91 merc xr4 won't idle

[goofy2me]

Hello, I am new to iboat.<br />I got a problem with my 91 merc xr4. It will not idle. I can let it sit at 2000 rpm and may stay for about 20 second and will die out. Can hit the choke and would stay alive for a little longer and still would die. I clean the carbs about three time thinking it is the carbs. De carb it with outboard decarb. Changed all the plugs with new after decarb,but still same result. Will start with no problem. Try to run it in open water and max out at 4500 rpm. Seem to run ok there. Any help would be great. Running out of ideas. Thanks

 

[eurolarva]

Re: 91 merc xr4 won't idle

Hey Mercsport. You might want to post this under outboard problems instead of fishing. Not a lot of motor type people here. Might try doing a search using mercury fuel problems. I am no expert but I am guessing something is still wrong with the carb. Might want to get a rebuild for it and replace the diaphram and gasket on the fuel filter. Both kits are around 20 dollars. Try posting this on outboards and you will get a lot better help<br /><br />Good Luck

 

[roscoe]

Re: 91 merc xr4 won't idle

4500 rpm seems low for wide open throttle. RPM should be closer to 5500. <br /><br />Have you checked the compression on the cylinders. They should all be above 100#, and be within 15# of each other.<br /><br />Have you checked for spark on all cylinders?<br /><br />It sure sounds like you are not firing on one cylinder, either because of lack of spark or low compression.<br /><br />What do the sparkplugs look like? Do they all look the same?<br /><br />I don't think you have a problem with the fuel pump diaphram, or it would run out of gas at full throttle.