So again, I am guessing there's an anti syphon valve on the bottom of that fitting that goes into the fuel tank correct?
So again, I am guessing there's an anti syphon valve on the bottom of that fitting that goes into the fuel tank correct?
should be in barb fitting where hose pushes on
.................................................. ...the scariest thing in life is the unknown ...................................
Thank you sir. I looked for 2 hours online last night and can't find a part specifically for my boat. Is there a generic part for part number anyone can recommend so I can replace this as well?
Last edited by OldDude7; 03-23-2021 at 11:49 PM.
Yes, but we really would need to know what size thread yours is (there are a couple different sizes... MOST commonly we see 1/4" NPT).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Update... my local dealer had everything I needed in stock. I replaced the fuel filter, the primer bulb, the diaphragm kit and o rings, the hose from the bulb to the motor, and the spark plugs. There was no debris in either bowl or even in the bulb or hose. Pulled it out of my shop. Put the muff on, primed it ( seemed like it took 50 pumps to fill the system) and it started right up. Played with it a bit to be sure. Loaded it up and took it to the lake. It ran as smooth as the day we brought it home. Lots of power. Planed quickly. Accelerated easily. We ran it for maybe 30 min.
Then we killed it to see it would restart. After sitting maybe 30 seconds I started it and turned around to take off again. It ran fine. About 30 more seconds and we hit a no wake zone. Shut it down to go under a bridge, then got back on it. It promptly fell on its face, coughed, and died. I checked the primer bulb. It was soft. I primed it 21 times before it would pressure back up. The boat started and took off easily, then died as it was accelerating.
Same thing.... pumped the primer bulb 22 times this time. Slowly drove back to the ramp, trailered it, and sadly pulled it home. Unfortunately the recommended fuel parts replacement fix didn't cure my problem.
Additionally, I can hear the fuel pump come on and pressure up when the key is turned to on position before starting. Air cleaner is new. Plugs are new NGK IZFR5J. I still hear a sucking noise from the tank area when squeezing the primer bulb. The hose to the tank is clamped tight.
All the new parts are OEM Mercury, not aftermarket.
Any other ideas?
Last edited by OldDude7; 03-24-2021 at 10:43 PM.
did you eliminate syp check at tank and check venting
.................................................. ...the scariest thing in life is the unknown ...................................
Syp check?
I was going to get portable tank today and see if it ran ok.
anti syphon valve in tank fitting
.................................................. ...the scariest thing in life is the unknown ...................................
The anti-siphon valve is likely the threaded "nipple" where the fuel line connects to the tank. Most of these are designed with a spring and check ball inside that fitting.
Fuel level that is too low or a pin hole or crack in the pickup tube that sucks air are two other relatively common possibilities.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
I tried to remove the anti siphon valve from the tank and the nipple basically came off in my hand. 8t appears to be attached to the fuel pick up hose as one piece. From the pics, if I remove the nut on top of the tank can I remove the assembly? My fear is removing the nut, then the assembly falling into the tank. It doesn't want to pull thru easily and I don't want to caveman it or break anything else.
The fitting appears to be attached to the hose.
A "portion" of the fitting is still attached to the hose. The pipe-treaded portion is still inside the aluminum 90-degree flange of the pickup tube.
DO NOT attempt to remove any other components from the top of the tank- those are not considered removeable. The pickup tube should be able to pass through the opening and remove from the tank (completely).
Replacement pickup tubes are available, as are replacement anti-siphon valves. Most common pickup tubes must be cut to fit tank (to have an angled cut and be approximately 1" above the bottom of the fuel tank).
You "might" be able to get that threaded portion out if you remove the pickup from the tank completely. Keyword here is "might".
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
I gently pulled the pickup tube from the tank. The tank is still half full. Owners manual shows it to be a 32 gallon, but it only measures 9 inches deep, 11 inches wide, and 71 inches long. I will figure the volume later.
Pics are of the pick up tube. It measures just over 33 inches long. It was dry as I pulled it out. I'm thinking it wasn't even low enough in the tank to pull gas. The sucking noise I was hearing was because the fuel level was lower than the end of the pick up. The hose appears to have a spring or something in it.
It looks pretty bad. Im not even going to attempt to repair it.
Last edited by OldDude7; 03-26-2021 at 12:31 AM.
Originally Posted by OldDude7
smart man indeed
.................................................. ...the scariest thing in life is the unknown ...................................
Assuming the worst here... let's say the fuel pick up doesn't fix it. I've tried running it with the gas cap cracked and off with similar results. Can the fuel pumps work intermittently? It just seems it isn't getting fuel to the motor.
It's possible for an electric pump to function intermittently, but based on what you've said about the anti-siphon valve and the pickup tube, it's very likely that replacing them may just resolve the problem.
Take a small wood dowel and push it down the threaded opening, straight to the bottom of the tank. Hold your finger on the dowel to mark the top of the tank.
Remove dowel and measure from your finger mark to the end (this measurement is used to assist in cutting a straight-tube pickup after removing about 3/4" to 1" from that length).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
It's impossible to go straight down. There is only about 6 inches of clearance.
So there is no need for the strainer on the end? No benefit to what you are suggesting over what was in there?
"Hose" type pickup tubes have their own unique challenges, as you often cannot see the orientation of the "hose" after the pickup is tightened in the tank.
Additionally, that pickup can bounce around in the tank, and flexes far more than a rigid tube does. However... extremely shallow tanks sometimes make it an absolute necessity.
I would definitely keep the screen on any flex-tube pickup, as it adds some weight to help keep it on the bottom of the tank.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
New twist... after making the recommended initial fuel parts replacement and having the same issue, I replaced the fuel pick up and anti siphon valve.
The fuel tank was at just under half full. I primed the system and it started right up using the muffs at the house. Ran it at different speeds for a little over 20 minutes, killed it, waited a minute, and started it right back up with no priming. I started to speed it up and it coughed and died. Yep ran out of fuel again. Primed the bulb and it started right up. As soon as it ran out of fuel it died again.
So I'm thinking maybe it doesn't like a half empty tank so I fill it up last night. I run it today maybe 20 minutes at the house again on the muffs and it does the same thing... runs out of fuel and dies. It's taking several primer bulb pumps to prime the system again. Then it starts. Its like its running on whatever amount of fuel is in the system between the primer bulb and the engine, then it dies.
Next, I opened the gas filler cap and primed it again. Started right up. Then after maybe 10 minutes of variable speed running, I killed it. I let it sit a few minutes and it started right back up. It ran for maybe another 5 minutes, ran out of gas and died. This time when I primed the fuel bulb I could hear an air noise coming from somewhere in the fuel tank area. I also noticed a strong gas fume smell from that area. Its always had this smell since we had it but I didn't think anything about it. Now I wonder....
Seems like negative pressure on the fuel system somehow. The motor is running great... just running out of gas. This alone makes me want to rule out either fuel pump being at fault.
How does the venting system work? After it runs maybe 10 min I kill it, the. Wait a couple of minutes and restart it. It then runs a few minutes and dies.
There are no visible fuel leaks in either the boat or motor.
Pics of what I assume is the venting system below.
Last edited by OldDude7; 03-31-2021 at 06:34 PM.
I just read the serial number is recommended... 1B507828 2007 Optimax 115
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