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1979 trihull with 305 gm chevy engine

B

birdy916

Member
pardon my retardedness but i b

pardon my retardedness but i bought a bought the other day. it ran good. i took it out and accidently forgot to take off the airmuff. i wasnt really sure wat was wrong and i thought it was jus the old gas as it was choking but didnt die as i give it throttle. so i could only cruise around. i finally got it home and realized i still had the airmuff on but a little of it was slipped off so it was pulling in water but jus not a lot. i got it home and started it up again but it still seems to choke. do u guys think i screwed anything up?? the water temp still looks fine and all. would doing a tune up help?? like spark plugs? wat other things should i do or check? thank you for your help and suggestions.
 
"Start with the basics; points

"Start with the basics; points, plugs, cap, rotor and wires if needed. See if the choke is working. Adjust mixture. Is it electric choke or stovepipe choke? The plugs' color should be light tan. If black w/soot it is running too rich. Let us know what you find."
 
WELL I'VE CHECKED THE CAP

WELL I'VE CHECKED THE CAP AND ROTORS AND THEY LOOK GOOD BUT I CHANGED THE SPARK PLUG. IT STARTS UP FINE. IDLES UP AND DOWN. AS I GIVE IT GAS ON NEUTRAL IT'LL START CHOKING AND DIE. HOW DO I CHECK AND SEE IF ITS ELECTRIC CHOKE OR STOVEPIPE CHOKE?? THE MOTOR IS A MERCRUISER 898.
 
"If electric, the choke will h

"If electric, the choke will have a canister on the end of the shaft that looks like a small hockey puck standing on its edge. It should have a single purple wire feeding it.

The choke butterfly should be completely closed before starting assuming the engine is cold. Immediately upon starting it should open about 3/16".

The choke heater is powered whenever the key switch is on, via the engine harness purple wire. If the choke does not open fully within 2-3 minutes of startup, check for +12 volts at the purple lead to the choke heater. If present, and the housing is not warm, the heater element is bad. Replace.

When it stalls out on you check the choke butterfly. It should be completely open.

Rod"
 
"If it's the stovepipe cho

"If it's the stovepipe choke, there is a tube that runs from the choke to the manifold that draws exhaust heat to the choke coil. This tube will plug with crud and the manifold crossover exhaust will plug w/carbon and grime preventing heat to the choke.

Change it to an electric choke. What is the tag number on the carb.?"
 
If the choke is open and it st

If the choke is open and it stalls when you increase throttle; carb may need a new accellerator pump.
 
"WELL GUYS...AFTER FIDDLING AR

"WELL GUYS...AFTER FIDDLING AROUND WITH THE 2 SCREWS ON THE CARB. I GOT IT TO RUN NICE. BUT THEN IT WAS LOW ON GAS SO THEN IT DIED. NOW IT WONT START ANYMORE. ADDED 10 GALLONS OF FUEL. CRANK IT BUT IT WONT START. EVEN AFTER I PRIME IT AND POUR GAS INTO THE CARB. SO I STARTED TO CHECK AND SEE IF THERE ARE ANY SPARKS BUT LOOKS LIKE THERE ISNT. SO I STARTED CHECKING THE COIL AND THERE IS LITTLE VOLTAGE AT THE COIL. LIKE 3-5 VOLTS ONLY. SO I STARTED TRACING THE WIRES FROM THE IGNITION. SEEMS TO HAVE 12+ VOLTS WITH THE KEY ON BUT WEN IT GETS TO THIS PLUG OR WATEVER ON THIS PLATE ON TOP OF THE ENGINE THERE IS 12+ VOLTS AS WELL. BUT BETWEEN THAT PLATE/PLUG AND THE COIL THERE IS ONLY 3-5 VOLTS. AND THE WIRE IS HOT. WAT DO U GUYS THINK IS WRONG?? SHORT SOMEWHERE?? THE BOAT ALSO HAS A MERCRUISER ELECTRONIC TIMING/IGNITION BOX. DO U GUYS THINK THAT THING IS FRIED??
151093.jpg
151094.jpg
151095.jpg
"
 
The hot (normal) wire

The hot (normal) wire is a resister wire which drops the voltage to the coil to 5-6 volts. Try another coil wire. I'll email you the TB IV test procedures since it won't post as a jpeg file.
 
THANKS...I WILL TRY TO TEST TH

THANKS...I WILL TRY TO TEST THE TB LATER AND WILL GET BACK AT U GUYS WITH THE RESULTS AS WELL AS TRY A NEW COIL. DOES THE COIL MATTER MUCH SINCE I AM JUS TRYING BUT I HAVE A 1990 TOYOTA PICKUP WITH A 4CYL 22RE SITTING THERE AND I WANT TO TRY USING THAT COIL OR DO I HAVE TO USE A V8 COIL??
 
If you start substituting auto

If you start substituting auto parts in a marine environment you are asking for trouble.

Just my opinion.
Rod
 
WELL I'M NOT SUBSTITUTING.

WELL I'M NOT SUBSTITUTING...I'M JUS TESTING TO SEE IF MY COIL IS BAD OR NOT BEFORE I GOT OUT AND BUY ONE.
 
WELL MY BRO WENT OUT AND GOT A

WELL MY BRO WENT OUT AND GOT A NEW COIL AND NOW THERES 12VOLTS AT THE COIL BUT STILL WONT START. I BELIEVE ITS THE TB IV...DARN AND I WAS HOPING TO TAKE IT OUT THIS WEEKEND TOO..THIS SUCKS! LOLZ...WILL GET BACK TO U GUYS WEN I GET A NEW ONE.
 
WELL I GUESS I TALKED TO THIS

WELL I GUESS I TALKED TO THIS BOAT SHOP NEAR ME AND THEY QUOTED ME AROUND 400 FOR A NEW ONE...DOES THAT SOUND REASONABLE OR SHOULD I CHECK OTHER THINGS BEFORE I EVEN REPLACE THE IGNITION MODULE?? I MEAN..IT WAS WORKING FINE AT THE RIVER AND BEFORE..STARTED UP FINE JUS A FEW HOURS BEFORE IT COMPLETELY DIED...
 
"What were your test results?

"What were your test results? Did the optic sensor work? I sent you an email as just a suggestion for your perusal. Replace the O. sensor, cap and rotor if they have been on awhile. Those items become the weakest link in the ignition system and you don't want to kill a new module w/an old part."
 
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