Chrysler 85 help needed

Hello all, been lurking for awhile, thanks for the great info.

I have a 1980 Chrysler 85 on a Glastron bow rider. I had the carbs cleaned out by a boat mech and he checked compression and it was great. I also emptied gas tank and added fresh pre-mixed 89 gas

My problem is that twice I have taken this boat out and cruised for hours at 5mph or less with no problems. Then I will go into the water ski area to open the boat up and it runs great. Full throttle to around 30mph. Then after cruising a little while longer I will put the boat in idle either to get trailer or to fish for a bit. Both times the boat died while idling. The first time I was in the open ocean. When I try to restart the boat it will not stay on and idle. My gear shift has a lever to disengage the prop so I did and gave it gas and it would start and run but when I would go back to idle it would die again. After numerous attempts I was able to quickly shift into forward and get under power. The motor ran really rough for about 5 minutes before I heard it smooth out. I then ran it at full throttle again and when I got back to dock it died while idling. Both times I had to row the boat onto the trailer.

Any thoughts? Previous owner said the impeller was replaced recently. A buddy thought it might be overheating? I don't have a temp or tach gauge.

Thanks for the help!

Re: Chrysler 85 help needed

Your plugs may be fouling during the extended idling around AND the idle rpms may be too low. Need a tach. for that one.

Re: Chrysler 85 help needed

foodfisher said:

Your plugs may be fouling during the extended idling around AND the idle rpms may be too low. Need a tach. for that one.

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I kept adjusting the idle screw at the dock until it was quite far out with no luck. I wouldn't say the idling was extended. Less then 10 minutes while I put the boat in the trailer

Re: Chrysler 85 help needed

I guess to correct possible fouling issue I would need new plugs?

Re: Chrysler 85 help needed

"Cruised for hours 5mph or less" is not much above idle. Not sure which plugs you have, but paint thinner and a wire brush have worked for me, to clean what i have. Mine are surface gap type.

Re: Chrysler 85 help needed

foodfisher said:

"Cruised for hours 5mph or less" is not much above idle. Not sure which plugs you have, but paint thinner and a wire brush have worked for me, to clean what i have. Mine are surface gap type.

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So as I am thinking this through and researching, I plan to operate this boat mostly cruising in the 5mph range. Is this going to be a continuing problem if indeed the plugs are fouling at low speeds? Is there anything I can do to address? I will check the plugs tonight and probably replace. I am wondering how long new plugs will last if this is the issue

Re: Chrysler 85 help needed

You gotta tell what idle screw you were adjusting???The screw ON the carb aren't idle screws.
The idle screw is on the towershaft.It goes IN to raise the RPM's.
I did a lot of slow trolling in Michigan for Eyes.
The only problem was once in a while you needed to rev up the motor to (clean) the gunk out.Keep a set of clean plugs.
Perma gaps are easy to clean.Just a wire brush and go.
Usually running back in cleared it out good.
Think about a kicker for the slow trolling???

Re: Chrysler 85 help needed

jerryjerry05 said:

You gotta tell what idle screw you were adjusting???The screw ON the carb aren't idle screws.
The idle screw is on the towershaft.It goes IN to raise the RPM's.
I did a lot of slow trolling in Michigan for Eyes.
The only problem was once in a while you needed to rev up the motor to (clean) the gunk out.Keep a set of clean plugs.
Perma gaps are easy to clean.Just a wire brush and go.
Usually running back in cleared it out good.
Think about a kicker for the slow trolling???

Click to expand...

Yes it was definitely the idle screw on the towershaft. Although I am thinking about adjusting the fuel air mix depending on what the plugs look like.

The weird thing is that I would run the boat at wot for 5-7 min or so and then straight back to the dock. It would sit at idle while I backed in trailer and die while I was away getting car.

Re: Chrysler 85 help needed

barbasol said:

Yes it was definitely the idle screw on the towershaft. Although I am thinking about adjusting the fuel air mix depending on what the plugs look like.

The weird thing is that I would run the boat at wot for 5-7 min or so and then straight back to the dock. It would sit at idle while I backed in trailer and die while I was away getting car.

Click to expand...

So I pulled the plugs and they were black and oily. I could wipe off the threads but the faces had deposits. They were gapless Champion L76v. I went on spark plugs.com and saw that my motor calls for L82c (not gapless). I'm thinking the hotter plug will burn more of the oil off and possibly cure my issue? Any thoughts?