Go Back   TeamTalk > Maintenance Tips, How-tos and Refurbishing Topics > Engine / Drive Train

Reply
 
Thread Tools Display Modes
  #1  
Old 08-08-2015, 01:26 PM
Yeaitsslo Yeaitsslo is offline
TT Newbie
 
Join Date: Aug 2015
Boat: 1988 Tristar 190 sport
Location: North East
Posts: 6
1988 Tristar, engine stumbles above 75% throttle

Just got my first boat a few weeks ago.. 88 tristar 190 sport.. has about 840hrs on the motor, got it from the original owner..


First time out on the boat i noticed that if i went full throttle it would stumble around a little bit.. almost like its either gasping for air or fuel.. So took the boat home and got a rebuild kit for the carb, inside of the carb was near perfect condition.. put it all back together and got out on the lake again and still doing the same thing.. I have no problem pulling people up on boards / ski's but its just when i want to go fast, ill feel the secondaries start to open and then the boat will stumble.. i've got it to about 4200rpm's and no idea on the speed as i dont have a gps (and dont trust the stock speedo's)


I was thinking about replacing the fuel filter, but it looks to be brand new already, is there a filter inside the fuelpump anywhere? that looks to be orginal and never touched.. Anything inside the tank?


Also developed the banging in idle while in gear, a quick search here says it could be the dampener or loose prop.. sure enough the nut on the prop was loose, hopefully that will fix that banging..


Any help or advice would be great!
Reply With Quote
  #2  
Old 08-08-2015, 02:14 PM
mikeg205's Avatar
mikeg205 mikeg205 is online now
Moderator
 
Join Date: Aug 2011
Boat: 1995 Pro Star 205 5.7 Liter
Location: Plainfield - Joliet, IL
Posts: 13,388
Send a message via Skype™ to mikeg205
stumbling probably fuel related... banging in back..sound like rocks rolling around? I bet the carb needs rebuilding... prolly developing a vacuum leak at higher revs
__________________
...A bad day water skiing still beats a good day at work...1995 Pro Star 205....
Reply With Quote
  #3  
Old 08-08-2015, 11:38 PM
wheelerd's Avatar
wheelerd wheelerd is offline
MC Devotee
 
Join Date: Dec 2007
Boat: 2005 X2
Location: Central Alberta, Canada
Posts: 1,208
There should also be a bronze filter in the fuel inlet at the carb to check. Does the boat have a fuel/water separator? If so, empty that. And yes, there should be a filter on the pickup in the fuel tank.
Timing maybe? If over-advanced it might run OK at lower RPMs but start to crap out at higher RPMs as the timing advances further.
__________________
"For every complex problem there is an answer that is clear, simple, and wrong." (Henry Louis Mencken)
2005 X2, Viper Red, MCX, OJ TZ-X5 prop, PPass, rear 750 sacs, KGB, IBS, Bennett Wake Plate, custom wake gate
(previous) 2001 X5, 1991 TriStar 190
Reply With Quote
  #4  
Old 08-09-2015, 10:51 PM
tockit's Avatar
tockit tockit is offline
TT Enthusiast
 
Join Date: Apr 2012
Boat: 1989 190 Tristar
Location: Southeast
Posts: 171
Quote:
Originally Posted by Yeaitsslo View Post
Just got my first boat a few weeks ago.. 88 tristar 190 sport.. has about 840hrs on the motor, got it from the original owner..

First time out on the boat i noticed that if i went full throttle it would stumble around a little bit.. almost like its either gasping for air or fuel.. So took the boat home and got a rebuild kit for the carb, inside of the carb was near perfect condition.. put it all back together and got out on the lake again and still doing the same thing.. I have no problem pulling people up on boards / ski's but its just when i want to go fast, ill feel the secondaries start to open and then the boat will stumble.. i've got it to about 4200rpm's and no idea on the speed as i dont have a gps (and dont trust the stock speedo's)

I was thinking about replacing the fuel filter, but it looks to be brand new already, is there a filter inside the fuelpump anywhere? that looks to be orginal and never touched.. Anything inside the tank?

Also developed the banging in idle while in gear, a quick search here says it could be the dampener or loose prop.. sure enough the nut on the prop was loose, hopefully that will fix that banging..

