'75 Mercruiser won't start

[SRV220]

1975 SRV220 w/188hp Mercruiser (Ford 302)

I bought this boat about 6 weeks ago and here is how it has gone so far.

When I first got the boat I was able to start it, but it would bog down and die if I tried to throttle it up, sometimes backfiring through the carb. After a few attempts, I would eventually not be able to restart it.

Replaced points and condenser, and it fired right up. Idled strong (best thus far) and long enough to set the timing, then died. After this initial run it would only run for a couple seconds at a time and either backfire through carb or just die. (Did the exact same thing the next day - fired up and idled for a minute and then just backfiring and dieing after that.)

Suspected fuel pump and replaced that today. Now it won't fire at all. I am able to make it fire for just a second with starting fluid, but can't keep it running and won't fire without the fluid.

The distributor cap is chipped in a couple of places (center hole and one other) but no where near the contact points, just the plastic at very top. I mention that because I'm not sure if it could be my problem because I think it was like this from the start, as in when it actually did fire and idle briefly before.

Tried to give all the pieces of the puzzle here, sorry it's kind of a mess of information. I do have a cap and rotor on the way but would like to know if anyone suspects this is my problem or do I need to keep looking elsewhere.

I've become very frustrated as I have not had a chance to get this boat on the water and the season in Minnesota is not very long, so I would greatly appreciate any help offered.

Thanks.


Edit: Replaced fuel/water separator filter along with fuel pump today, and there was a lot of water in the old one, is this to be expected? I was so sure the fuel pump was my issue that I filled the tank nearly full this morning before getting to work, expecting a trip to the lake to follow. Was nearly empty before, so I can't imagine there being a lot of water in there, but I don't know.

 

[jakebrake]

define a "lot of water". condensation is possible. how long was she sitting?

 

[SRV220]

Filter looked to be full of water when it came off. I didn't think to put into a container where I could see it separate, unfortunately. So I guess I could be mistaken about being water as opposed to old gas?

The guy I bought it from told me that he had and used it for the past 3 seasons, but I'm not sure if that included the beginning of this season or not. (I bought it the 2nd half of June.)

 

[jakebrake]

just a thought. did you blow out the fuel line? fuel starvation is what it sounds like.

 

[SRV220]

Hmm, fuel hose from access in floor to separator is new, there to fuel pump and then up to carb are old lines... Thanks for the thought, will be my first task tomorrow.

 

[jakebrake]

if you dump a little fuel down the carb and she starts, or starts with fluid, fuel starvation is the obvious suspect. good lick, keep us posted.

 

[fwebster]

Try running the engine on a fuel supply other then its main tank. rig a temporaty hose from a gas can to the fuel pump inlet and see what happens. If the engine runs, you've identified the problem as a fuel quality/quantity issue and work backwards from the engine to find it.

However, if the engine still idles but stalls when the throttle is advanced, take a look at the accelerator pump in the carburetor. You might have to buy a complete rebuid kit .....I don't know if you can even buy them by themselves anymore.

 

[SRV220]

OK, got it fired up. Ran it off a remote can first, then hooked up to the tank. Suppose the line just needed to be primed?

Anyway, ran great but when I shut it down I noticed the carb was flooding with fuel, so I adjusted the float and now I'm short on fuel, or so it seems. If I hold the choke shut it'll keep idling, let it open and she dies. I do believe it was warm enough that the choke should have been open at that point. Guess I need to do some reading and find out where exactly that float should be set, as I was just eyeballing it. Is there a tool that's used to set that, or is it just trial and error?

Thanks for the help.

 

[SRV220]

Another update:

Found a manual online with specs for the float and a couple of pictures of how to set it. Using a tape measure I think I got it pretty close and it ran good, able to idle and throttle up both. But when I shut it down there is still a little bit of fuel sitting in the bottom of the carb, is this normal, or do I have the float set just a little too high still? Should I leave well enough alone or what?

Thanks a lot everyone, hopefully I'll get this thing on the water for the first time tomorrow. :smt001