Fuel Issue when Idling for a long period of time. (10 min)

[TurboM700]

Adding more information. Ok I changed out everything but the fuel pump and everything seemed to be working fine. Except I had to take out the anti-sphion valve because my local marine place was out of stock on them, so I just replaced it with a normal brass barbed fitting. Drove the boat last Saturday all day and the fuel filter would stay full when driving.

The only disadvantage was if the boat would sit for an hr or so it would drain the fuel back to the tank. I replaced the anti-siphon valve on Tuesday and went back out yesterday for the 4th and started having the same issue. After idling for long periods of time the fuel filter would go empty causing a bad bog when trying to go faster then idle. I also noticed after cruising at 3krpm it wouldn’t fill the filter up either.

I'm starting to thing my fuel pump doesn’t have enough suction to pull past the anti-siphon valve. Is this possible?


I stuffed a Mercruiser 140 (3.0l) in a pontoon. Everything worked great my first time out except up at speeds water got pushed thru the vent and into the tank.

Drained the tank and continued on. Ever since then I have been having this issue when Idle for a long period of time my fuel filter will go empty. If I run the boat at 1500rpm this isn’t an issue. If I take the primer bulb and squeeze it, it will fill right back up. I'm thinking fuel pump doesn’t have enough pressure at idle but then again it shouldn’t take much at idle to keep up.

I know its not venting as I can leave the gas cap off and it does the same thing.

Thoughts.

I attached a few picture of the engine area so you can get an idea.

Thanks again
Mike

 

[achris]

Re: Fuel Issue when Idling for a long period of time. (10 min)

I see a PLASTIC fuel filter in the line to the carburetor.... USCG see that and there's going to be blood on the walls!

Please, please remove that thing and get a proper (single run, not a joined up one) fuel line installed... If you want a filter in the engine bay use an all metal one.... Preferably bulkhead mounted.

Your problem could be a weak pump. Having sucked up water the diaphragms might be damaged...

Chris.........

 

[TurboM700]

Re: Fuel Issue when Idling for a long period of time. (10 min)

Thanks for the information.

I have a metal bulkhead one that is on my to-do list. Looks like it just got pushed to the front of the list.

 

[Bt Doctur]

Re: Fuel Issue when Idling for a long period of time. (10 min)

anti-syphon valve corroded from the water intrusion restricting flow

 

[Don S]

Re: Fuel Issue when Idling for a long period of time. (10 min)

Is that a fuel fill hose in your engine compartment ?????????

That is a whole lot more dangerous than your fuel line and filter problem.

Also, a marine fuel pump has a fitting on the side for a clear hose that hooks t o your carb. That way, if the fuel pump diaphragm leakes the fuel goes into the carb, and not the bilge.
Automotive pumps just have a hole in them.

 

[TurboM700]

Re: Fuel Issue when Idling for a long period of time. (10 min)

Is that a fuel fill hose in your engine compartment ?????????

That is a whole lot more dangerous than your fuel line and filter problem.

Also, a marine fuel pump has a fitting on the side for a clear hose that hooks t o your carb. That way, if the fuel pump diaphragm leakes the fuel goes into the carb, and not the bilge.
Automotive pumps just have a hole in them.

Yes thats the fuel fill. Its a non vented cap and please correct me if I'm wrong but I dont see an issue with it being there. You have to open the "dog house" in order to fill there for any fumes will be let out the min its opened. I had many different thoughts about where to put the fuel fill on this boat and this seemed to be the best place for it.

As far as a clear line this pump doesnt have one. The motor is a early 1970 vintage and from the resarch I have been doing the clear lines didnt come till late 70's.

Not saying I'm going to do this as I'm not that cheap but if one where to tap the hole on a Auto pump for a 1/16th NPT and run a line to the carb he would have a marine Pump?

Also from looking at my pump it looks like it could be taken apart and rebuilt. I cant seem to find anyone with a rebuild kit. Does anyone offer one or is a new pump in store for me?

Thanks for you help. I'm not trying to be diffcult just learn thats why I'm asking alot of questions.

 

[TurboM700]

Re: Fuel Issue when Idling for a long period of time. (10 min)

Added more information to the first post.

 

[Bt Doctur]

Re: Fuel Issue when Idling for a long period of time. (10 min)

gasoline vapors are slightly heavier than air. any fumes go INTO THE BOAT and you now become a "DARWIN CANDIDATE" ,
Look at where all the marine fills are located, you`ll get the idea.

 

[TurboM700]

Re: Fuel Issue when Idling for a long period of time. (10 min)

I understand the fumes, gas fill scenario. I can see more gas fumes coming from the carburetor then out my SEALED GAS CAP.

Lets not focus on the gas filler and focus on why my filter and lines are going empty when idling for a long period of time.

Not trying to be rude but I’m not a dummy when it comes to gas fumes I have taken every step to insure that fumes cant exit the gas tank inside the engine area. I fail to see how having the gas cap in there is any different then having it on the side of the boat. As long as im not a complete idiot and ALL the gas goes down into the tank there is no issue here.

Mike