1988 3.0 Carbuerator Dumping Fuel

[tschmidty]

I have a 1988 3.0 which was running fine in my driveway (fairly new boat to me). I then trailer it over to the lake and it refuses to start. Looking down the carb it looks like it was just dumping fuel. I had figured I had knocked something loose driving over. It would almost start and sort of chug and even run for 5-10 seconds but just barely, almost as if it was running on one cylinder but not exactly.

Ended up pulling the carb and cleaning it out (not a rebuild), it had some serious chunky stuff in the fuel bowl. Oddly I can imagine it clogging things up but couldn't quite figure out how it would cause it to go so rich, on the other hand who knows what might be clogged. I will be rebuilding it in a bit since I need to replace the gasket anyway; I can only find a rebuild kit and not just the gasket itself.

I need to triple check the ignition to make sure I am getting good spark at all the cylinders (which I am pretty sure I am) but I need a helper for that. It is definitely getting good fuel to the carb (new gas, fuel pump working well).

But I really think it is just dumping fuel. When I pull the carbuerator there is a pool of gas in the intake manifold and it just looks soaked looking down the carb. Does anyone have any suggestions on what else to look at on this carb or engine?

 

[Aviator5]

Re: 1988 3.0 Carbuerator Dumping Fuel

Your needle valve is faulty, worn out, or something got stuck in it.
Just get that rebuild kit and replace everything what is in it.

 

[fixb52s]

Re: 1988 3.0 Carbuerator Dumping Fuel

Also check the float and see if it is not leaking. If you shake it and see/feel something in it, time for a new one. A float full of fuel does not float, and the result is the needle will not shut off the fuel as needed. Fuel will just dump into the carb, causing your problem.

 

[tschmidty]

Re: 1988 3.0 Carbuerator Dumping Fuel

Thanks, getting the kit in a bit and I'll update when I see what's going on. The needle looked clean, but there may have been some gunk in the accelerator pump under the check ball which would also do it. We'll see.

 

[Silvertip]

Re: 1988 3.0 Carbuerator Dumping Fuel

Chances are it was the debris under the check ball. That provides a straight shot for fuel to be dumped into the engine. The question is -- "where did all the debris come from and how did it get past the fuel filters?"

 

[180shabah]

Re: 1988 3.0 Carbuerator Dumping Fuel

Don't forget to check the fuel pump, ruptured diaphram will dump raw gas down the carb.

 

[tschmidty]

Re: 1988 3.0 Carbuerator Dumping Fuel

The gunk was almost more like corrosion in the fuel bowl, it was a pinkish white chalky kind of stuff. Pretty nasty. I have a feeling the boat sat for long periods, and the gas evaporated or something similar.

Here is a picture and you can see the white gunk to the right of the carb (black stuff is gasket remains) and some of the corrosion at the bottom of the fuel bowl.

 

[Don S]

Re: 1988 3.0 Carbuerator Dumping Fuel

It's corrosion caused by water in the fuel. I see it all the time.
After (and if) you get that carb cleaned up and working again, I would be installing a water seperating fuel filter between the tank and the engine to keep water out of the fuel pump and carb. It also wouldn't be a bad idea to clean any water out of the fuel tank.

 

[tschmidty]

Re: 1988 3.0 Carbuerator Dumping Fuel

So if it was the fuel pump diaphram I could disconnect the sight tube (leading it to a safe place of course) and crank and if I got fuel coming out, replace fuel pump. I don't *think* that is the case but I'll check that. Thanks.

 

[tschmidty]

Re: 1988 3.0 Carbuerator Dumping Fuel

And thanks, yeah, I figured it was water in the fuel that caused the corrosion. There actually is a fuel water seperating filter on it now, but that wasn't always there. It's not clogged at this point, but I will be changing it as soon as I can get a new filter.

 

[tschmidty]

Re: 1988 3.0 Carbuerator Dumping Fuel

Rebuilt carbuerator, got it running. Now on to the next project....