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Which point shall the fuel hose attach to at the fuel rail?

RobertL said:
Hi,

Have a 350 MAG MPI -02. I suspect that I have too high fuel pressure. Discovered that the fuel hose is connected to the upper tube on the fuel rail instead of the lower one. As shown here http://www.boats.net/parts/search/M...8371/Intake Manifold and Fuel Rail/parts.html

Part number 25 is connected to the lower tube on my engine, and not the upper as shown on the drawing.

Is that normal or is it mounted wrong?

Thanks,
Robert
Click to expand...
I believe you have the wording backwards someplace.:confused:

The fuel hose is usually mounted on the top part of the fuel rail.

Item number 25 is a PLUG, Fuel Rail Block Off, 22-8623601.
http://www.mercruiserparts.com/Show...2&bnbr=90&bdesc=Intake+Manifold+and+Fuel+Rail

The parts diagram is usually just to reference the items, In some cases, It's usually not the best idea to use it as an exact guide or illustration for parts location.

Did somebody work on your fuel system to make you wonder?

High fuel pressure is sometimes created from a restriction on the fuel return line. The filter under the fuel pressure regulator is sometimes the culprit.

Item number 14,
http://www.mercruiserparts.com/Show...=8093&bnbr=60&bdesc=Fuel+Pump+and+Fuel+Cooler
 
boat_tech said:
I believe you have the wording backwards someplace.:confused:

The fuel hose is usually mounted on the top part of the fuel rail.

Item number 25 is a PLUG, Fuel Rail Block Off, 22-8623601.
http://www.mercruiserparts.com/Show...2&bnbr=90&bdesc=Intake+Manifold+and+Fuel+Rail

The parts diagram is usually just to reference the items, In some cases, It's usually not the best idea to use it as an exact guide or illustration for parts location.

Did somebody work on your fuel system to make you wonder?

High fuel pressure is sometimes created from a restriction on the fuel return line. The filter under the fuel pressure regulator is sometimes the culprit.

Item number 14,
http://www.mercruiserparts.com/Show...=8093&bnbr=60&bdesc=Fuel+Pump+and+Fuel+Cooler
Click to expand...


Ops, maybe I did :)
My writing may be a mix of Swedish and English from time to time.

In that case my is mounded correctly. The reason why I wondered is because I have discovered several things the preveous owner have made wrong. So I just wanted to eleminate such a simple thing as a mixed up connection.

I will buy a pressure meter today and check the fuel pressure.

Should it be 43 PSI at the fuel rail at all times?

Thanks,

/Robert
 
43 PSI is the specification, But you may see it as low as 38 psi at idle with the vacuum line hooked up to the fuel pressure regulator. Unhook the vacuum line at idle and it should go up to about 43.
 
boat_tech said:
43 PSI is the specification, But you may see it as low as 38 psi at idle with the vacuum line hooked up to the fuel pressure regulator. Unhook the vacuum line at idle and it should go up to about 43.
Click to expand...


Thanks for the information!
I just picked up the pressure meter and will go to the boat tonight and do the measuring.

/Robert
 
The results from the measurement:
Engine off, ignition on: 42-45 PSI
At idle, vacuum hose connected: 35 PSI
At idle, vacuum hose disconnected: 40-41 PSI
0-50% throttle during load: 35-38 PSI
50-100% throttle: 40-41 PSI

I don't know how accurate the pressure gauge is. Maybe it has a little offset error.

I guess the values are quite normal?
 
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