View Full Version : High Idle - HELP!

07-10-2011, 12:05 AM
First trip out this year and the boat is acting up. Its a 1996 Maristar 200 VRS without the LT1. First it wouldn't start so I check that it was getting fuel and spark, both looked good. So puzzled I tried a few more times and finally got it to start after unplugging the TPS, but it was idling at 1800-2000 rpms. Plugged in the TPS and it started again but still has a fast idle. Fiddled with the TPS and the IAC but it still had a fast idle. The injectors appear to be dumping a large amount of fuel. I finally give up and put it back on the trailer. Take it to a local Marine shop and the soonest they can get it in is the end of July. They were kind enough to hook it up to the computer and the only thing that came up after running the diagnostics, was that the TPS had low voltage at 4.50 volts. They didn't think that would be causing the high idle, but recommended that I get it adjusted. So I get it home and replace the IAC hoping that might fix my problems, no such luck. ( I replaced both the IAC and the TPS last year because the boat was loading up, after I did that the boat ran the best it ever has for several outings.)

I'm out of ideas and really don't want to give up a month of my short Montana summer, any ideas on what else I should look at. Thanks in advance.

ProStar Slalom
07-10-2011, 02:27 AM
You've already done more troubleshooting than I would know how to do. JimN will be along shortly to offer some professional advice....

07-10-2011, 11:09 AM
I did some more tinkering I can't find any vacuum leaks. While I hate to do to I think I'm going to replace the TPS, and maybe the MAP sensor today and see if that makes a difference. Does anyone know if you can by the diagnostic computer that works on these boats. It has a different dongle than the GM dealership has , but I think it is the same computer.

07-10-2011, 03:55 PM
I have one of these,$400.00[ATTACH]6

07-10-2011, 09:00 PM
Well I replaced the TPS and it appears that has cured the problem. I can't believe the last one only lasted about 12 hours.