Fuel Pressure
 

I was having a problem that was intermittent. I would run my boat without a hitch, than run it and get stuck from it shutting down. I was always asked what my fuel pressure was. Never knew.I don't have a gauge. I bought a tester and it looks like I'm low 8- 10 psi. Is that significant? I'm not a mechanic, but even I know that can't be good. What can cause this, and what could fix this? I know there are a lot of variables to these questions. If I have a direction, that will help. I was told that Merc. has a pump kit that you put before the main pump to assist, if you will. It is only like a 4-5 psi pump to help with the fuel delivery. Anyone heard of this. I have a 2011 8.2 motor

I'm seeing a 97 232 in your sig, and the motor is a 2011. Is the 8.2 a 2011 MPI with CAT's, a 97 model MPI which was installed in 2011, or something else.

You mentioned adding another pump so I'm leaning toward a 97 model MPI with Gen 2 cool fuel

The boat is a 97, the motor is a 2011. MPI No cats? Motor Runs perfect other than fuel pressure issue.

The 97 and later had a Gen 2 cool fuel and also some had a boost pump which was later installed to help vapor lock and also to assist the Gen 2 pump. The Gen 2 cool fuel is located under the port side motor mount.
https://cimg6.ibsrv.net/gimg/www.off...4adaa66b1b.jpg


Yours being a 2011, it should have a Gen 3 cool fuel and the low pressure pump (boost pump) is inside the module. The Gen 3 cool fuel is located on the starboard side.
https://cimg2.ibsrv.net/gimg/www.off...7673286cbd.jpg

At 8 to 10 psi I'm wonder how the motor even runs

Where are you measuring the fuel pressure?

No, I worded it wrong pressure should be 43psi I'm testing 34psi at the rail with the shrader valve. Sorry. Are you saying that the Gen 3 cool fuel system already has the boost, (assist) pump?

Yes Gen 3 has the low and high pressure pumps inside the module

The 34 psi is a bit low but not enough to shut the motor down. What does it do when it shuts down? Is it all at once, after it sits or some thing other?

It shuts down like I turned the key off. Not able to restart for awhile Checked all the common points lanyard, breakers at batt.switch, batts. brand new. will sometimes run like no problem. Other times shuts down and I'm dead in the water??? Getting tired of Sea Tow bringing me back to Marina. When I tested it looked as if the more RPM's the pressure would drop off a little. Is that normal??

As the vacuum decreases the pressure should increase. Since it shuts off, when it shuts down, if you turn the key OFF then back ON do you hear beeps or the fuel pump run for a couple seconds? If you hear nothing might want to check the relays, main power and fuel pump. Might even be the key switch or bad ground.

I hear the beeps, but can't say anything about fuel pumps as I didn't listen for them.When you say the "vacuum decreases" the pressure should increase. What causes the vacuum to decrease?

When the throttle plates open vacuum decreases (going from idle to 1/2 to WOT). When vacuum decreases the regulator should increase the fuel pressure.

Since your hearing the beeps even when it won't start, then its probably not the MPR. Listen for the fuel pump, this could be that relay