Any help or advice would be great!
Banging noise at idle is probably the damper plate on the flywheel. They get old and the weights get loose and noisy. They go bad a lot on engines of that era if they haven't been replaced. You'll have to pull the tranny to change it. They're around $200 at www.skidim.com.

Make sure your carburetor idle mixture is adjusted correctly to start with. Try checking what squirter nozzle you have in your carb, and also check the adjustment of your accelerator pump. I've heard the Holley's come with a 25 squirter nozzle. The accelerator pump lever should touch, but not be pushed in, by the throttle linkage at idle. You should be able to get .015" feeler gauge between the linkage and accelerator pump lever at WOT.
You can also put a paper clip on your vacuum linkage on your carb to make sure it's opening the secondaries like it should. If it is, the paper clip will move.
Reply With Quote
  #5  
Old 08-09-2015, 11:09 PM
wheelerd's Avatar
wheelerd wheelerd is offline
MC Devotee
 
Join Date: Dec 2007
Boat: 2005 X2
Location: Central Alberta, Canada
Posts: 1,208
Further to the previous reply . . .
Some guys think there is something wrong with the secondaries because they don't open when testing the carb operation on the driveway or at the dock. Since they are vacuum driven the motor needs to be under load for them to open completely.
__________________
"For every complex problem there is an answer that is clear, simple, and wrong." (Henry Louis Mencken)
2005 X2, Viper Red, MCX, OJ TZ-X5 prop, PPass, rear 750 sacs, KGB, IBS, Bennett Wake Plate, custom wake gate
(previous) 2001 X5, 1991 TriStar 190
Reply With Quote
  #6  
Old 08-10-2015, 01:00 PM
Yeaitsslo Yeaitsslo is offline
TT Newbie
 
Join Date: Aug 2015
Boat: 1988 Tristar 190 sport
Location: North East
Posts: 6
I went through the carb the other day, there was no brass filter in there. Only a screen which was clean. I cleaned all the jets but didn't note what size they were.

I know the secondaries won't open while driveway testing, all my results are based upon actual water tests. I'm gonna bring a timing light with me out on the water and see what it looks like.

As far as the banging noise goes, the prop was loose so I'm hoping that was the case. If it turns out to be the dampener, will it do any major damage to finish the season with it like that? The noise goes away right around 1000rpms.


Also, I don't have a factory water separator. It looks like some aftermarket merc cruiser filter housing. I can try to get a part number off it.
Reply With Quote
  #7  
Old 08-12-2015, 03:21 AM
tockit's Avatar
tockit tockit is offline
TT Enthusiast
 
Join Date: Apr 2012
Boat: 1989 190 Tristar
Location: Southeast
Posts: 171
Quote:
Originally Posted by Yeaitsslo View Post
I went through the carb the other day, there was no brass filter in there. Only a screen which was clean. I cleaned all the jets but didn't note what size they were.
I know the secondaries won't open while driveway testing, all my results are based upon actual water tests. I'm gonna bring a timing light with me out on the water and see what it looks like.

As far as the banging noise goes, the prop was loose so I'm hoping that was the case. If it turns out to be the dampener, will it do any major damage to finish the season with it like that? The noise goes away right around 1000rpms.
Your stumble problem sounds like a tuning issue. Sounds like your accelerator pump isn't adjusted correctly or you need a different accelerator pump cam. It's causing you to get a lean bog (stumble) when you nail it.
Holley makes an accelerator pump cam kit for around $20. It comes with different cams to tune your carb to deliver the proper amount of fuel to get rid of your stumble.
Before changing pump cams, you need to check your accelerator pump adjustment first. You Tube has tons of videos on Holley carburetor accelerator pump adjustment.
Timing might could cause your problem too, if it's way off.

If your banging noise goes away around 1000, its prolly the dampener. Mine did the exact same thing. I'm sure running it like that won't do your engine/transmission any favors, but it might be ok through the end of the season. I'd monitor it and make sure it doesn't get worse, etc. Those things have weights encased in a riveted plate that get loose and start rattling. I guess the centrifugal force quietens the rattle above a certain RPM? Just keep a close eye on it. If it get worse, I'd change it now.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -4. The time now is 10:30 AM.