Fuel Problem?

[gilbert landin]

Its amazing how you too can become an accomplished A4 guru by reading and experiencing problems. My newest "challange" is the " starts fine, idles fine dies after 5-10 minutes" problem, sooner if in gear and under load. I have read the other threads and have read Don's FAQ on troubleshooting fuel problems. I have a new fuel tank new Fuel filter/seperator cartridge, and placed a fuel bulb and see-thru fuel filter between the facet fuel pump and the carb. can see that the fuel is getting to the carb, I have disconnected the fuel pump and watch the aortic spasms, so I know I have fuel going thru the pump, I just today found that some fuel pumps actually have filters on the trhem, that will be my next step. Befor I removed the old fuel tank I had quite a bit of gunk in it and I could see the turbidity in the fuel. Right after the change, I got the dreaded water backflow into the system, trying to start the motor. So I compounded the problem of a new fuel tank with this. I did take apart the carb enough times to memorize the process and be able to do it in the dark, with one hand tied behind my back. I blew out and cleaned all the visible parts and the rest as best as I could and reused the old gaskets that were stuck together. I ordered new gaskets but i am not sure if I am going to need a rebuild kit or what.

The Saga continues

gilbert

[baileyem]

When you were learning about the insides of your carburetor, did you set the float valve accurately. A float set incorrectly will give the symptoms that you describe.
Mike

[gilbert landin]

No, I did not check the float clearence, I simbly cleaned and reassemled, do have the overhaul manuals and will look at that.

gilbert

[gilbert landin]

Well, I totally disassembled and cleaned the carb today. Took a small brush and some carb cleaner and went to town. BailyM you asked me to check the float clearance, and I looked at the manual and my unassembled pieces, the manual doesnt give anything other than check to turn the top assembly float up and check that is level with the venturi tube. Shows a picture on fig.8. I do have 2 carbs and it looks like the P.O. had rebuilt it. That was the one I was using. Anyway after cleaning thoughroly, the engine cranked right up and filled me with hope. It did last a little longer before the idle kinda slowed down and hesitated and when I threw it into gear it did last a couple of minutes more before it died. Funny thing is the motor will start right up, but I do have throw the choke to get it going again...I am currently looking for a used Universal 25......

gilbert

[Alain Croteau]

Did you check the fuel tank vent to ensure its not blocked?

[JackConnick]

This may not be it. BUT an old/weak coil can do sort of what you describe, run for a few minutes (usually about 15 mins), then when it gets hot, it fails. If you think you're getting gas ok (check a plug), then it may be electrical in nature. Be sure to buy a coil rated for marine use 13-15 volts instead of 10-12. It's best to use some sort of spacers and move it away from the engine block. I usually change my coil out just for drill every 2-3 seasons, and carry a spare, they are a weak point in my experience.

When it stops running have you checked that there's fuel in the carb bowl? The plug on the back can be unscrewed over a cup and you can see if there's fuel there. See if there's any water in it, by letting it settle and seeing the drops at the bottom. It sounds like a blockage possibly, or water in the fuel.

Jack

[gilbert landin]

When I removed the carb for cleaning I was careful to keep it upright, so I could check if there was fuel in the bowl, and what the fuel looked like. The bowl had a very little sediment ( I had taken the carb apart and cleaned it 3-4 times last month) and the bowls were full of gas. I also have a see thru filter before between the pump and the carb. So I can see the condition of the gas, and that looks pretty clear. It does look like the PO had a spare coil so I will try that next. I will visit the electrical furom to see how to check the coil for problems. Man I am getting sooo good with the fuel delivery system...

gilbert

[MikeB.330]

You may want to re-think using those clear glass fuel filters. They are not rated for use on an inboard gas engine. That said in the past I used them for years without issue for I knew better.

I think the same goes for the Racor filters with the plastic lower bowl.

now about your problem. I once had the same issue. I cleaned the carb several times only to have the same problem. The problem turned out to how I was putting the carb. back together. Somehow I was allowing the gasket to shift a little bit and block the movement of the foat. The bowl would fill with fuel but not as fast as the engine would burn it.

I discovered the problem by noticing that I could hardly blow any air in the fuel inlet (mouth pressure only) I also could not hear the float rattle aound in the carb when I assembled it. Once corected I could hear the float and feel more air being blown in. I trimmed a little bit off of the gasket..





Mike

[gilbert landin]

Mr. Connick

Wow I was already pricing used diesels, I knew that is was getting close, I have already changed out everything else. I had used all the POs spare parts when I overhauled the engine 2 years ago, it took me a while to do this, I probably have no more than 50hrs on the new rebuild. Part of putting the engine together was also a tuneup kit that included wiring, rotor,cap, plugs and a nrand new Standard coil. I keep old stuff just cause I am male and thats what we do. Luckily I didnt throw the beat-up looking old coil out. Jconnic, you suggested changing it out, when I took the existing one off (still nice and shiny) I also cleaned the wires and reterminated one of the ground wires, I dont know if it was the retermination or the coil, but the moment I did that the engine has been staying on, I left it for 30min and it stopped once, and when I restarted it came right up and went for another 15 minutes. Its funny how I was so sure that it was a fuel problem. It sure acted like I t was fuel starvation, and I went thru all the other work. Oh well I know a lot more about my engine now.

gilbert