Mercury 50HP 4 stroke stalls at low speed

[miltonboater]

2006 50HP 4 stroke EFI

After several trips to the certified mechanic and much$$, they now tell me it's the injectors. Getting ready to send them off for cleaning. Does this sound right?

Engine starts fine and idles though somewhat roughly. If rpm's are run up to +/- 1400 to 1600 the motor will vacillate as much as 200 rpm and die. Will start right up and do the same thing. After it's run for a time at higher rpm, these symptoms get somewhat better and the motor will not usually stall.

They have hooked it up to the computer which initially indicated there was too much air in the mixture. They replace the throttle body. On the next trip in, they replaced a solenoid valve. They have had the computer hooked up as the motor sputtered and quit and say it shows no faults. Their next "guess" is the fuel injectors.

Replaced fuel injectors and now it runs worse.

Any ideas out there??

 

[Timestep]

Re: Mercury 50HP 4 stroke stalls at low speed

Call Mercury and ask them ?

Dave

 

[barnicalbill]

Re: Mercury 50HP 4 stroke stalls at low speed

BOY AM I GLAD TO HAVE MET YOU HERE.I AM HAVING THE EXACT SAME ISSUES WITH MY 2008 MERC 40 hp e.f.i...PLEASE LET ME KNOW THE FIX AS I HAVE SPENT ALOT OF TIME ANY MONEY CHASING THE SAME ISSUES TO NO AVAIL..THANKYOU IN ADVANCE

 

[barnicalbill]

Re: Mercury 50HP 4 stroke stalls at low speed

I have exact same issues with my 2008 MERC e.f.i..I TOO HAVE BEEN CHASING THIS ISSUE . NOT TO MENTION THE TIME AND MONEY.I SURE HOPE SOMEONE CAN HELP AS I AM OUT OF OPTIONS AND ,ONEY...THANKS IN ADVANCE ....BARNICAL BILL

 

[CharlieB]

Re: Mercury 50HP 4 stroke stalls at low speed

There is no fuel pressure sensor. The computer cannot tell a weak fuel pump from a failing primary fuel pump or a dirty VST filter sock.

Get a fuel pressure gauge and connect it to the fuel pressure port. Turn on the key and see what initial fuel pressure is, start the motor and read pressure, speed up the motor and watch fuel pressure.

What are the three readings. If the pressure ever reduces then there is a problem.

That's when you start checking to see why cause the computer won't tell you anything.

 

[barnicalbill]

Re: Mercury 50HP 4 stroke stalls at low speed

Hi Charlie...thx for the reply...fortunately I have the luxury to have another motor with exact same parts just a bad head..anyway I did a fuel pressure test (40 ps.i.) at start. And even when it quit at 1800 rpms..also I did switch out the v.s.t high pressure fuel pump as well as the mechanical fuel pump...also the stater..the voltage regulator..spark wires...spark plugs...check injectors( fine) inline fuel filter...changed map sensor..changed...I.a.c. Valve...........did I leave anything out........well as you can see..I have the exact same issues as does Milton boater....I hope Milton see this as. He probably has it fixed by now...and I hope he lets me know what the fix is ...or anyone ...I'm wide open for suggestions

 

[barnicalbill]

Re: Mercury 50HP 4 stroke stalls at low speed

Hi Milton...still waiting for Milton or anyone who might know the fix for Milton boaters issues as I have the same problems....please reply a.s.a.p. as I am out of suggestions.....thx on advance .....BARNICAL bills

 

[schematic]

Re: Mercury 50HP 4 stroke stalls at low speed

did I leave anything out........well as you can see..I have the exact same issues as does Milton boater....I hope Milton see this as. He probably has it fixed by now...and I hope he lets me know what the fix is ...or anyone ...I'm wide open for suggestions

Have you tested or swapped out the temp sensor? A bad sensor could cause low idle speed and stalling (too lean when cold)

 

[barnicalbill]

Re: Mercury 50HP 4 stroke stalls at low speed

Have you tested or swapped out the temp sensor? A bad sensor could cause low idle speed and stalling (too lean when cold)

Hi schematic...thx for reply....well great idea...believe it r not that is the only sensor I didn't switch out yet.....sounds plausible...I did notice after engine got warm...seamed to start acting up...after 5 min from dock....will try tomorrow...awesome THX again

 

[barnicalbill]

Re: Mercury 50HP 4 stroke stalls at low speed

Called MERC ..they me a list of the basics to check .nothing specific..still trying to find out if Milton got his mercury fixed and what was the fix....same issues..stals at about 1800 rpm. At dock in high idle and then when running wants to quit at 1800 but picks back up ..I leaning towards the intake ...sensors or related air to fuel pressure..any suggestions would be appreciated..I to have taken to mechanic to Jo avail.
".."..."..thx in advance

 

[schematic]

Re: Mercury 50HP 4 stroke stalls at low speed

Called MERC ..they me a list of the basics to check .nothing specific..still trying to find out if Milton got his mercury fixed and what was the fix....same issues..stals at about 1800 rpm. At dock in high idle and then when running wants to quit at 1800 but picks back up ..I leaning towards the intake ...sensors or related air to fuel pressure..any suggestions would be appreciated..I to have taken to mechanic to Jo avail.
".."..."..thx in advance

You really should start your own thread.

Have you put a timing lite on and observed spark consistency when it stalls at 1800?

 

[barnicalbill]

Re: Mercury 50HP 4 stroke stalls at low speed

You really should start your own thread.

Have you put a timing lite on and observed spark consistency when it stalls at 1800?

Hi schematic......will try this week and let you know the results ..thx a lot for the quick reply....

 

[rgibbs64]

I have a 2007 50 hp EFI doing the same thing, It starts and idles fine. It runs up to 1000rpm, and will run any where over 2000 RPMs. It however will not run anywhere in between 1000-2000 RPMs, it will run for 5 -8 seconds and shut down. No alarms or beeps. I have already been through the tune up and the entire fuel system. It seems im not alone and everyone has tried what i have tried or what i would have tried. Someone mentioned a temp. sensor, one the veriables on my engine is it started this when the weather started turning cooler. Is there any follow up on this as a fix? I really hope someone figures this out and post it. None of my local dealers seem to know anymore then we do. Thanks and heres hoping everyone finds the fix.

 

[GA_Boater]

Welcome rgibbs. Please start start a new topic with your problem. This one is over a year old and may or may not have anything to do with your problem. Thanks.

 

[rgibbs64]

thanks, I did finally notice the date and started a new thread.