Fuel Line Losing Pressure

[dcdayton1987]

Hi, I'm not sure if this is the best place to post this question so please let me know if I should move it. Some time last year I was idling out of a long no wake zone and suddenly my engine died and wouldn't crank until I finally primed the fuel bulb and then it fired right back up. Since then, the issue has persisted despite doing the following:

- Rebuilt pulse fuel pump
- Replaced fuel filter
- Replaced fuel line and primer bulb from the fuel tank fitting all the way into the motor.

I can prime the bulb until stiff but after an hour it will take about 2 squeezes to fully prime again and after several hours it takes 8-10 squeezes. This is without running the engine, just sitting in the garage. No issues at full throttle, getting about 5800 RPM with my 24p Fury.

Any ideas what could cause the line to lose pressure like that? The fitting on the fuel tank appears to be tight, no movement or fuel leaking anywhere that I can see or feel.

Motor Serial # 2B360372

Any help is greatly appreciated! Thanks.

[lpugh]

VST leak, check the water in fuel sensor at lower front of vst, two wires

[EuropeanAM]

Could also be the natural vaporization of your fuel in the line/system. This is why a primer bulb was placed in the line- it should be pumped firm before EVERY engine start (even more critical when temps get to 60F or above).

[dcdayton1987]

Could also be the natural vaporization of your fuel in the line/system. This is why a primer bulb was placed in the line- it should be pumped firm before EVERY engine start (even more critical when temps get to 60F or above).

Even when priming right before starting the engine, it will only idle for about 10-15 minutes before it dies.

[dcdayton1987]

VST leak, check the water in fuel sensor at lower front of vst, two wires

Will do, thanks!

[dcdayton1987]

VST leak, check the water in fuel sensor at lower front of vst, two wires

I see the two wires but not sure what I should be checking exactly. There are no alarms sounding when running the engine and I don't see any leakage from the VST.

[1BADAIR]

Could this be a fuel demand valve issue?

[dcdayton1987]

Could this be a fuel demand valve issue?

Between my fuel tank fitting and the fuel line is this part: BK02800041PSI Anti Siphon Demand Valve (ASDV) 3/8” NPT, 3/8” Barb

I'm no boat mechanic but I'm assuming this is essentially a fuel demand valve correct? I see that BluSkies was bought by SeaStar so I can't find an exact replacement part but will any 3/8" anti siphon valve work as a replacement?

[JOE54]

is it a genuine quicksilver bulb ???? for a test connect a known good fuel line to remote 6 gallon tank test run to eliminate boat as source of problem

[EuropeanAM]

is it a genuine quicksilver bulb ???? for a test connect a known good fuel line to remote 6 gallon tank test run to eliminate boat as source of problem

THIS ^^^^ is the BEST method. You'll know if the problem is inside the cowling, or outside the cowling (make sure the 6 gallon tank has it's OWN fuel line and bulb, connected DIRECTLY to the pulse fuel pump's inlet fitting).

[dcdayton1987]

is it a genuine quicksilver bulb ???? for a test connect a known good fuel line to remote 6 gallon tank test run to eliminate boat as source of problem

Not a quicksilver bulb but the issue has continued with 3 different bulbs, 2 of which are brand new. Unfortunately I don't have a remote tank to test with.

[dcdayton1987]

Update: Think I may have solved the issue. After hooking up to a remote tank with no change, I spoke with a Mercury mechanic and was told I could possibly have a broken reed valve but to double check everything else first. He also mentioned the check valves in the pulse pump must sit flat on the pump body so I pulled the pulse fuel pump back off and inspected the check valves at which point I found that one of the valves had a concave shape and did not sit flush. Picked up a new rebuild kit and carefully seated the retaining pins in the check valves. Bad weather today so I won't be able to confirm until tomorrow.

[EuropeanAM]

That could do it.

[dcdayton1987]

Finally had a chance to get out after replacing the bad check valve in the pulse pump but unfortunately the issue still persists. Now I need to check my reed valves but can't find any how-to videos on replacing them. As I understand, I need to remove the air plenum to access them but is there anything I need to know before getting started?

[EuropeanAM]

I wouldn't even think of using "tube videos" as a guide for this type of work. Get a Service Manual- remove the Air Handler Assembly (complete) and inspect the reeds from the back side (crankcase side).