Merc 1999 40hp ?fuel issues.

[teelake]

I have 40 hp 3cyclinder 1999 outboard on a pontoon boat. On our last outing the engine started great , ran for about 10 minutes and started surging and dying and finally died. Could not restart. Removed the fuel filter and found some debris, restrained the fuel tank and found little debris. Replaced the filter, started, fine ran for about 15 minutes at idle,died again. Could not restart,let it rest for a couple of minutes and it restarted. but started surging and dying. Rechecked everying including plugs, added fuel cleaner and injected seafoam into the carbs. In neuteral at about 2500rpm the engine varies in rpm by about two to three hundred. In gear I did not see that varience. ??? Could it be the fuel pump,or the gas or someting bigger???
JIMD

 

[pootnic]

Re: Merc 1999 40hp ?fuel issues.

Could be a bunch of things.
Would it stay running if you keep sqeezing the primer ball?(like checking the little things first)
Carbs could still be dirty,them little ports can get blocked easily at times.(did run for awhile though)

 

[Silvertip]

Re: Merc 1999 40hp ?fuel issues.

Spraying stuff through the throat of the carb is of little value since the fuel must pass through the tiny jets and passages INSIDE the carb which is where things get clogged. It would appear you need to disassemble, thoroughly clean and ressemble the carbs with new kits. Obviously rule out fuel pump, fuel deliver, bad/contaminated fuel and ignitiion problems first.

 

[teelake]

Re: Merc 1999 40hp ?fuel issues.

Could be a bunch of things.
Would it stay running if you keep sqeezing the primer ball?(like checking the little things first)
Carbs could still be dirty,them little ports can get blocked easily at times.(did run for awhile though)

THANkS FOR YOUR REPLY. I ran the test to determine the fuel pump diaphram was frassctured , in which I squeezed the bulb and held it while the engine was running . It did nothing to the rpm"s. The Carb's were overhauled last spring,I guess they could be plugged. When the motor is running it rus great.
JimD

 

[teelake]

Re: Merc 1999 40hp ?fuel issues.

Spraying stuff through the throat of the carb is of little value since the fuel must pass through the tiny jets and passages INSIDE the carb which is where things get clogged. It would appear you need to disassemble, thoroughly clean and ressemble the carbs with new kits. Obviously rule out fuel pump, fuel deliver, bad/contaminated fuel and ignitiion problems first.

THANKS FOR YOUR RESPONSE. Your correct about the spraying stuff!What should I look at in the ignition system? One thing I did not mention:in idle at higher RPM's it seems I am getting engine knock, or preignition.? (timing issue) Could this cause the bogging and rough running to complete shut down?
Jimd