Problems starting after fuel filter/water separator change

[helix757]

I recently changed the fuel filter/water separator on my “new to me” boat. I filled the new filter with fresh gas before installing. I then launched the boat, started the boat, and drove it to the dock from the ramp. It sat for about 2 days, and now only cranks with no start.
I have since installed a primer bulb thinking there was air in the lines. I primed the bulb until hard, tried to start still nothing. I took the filter off again figuring maybe it didn’t seal correctly. It all looked good but did definitely spray some gas under pressure while coming off, which it didn’t do the first time — maybe because of the primer bulb? I pressed the shrader valve on the fuel rail and gas does come out but not under a huge amount of pressure — not a spray like I would expect. When key is turned to the “on” position, you hear the electric fuel pump run for a few seconds.

Engine is a 6.2L MX MPI Mericruiser

Any advice would be helpful!

 

[airshot]

Is there spark when cranking ?

 

[alldodge]

Did the kill switch get tripped?

 

[dingbat]

You can’t prime a EFI high pressure pump with air in the system.

I’ve tried many different ways of “priming” fuel systems after changing a coalescing filter.

The only method that works for me most of the time is to start the motor and let it run to make sure the fuel system is fully primed and warmed up.

Then change the filter, making sure to fill it with fuel prior to installation. Start the motor and let it run for a bit to clear all the air from the system.

If this doesn’t work, you have to crack and bleed the pump at the fuel rail. Some HP pumps have bleed ports, others you have to “crack” the rail to bleed

If neither of these work, you have a leak in the fuel system, typically the filter gasket.

 

[helix757]

You can’t prime a EFI high pressure pump with air in the system.

I’ve tried many different ways of “priming” fuel systems after changing a coalescing filter.

The only method that works for me most of the time is to start the motor and let it run to make sure the fuel system is fully primed and warmed up.

Then change the filter, making sure to fill it with fuel prior to installation. Start the motor and let it run for a bit to clear all the air from the system.

If this doesn’t work, you have to crack and bleed the pump at the fuel rail. Some HP pumps have bleed ports, others you have to “crack” the rail to bleed

If neither of these work, you have a leak in the fuel system, typically the filter gasket.

Thanks for the reply! I am leaning towards the need to bleed air. What does the HP bleed port look like? If it doesn't have one, do I just hook up a hose to the Schrader valve to bleed at the rail?

I was thinking hookup a hose to the Schrader valve into a bucket, temporarily hookup a primer bulb between the filter and fuel line, and have someone squeeze the ball while I cycle the key to "on" and hopefully push air/fuel through the pump, and bleed out the Schrader?

 

[helix757]

Did the kill switch get tripped?

Are you referring to the red switch at the controller? If so, yes I confirmed.

 

[alldodge]

Are you referring to the red switch at the controller? If so, yes I confirmed.

Use a voltmeter and see if 12V is at the coil pink/white wire with key ON

 

[helix757]

Use a voltmeter and see if 12V is at the coil pink/white wire with key ON

I will check this today -- ty!

 

[Scott06]

Thanks for the reply! I am leaning towards the need to bleed air. What does the HP bleed port look like? If it doesn't have one, do I just hook up a hose to the Schrader valve to bleed at the rail?

I was thinking hookup a hose to the Schrader valve into a bucket, temporarily hookup a primer bulb between the filter and fuel line, and have someone squeeze the ball while I cycle the key to "on" and hopefully push air/fuel through the pump, and bleed out the Schrader?

if you take a rag and push the schrader in with a small screw driver - you can quickly see if there is air there or not. if its fuel or not under pressure no need to rig up a way to vent it.

 

[helix757]

Okay everyone. So I hooked a hose up the schrader valve, and when we cycled the key, pure fuel came out. After doing that a few times, I hooked up a pressure gauge, and I am getting 30 PSI.
Coil has 12v when key is “On”. Going to test with a real spark tester next.

 

[helix757]

You can’t prime a EFI high pressure pump with air in the system.

I’ve tried many different ways of “priming” fuel systems after changing a coalescing filter.

The only method that works for me most of the time is to start the motor and let it run to make sure the fuel system is fully primed and warmed up.

Then change the filter, making sure to fill it with fuel prior to installation. Start the motor and let it run for a bit to clear all the air from the system.

If this doesn’t work, you have to crack and bleed the pump at the fuel rail. Some HP pumps have bleed ports, others you have to “crack” the rail to bleed

If neither of these work, you have a leak in the fuel system, typically the filter gasket.

The filter gasket, are you referring to the rubber ring that comes installed on the filter?

 

[Scott06]

Okay everyone. So I hooked a hose up the schrader valve, and when we cycled the key, pure fuel came out. After doing that a few times, I hooked up a pressure gauge, and I am getting 30 PSI.
Coil has 12v when key is “On”. Going to test with a real spark tester next.

I think fuel pressure should be 40-43 psi not 30. I would assume it would still start with only 30 psi so this may not be the issue at the moment unless it is indicative of a suction side restriction

 

[helix757]

I think fuel pressure should be 40-43 psi not 30. I would assume it would still start with only 30 psi so this may not be the issue at the moment unless it is indicative of a suction side restriction

I am going to check with a spark tester tomorrow to confirm real spark. To your point about a suction side restriction, could it be a bad anti siphon valve? It perhaps is not opening the whole way?

 

[Scott06]

I am going to check with a spark tester tomorrow to confirm real spark. To your point about a suction side restriction, could it be a bad anti siphon valve? It perhaps is not opening the whole way?

anti-siphon valve or clog in puck up tube, some have screes in them.

I would check for spark first as there is fuel to the rail so would think either injectors are not opening or there is no spark. Simple spark gap tester off coil and at plugs to see if coil is firing and then if spark is getting to the plugs

 

[alldodge]

Agree it should be 43 psi and also agree it should start with 30 psi

Need a scanner

 

[helix757]

anti-siphon valve or clog in puck up tube, some have screes in them.

I would check for spark first as there is fuel to the rail so would think either injectors are not opening or there is no spark. Simple spark gap tester off coil and at plugs to see if coil is firing and then if spark is getting to the plugs

I will check for spark with tester this evening. To your point about clog in anti-siphon valve or pickup tube, should I try running it off an auxiliary tank?

In my bleeding test, I temporarily put an inline primer bulb. Would that have gone flat if there was a restriction?

 

[Scott06]

I will check for spark with tester this evening. To your point about clog in anti-siphon valve or pickup tube, should I try running it off an auxiliary tank?

In my bleeding test, I temporarily put an inline primer bulb. Would that have gone flat if there was a restriction?

At this point no you have enough fuel pressure that is should start.
So at this point find out why its not starting.

could be lack of spark or something else hence why AD mentioned the scan tool.

 

[helix757]

At this point no you have enough fuel pressure that is should start.
So at this point find out why its not starting.

could be lack of spark or something else hence why AD mentioned the scan tool.

Understood. By any chance do you have a link where I could purchase. I believe you are referring to the "Tech Mate" tool, correct?