Fuel Pump or Ingnition coils?

[WeileMom]

Hi
I've been searching through the forum to try to figure out what is going on with my sienna.

Its a 2002 and has about 120,000 miles on it. Yesterday, twice, I had to use the gas pedal to get it started. It would crank but then stop, unless I gave it gas. I've never had this problem before. It didn't happen the first time I started it, but the second time, after it had been sitting about an hour and a half. The next few times it was fine, but those were short stops.

Then I went to use it again later in the day and it happened again. It worked fine for the next two short stops.

I've been noticing for a while that the acceleration seems weak and when I'm driving on the highway, with the speed constant, I can feel a bit of hesitation occasionally. I thought I was imagining it, but now I don't think so.

So, I've narrowed it down to the fuel filter and fuel pump or the ignition coils.

I don't have a check engine light on, but one did come on about two months ago, went away, came back on a month later, and went away. We assumed it was another O2 sensor going bad. We have already replaced one.

Any ideas? I appreciate any help before I buy the parts. I'm tempted to replace the ignition coils first. If it's the fuel pump or filter I'll probably have to have the work done for me.

Thanks!
Nicole

[wiswind]

One thing that comes to mind when you say that you have to press the accellerator to get it to start is the Idle Air Control Valve (IAC).
I cannot see the fuel pump causing the problem that is solved by pressing the accellerator or the coils.

The IAC is a valve that is controlled by the computer and controls the idle speed when your foot is OFF the accellerator.
It bypasses the throttle plate that the accellerator is opening when you press on it.

The IAC is known for getting dirty and sticking.
So, do a search on IAC and see if you can come up with a picture of where to squirt some cleaner to clean it up.
My 2003 has a dual throttle and it is located in the one that is to the rear.
The hole to spray in is in the base of the throttle body, in front of the throttle plate.

This is a picture of it on my 2003, and you can see the hole in the throttle body to the right in the picture.
The black box on the bottom of the throttle body is the IAC.


You spray some throttle cleaner, I've used Berryman's B12 Chemtool in the spray can.
Seafoam Deep Creep will also give some cleaning (not as strong as the Berryman's) and also give some lubrication, which the Berryman's does not (lubricate).
It does not take much cleaner to do the job....spray it in and let it soak......connect things back up and start the vehicle.
Worth a try, as a can of cleaner and 20 minutes of you time is a LOT cheaper than coils or fuel pump.
Of course, if it has been a while since the fuel filter has been changed, then that is a good idea.......IF you have the version that has a changable fuel filter.
My 2003 does not, it is part of the fuel pump assembly.
Earlier Sienna did have a fuel filter in the engine compartment that you can change, I don't know when they changed over to the one in the tank.

[WeileMom]

Thank you! I will definitely try that first, then. Would this also cause the slight jerk when driving at a constant speed? I'm not familiar with this part of the vehicle. Usually when my car doesn't start it's the alternator, we're on our third, but nothing happens when I turn the key when the alternator's bad. This time the engine actually sounds like it's starting and then it doesn't.

One other thing I've noticed is that the idle rpm is lower than I remembered. Actually, we took it to the shop once because it always seemed too high, but they said it was within specs. Now it's below 1000 when I'm sitting at a stop light, etc. When I start it, though, it stays at 2000 for awhile before slowly going down.

According to the repair manual I have, starting in 2001 they put the fuel filter in the fuel pump assembly, so I can't change that unfortunately.

[WeileMom]

Ok, wasn't sure where the hole was, but then I found this picture on the Siennachat forums, which I didn't realize were back up!


Thanks so much for your suggestion. I'm so glad you posted because this will be much easier to clean or even replace than what I thought the problem was.

[WeileMom]

Also, when I started the car up to put it on the driveway, the idle was all over the place. I hope this works!

[Black Sunshine]

Generally speaking, if any electronic parts are failing they will throw codes. Just something to keep in mind.

[WeileMom]

Will the check engine light go on? Or could there be codes without the light? If so, I'll have Autozone check for codes.

I couldn't find Seafoam Deep Creep, so I used Seafoam spray and followed the directions on the can. My only concern is that this is a double barrel throttle and the directions for the spray don't tell you what to do in that case. I decided to use it in the throttle body with the IAC opening.

Currently the car is starting. Seafoam says it could take a few days to really get things cleaned but I'm not getting any more white smoke out of the tailpipe. If this doesn't work I will try to find the Deep Creep or order online. In the meantime I can have the car checked for codes. I have 122K miles on it so I'm not surprised with any problem that might occur, but we're moving across country this month and I'd like to make sure I fix what needs to be fixed before that happens. Thanks so much for the help!

[wiswind]

Deep Creep is the spray version of Seafoam......same product at the can of liquid, but just in the spray can.
It is possible that they have changed their labeling since I bought it.
If it says Seafoam on the can, then it is the correct product.

To clean the IAC, you just spray it into the hole that is at the bottom of the throttle body that is closest to the firewall.
If you look at the picture I posted......you can see that the throttle body on the right has a hole at the bottom, right in front of the throttle plate, whereas the one on the left does not.

The IAC can stick and not function and not light the CEL.
I mention the IAC because the symptom you mention can be caused by a sticking IAC and it is the cheapest and easiest solution.
There is a motor in there that opens an closes a valve......so it is going back and forth, as driven by the computer.
The seafoam will clean AND lubricate this mechanism.
The IAC can fail and need replacement......but trying to clean it first is a good idea.