2001 Malibu Sportster LX giving me problems.....

[shualin]

Looking for a little help trouble shouting with my 2001 Sportster.  Purchase the boat last year from a great guy in Indiana and it ran beauty good last year.  I was having issues starting, taking off pulling a skier, and coming off of full throttle it would stall out.  The last fall day 2019 before we put it away we took it out and the ran it around the lake.  When coming into the dock the master alarm sounds.  Gauges look good but the temp was starting to get higher so we let her idle thinking that was the problem.  Once the temp was down we turn her off and got the trailer.  When I restarted her the alarm turned off. 

Fast forward to 2020 the year of the Covid... She will not start.  Found out the choke plate was stuck and bent.  The mechanic said I should replace the carburetor which was going to take 7-10 day keep in mind it had already been 7-10 days.  I ordered a new carburetor from onlyinboard parts online (great place and super nice people).  The carburetor I ordered was a 4150-004 but the original carb was a 4150-001 and not a 004. Other than the mounting plate to the motor is there any other differences?  When we go the boat back the tach now does not work and the master alarm will not shut off.  All systems look great from oil to temp to voltage.  I think I'm getting a false positive.  She does not want to idle but runs great at high idle and all the way to full throttle but stalls out on idle.  Any help would be great!   

[drh]

@shualin I'll take a shot at this since I have the same boat and engine/carb combo.

First off I'm not sure of the carb differences between the -001 and -004; sorry can't comment on that.

Regarding the tach. - does it reset and buzz at startup? In my experience these gauges just go bad over time. If they don't reset and buzz at key on it's almost always the gauge. I've had to replace all of my gauges, except the tach ironically, over the course of the few years I've have my boat. There's a troubleshooting guide here you can try: 

 

Regarding the alarm you should know that there are separate sensors and switches for the alarm/check engine light and the gauges. Meaning that you could have bad switch or connection for the alarm that wouldn't be reflected in the gauge readings - a false positive like you said. Here are the possible alarms: high engine temp, high trans temp, low oil pressure. There will be a separate oil pressure sender (running to the gauges) and oil pressure switch (running to alarm) - both by the oil filter. Same for engine temp near the front of the manifold. There's no trans temp gauge so you'll only have a trans temp switch near the shift linkage running to the alarm. Make sure all these wires are connected to the right terminals on the switches. If one is loose or they are reversed you will have a constant alarm. 

Regarding the drive-ability issues - this is a tough one to diagnose remotely. First question - what RPM are you getting at WOT? Also who set the carb up and how was it done? You'll need to make sure the float levels are correct, the idle mix screws are set using a vacuum gauge and the idle curb screw is correctly set if you want it to idle smoothly. It almost sounds like you may need to increase the idle speed a bit with the curb screw although you don't want to open too much and start running off the transition slots. Other things to consider - do you have a vacuum leak? are the ignition components all in good working order (cap, coil, plug wires, plugs)? did a plug wire come loose during the work?

Any more details you can provide on these questions will help.

[Woodski]

@shualin - For the tach and alarm I suggest you retrace your steps and determine if all wires and grounds are good and tight.  You should be able to determine carb difference either from the Holley website or any of the carb rebuild experts you can reach online.  Previous post offered good tips on driveability troubleshooting.  Also check for any open vacuum ports that may not be plugged on the new carb.

[shualin]

Thank you Guys!  I'm having a mechanic look at the boat this weekend on the lake with me and hoping he can resolve the idle issue.   He came recommend by a friend so I'm hoping this recommendation works out.  I have checked the grounds for the alarm and most of the wire connections.  I did find a couple that are where not connected but the alarm still goes keeps on going....  I wish I could find a wring diagram for the boat to make i have check all the connects.  I'm hopping to look at the rpm gauge tonight.  

[shualin]

So some good news!  I found the issue the constant alarm!! It was the oil pressure sensor.  Found solutions on the forums under constant alarm go figure.  Now just the low idle and the rpm gauge.  I did order a rpm gauge but with out engine hour meter on it.  I was thinking of adding a separate stand alone hour meter for the dash.  Thoughts....   

[shualin]

Here is the forum for the Constant Alarm