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Old 04-21-2017, 04:40 PM   #1
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Default 4.3 starting problem

Hi friends,

I've had my 1992 SCR2300 with 4.3 V6 mercruiser and thunderbolt ignition since last August.
She has always took her time to start, once running she is fine for the day but the first start up of the day always takes a good couple of minutes of turning over before she fires.
Upon starting her after the winter lay up I dropped a bit of fuel down the carbs and she fired up first turn of the key.
If I do this when I try and start her she fires right up every time but if I don't she spins for a couple of minutes.
Any ideas as obviously this is not the correct way to start.
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Old 04-21-2017, 05:14 PM   #2
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The carb is loosing fuel as it sets, time for a rebuild!
That would be my first place to start!
Had the same problem with my 4.3! But could not comfirm that was the problem as I lost that boat in a fire!
Good luck and let us know what cured the problem!
Don
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Old 04-21-2017, 05:23 PM   #3
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Thanks Donald,

Not what I wanted to hear but sounds bout right.
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Old 04-21-2017, 06:46 PM   #4
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What is your starting procedure before cranking it over? Are you priming the carbs correctly with the throttle before cranking?
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Old 04-21-2017, 06:49 PM   #5
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Hi Richard

I turn on the blower,
Put boat in neutral
Click ignition on to start fuel pump
Push throttle forward full on twice and leave at half on
Turn engine over
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Old 04-21-2017, 06:52 PM   #6
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Pushing the throttle forward all the way is what engages the primer in the carb. You could always try 5 times, but I would suggest replacing the rubber valve in the carb that is your primer. Also, make sure when you try to prime afterwards, the jets are shooting gas out. You can look down into the carb when testing this, but dont try to start it until you are clear of it.
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Old 04-21-2017, 10:26 PM   #7
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1992 has a mechanical fuel pump.

Turn on blower
Crank engine for 5 seconds twice.
Pump throttle two times
Crank engine.

The gas tends to evaporate in boat carbs. Cranking the engine refill the carb bowl. Pumping throttle primes engine and sets the choke.
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Old 04-24-2017, 02:27 PM   #8
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Totally agree about cranking engine over to engage the fuel pump to fill the carbs!! On my last boat I had the fuel pump wired into the ignition so when I put the key it, I turn it once and I would push it in, which engages the fuel pump with turning the engine over. Then I would prime using the throttle and the turn the key one more click fir the starter.
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Old 04-24-2017, 03:03 PM   #9
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I thought it was an electrical fuel pump as when I turn he key once I can hear a hum in the engine bay?
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Old 04-24-2017, 03:36 PM   #10
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My fuel pump was electrical as well, but was only engaged when the engine was running. I believe that is a safety requirement so if the motor catches fire and stops running, no more fuel keeps getting dumped into it.
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Old 04-24-2017, 04:25 PM   #11
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Quote:
Originally Posted by Stevie.UK View Post
I thought it was an electrical fuel pump as when I turn he key once I can hear a hum in the engine bay?
May have a newer engine with an electric pump. 92' did not.

The electric pump with carb does not get power to the pump until key is in the cranking position. Once started a oil pressure switch provides power to the pump. This way if the engine stalls the oil pressure goes to zero and the switch opens removing power from the pump preventing overfilling the carb.

Either case try the starting method I mentioned.
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Old 04-24-2017, 05:41 PM   #12
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Ok Mike, not at the boat till the weekend so I will give it a go
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Old 04-28-2017, 06:37 PM   #13
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The fuel pump runs power from the oil pressure switch at port side of the engine check connections I would take them off clean them up and put back on I had same problem and was just needing the terminals clean
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Old 04-28-2017, 08:22 PM   #14
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Hey Mike

Went to the boat today and tried your routine, she started right up.
You are the man!
Thanks buddy
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Old 04-28-2017, 09:55 PM   #15
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Quote:
Originally Posted by Stevie.UK View Post
Hey Mike

Went to the boat today and tried your routine, she started right up.
You are the man!
Thanks buddy

Glad it worked for you.
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