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View Full Version : Water crossings and 05+ tacoma EVAP system



zolo
01-17-2012, 03:07 PM
Well, Ive driven my truck through a fair number of water crossing. Some when it was newer and had less miles equaling to less wear and tear on the various components. The truck now has 105,000 miles all of which Ive put on it. They have not been easy miles.

Recently I was exploring a new area this past week and it had a small water crossing nothing crazy the road was built for it and the river bed was all rock and shallow. Maybe 2' at the deepest. However after that crossing the truck (2006 Tacoma) displayed a check engine light a few nights latter when is was very cold at night.
I'm a mechanic and have a pretty nice scanner, a Snap-On Verus. So it will read all of the systems on the Toyota brand.
It displayed 5 codes.
PO43E- Evap Emission system leak detection reference orifice low flow.
PO43F- Evap Emission system leak detection reference orifice high flow.
P2401- Evap Emission system leak detection pump stuck off.
P2402- Evap Emission system leak detection pump stuck on.
P2419- Evap Emission Pressure switching valve stuck on.

A little info about the pump and the EVAP system. After the truck is shut down and after it sits for a while the pump turns on and pressurizes the system to check for possible leaks. It has pressure sensors and a small pump and If it doesn't hold pressure it will set a code for EVAP Emission leak small or large depending on what it reads.

Now all of these various parts are located in the same place and bolted to the Carbon canister. It sits right under the bed and on top of a cross member from frame rail to frame rail. Toyota does not sell the pump or valve separate from the whole carbon canister. My cost on the canister was $360. I started to think why that would have failed?

I then realized the river crossing days before the issue might have a part in all this. Also realizing the freezing temp at night on the days the Check engine light came on.
I figured water had some how gotten into the canister and or pump. The canister and pump have 3 different hoses going into it. One large one going into the pump and one large one going directly from the gas tank to the canister itself. Then a smaller one going into the canister. The pump somehow ingested water and at night when the pump needed to run and check the EVAP system the water had frozen and it was unable to work.

I found this out by taking the whole rig apart then separating the pump form the canister and watched as about a cup of water pored out of the pump and valve assembly. I was lucky it did not appear to have gotten into the carbon canister itself. However I drained the water out and let it all sit over night in the shop to dry out. This AM I assembled it all.

The scanner has a EVAP auto check test. I ran the test takes about 5 minutes and all is good.

Now the water was ingested from the large hose that goes to the pump. So My cure was a set of new hose clamps on that hose to seal them better.
The other hoses have a very tight fit and the one from the gas tank to the canister is a special slip fitting hose with a real special clip to hold it on and tight.

This is just another thing to think about to help our trucks out when a water crossing is encountered. I know that Ive been in situations that I have had no other choice but I never once thought about water getting into the Pressure pump and causing such problems. I hope this makes sense and helps any Tacoma folks out with possible issues and or helping to prevent this and keeping the water out.


Below are the various photos that show the canister out and the pump separated and then reinstalled. Also the hoses that connect to it.
The lone hose on the red shop rags is the one that allowed water to get in and the one that now is hose clamped.

Hope this is a bit of info that can help folks out.

maxama10
01-17-2012, 03:37 PM
Another thing to check. Thanks for the tip.

TangoBlue
01-17-2012, 03:41 PM
Great write-up and even better sleuthing. I don't care what Hilldweller says, you're a pretty handy guy to have around.

thefatkid
01-17-2012, 03:55 PM
The canisters fresh air inlet is in/from one of the hoses that go to the fuel filler neck. If your crossing water at/above the fuel filler level you should relocate that hose to a higher location.

zolo
01-17-2012, 04:23 PM
The canisters fresh air inlet is in/from one of the hoses that go to the fuel filler neck. If your crossing water at/above the fuel filler level you should relocate that hose to a higher location.

Yep, The hose I put clamps on was from the fresh air inlet from the fuel filler.

Any way the water gets in the system can cause problems with the pump. Better safe than sorry.

frobuster
01-17-2012, 04:48 PM
Thank you....

zolo
01-17-2012, 04:59 PM
Great write-up and even better sleuthing. I don't care what Hilldweller says, you're a pretty handy guy to have around.

Thanks, Nice use of the word sleuthing. I had to look that one up!
I don't know, but I do know I'm 100% the problems Ive had with my Toyota have all been self induced and a product of the various modifications and use.:) Lucky me.

Ryanc
01-17-2012, 07:27 PM
I always wondered why manufacturers put these evap canisters where they do. On the jeep it is hanging as low and the rear lower control arms, so you either knock it off or flood it. I replumbed mine for this exact reason and attached it to the bottom of the tub. Sorry for a jeep guy hijacking a toyota thread. :smiley_drive:

TACODOC
01-17-2012, 08:37 PM
Good to know, thanks!

keezer37
01-17-2012, 09:56 PM
Did you use OE (spring loaded type) clamps or the old style screw type for replacements? I occasionally find some of the spring loaded ones questionable.

zolo
01-17-2012, 10:21 PM
Did you use OE (spring loaded type) clamps or the old style screw type for replacements? I occasionally find some of the spring loaded ones questionable.

I used the screw type clamps.
I also didnt over tighten them just tight enough to get a better seal on that large hose going to the pump.
My hose is showing wear. Nothing to be overly alarmed about but I think it contributed to the water getting it. So a little extra securtiy with the screw clamp seemed to help a lot.

JLink
03-01-2012, 02:32 AM
Thanks for sharing!! I've always wondered what that box was.. now I know!

toyotech
03-02-2012, 05:01 AM
good to know. imo the spring type are better. they are always self adjusting to be tight. screw type dont hold over time.