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Merc 43LX 1997

S

seaview

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"Hi Guys. Great forum, Engine

"Hi Guys. Great forum, Engine revs ok not in gear, in gear only 2300rpm, then ignition off engine runs on. Any ideas on best place to start.
Many Thanks"
 
"Is it carb. or TBI? Have you

"Is it carb. or TBI? Have you gone thru the basics? Plugs, timing set? What has been done?"
 
"Thank you for the interest Gu

"Thank you for the interest Guy and Bondo, the operator lost the gas filler cap last year, did not replace it, then had water in the fuel tank, that was pumped out, but then had a leaking manifold, had to replace a piston, all the bearings, new manifolds and risers. Boat then launched and no power under load yesterday Sunday and runs on when ignition turned off. Pulled fuel filter and found 3/4 full of water, replaced filter and engine starts and runs much better, no spitting back through double Weber carb, but still runs on fot 10-12 secs. Checked fuel pipe going into carb for clogged gauze filter, but no filter fitted. Suspect contaminated carb. Tried timing light but no trim plate fitted to crankshaft pulley area. Retarded timing to bring idle rpm back from 1000 to 650 but it still runs on. Will a carb service solve both power and run on problems? Thank you for your time"
 
"You do not retard timing to l

"You do not retard timing to lower the idle speed, Nominal idle speed is 650-700 or so in gear(in the water).Set the timing to spec and use the idle speed screw to lower the idle."
 
"Hello BT, Would love to set t

"Hello BT, Would love to set timing to spec but no evidence of any markings to go on in the crank pulley area"
 
"Guess we use the "Shade T

"Guess we use the "Shade Tree Method"
USE AT YOUR OWN RISK
1 This is for standard ign. systems that do not have to set the dist. in "Base Timing Mode"
start the motor and retard timing untill it starts to miss ,mark this point.
Advance timing untill it begins to run rough.
mark that point. Split the difference and test run CAREFULLY listening for any pinging.Retard as necessary.

2 Pull spark plugs,Get #1 on TDC compression stroke.Verify using a wood dowel, etc.(unbreakable).rotate crank back and forth to insure TDC.You should see a line in the crankpully .devise a pointer system.About 3/8ths of an inch before this line should be 8deg.BTDC"
 
"Mr BT, You are remarkable, th

"Mr BT, You are remarkable, that is brilliant info. Thank you very much. Do you think a carb service/clean will solve our loss of power issue, or should we be replacing dist cap and leads as well"
 
"you need to start with some b

"you need to start with some basics
Compression test
complete tune up
fuel filters
carb inspection and cleaning/rebuild
fuel delivery issue:fuel pump getting weak, anti-syphon sticking partially closed, vent line restricted,tank pick-up sock/screen."
 
"Tom...

Another old racers

"Tom...

Another old racers trick for setting timing without a timing light is to use a vacuum gauge. Connect the vacuum gauge (rubber hose) on to a vacuum port below the throttle plates of the carb. This will give you a reading of manifold vacuum. Start up the engine and advance the dist. until you get the highest vacuum reading that the the engine will give. When the highest reading is obtained, back off the dist. by one inch of Hg on the vacuum gauge. Tighten down the dist. and drive it. Listen for ping. If it pings, back it off one more inch on the gauge. If no ping, you're good to go.

Wrench"
 
Carb. rebuild may be in order.

Carb. rebuild may be in order. Floats out of adj. and leaking gaskets are dumping raw fuel to cause run-on or dieseling. Wrong timing not helping.
 
"Ayuh,.....

It Sounds like

"Ayuh,.....

It Sounds like the Carb needs a Rebuild, which may possibly fix Both Issues....
And,....
A 97 should have the Plastic Timing Cover, which has it's timing scale imbossed On it,....There's No Tab sticking out of it...
Look Closer....."
 
"Really appreciate all your ad

"Really appreciate all your advice, really great information. Thank you all very much. Hope to have a look at that carb tomorrow."
 
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