After years passing by of not working on carbs, I rebuilt the carb on my 1997 4.3L Mercruiser engine last fall and ran it up and down the lake once. It appeared to work well. Last week I took the boat out for the first time of 2013. It started and ran well. If it was shut off for a minute or two, it would fire right up. After being shut off for more than 30 minutes, it is difficult to start. No fuel smell and it doesn't look flooded when I remove the air filter / spark arrestor. I have yet to try to fix it, but was thinking float level, mixture or maybe even the fuel pump (getting weak causing vapor lock, though the yellow tube does not smell like gas). I was wondering if anyone else has had this problem or if anyone has any suggestions.
Carb question 4.3L Mercruiser
- Thread starter Michael_P
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I remember this problem. For me, tracked it down to something with oil pressure sender, think thats used to turn the fuel pump on. When its warm you may have low oil pressure, something like that. Changed the oil and filter recently, right?
What kind of carb is it?
What kind of fuel pump, mechanical or electric.
Heat soak?? just a thought in a I/O engine compartment. 16 year old coils. Sorry I really like to blame heat soak for stuff.
No gas smell? do you have the gas turned on?.,,
I had the same problem with an Edelbrock carb on my Bayliner with a 355. Talked with some techs from Edelbrock, and they said it was the fuel evaporating from the bowl due to the nature of a marine carb. So when the fuel evaporates from the bowl, the fuel pump has to fill it back up before it will start. Solution was to move to an electric fuel pump, or put a phenolic spacer under the card to help keep it cooler.
I bought a TKS retrofit kit from eBay for $400. It came with thermostat housing, all wires sensors and carb. Problem solved. Best of all, no more choke. Its almost like starting an FI engine (but not quite) I have heard mixed reviews about TKS carbs, but I took the chance and so far, it works like a charm. When the ignition is shut off, the float bowl vent closes via a solenoid.
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