Engine trouble?? any mechanics out there??

[Hunter 2]

  I have a full inboard 1988 350 Crusader with a carb on my 23' 1972 Chris Craft. I'm getting an rpm drop than up, Kind of like I'm Moving the throttle back and forth fast. the rpms go up down up down up down... Sometimes I stall, Than it usually starts right up and I'm fine. I think its a fuel issue. Or maybe a carb issue. Last week for the first time I waited about an hour after the incident, I was ready to call Boat US, Than it started right up and I was fine the rest of the day.. Since then I went down to the marina and Used Carb, Cleaner and seems OK but this is a sporadic problem. Do any of you have any suggestions?
Thanks in advance, Eddie

[IrishAyes]

Possible clogged fuel filter or water in fuel. Change fuel and water seperator filters for a start.

[shkbilly]

I'm not a great fisherman, but I am a diesel mechanic so I can help here.

Start with the basics. Like IrishAyes said, start with filters. How fresh are the plugs and wires? It does sound fuel related. How old is the carb? Ever been rebuilt? Possibly an intermittent stuck float.

[Still Running]

Start with the basics. Like IrishAyes said, start with filters. How fresh are the plugs and wires? It does sound fuel related. How old is the carb? Ever been rebuilt? Possibly an intermittent stuck float.

  

[Hunter 2]

I will try that, Thanks

[Still Running]

The first thing I would check is the fuel tank vent. The easiest way to do that is open the fill and see if the problem goes away. I have seen that a few times on boats. One stupid bee goers in the hole and you’re done. I saw a bee fly in my water pisser, I started the engine and no water came out even if I revved it up. Had to stick a wire in it to clean it out.

[Maritime Matt]

Hi Eddie. In addition to the above, I would check a few more things.
choke: Opening and closing as it should
Ign. Wires: I've had this happen on cars and trucks many years ago. Once it was warmed up and running on the road, the problem stopped.
I assumed the wires were absorbing moisture and once it got hot in the engine compartment they dried out.
Distributor advance weights.[ if it appies.]
It does sound like a carb issue, especially with all the fuel issues this season, but don't overlook or rush to judgement. Matt.

[wb]

If it's not the fuel or filter it could be a weak flexible fuel line collapsing, or a loose clamp sucking air into the fuel. You prolly have a spin-on fuelfilter/water separator and in addition a small filter right at the carb fuel inlet (may actually be in the carb.) Use lots of rags when loosening the nut; filter may be porous bronze or folded paper. If you ran the tank very low you may have sucked up some cr@p off the tank bottom into the lines and filter...

Maybe also air or vacuum leak at carb base or rubber hoses?

[PeggyLee]

Plenty of good suggestions. 
From what you describe,sounds like water in fuel or fuel flow restrictions to carb.
Check all hoses,filters and fuel pump to make sure the flow is a go.Trace it from the fuel vent to the and including carb.Thats were I stop with limited ability at the carb.Good Luck

[mckee17]

Sounds familiar, had the same issue.  Turned out to be a small screen filter at the end of the fuel pick up tube in the fuel tank.  Took a while to dope out. It would get clogged when your drawing fuel until the engine dies.  Then when fuel sloshed around in tank would free up again.  Had fuel tank cleaned.  It does sound like a fuel issue.

[Hunter 2]

Ah, Yes, I forgot to mention that I ran the fuel tank very low last week. I will replace the Water separator, Change the filter at the carb, check for collapsed lines, check the vent, make sure the carb is tightened snug, and over the winter change the distributor cap and rotor, plugs and wires. And thankyou Rick 'AKA' dieselhp, for the phone call, Your a great guy 

[Still Running]

  anytime!

[dikdanger]

you can always try torchen it...