No fuel at rail with KO/EO merc 350 mag mpi tow sport (02 centurion)

alldodge

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I have not ever done business with EMP
Bad fuel pump out of the box from quicksilver?

Pump/cooler kit installed
Fuel Cooler & Pump Kit | EMP 1397-97004
Is this a QS pump or EMP pump?

Has the fuel pressure gauge had the air bleed out of it?

If it has then Try another test gauge

Again we are talking about simple stuff. The correct HP pump can produce more then 60 psi, the correct Reg will reduce and hold pressure real close to 43 psi.
 

jetskiD

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I have not ever done business with EMP

Is this a QS pump or EMP pump?

Has the fuel pressure gauge had the air bleed out of it?

If it has then Try another test gauge

Again we are talking about simple stuff. The correct HP pump can produce more then 60 psi, the correct Reg will reduce and hold pressure real close to 43 psi.
It is kit is from "emp" I just got off their website I thought it was quicksilver. It appears to be theirs but says it replaces the merc part number Mercury 8M0125852 | 861156A03. I'm not getting fuel to Schrader valve, just air. I may go buy another gauge but this one was brand new.
Also on voltage test of LP pump I only get voltage for a split second of the KO... I figure that's normal as I read other post you are in talking about that's primarily for vapor lock prevention.

I know this is elementary stuff that's why I'm scratching my head. I have no way of bench testing pump currently.
 

alldodge

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I'm not getting fuel to Schrader valve, just air.

Also on voltage test of LP pump I only get voltage for a split second of the KO
Now this helps
Both pumps should run for the same amount of time when key is first turned ON. With the LP pump not running but a split second, trace the wiring and connections, something has a bad connection

You could for testing, is replace the LP pump with a piece of fuel line. The pump was only installed to help stop vapor lock with hot motors. It will run just fine without it

Make sure your fuel filter is full of fuel
 

jetskiD

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Mr alldodge. Wow! I by bypassed LP pump with a hose as suggested and have 40ish psi almost instantly! I will check my wiring.
 

jetskiD

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Took the boat out to the lake for a shake down with fuel pressure gauge. I have fuel pressure at over 40 at idle, from the hole shot she wants to bog down. Pressure slightly dips to about 35 but comes right back up. She idles good sometimes and like **** other times. Ran about 15 gal of fresh premium through it. Runs top speed like a champ. Wants to bog about 2k rpms but picks right up quickly.
It seems like the ecu is struggling to find the correct air fuel ratio when taking off or coming down to idle.
I have not replaced the IAC or TPS.
Tired loading the parts cannon and draining my wallet. 😂
Thoughts?
 

alldodge

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Could use a scanner to look at readings, but without that:
With KOMO
Disconnect throttle cable from TPS.
Measure TPS voltage, from idle thru WOT. Idle should be 0.7V or so to 4.8V at WOT. See that the voltage changes smoothly as it is slowly opened

Dark Blue wire is wiper
Gray wire should read 5V
Black wire is ground

The IAC uses 12V and end should be clean

Also check MAP
Light Green wiper
Gray 5V
Black ground

Could even be a bad connection somewhere
 

jetskiD

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Aug 21, 2024
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Could use a scanner to look at readings, but without that:
With KOMO
Disconnect throttle cable from TPS.
Measure TPS voltage, from idle thru WOT. Idle should be 0.7V or so to 4.8V at WOT. See that the voltage changes smoothly as it is slowly opened

Dark Blue wire is wiper
Gray wire should read 5V
Black wire is ground

The IAC uses 12V and end should be clean

Also check MAP
Light Green wiper
Gray 5V
Black ground

Could even be a bad connection somewhere
Got it. I'll start there. Thank you, again.
 
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