Mercruiser 4.3 only runs pumping throttle

[MOTRhead]

Hey all,

I've got a 1990 4.3 that had the motor mounts rebuilt by a local marine 1 1/2 years ago, obviuosly the engine was completely removed etc. then it was winterized by them and put away in my shop.
I haven't run it since until last wknd, had some trouble starting it, used quick start, would run then stall, finally poured some gas down the carb and she started up and ran. Shut her off and then she would start up again no problems.
Put her in the water, started up great, idles in gear at low speed, when i accellerate she wants to go then bogs, if i continously pump the throttle she will come up on plane, as soon as i stop pumping, the rpms drops slowly and she will stall, she did this all day while trying to figure out the problem. I removed all the fuel and put in new gas, tried again, same thing, this time right out of idle she went to go then stalled and wouldn't start again.
So, i pulled apart the mechanical pump, cleaned it, checked it, pumping great up the steel line the carb, cleaned the filter at the top of that line, checked the line from the tank, all clean. It's pumping fuel in to the carb when pumping, can't see any when not, (but it's not running either, should i see fuel?)
I have seen a few things saying a shift interupter switch. Since they had the linkage out, would this be likely the problem. I have owned the boat since new, maybe 120 hrs, never had any problems like this before.

Any ideas or help would be much appreciated. I'm no wizz mechanic with this sort of thing, but can usually figure things out problem solving them, now i'm stumped.

thanks

 

[Alpheus]

Re: Mercruiser 4.3 only runs pumping throttle

Your idle circuit is clogged up.

http://forums.iboats.com/showthread.php?t=409253

 

[jtmarten]

Re: Mercruiser 4.3 only runs pumping throttle

If she idles fine, your idle circuit has fuel flow, but may still be partially plugged. Your main jets and/or main passages are plugged up. She runs when pumping the throttle because the accel pump is working and shooting fuel.
Time for a disassembly and cleaning/rebuild. I clean fuel passages with a small wire (like a garbage bag wire with the paper/platic covering stripped/burned off), carb cleaner, and compressed air.
Make sure the float level is set properly, too low of a fuel level can have the same effect.

 

[zbnutcase]

Re: Mercruiser 4.3 only runs pumping throttle

Never, ever use wire to clean carb parts!

 

[jtmarten]

Re: Mercruiser 4.3 only runs pumping throttle

If a passage is completely plugged, and carb cleaner/compressed air won't clear it, what is a better option? Soaking in carb cleaner for weeks?? Just toss the carb and replace it?? Niether is a better option.