Hard Start After Long Periods of Off-Time.

[Aaron Anderson]

I have a 2006 Kia Optima EX V6.
Lately, my vehicle has been giving me a hard, or slow, start in the mornings. (after being off for like 12 hours)
It turns over faithfully ever time (so far), but this problem continually occurs. It doesn’t occur if the vehicle has only been off for around 9 hours because it turns over right away when I get out of work.

I went ahead and replaced my spark plugs to see if it would help. (they needed to be replaced anyway)
Problem appeared to stop for a day or two and then came back.
I’ve had the battery, charger, starter, and alternator tested with positive results.
I left the vehicle overnight at a local mechanic to test the fuel pump pressure (perhaps it wasn’t off long enough) with positive results.
Just to be on the safe side, I replaced my gas cap with a brand new one.

Please note that I was not raised around working on cars and have very limited knowledge regarding them…
However, it appears to me to be a loss of fuel pressure. (turning the key to the “on” position a few times helps the problem, but doesn’t make it go away)
I don’t want to just replace things based on shooting in the dark, because I’d rather not burn through my money.
On the same note, I’d rather not get bent over by a mechanic that may change me a bunch of money to find inconclusive results.

To give you an explanation of my engine knowledge:
I understand the combustion cycle, from engineering school, but absolutely do not know my way around an actual engine. (thank you, modern education system for not teaching me useful life skills)

I greatly appreciate any insight and would be happy to clarify any details to the best of my ability.

(I’ve thought about replacing the fuel pump or the fuel pump relay, but I don’t want to make hasty decisions)

Thanks in advance!

Topic

[Aaron Anderson]

Update:
After reading through the Haynes manual, looks like I’ll need to hook up a fuel pressure gauge in-line with the fuel rail. In order to test adequately, I’ll need to monitor it over a couple of hours, at least. So this will likely be a weekend task.

Does anyone have a pressure gauge kit they would recommend for an in-line test?

Also, the Haynes manual doesn’t advise any information on the check valve. Is that common?

[Author]

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