9.8HP Dying at WOT

dvalcourt

Cadet
Joined
Apr 27, 2007
Messages
8
Ok guys, First of I must say that this forum is one of the most informative and helpful group I've seen on the net. I've spent a lot of time the past couple of weeks just reading threads to get ideas on my problem before posting, but I think I may need specific help.

A little background info... recently bought 12' v-hull alumacraft with a 9.8HP Mercury motor (year 83 I think) The owner said he had a friend rebuild the carb recently and since then it just needed to be tuned. -my mistake, I shoulda had him tune it before i bought it.... I get on the river and it starts up without problem but it idles really high. After pushing in the choke and lowering the throttle it slows down so I can put it in gear. At low throttle it farts occasionally.. at mid throttle it runs fine, just slow... at WOT it dies immediately.

I've played with the screw.. 1 1/4 turns from just closed.. closing or opening the screw doesn't change how it runs at all. so I take it to a mechanic.

The mechanic tells me that its dead, but Im thinking I'll try the link and sync. He calls me back and says he thinks its a bad fuel pump.

Either way I can tell that I know more about the engine now from reading this forum than he does so I'll try fixing it myself.

Sorry for the long post, but does anyone have any ideas? Think it may be the fuel diaphragm? The mechanic did say that it looked like a new carburettor.
 

Jugfisher

Petty Officer 3rd Class
Joined
Apr 19, 2007
Messages
83
Re: 9.8HP Dying at WOT

While going WOT try priming the fuel bulb. This will help you with you fuel pump question. If it helps it run better when priming then chances are that your pump is getting weak. I it doesnt help we will have to try somthing else.
 

Harker

Chief Petty Officer
Joined
Sep 21, 2003
Messages
452
Re: 9.8HP Dying at WOT

Is it a tiller or remote? After doing the squeeze ball test..if that doesn't work...disconnect the kill switch to see if it's shorting when the throttle is opened fully. Also make sure the tank is REALLY vented..I have to almost totally unscrew a couple of vents on my tank to vent.
 

dvalcourt

Cadet
Joined
Apr 27, 2007
Messages
8
Re: 9.8HP Dying at WOT

I'll get it back from the mechanic tomorrow and try priming the bulb. Also, Its a tiller.

One question, when reading my seloc and different forums I get the impression that there are 2 screws to adjust air/fuel flow. I'm only seeing one on my engine. Maybe there's another one Im missing?
 

dvalcourt

Cadet
Joined
Apr 27, 2007
Messages
8
Re: 9.8HP Dying at WOT

Just got off the phone with the mechanic... he says he can now get it to idle normally as long as he pumps the bulb. He's gonna keep it over the weekend to replace the pump diaphragm. Hopefully this will resolve the problem. I'll let you guys know.
 

dvalcourt

Cadet
Joined
Apr 27, 2007
Messages
8
Re: 9.8HP Dying at WOT

*UPDATE*

The mechanic rebuilt the fuel pump and that solved the problem. It idles wonderfully; Can't wait for the weekend so I can see how it handles WOT!
 
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