Hard time priming the fuel to the engine

[Magnumpl]

Hi. I am doing some renovations to my Angler 204FX boat with a 2005 Mercury 150hp XL SWB 2-stroke oil injected outboard. I think the issue that I am having should be my priority, before doing any other upgrades but I learned to live with it I guess.
Most of the time I need to prime the bulb for at least a minute or two for the fuel to start showing in the fuel filter. I think it primes a bit faster if I remove the fuel line from the filter, but might just be a coincidence. The bulb feels soft and empty even if the engine gets the fuel. I am having a hard time starting the boat on most of my trips. It is a lottery if it starts or it I will have to spend a few minutes priming the bulb. Sometimes it even requires priming on the water when the engine is off for an hour or so.
I replaced the fuel separator and fuel pump last year but I don't think it got any better.

This is my boats fuel layout:


What could be the issue?
What would you recommend on doing to find the cause?

 

[dingbat]

Primer bulb needs to be downstream of the water separator. Otherwise you pump "debris" through the filter.

My primer bulb is in the splash well. No more that 36" away from carb inlet, if that

Do you have a anti-siphon valve on the fuel line?
If not, and you have a vacuum leak, it's going to take a long time to prime each time.

 

[kcassells]

The problem can be so many things. Try posting in the outboard section. Lots of Merc guys there to help.

Mercury & Mariner Outboards

Sponsored by Uflex

forums.iboats.com

 

[Magnumpl]

Primer bulb needs to be downstream of the water separator. Otherwise you pump "debris" through the filter.

My primer bulb is in the splash well. No more that 36" away from carb inlet, if that

Do you have a anti-siphon valve on the fuel line?
If not, and you have a vacuum leak, it's going to take a long time to prime each time.

Yes, there is an anti-siphon valve directly on the fuel tank.

I've been thinking of switching out the fuel lines and moving the bulb to the splash well but it would need to be horizontally if placed right before the water separator. Would that be fine?

Right not its horizontally right below the fuel separator since its under the deck.

There are mixed opinions on priming bulb placement, some state that it should be placed before the water separator, and other say that it should be located after.

 

[Magnumpl]

The anti-siphon valve on the fuel tank is easily accessible.
The bulb is located 1-2' from the tank below the deck, then the fuel lines goes up to the water separator.
Tank (anti-siphon) -> Bulb -> Water separator -> Engine inlet -> Fuel pump -> Fuel filter -> Engine

I would need to check if the fuel pump if before or after the fuel filter because after watching some youtube videos I got a little confused but I am pretty sure that the fuel filter line is connected with the "out" connecter of the fuel pump

 

[dingbat]

There are mixed opinions on priming bulb placement, some state that it should be placed before the water separator, and other say that it should be located after.

Opinions on the internet are worth exactly what you paid for them....

Why not follow the manufacturer's recommendation of putting the "transfer pump" (primer bulb) on the vacuum side?

 

[Magnumpl]

Opinions on the internet are worth exactly what you paid for them....

Why not follow the manufacturer's recommendation of putting the "transfer pump" (primer bulb) on the vacuum side?
View attachment 389316

Thank you so much!



I will relocate the bulb.

In my case the fuel tank is located below the filter.



I can't too much information about the vacuum/pressure side. Would vacuum mean the side where the bulb and engine (suction) is located?

Would anti-siphon be considered a check valve in my case?

 

[flashback]

The bulb has valves in it. You may solve the problem by replacing the bulb. Just be sure you replace it in the right direction...

 

[kcassells]

Solution1 of 500 more coming.
Best of luck.
Keep us in the loop.