Intermittent Starting Isssue
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Pit Crew
Joined: Jul 2010
Posts: 126
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From: Hawaii
Intermittent Starting Isssue
Hello,
I have a 99 RX300 with about 250,000 miles on it. My wife recently took the car on a trip longer than I typically like to drive it. The drive was about 90 miles each way and goes from sea level, to 6600 ft,, and back down to sea level. I took the car shortly after she returned and noticed it didn't start the first time. I always think "maybe I just didn't hold the key long enough" and so I attempted to start the car again. It started up and drove fine.
Today it was stumbling a bit when heading into town and then later in the day it didn't start again. It took a few tries but I realized that when I pumped the gas a bit on startup it would idle and I could drive home. I'm not getting any codes and the only thing I notice is that there seems to be a bumping sound that seems like it's coming from around where the air filter/mass flow sensor is located.
The fact that it requires me to pump the gas to start it up, should I direct my efforts toward the fuel filter/pump/pressure? Because I'm not getting any codes I'm a bit confused where to start.
Thanks
I have a 99 RX300 with about 250,000 miles on it. My wife recently took the car on a trip longer than I typically like to drive it. The drive was about 90 miles each way and goes from sea level, to 6600 ft,, and back down to sea level. I took the car shortly after she returned and noticed it didn't start the first time. I always think "maybe I just didn't hold the key long enough" and so I attempted to start the car again. It started up and drove fine.
Today it was stumbling a bit when heading into town and then later in the day it didn't start again. It took a few tries but I realized that when I pumped the gas a bit on startup it would idle and I could drive home. I'm not getting any codes and the only thing I notice is that there seems to be a bumping sound that seems like it's coming from around where the air filter/mass flow sensor is located.
The fact that it requires me to pump the gas to start it up, should I direct my efforts toward the fuel filter/pump/pressure? Because I'm not getting any codes I'm a bit confused where to start.
Thanks
CL Community Team
Joined: Apr 2001
Posts: 16,557
Likes: 1,385
From: Austin, TX
RX does not have a carburetor where pumping the gas pedal would inject fuel.
Next time just hold the pedal 1/4 or 1/3 down and try to start. If it starts and when you let off the pedal it stumbles then the culprit is most likely the IACV. Do a search on IACV and you will find lot of detailed information.
You may also like to look at the air cleaner and MAF [use appropriate cleaner for RX MAF]. You will find plenty to information on cleaning the MAF as well.
You can have the pressure on fuel line tested, but you would need specifications as well as test set up.
I would not suggest start changing out things on hunch. Instead gather evidence.
Salim
PS: Failing to hold idle/or sustain idle is slightly different from failing to start.
Next time just hold the pedal 1/4 or 1/3 down and try to start. If it starts and when you let off the pedal it stumbles then the culprit is most likely the IACV. Do a search on IACV and you will find lot of detailed information.
You may also like to look at the air cleaner and MAF [use appropriate cleaner for RX MAF]. You will find plenty to information on cleaning the MAF as well.
You can have the pressure on fuel line tested, but you would need specifications as well as test set up.
I would not suggest start changing out things on hunch. Instead gather evidence.
Salim
PS: Failing to hold idle/or sustain idle is slightly different from failing to start.
Thread Starter
Pit Crew
Joined: Jul 2010
Posts: 126
Likes: 3
From: Hawaii
Thank you saimshah. That is the direction my research began taking me last night as well. I'll start with cleaning the MAF (using MAF cleaner) and IACV (using throttle body cleaner). I'll also be sure the clean the throttle body to make sure it's not sticking. Is there a schrader valve on the fuel rail that would allow for a fuel pressure tester to be screwed on?
CL Community Team
Joined: Apr 2001
Posts: 16,557
Likes: 1,385
From: Austin, TX
There is no schrader valve in line with the fuel line. You can check for standing pressure by disconnecting ... make sure everything is cold and no open flame near ...dangerous as fuel comes out under pressure. Right procedure is to test for the pressure [static] and flow. You can hear the fuel pump prime up, but you need quiet surroundings.
Start with the air and then move to gasoline afterwards. Don't be too tempted to clean the throttle body just yet. Stay on the IACV section to begin with. Make sure the plug can move freely and the passages are clear.
Salim
Start with the air and then move to gasoline afterwards. Don't be too tempted to clean the throttle body just yet. Stay on the IACV section to begin with. Make sure the plug can move freely and the passages are clear.
Salim
Thread Starter
Pit Crew
Joined: Jul 2010
Posts: 126
Likes: 3
From: Hawaii
Just wanted to provide an update. I got access to the IACV, found the plunger(?), and was able to rotate it back and forth fairly easily. I remembered that I had cleaned it when I replaced the rear valve cover a few year back. I went ahead and cleaned out the IACV with throttle body cleaner, working the plunger back and forth, and draining from the copper tube.
I also noticed that the throttle body was attached to the intake with only two of the three bolts and one of the two was fairly loose. This caused a gap that allowed air to enter the intake post MAF and IACV sensors.
I added a new bolt, tightened all three, and reassembled everything. Thankfully the engine started up without the need to depress the pedal. I'm not sure if the minimal amount of attention I gave to the IACV was the reason the issue went away or whether it was due to the intake to throttle body gap. In any case, I'm a happy camper to have a properly running vehicle again.
Thank you Salim as always for your assistance.
I also noticed that the throttle body was attached to the intake with only two of the three bolts and one of the two was fairly loose. This caused a gap that allowed air to enter the intake post MAF and IACV sensors.
I added a new bolt, tightened all three, and reassembled everything. Thankfully the engine started up without the need to depress the pedal. I'm not sure if the minimal amount of attention I gave to the IACV was the reason the issue went away or whether it was due to the intake to throttle body gap. In any case, I'm a happy camper to have a properly running vehicle again.
Thank you Salim as always for your assistance.
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