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No power over 3500 revs

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finneran1

New member
"I have a Maxium 23 sc, which

"I have a Maxium 23 sc, which currently has a 5.7 LX engine 1998, boat is great until it reachs 3,500 revs as it dies, also when the boat is standing and the throttle is pushed forward fully fast, i have the same problem. But when the boat is neutral the boat can be revved up to 5,500 revs and sounds sweet as a nut.

Any suggestions

Steve"
 
""But when the boat is neu

""But when the boat is neutral the boat can be revved up to 5,500 revs..."

DON'T; there is virtually no load on the engine so limit neutral to 1500 RPMs.

"...boat is great until it reachs 3,500 revs as it dies..."

Try replacing all of the fuel filters. Did you check for spark when it dies?

"...when the boat is standing and the throttle is pushed forward fully fast, i have the same problem."

That issue sounds like it needs an accellerator pump."
 
EFI or which carburetor? Deta

EFI or which carburetor? Details please.

"Try replacing all of the fuel filters."???
 
"Replace all of the fuel filte

"Replace all of the fuel filters first. Clean flame arrestor. Weber carb; 2 or 4 BBL? Replace accellerator pump or rebuild carb. If 4 BBL then make sure secondaries are opening up. When was the last time the engine was tuned up w/new plugs, etc.? Is the hull clean and slick w/o sea growth?"
 
I have a 350 with a Weber 4bbl

I have a 350 with a Weber 4bbl carb. I've been working on mine for 4 yrs. I went down to a 15 pitch prop and now get 3600 rpms at 12 MPH @ WOT.
 
is the acellerater pump the fu

is the acellerater pump the fuel pump . the eng was tuned up 2 weeks ago looking for this plob .the hull is clean there has been new sparks and plugs installed is this an common plob with this eng as i am going around in circles
 
"is the acellerater pump t

"is the acellerater pump the fuel pump"

No; it's part of the carburetor that pumps an extra squirt of fuel when the throttle is shoved forward. The fuel pump sends fuel to the carburetor bowl.
 
"same problem. New plugs, wire

"same problem. New plugs, wires, distributor sensor, flappers for exhaust, rebuilt outdrive, proper prop, new fuel pump, new water fuel separator, twice rebuilt carb, still goes no place. Just 3500 rpm max and sits in water going slowly. Was going to now buy module??? SHOULD I"
 
If you do and it solves the pr

If you do and it solves the problem then report your success so several others can get their boats running again.
 
"Bruce Hubbard, I replaced eve

"Bruce Hubbard, I replaced everything you have and I did the module (got it off another boat) and it cured my timing advance problems but that was all. The darn modules cost 300.00 a peice where I went to buy one, I said no way! It didn't help mine attain the proper rpms. Bob"
 
"I think you are running out o

"I think you are running out of fuel due to restriction in the suction side of the fuel pump. could be ne where between pump and tank. set up a temp fuel tank from out board tank or gravity feed straight into carby and take for another run. The other thing about reving may be accel pump within carby as Guy suggested, but that means two seperate problems. My money is with fuel supply restriction. TM."
 
"I've seen the top seconda

"I've seen the top secondary plates not open due to corrosion. They open as more air is drawn by them. They need to move freely.

BUT

Before running the boat again, check if the lower secondary plates are opening or not, if the engine is cold, they shouldn't,

then warm the engine, noting the choke plate opening, then check again, the plates should open (check with the engine off)

there is a choke mechanism that if not working correctly will block them and keep the lower plates from opening, preventing top speed.

If the choke isn't set properly, and the engine warmed properly, it will dies, also when the boat is standing and the throttle is pushed forward fully fast,

However as Guy mentioned there is the Accelerator Pump in the Carb that when you move the throttle lever it squirts a little extra fuel into the carb. TOO MUCH or TOO LITTLE and then engine will DIE out, or Bog down.

Has the carb ever been rebuilt by an experience person?

Then as Mark said it could be a fuel restriction previous the carb, and there is a way to check that, but it's a little more on the dangerous side."
 
"Of course another cause of la

"Of course another cause of lack of power is bad fuel, even with a fuel water separator."
 
"Had a similar problem. Would

"Had a similar problem. Would rev to 2800 rpm and go no further. I did not bog, just no more speed with about 1/3 throttle left. Turned out to be a loose and damaged plug wire.It sounds like some of you have replaced the plugs but not the wires. Just thought I'd throw in an idea. You have all been very helpful to me in the past."
 
Still problem. Even changed to

Still problem. Even changed to new Module. Boat will only get to 3400 rpm under max power on water. Trims good. OUTDRIVE IN PERFECT POSITION. WILL CHANGE PITCH ON PROP. ANOTHER MEMBER SAID CHANGE PLUG WIRES? I AM LOST. ONLY OTHER THING IS (AS I HAVE SEEN BEFORE IN MICHIGAN AND FLORIDA) IS THE HULL MAYBE FILLED WITH WATER IN BETWEEN FIBERGLASS.

LOST?
 
get a can of choke cleaner kee

get a can of choke cleaner keep fire ex handy take off flame aresta get boat up to 3500 if it wont go any more spray a little choke spray in carb if rpms go up slightly its a fuel prob take off gas line to carb get a jar about 8oz you may have to put a piece of hose on the line start eng should fill jar half way in about 20secs if not mabe bad pump disconect line to pump use and aux gas tank and try again if good its the line or tank ethanol i fuel has been eating rubber lines also ck anti syphon valve should in the tank fitting if it has one if the jar fills half way okthen its the carb hope this helps lew ps can put a fuel pump gague on lint carbshould be 4 to 8 pounds cant think of any thing eles good luck
 
"After all I did I decided to

"After all I did I decided to check wires that looked new. They were bad! Put new plus in, new marine wires, retimed and it is now at 4000 rpm?
What a joke. So as I always told customers before I do anything new plugs and wires. Did not do that for customer said wires good. Don't trust your customers statements."
 
"I HAVE A 1997 BAJA 350 V=8 DI

"I HAVE A 1997 BAJA 350 V=8 DID THE SAME THING WIRES,PLUGS,NEW CARB STILL THE SAME THING CANT GET IT OVER 1500RPMS BUT IN NEUTRAL SOUND LIKE A ROCKET!!!"
 
"Here is where I am. We are go

"Here is where I am. We are going to tear down my engine this week if I can find an upper end gasket kit and a starter soleniod along the way. I spoke to 5 different mechanics and what all said involves taking the heads off. Two say a valve full of carbon that is leaking and one says a burnt valve. The other two say a torn head gasket. Apparently the head gasket is torn between a water hole and oil hole in the head. The oil is then leaking into the water, going out the exhaust manifold and out through the hub. Since the oil is so much hotter than the water it is causing the over heating condition when passing through the exhaust manifold. I'll post our results Thurs. or Fri. in hopes it may help some of you men. Thanks again, Bob"
 
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