Checking fuel pressure

[KetchiMan]

2004 Merc 5.0L MPI

Looking for some advice on checking my fuel pressure.

Does anybody know what the psi "should" be in my system?

Do I check it at idle? While the boat is under load? Both???

Thanks

 

[Don S]

Re: Checking fuel pressure

Going to say this again, need a serial number not year. NOTHING is listed by year, only by Sn.

 

[KetchiMan]

Re: Checking fuel pressure

Sorry, I should know better.......

Serial # is OWO18920

 

[Fun Times]

Re: Checking fuel pressure

2004 Merc 5.0L MPI

Looking for some advice on checking my fuel pressure.

Does anybody know what the psi "should" be in my system?

Do I check it at idle? While the boat is under load? Both???

Thanks

Your looking to stay within the 43 PSI range at both key up & all RPM's.

 

[KetchiMan]

Re: Checking fuel pressure

So, I just checked the pressure and she's running at 15-16 PSI. Not good. I replaced the LP pump and filter.water separator a few weeks ago.

Also, I took some fuel out of that schrader valve today and looked at it. It had tiny little shiny flicks in it, like little pieces of metal. I put a magnet in it and the flicks are NOT magnetic. Maybe Aluminum?

Is the HP fuel pump made of Aluminum? Are these tiny flecks of shredded fuel pump?

The flecks seem to indicate that there is no filter between the HP pump and the injector rail, so it can't be a clogged filter.

My best idea right now is to replace the HP pump.

Am I missing anything or is this the thing to do?

Thanks

 

[Scorpion8]

Re: Checking fuel pressure

The flecks seem to indicate that there is no filter between the HP pump and the injector rail, so it can't be a clogged filter.

I would replace the HP pump because you're not getting the boost in pressure needed to run at higher RPMs. I'd also look at adding a fuel filter/strainer in the line before the fuel rail.

And I'd move away from Ketchikan. Way too much rain down there.

 

[KetchiMan]

Re: Checking fuel pressure

I would replace the HP pump because you're not getting the boost in pressure needed to run at higher RPMs. I'd also look at adding a fuel filter/strainer in the line before the fuel rail.

And I'd move away from Ketchikan. Way too much rain down there.

Would a filter after the HP pump cause resistance and restrict the fuel pressure?

Rain?
We only had about 4 inches of drizzle today, and the wind is gently blowing about 25 knots, so I don't really know what anybody would have to complain about.....

 

[Scorpion8]

Re: Checking fuel pressure

Would a filter after the HP pump cause resistance and restrict the fuel pressure?

Rain?
We only had about 4 inches of drizzle today, and the wind is gently blowing about 25 knots, so I don't really know what anybody would have to complain about.....

It may, if your pump is putting out metal shavings. If not, then a simple strainer would suffice after you replace the HP pump.

Lucky you, we had 2" of liquid sunshine all day at 15 mph.