Mercruiser 5.7L Fuel Pressure Regulator ?
 

Engine is a 2003 5.7L 350/300HP.

Narrowing down a low fuel pressure issue. Removed the cool fuel fuel pressure regulator ( a real bear to get to and remove )
A few questions:

• I'd like to test the fuel pressure regulator's function while out of the boat - is this possible ? If so, how do you do it ?
• Or, I'd replace it - is there an aftermarket or GM equivalent to this part ? The part # is: 861126A 1
• The fuel filter screen that sits under the pressure regulator is still seated in the cool fuel housing - it looks good from what I can see, besides it's in there pretty well and might be a PITA to remove. Does the fuel flow through the FPR into the screen or from the cool fuel housing, screen into the FPR ( this will let me know which side of the screen would have gunk - if any.

Lastly, there's a brass nut on the end of the fuel pressure regulator - is this removable or is it one with the unit ?

Thx

Bump

The regulator opens when the fuel pressure exceeds its setting, in your case is 43 psi. When it opens it sends the fuel back to the fuel filter

To test the Reg, remove it and use air. Slowly increase pressure watching a gauge to see when it opens.

To test the pump, you need to run it with a gauge which can read 100 psi and connect gauge to the output of the pump by itself.

Ok - great - I can do those tests.

sounds like I’ll have to put a ‘test’ cover plate over where FPR normally seats to do fuel pump test. Correct ?

which direction does fuel flow ? Forward to aft or vice versa ?

will I do damage to fuel pump by inhibiting fuel flow with the gauge in place ?

No, remove the fuel pump from the cool fuel tube to do the test

Comes in from the filter thru the pump

No, but only do it for a short period. The pump either pumps up above 60 psi or it doesn't. 10 to 20 seconds will tell you that

Quote:

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To test the Reg, remove it and use air. Slowly increase pressure watching a gauge to see when it opens.

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Which end do I blow air through - the brass coupler side ?

THE cool fuel side is the outlet return)

Ok
thanks...

Blow into the inlet.

I just tested the FPR.

There are (3) openings once removed from the cool tube;

• one that sits down on the cool fuel tube - there's an O ring
• The brass coupler that connects to a fuel line
• the vacuum hose nipple

The only location that has any effect on air flow is when I connect the air source to the first option - the one that seats onto the cool tube. This does not allow any air through at 35-40 PSI, it starts to allow a slight air flow at about 40 PSI. At 43 PSI, it flows.

Is this the right test ? If so, it sounds like the FPR is OK. Is this a correct assessment ?

FUEL PUMP

If so, I will need to test my fuel pump. Something I loathe to do, just because I have to remove it from the h*ll hole its in. Is there an easy way to test the fuel pump while it's in place ? If not, and I pull the fuel pump - how do I test it while out ?

Do I provide a fuel source to pull from, connect to (+) and (-) source, connect PSI gauge to output side and read the results ?

Thanks !