump with the float switch to the 3-position switch. Then, run thelarger pump hardwired to the battery and the on-off switch. I call this my 'oh ****' switch. Heaven forbid you take on lots of water (storm, high waves, pump failure, fuse out, switch goes bad, etc.) you can turn on the big boy.

As far as tubing, pull your old tube out and go to the hardware store. Find the tube with the same inner diameter as your new pump requires (it will say on the package), and get the same legnth. (same type of stuff one would use to build a beer bong).

I did this for both pumps. I ran a new thru-hull fitting ($5 or so) on the other side of the boat for the other pump (you COULD run them right next to one another).

This shouldn't be a huge deal with on OB, but the I/O took on enough water to kill the motor when my first pump failed. Learned my lesson the hard way.

I would also look into finding your leak as any water coming through the transom is bad for business and can lead eventually to transom rot. Some people use a flashlight. You could just put it in the water and play the waiting game while tied up to the dock. Or, you could try re-sealing things around the transom.

Hope this helps!

 

[Needafunboat]

Thanks again Acer!

First, I think my 2gal estimate was real high. Last time out, it only took on a little dribble's worth when I pulled out. The boat sits pretty low in back and if you slow down too fast, you get water up over the spashwell and it dumps right between the well and the rear seat into the bilge. So I think (HOPE) there are no major leaks in the boat. If there are, it's only in the splashwell. Ok, for some reason I feel better now...

A few (great) weeks out of he year it will sit in the water, so the automatic pump will be good then. And based on my seadoo experience (and learning how to submerge it) - more pump is better than less.

Anyhow, after next week, I'll pull the tank and see what the issue is with the pump. I suspect it's also a clogged pump.

 

[Acer2428]

be careful with the auto pump. It's better than nothing, but can drain your battery if you have a slow leak. It doesn't draw much, but can still kill the batt. People with a larger leak do this, batt. dies = pump dies = boat sinks...lol

If you're just getting a dribble, you'll be fine. Just try to seal things off so that you minimize water through the transom.

 

[Needafunboat]

I've had her out a few more times since the last post and most of the water getting in is a result of it splashing up over the splashwell. So I don't think there's much (if any) leak.

I'm puttin' her up for the winter and the tank's just about empty so I'll yank it and see what's up with the pump. May just put a couple of new ones in. I don't think it would drain the battery overnight. When it will be in over the weekend, we're at the cabin and run it each day.

 

[Needafunboat]

update - comp OK

Well the compression is about 120 in all 6 cyl. So that wasn't it. I also pulled the gas tank - the bilge pump just had some leaves stuck in it - so I vacumed the whole area and dried it out and that's all fine. Nice to store it for the winter knowing it's bone dry in there.

So I'll wait 'til next year for that bog issue. It's tucked safe up north in our garage - with lots of mothballs to (help) keep the mice out.

Ugh - May is far away..

 

[illMATTic]

Anthony, i felt mine was doing the same thing when i got it. BUT, if you look at the side of the carbs with the throttle linkage you will see a a cam like lever that opens the carbs. open the throttle and look at how these work. they don't open up until 1/2 throttle or so.

could this be what you are feeling?


also, when you are coming to a stop, don't just back off all the way. you can let off 3/4, then when the water looks like it is about to come over the stern, give it some gas and run away from the water just enough to keep it out. works every time.