Engine fires but won't run

[nitedmn]

My dad recently gave me his old boat. He has owned it since 1972 and took really good care of it however it had been sitting for a long time (10+ years) before he gave it to me. The boat spent it's entire life in Wisconsin and I live in Denver (I only mention this because of the elevation change).

I drained all the fuel and other fluids out of it and cleaned everything (it was easy work considering how clean it was) then filled it up with fresh gas/oil. The engine fired up and ran perfectly on the first try. A couple of weekends ago I took it out for its first voyage in many years. I got a late start on Saturday so I didn't have much time on the lake but everything seemed to be running fine. I wasn't going as fast as I though I should but I figured that was because I was at 8500 feet of elevation and propped way to big (I'll start playing with props once I know everything else is working good). On Sunday we went back out, cruised around the lake for a while, then pulled up to a sandbar to eat lunch. After lunch I tried to start the engine without any luck. The engine will fire immediately, like it wanted to run, but then promptly quit.

When pumping the throttle I can see fuel squirting into the carb so I'm getting fuel to the carb, I'm assuming the fuel pump is good, but I'm at a loss of what to check next. I know the basic concept of how a carburetor works but I've never taken one apart. I'm assuming something is clogged in the carb. Here's a list of things I've checked so far.

Fuel line and tank are clear. (I can blow compressed air through the line, into the tank, and have it exit through the vent)
Filters are clean and have been replace.
Electrical seems fine. The engine will fire just fine.
Fuel is getting to the carb

Boat is a '72 Marlin Leo with a Mercruiser 888 (188 HP Ford 302 with the Holley 2bbl carb).

Any suggestions where to look next before I attempt to dig into the carb more would be great.

 

[mr 88]

How are your points ? Have you put new ones in or has it been converted to a Petronix system ? Are your spark plugs showing a good arc ? If your timing is dead on and your getting spark at the plugs along with fuel being delivered there is no reason that it shouldn't fire. Try spraying some fuel down the carb if your getting spark and see if it fires up,have your fire extinguisher close by in case she backfires.

 

[nitedmn]

It does fire up off the squirt of fuel it gets when I pump the throttle before trying to start it. It just won't run beyond that one second. I haven't checked the ignition system at all but, since it does fire, and it was running perfectly before this problem, I'm making the assumption it's fine (assumptions usually back fire on me though).

I just pulled the carb off, pulled the bowl off of it, and cleaned everything out good. It looked pretty clean to begin with and the float appears to be functioning properly. I did drop the bowl right as I pulled it off so It's possible the float was stuck and I freed it when I dropped it. After reassembling everything, I can't seem to get the fuel lines and carb primed. I cranked the engine for a while and didn't get any fuel to the carb. I pulled the gas line off the fuel/water separator and the fuel line was dry. Is it normal for it to be this difficult to prime the fuel lines or is my fuel pump bad? The glass bowl on the pump is empty.

 

[NHGuy]

Sounds like a clog in the fuel system. If you put a spoonful of gas or a shot of carb cleaner down the throat and it starts it could be a fuel clog, or air in the line from a break in the rubber supply line from the tank.
If it starts but quits the second you release the start switch and go to the run position, there is another possibility. Let us know.
What I am saying is if it will run only on the starter electric circuit, tell us.
Sounds like it was running well, check all the fuel filters leading into the carb too.

 

[nitedmn]

Now that you mention it, the engine did always seem to die as soon as I released the ignition switch.

Fuel filters are new and clean. Tomorrow I'm going to pick up a fuel primer bulb and manually prime the fuel system (I want a bulb for other uses anyway). Once I get it to fire again I'll check and see if it dies as soon as I release the switch. If so does this motor use a ballast resistor (that's the direction google started pointing me). If so, where is this normally located? Or what else should I be looking at?

 

[thumpar]

You can try running a jumper wire from 12v to the coil. If it stays running you know it is the resistor wire.

 

[nitedmn]

Looks like it was simply a gummed up carb. I got the fuel line primed today, after cleaning the carb yesterday, and it fired right up. Now I think I'm going to make a trip to the store and get an new anti-siphon valve to replace the one that doesn't currently exist.

https://photos.google.com/photo/AF1QipND2A8Zrlr8IH7tU5CIuu6dOHS4kvSoQk-8BJRq