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blakjack23

'99 Mercury 90hp problem....HELP!

9 posts in this topic

Hi everyone, I decided to take the boat out last night to get some fishing in but it didn't turn out too well. I launched the boat, started the engine as usual, slowly left the launch and about 50 yards out it died. After that I could start it, but anytime I put it in gear and gave it a little gas it died again. I could also start it while having the throttle on full (out of gear of course), it would start and right when it would start getting rev'd high I would pull back on the throttle and it would die again. The bulb it hard and water is coming out of the pee hole. There is also plenty of gas and oil. Any idea's? She has been running great all summer until now.

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Verify spark on each cylinder. Sounds like the carbs and the fuel pump need to be rebuilt

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My buddies dad has a 75 merc and his motor does the exact same thing until warmed up good. We have to sit at the landing for a good 5-10 min letting it warm up before we can think of taking off.

Sounds dumb, but did you give it plenty of time to warm up? With the summer winding down, the water is colder along with the air temps and it might take an extra few minutes to get up to operating temps.

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Sounds like a collapesed (sp) fuel line...

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I would say fuel starvation, could be dirty carbs or bad fuel pump. Try to start it and see if it keeps running while pushing key in (choke).

If it gets better then your carbs needs cleaned or rebuilt.

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Mine started doing that a bit last year but didn't think much about it at the time.

This year, I needed to get the carbs cleaned...

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Check the fuel filter, check spark, etc.

Also make sure you don't have water in your gas. I had a problem this summer with my boat starting on full throttle and then cutting out as I dropped the RPM's down. I was suspecting the carbs, but turns out I had a bunch of water at the bottom of the tank. Too bad the dealer figured that one out!

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WHAT KIND OF GAS DO YOU USE? TRY PREIMIUM AND ADD A CAN OF SEA FOAM TO 20 GALS OF GAS OR HALF CAN TO 10 GAL OF GAS I DO THIS WITH MY 2002 9O AND SHE RUNS LIKE A TOP YOU WILL NOTICE TOP END IS MUCH BETTER TWO. GOOD LUCK. DAN

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Does it come to life when you hit the choke just before it dies? I have a merc 90 2002 model. Does the same thing. Been to the shop for a checkup. All was fine. I concluded its just cold blooded! Mine comes to life when i hit the choke! sure is irritating specially when the ramp is busy!!

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