Can a few gallons of bad gas cause this?

[pktaske]

I've been out a few times this year already and have added about 20 gallons to the tank over that stretch (I always try to keep her filled since my fuel gauge is kaput). Anyway, I start her up this morning in the driveway and she's humming. On the way to the ramp I stop and she takes about 4 gallons. I put her in the water and take off. I get about 1/4 mile out and something is wrong. Puttering...stall. I try to start her and she will only do start by furiously pumping the throttle up and down. I can get some high RPM's by doing this but lots of strange sounds, some backfiring and as soon as I stop pumping RPMs drop and she stalls out. Luckily I get someone to bring me back in to the dock. Once home, I try for about 15 minutes to get her going again - same problem. I then take my 3 gallon portable tank and hook her up and in a minute she's humming so it's definitely a fuel problem. My question is - do you think its the new gas (again only about 4 gallons that I added to an almost full tank)? Did water somehow get in the tank between last week and this week? Something else? Thanks...

2.5L 120 powering an Alpha I.

 

[Limited-Time]

Re: Can a few gallons of bad gas cause this?

Sounds as if your anti siphon valve may be an issue. Don has a link for trouble shooting the entire fuel system.................I'm sure he or some oneelse will post it for you.

 

[BMOLCHANY]

Re: Can a few gallons of bad gas cause this?

Could be a few line issue. Had similar issues and replaced mine with great results.

 

[pktaske]

Re: Can a few gallons of bad gas cause this?

Could be a few line issue. Had similar issues and replaced mine with great results.

Fuel line from the tank to the fuel filter? past that? Again, I pulled the line coming off the fuel filter and stuck it on the portable tank and no problems. My first thought was I had deisel in the tank but they have totally separate hoses for that at the gas station. I'm going to pull the gas float out and try to fix that. While it's out, I'm going to pump some of the gas from the tank into my portable tank and see if that creates the problem again. I'm also going to check for water.

Where is the anti siphon valve located?

 

[Bondo]

Re: Can a few gallons of bad gas cause this?

Ayuh,....

The Antisiphon Valve is the Hose Barb at the Tank's Outlet.....
Usually Aluminum....

 

[J JACKSON]

Re: Can a few gallons of bad gas cause this?

a few gallons of diesel can cause this i work on construction equipment and it is very common for this to happen try running it on whats n your fuel tank and then pull a spark plug if its wet looking and black its probably diesel it will smoke some as well but it will def. black the plugs

 

[cgrooves]

Re: Can a few gallons of bad gas cause this?

Ayuh,....

The Antisiphon Valve is the Hose Barb at the Tank's Outlet.....
Usually Aluminum....

Bond-O-
I know an Antisiphon Valve only allows fluid to move in 1 direction. Is the purpose of the Antisiphon Valve (in this application) to prevent fuel that is between the tank and the fuel pump from siphoning back into the tank when you shut down the engine?

-Sorry for the thread jack, pktaske-

Since this problem didn't show up until immediately following a 4 gallon top-off, I would say that bad fuel is a possible culprit. I wouldn't want to empty out the entire tank since it is full, but you could siphon out 5 gallons the way I explained in this thread:http://forums.iboats.com/showthread.php?t=266886

If the boat is left sitting level prior to doing that, any water in the fuel tank will be settled in the bottom and will be the first thing to come out. It is a simple enough task to eliminate bad fuel as the source of the problem.

 

[Bondo]

Re: Can a few gallons of bad gas cause this?

Bond-O-
I know an Antisiphon Valve only allows fluid to move in 1 direction. Is the purpose of the Antisiphon Valve (in this application) to prevent fuel that is between the tank and the fuel pump from siphoning back into the tank when you shut down the engine?

Nope,......

It's to Stop the fueltank from emptying itself into the bilge, in the event of a fuel line Failure.....

 

[cgrooves]

Re: Can a few gallons of bad gas cause this?

Nope,......

It's to Stop the fueltank from emptying itself into the bilge, in the event of a fuel line Failure.....

School me on this, as I'm still confused.

If the anti-siphon valve is a 1-way valve, I assume it will allow fuel to flow in the direction 'from the tank to the fuel pump'. In the event of a fuel line failure between the anti-siphon valve (at the tank outlet, as I understand it) and the fuel pump, how would it keep fuel from emptying into the bilge?

Am I just wrong in my description that it is a 1-way valve? All anti-siphon valves that I am familiar with (i.e. plumbing related) are 1-way valves, but it sounds like what you are describing will allow fuel to flow if there is a strong vacuum created (i.e. fuel pump) but not allow fuel to flow if there is just the pull of gravity present (i.e. fuel line failure causing an open system).

 

[pktaske]

Re: Can a few gallons of bad gas cause this?

ok, so I unscrewed the 'square' aluminum elbow from the gas tank. Man that sucker was on tight. All it has in it is a small screen (which was clear) to prevent any large particles from getting out of the tank. No sign of any valve and the such. Looking into the hole, there seems to be an aluminum tube running from this opening to the bottom of the tank. This I assume is the pick up tube. The elbow was so hard to get off that when I first looked I thought this tube was supposed to be attached and I had sheared it off. Doesn't look like that was the case ( I hope!). I also stuck a screwdriver down the hole to see it there were any funny obstructions or valves on the bottom of the tube but it doesn't seem there is. Anyway, after checking for water at the bottom (none), I siphoned off a gallon of gas and ran it with my portable tank. Ran fine. Took off the fuel/water sep filter for good measure and emptied that out. No water or junk.

I'm 100% positive this was a fuel delivery problem but I'm perplexed on what could have caused it. I would guess maybe a clogged vent line causing a vacuum but that's working fine because when I topped off the tank, a bit gurgled out when the tank filled up.

Also - when I tried to put the elbow back on the tank - stripped! Now I have to tap the threads go find something to replace this. Can I use a brass or copper fitting from home depot? What about black pipe that you use for natural gas? Where could i get a replacement part direct? Thanks guys...

 

[180shabah]

Re: Can a few gallons of bad gas cause this?

For the elbow, any brass one will do, it is just standard pipethread. While you have it all apart, install an anti-siphon valve - they're cheap and it could save your life one day.

 

[Fishermark]

Re: Can a few gallons of bad gas cause this?

it sounds like what you are describing will allow fuel to flow if there is a strong vacuum created (i.e. fuel pump) but not allow fuel to flow if there is just the pull of gravity present (i.e. fuel line failure causing an open system).

That's exactly right.

 

[pktaske]

Re: Can a few gallons of bad gas cause this?

Just an fyi that everything is ok now. I'm not really sure what the heck the problem was. Maybe something was clogging the screen and dislodged when I pulled it. Anyway, put a new brass elbow and barb on and she's working great. Now I have starter problems though!

 

[gamarines2]

Re: Can a few gallons of bad gas cause this?

Just an fyi that everything is ok now. I'm not really sure what the heck the problem was. Maybe something was clogging the screen and dislodged when I pulled it. Anyway, put a new brass elbow and barb on and she's working great. Now I have starter problems though!

Glad you got the fuel problems fixed. I just did a whole lot of work on my starting system.......what is your issue?

 

[pktaske]

Re: Can a few gallons of bad gas cause this?

had disty/timing issues at first . those were fixed. Now my starter pinion gear was stripped. Fixed and now out on the water again!