[Solved] 2004 Gen5 Camry 2.4L long crank when warm

[firstsecondlast]

UPDATE 1/11/13:

all these hassle was simply caused by a dirty fuel filter only. Problem solved this morning by only replacing with a new fuel filter.

This is an uncommon problem. my car is currently 115k KM, regularly serviced.

when cold, in the morning, it starts fine, normal with one quick crank. Drove it around, engine warms up, went to woolies to get some stuff. Then when it's warm, engine only starts with longer cranking. sometimes only starts on the second crank attempt.

the cranking is normal as when its cold. Just that the engine fires up with longer crank when warm. google around doesn't show much information. some talks about a possible going-to-be-faulty Open Circuit Relay (fuel pump relay), fuel pump wearing out, low fuel pressure, faulty spark plugs, carbon built up in combustion chamber.

I figured out it couldnt be fuel pump faulty or low fuel pressure or faulty spark plugs- engine doesnt hesitate at all during normal driving and hard acceleration. idling is normal and smooth.

i havent check on the plugs. as for carbon built up, might need to try putting some injector cleaner and see if there's improvement.

Edited November 2, 2013 by firstsecondlast

[firstsecondlast]

i am still googling around and seems to point to a possible faulty fuel pressure regulator. For its mileage i think is still too new to happen. but it doesnt make sense, if it can't hold pressure then car should take long to crank up in the cold as well.

i tried putting in fuel injector cleaner, ran that half tank up. and now just filled up RON98. see if there's any improvement after few hundred km.

[firstsecondlast]

today i tried cleaning the MAF sensor. it was found to be quite dirty with dirt stuck covering entirely half of the red bulb. spray it and the hot wires with CRC's MAF sensor cleaner. so far the warm engine hard start remain unchanged.

[mbruce]

I had a problem with the same symptoms a few years ago, turned out to be a fuel pressure issue, caused by an incorrectly seated / pinched O ring in the filter. Given your mileage the filter should have been done about 15.000kms ago, so its possible, since it was about that mileage before mine played up too.

Edited August 17, 2013 by mbruce

[firstsecondlast]

Hi mbruce..

that's what i least wanted haha. means i have to take out the fuel pump assembly. do you know exactly which oring was causing it? My guess would be the fuel pressure regulator oring?

[mbruce]

Nah, sorry i don't know which O ring it was exactly.

[firstsecondlast]

Today checked my sensors. Coolant temp sensor, camshaft position sensor and a/f sensor. all are within spec except for a/f sensor. it requires 1.8 - 3.4 ohm but i measured 13 ohm. i need to reconfirm this reading again.

[firstsecondlast]

Read in some forum people had same issue and was resolved by replacing new battery. I changed a new one too but no resolution still.

Now I'm wondering if my measured air fuel sensor resistance of 13ohm, is in fact an oxygen sensor.. not sure previous owner replaced it before and mistakenly put an oxygen sensor in instead of air fuel sensor.

13ohm seems to be reading of an oxygen sensor at 20c

[coolstar]

I am facing exactly the same problem.

firstsecondlast did you manage to solve this issue, if so please provide details.

[firstsecondlast]

Not yet solved. I am now waiting for a new air fuel ratio sensor to arrive. I speak to few person and at this moment looks like it may be the cause. Although there's no MIL, but I measured it to be 13ohm whereas spec requires 0.4 to 1.8ohm.

After I install the new denso 234-9010 sensor I'll update again.

[coolstar]

Thanks. Where can I get the sensor specifications. I also thought to check the senors before going into the fuel filter/ pump/ regulator.

I was also wondering why it was not showing MIL with wrong sensor.

Not yet solved. I am now waiting for a new air fuel ratio sensor to arrive. I speak to few person and at this moment looks like it may be the cause. Although there's no MIL, but I measured it to be 13ohm whereas spec requires 0.4 to 1.8ohm.

After I install the new denso 234-9010 sensor I'll update again.

[firstsecondlast]

sorry it should be 1.8 - 3.4ohm at 20 degree C.

[firstsecondlast]

Just replaced with new AF sensor i ordered from Denso USA. part no. 234-9010. connector has slightly different groove, therefore had to swap out the connector.

after first drive around just now, the problem is still there. next would have to try replacing fuel pressure regulator o-ring,.

[firstsecondlast]

problem solved with just a fuel filter change this morning!!!

[bstaver]

Just wanted to thank you for the post, had the same exact problem, tried a few things to no avail, came across this post, changed the pump and now no more problem. Also my fuel efficiency went up considerably.