90EFI mercury model 1F904531D S/N 2B185185. Changed the low pressure fuel pump in the FSM. Will not fire off, it’s getting fuel.

[Dranew]

I recently changed took apart the FSM to changed the low pressure fuel pump. Put a new seal kit in it. Inspected/cleaned all components in it. Did not change the pressure regulator. This model FSM does not have a float in it. Re assembled and tried to start the motor. It cranks but will not fire off. Fuel is coming out the exhaust so it’s getting fuel. Have not check fuel rail pressure yet. The attachment is the FSM I have installed.before the FSM was disassembled the engine would run so it’s getting fire plus I checked the plug wires, changed the spark plugs and ohmed out the ignition solinoid. I cleaned the fuel injectors and bench tested each of them. I believe the fuel pressure should be 38 to 40 PSI. Once I confirm that it is good I am clueless how to move forward. Questions: can it be getting too much gas? If so pressure regulator in the FSM? Can the injectors be staying open?

 

[alldodge]

Seeing fuel out the exhaust would tell me there is to much pressure or the injectors are stuck open. Don't know what the pressure should be

 

[Dranew]

so I just went and rented a fuel pressure gauge to check the pressure in the rail. No pressure. However fuel is come out the exhaust through this hose coming off the bottom of the FSM. The lift pump is working I can here it.

 

[alldodge]

However fuel is come out the exhaust through this hose coming off the bottom of the FSM.

Something isn't adding up for the parts list.
Post list S/N is 2B185185 and when it is used it shows the diagram shown in post 1, but the hose going in at the bottom of the FSM comes from supply. This hose should not go to anything that connects it to the motor where it would come out the exhaust

Did you connect the hose at the wrong place maybe?

When I look up the S/N it does not list a 90* fitting where a hose connects to the bottom.

 

[QBhoy]

Hi. The line at the bottom of the FSM is a fuel supply line from the in line filter surely?
I think you’re just needing to purge the fuel rail and module of air. It will take a while.

 

[Dranew]

Hi. The line at the bottom of the FSM is a fuel supply line from the in line filter surely?
I think you’re just needing to purge the fuel rail and module of air. It will take a while.

Yes the line does come from the in line filter. Ok I will try and purging the the fuel rail a little better

 

[alldodge]

Check connections on the injectors. Need to know if something is keeping them turned ON

The ECM fires injectors with a ground being switched. With key ON and motor not cranking should see 12V on both pins. If 0V is seen on one side this means a ground is applied and keeping it turned ON

A Mod moved this to Merc OB section for better viewing

 

[QBhoy]

Yes the line does come from the in line filter. Ok I will try and purging the the fuel rail a little better

With the cover off, turn the ignition on and listen closely for the pump coming on for a second or two. You’ll soon know if there is air in it. Then press the shrader valve on the fuel rail whilst someone does it at the key again. You’ll likely have air in there. It’s going to take a while to prime if the fsm was dry. Key on and off a max of 16 times in the manual. I wouldn’t do it too close together though or you may damage the lift pump running dry.