04 Mercury 75 hp 4-stroke problems

Has anyone had problems with this engine starting and or ideling?

Some more background would be helpful…winterized, first run of the year, old gas, stabilized? How long has it been acting up?

BIRDDOG

I purchased the boat a week ago tested it on the river everything seemed fine. Took the boat out this morning motor turned over right away but idled for a 30 seconds to a min jumping between 500-900 rpms, sputtering at times then died and could not get it restarted. After a couple attemps and making sure all the basic were covered with no luck just turning over but not catching. I called the selller of the boat said he never had any problems of the sort. He recently had run the boat on land everything was fine. The last time he got gas was Dec. Which there was a 1/4 tank, he filled it up and also added stabill followed all manufacture specs for proper mixing.

After letting the boat sit for about 10 mins It did start I was able to run it at full throttle seemed alright.But still wasnt idling properly. Turned it on and off about 5 times for various amounts of time. So it did run. But ive found some people on the net that have had some issues with the 90 hp 4 stroke that seemed pretty similar to what I experienced.

Is the motor an EFI? If not, I had a buddy that had the same problem with a 2002 90hp carb 4stroke. The place he bought the boat from (I won’t mention names) told him if they rejet the carbs it would run like a top, but it would void his warranty. He waited till the warranty was up and recently rejetted and it runs like a completely different motor. Dealer said this was a very common problem. Hope this helps.

So…the motor (under warranty) ran like crap and the only way to fix it is to void the warranty, doesn’t seem like a very good warranty or service. Wow!

BIRDDOG

I have a 2002 90 merc it has carbs half can of sea foam per tank of gas is what i was told by dealer your 04 i would think would be EFI try alittle sea foam it coudnt hurt maybe plugs?

Its not an EFI, I was thinking of trying some seafoam it cant hurt. There is another year and a half on the warranty so at least its covered. The plugs were just recetly replaced by the previous owner. I checked them and they seemed fine.

Quote:

---

There is another year and a half on the warranty so at least its covered.

---

That makes it simple!
Take it in!!!!

i own a 2001 merc 60hp 4 stroke, big foot. i had these problems when it was new. they made it run okay but near end of warranty it started doing it again. the dealer took it in and drained and cleaned the tank (20 gallon)and the carbs (4). they also put one of the inboard engine water separator/gas filter units on the boat. but now its doing the same thing.

what the problem is that these 4 strokes with carbs have very small jets that are easily clogged so the motor runs like crap particularly at idle and acceleration

i talked to a different dealer and was told he was working on a 40hp merc 4 stroke with carbs that they had done all the normal maintenance and still had problems. he said he called mercury tech support hot line again and this guy him that there is a kit for these motors to rejet them. they won’t meet the emissions standard afterwards but supposedly will run just fine

i haven’t done this yet but am considering approaching that dealer or the original selling dealer to see if the factory will do something. it’s really BS that an essentially brand new motor would run that crummy, even when it was at its best it wasn’t smooth at idle.