Please help! Got myself a used '91 Wellcraft 21.5' Eclipse bowrider/mercruiser sterndrive. The dates of the major components are unknown. The 305 cu in. is supposedly fairly recent, with an Alpha One Gen I drive. The guy who fitted the engine opted for a rebuilt Quadrajet 4MV with a Jms 1389-p4389 fuel pump.( Carter equivalent P4389).
My problem is a continuing fuel leak out of the throttle rod area on both sides.
Fuel is seeping and dripping down onto the manifold where the rods exit the throttle plate casting.
The leakage rate is significant and puddles up on the manifold. This even occurs before ignition, and after the engine is shut off. The intake seems full of fuel, and flooded. I usually abort the "start sequence" as I don't want to end up as a fireball, flying through the air into my neighbors yard. I have rebuild the carb twice, check and rechecked the float level, and even lowered it greater than the recommended .25" . The carb # is 17059280. I replaced the float with a brass one, as well. Nothing seems to help. Forgot to mention, the previous owner epoxy weld those "leaky bottom plugs" as is generally recommended.
I have narrowed this saga down to three possibilities, that I am hoping you experienced quadrajet folks can help with.
1) Throttle body main rod bushings. From what I can tell there is play in this area, however some other threads indicate that this should not be source of fuel leakage in any case, just may cause vacuum leaks, if the rest of the carb is functioning properly. What do you guys think?
2) Electric fuel pump over-pressure situation: Inlet delivery pressure specification for this pump is a max of 5.75 psi. Can this over power the new needle valve and seat?
Should I put a regulator of some sort in-line?
3) Float still mis-adjusted:. This one I worked on diligently,and I think it looks fine. But I suppose it could still be contributing factor if #1 and #2 from above list, are eliminated.
4) Other thoughts, recommendations?
Thanks very much. Getting ready to consider letting someone else rebuild this unit, or buying a rebuild carb to replace this one. Your kind assistance is really appreciated!
My problem is a continuing fuel leak out of the throttle rod area on both sides.
Fuel is seeping and dripping down onto the manifold where the rods exit the throttle plate casting.
The leakage rate is significant and puddles up on the manifold. This even occurs before ignition, and after the engine is shut off. The intake seems full of fuel, and flooded. I usually abort the "start sequence" as I don't want to end up as a fireball, flying through the air into my neighbors yard. I have rebuild the carb twice, check and rechecked the float level, and even lowered it greater than the recommended .25" . The carb # is 17059280. I replaced the float with a brass one, as well. Nothing seems to help. Forgot to mention, the previous owner epoxy weld those "leaky bottom plugs" as is generally recommended.
I have narrowed this saga down to three possibilities, that I am hoping you experienced quadrajet folks can help with.
1) Throttle body main rod bushings. From what I can tell there is play in this area, however some other threads indicate that this should not be source of fuel leakage in any case, just may cause vacuum leaks, if the rest of the carb is functioning properly. What do you guys think?
2) Electric fuel pump over-pressure situation: Inlet delivery pressure specification for this pump is a max of 5.75 psi. Can this over power the new needle valve and seat?
Should I put a regulator of some sort in-line?
3) Float still mis-adjusted:. This one I worked on diligently,and I think it looks fine. But I suppose it could still be contributing factor if #1 and #2 from above list, are eliminated.
4) Other thoughts, recommendations?
Thanks very much. Getting ready to consider letting someone else rebuild this unit, or buying a rebuild carb to replace this one. Your kind assistance is really appreciated!
