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502 hard to start when cold


502 hard to start when cold

Old 04-28-2013, 08:30 PM
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Location: Lexington Ky
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Today i was able to check the fuel pressure. When i first turn the key on the pressure goes to 45 lbs then drops and stays at 37 to 38 lbs. When i get it started the pressure holds at 40 lbs. I think these numbers are about right.
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Old 07-12-2013, 03:27 PM
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Hey csharpo,

Did you ever have any luck tracking this down? I have a 97 with a 502 EFI and have the exact same issue. When i start from cold it takes quite a few seconds of cranking before it finally hits, once it does it runs like a top, no idle issues no top end issues. If i turn it off for a few hours at a restaurant or in cove, it fires right up no problem when i go to restart it. After it sits over night it's hard to start again. Changed Cap, Rotor, Plugs, and Wires last year, and I always put a new water seperator on every year, along with Ethanol free fuel. It's been doing this for well over a year now.

Guys what is the water temp switch/sensor? I tried to search google by these phrases and did not come up with much of anything i could use. Does it have a Mercury proper name?

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Old 07-13-2013, 07:45 AM
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Having the exact same problem. I had the injectors cleaned and replaced the ect sensor and problem is still there. This is on an efi motor but find giving it a little throttle helps the amount of time cranking. Been talking about this with my mechanic he thinks the fuel is going back to the tank because I don't have a fuel/water separator or anti siphon valve...could this be my problem and possibly the others. I'm not sure if mine counts as the same as the others since my motor isn't stock and has a blower? But it does have the exact same symptoms as the others...cold start problem after sitting over night-needs to be cranked a long time to get started, after started it runs perfect and refires if not sitting over night...a few hours is fine.
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