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Motor Performance Problem

aufevermike

New member
"I too may have a carb problem

"I too may have a carb problem but have no idea what I might need to check. This is my first boat and am learning much. However this one has stumped me. I have a 24' Bayliner with the 454 Merc. It starts up just fine and travels all rmp ranges when in neutral. However, under load it doesn't want to accept anymore gas above 3500 rpms and want to cut out. At this 3500 rmp range it runs just fine which is just above half throttle and I can cruise all day but at only 18 mph and I know this boat can go faster. But like stated before if I try to give it mor gas it wants to stall out so I have to back off the throttle. Would anyone have any ideas for what I may need to look at?
Thank You,
Mike"
 
"I think your secondaries are

"I think your secondaries are clogged/stuck/etc. If you can slowly raise the RPM with no trouble, but it bogs if you punch it, thats a tell-tale sign of clogged and/or stuck secondaries. If it coughs or backfires, that means bad accelerator pump, but I've had the almost identical problem you've described and a good cleaning will usually smooth it out. If its a Quadrajet carb, you can spray carb cleaner (with engine running) directly down the secondary metering rod canals without having to remove anything except the flame arrestor."
 
"sounds like fuel starvation.

"sounds like fuel starvation. Things to check:
*fuel filters, both the main and carb filter
*make sure the seconsaries are opening on the carb (not likely to cause a stall condition though."
 
"I'm with David: obvious f

"I'm with David: obvious fuel starvation. Is there a fuel filter before the fuel pump, instead of water separator only? Placing a filter (fine filtration) before the pump can cause this problem--I had it happen to me. Only strainers (coarse filters) should be before a fuel pump.

One more thing to check: If that is a Quadrajet carb, then it has this tiny, dopey little filter at the carb. Get some crappy gas from a marina and that worse-than-nothing filter can plug, starving the motor. I strongly recommend throwing it out and installing a METAL in-line filter before the carb. NAPA sells a nice one that can be hose-clamped in place, using double hose clamps at the tubing end. Also, you need to use USCG approved hoses, not the automotive ones that come with the filter.

Jeff

PS: That thing should fly with a 454!"
 
Thank You Gentlemen. I spray c

Thank You Gentlemen. I spray cleaned the carb and noticed that when the plunger was pushed donw when just past half throttle it wasn't spraying fuel. On the quadrajet the left side would get fuel but the right wasn't. So I sprayed the rightside real good. There is this little tiny place just above where the fuel shoots out and it filled with fuel but would spray out. Si I shot it real well and it finnaly budged and now when it hits half throttle it kicks fuel into the carb....... That did the trick and now I know a little more about this carb..... Thanx again all!!!!!!

Mike
 
"Good to hear that, Mike, but

"Good to hear that, Mike, but you can't rebuild a carb from the outside. It needs to be boiled out and rebuilt to perform properly.

Does it wind out to 4,500 rpms now?

Jeff"
 
Thanx for the advise Jeff. I w

Thanx for the advise Jeff. I will have it taken out here next week and rebuilt. It winds out nicely and has more power than it needs. Get right up on step and I just back it off to save some of that precious fluid that keeps it running.

Mike
 
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