Starts, coughs and dies

[Phillipj]

Just traded for a 1980 Chrysler 85 HP boat and motor. took it to the lake and wouldn't start. Brought it home and hooked the hose to it. Started right up and ran for 10 minutes just fine. took it back to lake, it started, ran for a few seconds, coughed and died. Went through this several times. Brought it back home, hooked to the hose and it ran fine.
Bought new tank and bulb. No luck. Any suggestions? thank you.

 

[roscoe]

Re: Starts, coughs and dies

Either you are not sparking on all cylinders, have low compression on one, or are running too lean.

First check for spark.
Then compression.
If they are ok, then look at the carbs.

Welcome to iboats.

 

[john from md]

Re: Starts, coughs and dies

The water pressure is causing back pressure and your engine cannot overcome it. This may be caused by low compression but it also may be from the exhaust relief holes on the back of the of the engine leg being clogged. Or the bellows is broken allowing exhaust gas to enter the carbs. This will cause the engine to starve for oxygen.

Check the relief holes by pushing a pencil or something into them. Check the exhaust bellows by hand, looking for brittleness and tears.

It runs good on the hose because the main exhaust has no back pressure.

Regards,

John

 

[foodfisher]

Re: Starts, coughs and dies

Idle rpm in gear 750-800

 

[john from md]

Re: Starts, coughs and dies

In gear, tied to the dock. Don't set up your idle on the hose as it won't work.

John