Off Topic Mercury 9.9 Troubleshooting

[Leftys Buoy]

I have a 2004 9.9 4 stroke. Had trouble starting. It had sat last year [didn't make it out]. Got it running but wouldn't rev up without choke on, then after taking choke off would stall. I replaced inline fuel filter, took carb apart and cleaned it. Tried again, started first pull and ran alright with choke on, took choke off and ran smooth at idle to very low RPMs. When throttle increased it would bog down then rev right up then bog down to the point of almost stalling and repeat. I was thinking fuel pump but before I drop money on it, I thought I would ask the good and knowledgeable people of Channel 68. Trying to get the boat wet this year!
Thanking you in advance.

 

[gilfisher]

I have a 2004 9.9 4 stroke. Had trouble starting. It had sat last year [didn't make it out]. Got it running but wouldn't rev up without choke on, then after taking choke off would stall. I replaced inline fuel filter, took carb apart and cleaned it. Tried again, started first pull and ran alright with choke on, took choke off and ran smooth at idle to very low RPMs. When throttle increased it would bog down then rev right up then bog down to the point of almost stalling and repeat. I was thinking fuel pump but before I drop money on it, I thought I would ask the good and knowledgeable people of Channel 68. Trying to get the boat wet this year!
Thanking you in advance.

Check O rings on fuel line..I've had that problem before ..run some sea foam through it...good luck

 

[Reel Therapy]

Check the fuel line to make sure the ethanol has not swelled the inside, I had that happen last year on my 30 horse, couldn't figure out why we could not get any speed once changed ran like new.

 

[DaveJ]

Sounds like its definitely starving for gas. It runs with the choke because it creates a richer gas/air mix to the carbs and creates more available fuel in the combustion chamber. I would also change the fuel line/bulb 1st. Does it have a separate fuel tank? Check the filter and pickup line inside. Have you tried adjusting the carb to run a bit richer to see if it helps? Testing the pump would likely be next.

 

[Beagles]

Did you let gas sit in it for more than three weeks? I had the same problem with my Tohatsu 9.8. I took the carb apart, and soaked it in a carb cleaner bath. Just using the spray, doesn't work nearly as well. I always let my engine run out of fuel now. It starts first pull, every time.

 

[TonyV]

If it's the same as my 2006 you can take the fuel pump apart and check it
It's on the back of the engine follow the fuel line. Two screws remove it, careful there is an o ring that seals to the crankcase. Four screws remove the back plate and you can see inside. It's a mechanical pump. This is assuming its the same as my 06.