high idle rpm

[prawntrap]

Just started up engines in the driveway for the first time this year.So there are no surprises at the launch.twin 1997 johnson oceanrunners.I was idleing the engines in a large water container so I could also check the waterpump.What was odd was the fact that both engines seemed to go into fast idle with the quickstart system but even after they were run for about 5 min. the rpm did not drop below 1050.The tell tale did not seem real warm so I was thinking thermostat, but it seems too much of a coincidence that both would go at the same time.The dealer who winterized it did tell me he had adjusted the idle rpm to match both engines up.My question is ,could he have adjusted the idle rpm and not knowingly messed up the quickstart system low idle rpm?When I was running the engines in the tank I had the props off.Could this have caused a higher idle rpm in the tank?I won't be able to call the dealer till monday.Just wanted to know if anyone had any ideas.I know 1050 is too high for an idle and would be hard on the engine for shifting.

pt

[RUSTY63]

The Quick Start system will turn off when the port cylinder head sensor reaches a predetermined temperature.

You are right, the motors should not idle that high, sounds as though your tech bumped the idle to much.

[prawntrap]

thanks Rusty,

I will talk to him monday and see what he says.Just for interest,is changing the thermostat an easy job?The book makes it sound easy but it refers to a special tool.

pt

[SEAHORSE]

In the driveway, running on a hose, the big V6 OceanRunners etc. will idle at a lot higher rpm than in the water due to the lack of exhaust backpressure. Some models normally "idle" around 1200 rpm on a hose.

Try your motor in the water before calling the tech. It is a good idea to check the temp operation also. After a good run, let the motor idle for a few minutes then "take its temperature". The shade tree way is to see if you can hold your fingers on the top of each cylinder head for a count of 3 or longer. If so, then your motor is running less than 125 degrees.

[prawntrap]

thanks seahorse,

I will try the run in the water and see if it was just a lack of back pressure.I did run the engines in a big container in the driveway.Would that provide enough back pressure, or no.Once I get it down to the marina and run it, if there is no change,is adjusting the warm engine idle easy for me to do?Do I need the tech?One last question.I will try the temp check,if my problem is thermostats that are stuck open are they any easy change.Thanks for all your help.....probably just worrying too much here.

pt

[RUSTY63]

The thermostats are easy to change, you need a 13/16 wrench or socket, the thermos are above the top spark plugs on both heads

[prawntrap]

Thanks guys for the suggestions.Just for curiosity what should the temps be for this engine.ie. at idle....after a good run etc.

thanks pt

[RUSTY63]

140 to 160 Degrees.

[prawntrap]

Thanks Rusty,

I am launching tomorrow.I will see how this idle turns out.

pt

[prawntrap]

Ran the boat last night.I checked all the theremostats and found one was stuck open.I changed it,launched and the quickstart system seems to be working fine, but....Earlier in the post I mentioned that the tech had adjusted the idle last november and he said he had matched up the pair.In fact they are now quite unmatched.port engine...idle at 950 in gear idle 800

stbd engine...idle at 700 in gear idle 5-600

What is the target idle rpm and target in gear idle rpm?Is it an easy job to adjust this idle and in gear idle on this engine?Probably too easy if it was just a simple screw. Thanks in advance.I know I have an offshore boat and this is BBC.I appreciate all the good advice you guys have given me.I figure we have lots of common ground.....engines,fishing,boating,spending cash.........etc.

thanks pt

[RUSTY63]

You might want to have your Tech set it, you have to adjust the timing to set the idle.

[prawntrap]

thanks rusty

pt

[RUSTY63]

Glad to help.