WOT RPM Low. MAG350 MPI B3

[alldodge]

The fuel module did not pass step 4, correct?
It did not pass step 4 is the reason to go to step 5

35 psi fuel pressure and 13 in Hg vacuum

 

[gcarmich]

Fuel pressure did not exceed 44PSI (it was 35psi) so I proceeded to step 5. With engine running and fuel valve shut off, fuel pressure stayed at 35PSI as vacuum on fuel inlet increased. Fuel pressure eventually dropped as engine started to sputter because of lack of fuel.

 

[alldodge]

Looks like your fuel module passed all test, unless there is a newer test or bulletin out. Maybe @muc might have an idea

 

[gcarmich]

Could the regulator be under performing?

 

[alldodge]

Could the regulator be under performing?

Maybe but that's why I'm asking member MUC

 

[muc]

First I would check that the fuel pressure gauge is accurate.
Might be relevant why the heads and injectors were replaced.

In‑Water Test done in gear under load.
1. With a vacuum gauge and a fuel pressure gauge in place, operate the boat throughout the RPM range and record the pressure
and vacuum readings.
2. If the fuel the supply vacuum reading is greater than 2 in. Hg (7 kPa) , find and correct the fuel supply restriction.
3. If fuel pressure is less than 40 psi (276 kPa), but greater than 13 psi (90 kPa):
a. Verify that the vacuum from the fuel source is within specification. If the vacuum exceeds 2 in. Hg (7 kPa) , excessive
fuel restriction exists. Correct the fuel restriction before proceeding.
b. If no excessive fuel supply restriction exists, replace low‑pressure fuel pump.
4. If fuel pressure is 13 psi (90 kPa) or less and no excessive fuel supply restriction exists, replace high‑pressure pump and fuel
pressure regulator.
IMPORTANT: It will be necessary to sea‑trial the boat following repairs to be sure that the pressure and the fuel system vacuum
remain within specification throughout the RPM range.

Probably time to pull the cool fuel 3, pop the top cover and look at the paint inside.

 

[gcarmich]

I verified the fuel pressure gauge this morning against a couple other gauges and compressed air at different pressures. It is accurate.

Heads/valves were serviced because two valves tuliped and engine wouldnt run right. Cleaned injectors while heads were being serviced.

Ill have to rig a test setup for the gauges for testing under load and get a helper to tests through RPMs.

Then pull the cool fuel and check paint inside

 

[gcarmich]

Did a compression test today. 170psi pn all cylinders. Was going to do leak down but valve cover removal is difficult because of fuel rail/exhaust headers. Will use borescope later to confirm TDC.

Pulled the CoolFuel module. Will take home and disassemble and check interior paint. Broke bolt on back of midule - will try to extract.

Question: Can individual components in cool fuel module be tested independently?