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Mercury EFI outboard problem

Posted: Mon Jan 09, 2012 2:56 pm
by poorboy
i have a 1998 Merc EFI and the last few times i've had it on the water it's been acting up. first of all it has a hard time starting even with a new, fully charged and recently tested battery. then it usually start up no prob the rest of the time. however, lately, after a few hours of fishing and moving from place to place, the engine will shut off while moving slowly through the 5's. one time it shut off will on plane at low RPM. when it dies, i pump the bulb and seems to be fine after that. is it a fuel issue, or electrical? any help would be greatly appreciated before i spend all my money at the shop!

Re: Mercury EFI outboard problem

Posted: Mon Jan 09, 2012 3:54 pm
by Lake
My 96 EFI acts the same way. Worse when its cold. I change plugs about 4 times a year, seems to help

Re: Mercury EFI outboard problem

Posted: Mon Jan 09, 2012 5:24 pm
by poorboy
Lake wrote:My 96 EFI acts the same way. Worse when its cold. I change plugs about 4 times a year, seems to help
4 times a year? i've changed them 2 times in 5 years. i need to do a much needed tune up it sounds like

Re: Mercury EFI outboard problem

Posted: Mon Jan 09, 2012 5:41 pm
by sdisturber
next time you start the motor pull the cowling off.listen for the pumping noise of the electric fuel pump.my 93 efi did the same thing .real frustrating .post this on (bass boat central) mercury motor page if you are mechanically inclined and they can tell you how to confirm its the fuel pump its pretty easy to replace. david hill

Re: Mercury EFI outboard problem

Posted: Mon Jan 09, 2012 7:16 pm
by poorboy
sdisturber wrote:next time you start the motor pull the cowling off.listen for the pumping noise of the electric fuel pump.my 93 efi did the same thing .real frustrating .post this on (bass boat central) mercury motor page if you are mechanically inclined and they can tell you how to confirm its the fuel pump its pretty easy to replace. david hill
thanks for the info. i'm in welding construction and have built a few chevy 4x4's so i'm sure if i knew the prob i could fix it. i just hope its not too expensive regardless of the problem.

Re: Mercury EFI outboard problem

Posted: Mon Jan 09, 2012 9:51 pm
by mrbassin0614
Does the bulb stay hard when you pump it make sure to look for gas in the water whenyou pump it also does it make sound like its about to die then it comes back or does it just die. Also check your pressure if you have a tester.

Re: Mercury EFI outboard problem

Posted: Mon Jan 09, 2012 9:51 pm
by mrbassin0614
Also do you run gas with ethanol in it.

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 7:57 am
by poorboy
the boat just dies like you pulled the kill switch. the bulb is not hard until i pump it but i dont see fuel in the water or elsewhere. i use only premium gas but im sure it still has plenty of ethanol in it. thanks to the epa we're ruining our outboards. what's the best additive . quick clean?

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 8:33 am
by bob tratar
I had a '98 200hp EFI. Had the same type of problems, turned out to be the "brain" computer. After having it changed no more problems.

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 2:06 pm
by kane-o
bassboatcentral, mercury motor section... lots of good guys and info !! im sure you will have a bunch of responses..

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 4:16 pm
by FredP
Poorboy I have the same motor you do I changed the squeeze bulb, used metal check valve not plastic, for the running problem and tightened all the grounds on the engine. Take off, clean , reinstall ALL grounds, coils, starter, etc. This worked very well for me.

At low rpm the check valve was not sealing and letting the pressure off. Been great for 9 years now. Good luck

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 5:27 pm
by poorboy
thanks for all the replies and suggestions. i'm going to rebuild diaphragm pump, replace bulb, replace fuel lines, install new spark plugs then see what happens. if the problem still exist after that, i'll try plan b-z. thanks y'all!

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 6:01 pm
by Dave Wilson
great ideas- also check the voltage at idle- my efi was doing same thing, I changed the fuel lines and etc.- still had problem, then checked voltage- mine would run up to 17 volts at low speeds- causes engine to shut down. It would always restart. Replaced Voltage regulator(s)- never a problem now.

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 6:58 pm
by poorboy
Dave Wilson wrote:great ideas- also check the voltage at idle- my efi was doing same thing, I changed the fuel lines and etc.- still had problem, then checked voltage- mine would run up to 17 volts at low speeds- causes engine to shut down. It would always restart. Replaced Voltage regulator(s)- never a problem now.
was volt regulator expensive?

Re: Mercury EFI outboard problem

Posted: Tue Jan 10, 2012 10:31 pm
by mrbassin0614
Ok so the bulb doesnt stay hard after youve been running it for a while. go and look for cracks in the bulb or around the hose, sounds like it could be sucking some air i am not an outboard mechanic or anything but i have had my share of fuel line problems. Also i run carbon guard by evinrude in my engine and test the gas for ethanol

Re: Mercury EFI outboard problem

Posted: Wed Jan 11, 2012 10:27 am
by Mike
ECU

Mine did the exact same thing and the marine shop I went to charged me $500+ each te I took it there saying it was a fuel problem. Finally I took it to Boatmasters in Livernore and they fixed it first shot. They new what it was right a way. They might even have a used one to save you a few bucks. Give them a call

Re: Mercury EFI outboard problem

Posted: Fri Jan 13, 2012 8:38 am
by RAC
Same issues here but a little different. I have a 96 200 EFI, never a problem. Out of the blue it started cutting out a WOT. It would always restart. It would also start every time 1st thing in the morning. I changed out the fuel lines, ball, filters etc.. checked everything, thought that would fix it. Then it would die after a restart when I was idling from point to point. sometimes it would start, other times it would take up to 4 hrs or more, then it would restart, smoke like crazy and run fine. Could not figure it out so took it to Lyle. I told him my story, he said"computer". I left it with him he put a computer on it and it was fixed. From what he told me if things start happening like this it's almost always the computer on these models.

RAC

Re: Mercury EFI outboard problem

Posted: Sat Jan 14, 2012 7:15 pm
by Trace
I had that happen once and all it was was some corrosion on the wire connectors from the CPU. I cleaned them, put some dielectric grease on there, and reconnected it. Never had a problem again. The clear plastic connector covers were darkened which made me check them. It's worth checking.