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2007 Mercury 60hp losing fuel pressure

mwake83

New member
I have a 2007 60hp 4 stroke efi that keeps losing fuel pressure. I can turn the ignition on and get 42psi at the VST schrader valve. I can run the motor for anywhere between 1 minute and 1 hour at normal speeds under a load with no loss of power and then the fuel pressure will drop to 5 psi then start bouncing between 5 and 30 until the motor stalls or I turn it off. If I turn the ignition back on I will have 42 psi again, engine will start right back up and the process repeats itself. I also occasionally get a 6 beep alarm, at startup only, although this does not happen every time. There are no stored codes. The primer bulb stays hard throughout the process, pumping it has no effect on the issue. I also have 13.6 volts at the electronic fuel pump at all times, even when the fuel pressure drops. I have changed the electric fuel pump in the VST twice, the mechanical fuel pump, fuel filters, drained and cleaned the gas tank multiple times, connected an external tank directly to the canister fuel filter, all with no change.

Any suggestions would be appreciated. Thanks in advance.
 
There should be a fuel pressure regulator inside the VST. Sometimes they fail and thus causes a loss in fuel pressure...
 
Thanks for the idea, I will look into it. Would this cause the 6 beep alarm at startup? What does the alarm warn for? I was hoping it would point me in a direction but the manual only lists to see a dealer for this warning. Thanks.
 
Think of it as a check engine light. Your engine's ECM is throwing a code. But the only way to know what code it's throwing is to bring it in and have them run the DDT scan tool or Mercury diagnostic software on it. Willing to bet it's fuel/misfire codes.
 
I have taken it to 2 mercury dealers, both have have said it has no stored codes. Although, neither have been able to reproduce the alarm while they have the boat. I only get the warning about 25% of the time on the restart after the motor stumbles or stalls. So 6 beeps is just a generic warning and doesn't point to anything specific?
 
Thanks LSXG8GT... the problem ended up being that the small screen at the top of the fuel pressure regulator was plugged. Got it all cleaned out and seems to be running perfect again. Thanks for the help.
 
6 beep alarm can only be caused by:
MAP sensor fault
MAT sensor fault
TPS fault.

It's just a matter of resistance testing them.

I got the same strange thing, that it fires up cold perfect - but every.. 5th hotstart or so, it starts, and stalls, has to be cranked 3 times with idle lever up. So I'll try to clean out the VST too.
 
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