Driving me NUTS!!!

[Johnny O']

I need help before I break down and have to bring my boat to a repair shop.
Info: 1989 75Hp Mercury Mariner O/B on a '90 Procraft.
Issue: Starts fine and runs well for approx 10 minutes but then stalls out.
Evidence: Primer ball is flat like the life is being sucked out of it.
I know/believe its a venting issue. Replaced everything from primer hose back to motor. Re-built fuel pump (Twice) with the right kit, but same issue happens again. Stalls, primer bulb sucked flat. Ran with fuel tank cap off as suggested in another tread but it did not improve my situation.
Any suggestions would be greatly apprecaited.

Tks
JO

 

[MCC371]

Re: Driving me NUTS!!!

Maybe some crap in the gas tank plugging the line. If the primer bulb is getting sucked flat, it's something blocking the gas flow between the bulb and the tank.

 

[ckc]

Re: Driving me NUTS!!!

Check anti-siphon valve in fuel supply line from fuel tank.Replace with a brass fitting and see if that helps.It is sometimes made of aluminum and gets corroded over time and the fuel pump can't pull fuel to the motor

 

[CharlieB]

Re: Driving me NUTS!!!

Pull the dip tube out of the tank, check to see that it isn't restricted with crap.

 

[jerryjerry05]

Re: Driving me NUTS!!!

The air vent on the tank is probably blocked.If you have a built in tank the vent can be blocked by mud daubers.The portable tank the vent might be closed.Start at the fill and follow it back.Jerry

 

[Johnny O']

Re: Driving me NUTS!!!

Thanks for all the feedback and sorry for the delay in responding. I have been swamped with other things!!
the tank is enclosed and under the deck. Access panels on floor for furl shut off and for what I believe is the fuel gauge. Sorry for my stupidity as I am one of those guys that if I can't see it I get lost.
1. Jerry: where would the tank veny be located? Would it be part of the fill hose?
2. Charlie B: Dip Tube: Do you mean dip guage that reflects the amount of fuel in the tank?
3. CKC: anti-siphon valve: where is this typically located? I have looked but don't see any fitting that can be changed out?
4. MCC321: I figured that there is junk blocking the fuel from the tank to the promer bulb but don't know how to clean it out. I can disconnect the primer bulb line but have no access to tank from that end except for the nozzel coming out of tank.

Guys thanks again for the feedback and sorry if my lack of knowledge is annoying you.

Johnny O'

 

[Johnny O']

Re: Driving me NUTS!!!

Jerry, I just went through everything again and here is the story.
Opened the fuel shut off cover and removed and checked the fuel line and the shut off valve from tank to primer bulb. All clear. Removed and checked the vent line from the fuel tank to the outside and thats all clear. Checked the vent pipe into tank and thats all clear. It is seperate line to the exterior of the boat. I removed/replaced the fuel guage in the tank and its working fine. I stumped. Guess its the shop form me!!

 

[Silvertip]

Re: Driving me NUTS!!!

You missed the anti-siphon valve. The is the fitting the gas line hooks to at the tank. It has a check ball in it and they do stick shut. Remove it, clean it, and before you install it, blow air into the tank to clear anything blocking the pickup tube in the tank. It may fix the problem for a day, a week or perhaps for good -- but there is obviously something blocking the flow of fuel.

 

[Johnny O']

Re: Driving me NUTS!!!

Anti-Siphon valve? The fuel line attaches to the tank via a shut off valve which I removed and checked and it was clear. The shut off valve is connected to a SQUARE shaped adapter type fitting before entering the tank. It this the anit-siphon valve and if so can that be screwed off with a wrench?

 

[engine-boy]

Re: Driving me NUTS!!!

Check the fuel line?.. Some fuel lines are made from 2 layers. An outer layer that is OK for UV and other environment stuff and the inside layer is OK for fuel. After some time the inner layer can separate from the outer layer. When this happens the inner layer becomes easy to collapse. When it collapses in the line between the tank and the bulb the engine will be starved of fuel and the bulb will collapse. Pull the fuel hose off and look at the end to see if it has 2 layers and check to see if the layers are separated. This may be hard to do since it could be separated in the middle of the hose.

 

[Chris1956]

Re: Driving me NUTS!!!

Johnny, The antisiphon valve is sometimes located in the elbow of the fuel pickup tube. Sometimes the pickup tube unscrews from the elbow. Your '90 procraft is extremely likely to have an A-S valve. You need to find it.

 

[Johnny O']

Re: Driving me NUTS!!!

Hi all, I have attempted to upload a photo so lets see if this helps at all. I am now convinced that the issue is the anti-siphon valve where ever that may be?? I removed all the lines and blew clear and there is no blockage so its got to be the cube type connection labled in the photo. Sorry to all for my lack of knowledge and a big thanks for all the very sound help and guidence.

Johnny O'

 

[Chris1956]

Re: Driving me NUTS!!!

Johnny O, It is likely the A-S valve is located either inside the elbow, on in the fuel pickup tube attached to the elbow on the "down" side. I recommend you remove the shutoff valve and unscrew the elbow from the tank. Now see if the fuel pickup tube threads into it. Mine had a screen under the fuel pickup tube that was clogged with junk. The A-S seemed OK.

 

[Silvertip]

Re: Driving me NUTS!!!

If an anti-siphon valve is used, that's where it should be. If you remove the shutoff, then remove the elbow, you should see a check ball in the back side of the elbow. you can also disonnect the fuel line at the shutoff and temporarily connect it to a portable tank. If the problem goes away you have a tank/anti-siphon valve issue. If not, its a fuel line problem.

 

[Johnny O']

Re: Driving me NUTS!!!

alright I got the piece screwed off and the screen was clear both from the top and the bottom. There was nothing attached to it. There appears to be a tube connected directly to the inside of the tank as you look in but that appears to be it??? I can see fuel at the bottom of the tube. Does this tube need to come out and if so how if is attached to the tank??

 

[Johnny O']

Re: Driving me NUTS!!!

second photo for review. One more on route shortly

 

[Johnny O']

Re: Driving me NUTS!!!

Photo of the entrance to tank. Photo shows what appears to be the top of a tupe inside but it does not apperar to move. I haven't applied too much force as i'm afraid that I will damage it. The tube also apperrs to get nerrower towards the bottom. Any ideas boys??

 

[hkeiner]

Re: Driving me NUTS!!!

you can also disconnect the fuel line at the shutoff and temporarily connect it to a portable tank. If the problem goes away you have a tank/anti-siphon valve issue. If not, its a fuel line problem.

If I was in your situation, my next step would be to follow Silvertip's excellent advice above before working on the tube in the tank.

If the problem does not go away with the portable tank, you might consider testing the fuel line and the fuel pump with a vacuum gauge. The changes in vacuum level readings under different hookups/conditions will tell a lot about what the problem may be. For example, if your fuel pump is weak and the squeeze bulb is too easily collapsed, it might also cause the symptoms you describe. Or the upstream check valve on the squeeze bulb could be restricted. As an alternative to "fixing" possible culprits until the problem goes away, using systematic troubleshooting steps is a good way to narrow down and solve this type of problem. The below Mercury service advisory describes how to test the fuel supply system using a vacuum gauge.

http://www.marinepartsman.com/Mercur...2001/EN_17.PDF

 

[Johnny O']

Re: Driving me NUTS!!!

alright boys i'm going to go with silvertips suggestion. this will take awhile so i'll get back to you all later.