Does the pressure drop to 25 psi the moment you gun it, or does is drop gradually?
Pressure regulators aren't normally "intermittent". Much more likely that you have a supply problem or a pump problem.
Does the pressure drop to 25 psi the moment you gun it, or does is drop gradually?
Pressure regulators aren't normally "intermittent". Much more likely that you have a supply problem or a pump problem.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
It was a constant 25psi from the moment I started it. It didn't even move when I gunned it to try and get it out of the hole.
But even the time before this when I ran it and had 25psi, it would get up and move. Now it won't do that.
Tach was also jumping around at idle. when I gave it gas it would stop jumping.
It's weird though that I had 35psi running it on the ears before I put it in the water.
Thanks,
Darrall
Darrall Dougherty
Don and Joe - I've been tracking all the EFI issues on the older Mercury outboards including a couple of threads of my own. It seems a lot of time is spent running a similar course checking fuel, electrical and control items. Many things get addressed and it usually doesn't solve the problem or it ends up leading to the ECM which is expensive ($800 to $1500). In your experience, how often is it the ECM based on age (These engines are 20+ years old).
Thank you for any insight or feedback you are willing to share on this.
2008 BassCat Puma with a Mercury 250 Pro XS / 1996 Champion 186 with a Mercury 175 EFI
In MOST cases, the ECM is intermittent (ie: A driver works one minute, doesn't work the next). Caused by loose drivers on the circuit board of the ECU.
Unusual for them to act this way (but it's obviously not impossible).
In this case- he could check the fuel pump voltage and reference it to the Service Manual based on engine RPM's.
Darrall: Checked the Voltage Regulators?
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Darrall Dougherty
.................................................. ...the scariest thing in life is the unknown ...................................
Darrall Dougherty
while im deer hunting
.................................................. ...the scariest thing in life is the unknown ...................................
And to answer your question about Voltage: No. Voltage readings should be taken with a DVOM (at the battery, unless specified otherwise for a specific test).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Darrall Dougherty
Darrall Dougherty
That is only one of several possible failure modes.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Darrall Dougherty
Checked spark on all the plugs and they were good.
Darrall Dougherty
Darrall - thank you for keeping us up to date as you try and figure this out. I have a 96 175 EFI and chasing some similar issues. I will continue to do the same on my other threads the best that I can. I would take mine into a shop but they are extremely busy and backed up until mid November. My next step is to test and/or replace the Intake Air Temp sensor.
I appreciate having this forum especially with Don and Joe's guidance and leadership!!!
2008 BassCat Puma with a Mercury 250 Pro XS / 1996 Champion 186 with a Mercury 175 EFI
Darrall Dougherty
Fuel pump in the VST or the pulse pump?
2008 BassCat Puma with a Mercury 250 Pro XS / 1996 Champion 186 with a Mercury 175 EFI
Darrall Dougherty
Darrall, Just following up. My issue ended up being a lack of spark in two cylinders and needed to replace the trigger. Boat is now starting and running.
Good luck with your search. I know how frustrating this can be.
2008 BassCat Puma with a Mercury 250 Pro XS / 1996 Champion 186 with a Mercury 175 EFI
I called my local marine shop today. They said the manual states 20 - 30 psi at the pump is recommended. What's correct, the 35psi that's been posted or what they are telling me?
I'm constant 25psi. Idle is fine. Totally bogs down when I try and get it out of the hole & runs rough. I don't want to replace something that isn't needed.
Thanks,
Darrall
Darrall Dougherty