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Hard to start when warm

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donmega

Member
"hi so I have this not big but

"hi so I have this not big but annoying problem that when my 4.3 mercruiser (carbureted) is warm, and I go for a good run (tubing, skiing etc.) i stop and shut down the engine to let the person back on, then when I go to start again it cranks and cranks and I really have to pump the throttle to get it going... shouldnt it re start when warm just in neutral? It does start every time and runs perfect... what could it be?"
 
I don't know the answer bu

I don't know the answer but let me know what you find out because I have the same problem with my 165 L6. And it's a bran new completely over-hauled engine.
 
Hi
If your using E10 gasoline

Hi
If your using E10 gasoline it could be vapor locking. Alcohol has a lower flash point than gasoline and that makes it more prone to vapor lock.


Jon Allen
 
the E10 gas... which gas stati

the E10 gas... which gas stations have it?... the last gas type I put in was at ESSO... what exactly is vapor locking?
 
"You also might need a carbure

"You also might need a carburetor kit. If the needle valve leaks fuel into the carburetor when it's hot, it floods. And you have to open the throttle in order to make the air/fuel mixture right. Or you can just pump it and it will eventually start. When it does this again, try just opening the throttle a lot, but don't pump it. If it starts after about 2-3 seconds of cranking, then this is probably your problem."
 
"matt;
If it is flooded, you

"matt;
If it is flooded, you will get a lot of smoke for a few seconds right after startup. Do you get this? If not, you likely have vapor locking. That is when the gas in the line that goes over the top of the engine to the carb soaks up heat from the engine when you shut down, and forms bubbles. These bubbles prevent fuel flow to the carb until the lines can clear and flow only gas again. If you have a lot of hours on the engine, your electric fuel pump may be getting weak. Is your engine getting enough cooling water flow so it is not overheating? An overheated engine really compounds a vapor lock situation.
Rod"
 
"Rod: there is a little bit o

"Rod: there is a little bit of smoke after hard starting, but just a puff for a second or two, but its not very thick... ive never had overheating problems... always stays right around 150... theres 550 hrs on the motor"
 
"arn't carbureted engines

"arn't carbureted engines fun???
when you power down do you let the engine run for a few seconds or just shut it off? i used to have the same problem... go from half/full throttle to dead stop and shut off the motor, but as the engine got older i had to wait for about 5-10 seconds untill i shut it off to let the extra gas burn off or it would flood."
 
matt;
The puff of smoke indic

matt;
The puff of smoke indicates to me that it is flooding or leaking gas into the intake manifold on shutdown. You likely need to rebuild the carb or get a rebuilt carb to cure this problem. There have been a couple of other topics just in the last few days about carb flooding; you should check them for some further ideas.
Rod
 
The previous topic was titled

The previous topic was titled "Hard Starting When Warm" and the last post was June 1.
That is the most likely reason for your hard starting issue I think.
My last 4.3 w/4 bbl Webber started just fine after being shutdown. It would crank for a few seconds then catch easily with no trace of smoke at all.
Rod
 
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