Not feeling lucky enough that it's not going to get worse and leave me up a creek. Pump is ordered and on its way. I'll be swapping it asap unless my recent CEL (P0442) changes anything (see my last post).

 

Yes, that could change things. That indicates a "small" leak in the EVAP system, somewhere between the gas tank and the EVAP purge valve (under the hood).

 

Another place your fuel pressure can be lost is through a leaking fuel injector. I got in the habit of turning the key to on for a few seconds before turning it to start when I had the crappy leaking fuel lines. I still do it.

 

I'm planning on dropping the tank tomorrow, but I wanted to ask one last question before committing.

The problem is definitely affected by ambient temperature. The colder it is, the bigger the delay in crank to start time and more pronounced the chugging/rough idle is (from rough enough to kill the engine when below freezing up to no noticable issue when warm outside). However, it was ~75-80 degrees today, and the car started much more quickly (still a touch longer than normal but just barely) with no abnormal idle.

Would a fuel pump or some part of the fuel pump assembly be affected by ambient temperature like this? I tried searching but couldn't really find anything regarding ambient temperature and fuel pump/fuel pump assembly operation.

Thanks

 

My 2007 LS , the fuel pressure regulator slowly gave up, longer starts, rough idle, I replaced the whole pump assembly, problem solved. I did notice a difference in colder weather like you, so I drove to empty the tank , and changed the fuel pump, I wasn’t going to gamble with complete pump failure away from home or with a full tank.
Check your fuel lines under the insulation where the lines run close to the exhaust, that’s where my vapour line had corrosion.

 

Here's an update on the situation. I'll keep it as brief as possible, but I want to provide as many details as I can to help diagnose/fix the issue.

I changed the fuel pump yesterday. It went very well overall (the nice weather really helped) and was not nearly as bad as I was expecting. The hardest part was wiggling the tank out and re-tightening the lock ring (I was finally able to do it using two channel lock pliers across from each other).

Unfortunately, the problem remains. I went to start the car this morning, and it was delayed. It didn't chug/idle roughly, but the weather is warmer outside.

To recap the problem and work done so far:

• After the car is sitting for ~3.5-4 or more hours, it takes longer from cranking to starting. If it's sitting less than that amount of time it seems to start fine.

• The problem initially started last Fall. I then discovered a rusted/leaking fuel line near the L back wheel. The bad section was replaced with rubber hosing (rated for pressure/fuel), and the problem resolved. It returned about a month ago with the same signs. I assumed that either my patch job was failing or further rusting/leaking was developing. I replaced both fuel lines, but the problem remained.

• The ambient temperature impacts how long of a delay there is as well as whether and how long it idles roughly (colder = more delayed, long rough idle; warm = shorter delay, no rough idle). When it occurs, the rough idle lasts for anywhere from 3-20 seconds (longer when colder) and then smooths out. In all of the time the issue has been present, the car has only died once during the rough idle.

• After getting the car started through the delay, I can immediately turn off the car and restart it with no delay or problems (doesn't matter if car was running for 1 second or 1 hour, it will immediately start once turned off and back on).

• Once the car is running, it seems to have no issues.

• The check engine light came on at the end of last week and gave a P0442 code (small evap leak). I couldn't find an obvious cause, so last weekend I swapped out the EVAP vent and purge valves to be safe (yes, it was probably unnecessary/overkill, but they're cheap/easy to replace; I was tired of messing around and figured it was worth trying before dropping the tank/replacing the fuel pump). I cleared the code, and it hasn't returned so far, so we'll see how that goes.

• There is no evidence of a fuel leak along the fuel lines from what I can tell (based on visual inspection, no gas smell, and no findings when using a combustible gas detector).

• Fuel pressure (measured at the rail) is within specifications as listed in the Hayne's repair manual.

Something that I recently noticed (a few days now, may have started longer ago) is a short burst of sound when I turn off the engine. It sounds like a hiss or a burst of air escaping somewhere. When listening with my head out the driver window, it seems to be from near the front of the engine (area of the air intake "wooly worm" and air filter housing. I didn't have a helper when I was looking into the noise today, but I'm planning on having someone else start/stop the engine later tonight so I can try to more specifically pin point where the sound is coming from.

I've attached an audio clip of the sound to help assess. You'll hear the sound shortly after the engine stops. I've also attached an audio clip of the delayed start itself (in case someone hears something that I'm not).

I did check the air filter housing, air filter, wooly worm, and spark plugs today. Everything seems fine except one of my coils (cylinder #1-furthest on the passenger side) had a very small smudge of brown gunk on the outside rubber/on the wall of the spark plug well. That spark plug appeared normal with no evidence of anything on the electrodes, threads, or ceramic insulator. The spark plug well itself also appeared otherwise normal except for the small smudge on the one side of the wall. All four spark plugs seemed normal with normal gapping and electrode appearance.

So, any other thoughts?

Thanks!

 

There are 2 "fuel lines" 1 actually carries gasoline, the other carries vapor to the EVAP purge valve. The vapor line can corrode, since it carries vapor it does not show sign of liquid leaking from it. It would however, cause a vacuum leak (P0442, which is tested AFTER shutdown).

It is a sealed system. Part of what holds fuel in the fuel rail is the vapor pressure in the fuel tank. If there is a hole in the vapor line there is no pressure in the tank.

 

I replaced both the vapor and fuel lines, so I know they're not corroded. I went through and checked all of the connectors, and they seem tight. I guess the next step for that would be to smoke check the vapor line to see if/where there's a leak? Any other diagnostics I can or should do?

Any thoughts on the sound when the engine shuts off?

 

Sorry, I can't hear anything but keys clunking.

I guess it could be the EVAP vent valve, or the O-ring seal.

 

O ring of the vent valve or another O ring?

Also, apart from potentially creating a vacuum leak, would an EVAP leak lead to the slow start, or are the issues separate?