Public Service Announcement.... is your EVAP system malfunctioning ?

[nrgetic99]

I have been chasing a problem on my 98 Ltd for a few months now. At idle, when warm, you can hear a noise that sounds like a knocking in the engine or perhaps a bad lifter. It is loud enough to hear inside the cab. Simulataneously, I tend to get a bad smell of gas around the car after I fill up or on hot days.

After much probing and prodding, I was able to diagnose that when i could hear this noise, the EVAP cannister Purge valve was pulsing. Sure enough, disconnect the purge valve electrical input and the sound stops.

After much research, I determined that the only real reason for the EVAP cannister to be purging ALL THE TIME was a likely leak in the EVAP system. The EVAP system essential ensures any fuel vapors are stored in the vapor cannister and purged into the intake air at an appropriate time.

Even with my limited knowledge, the purge valve running all the time is not correct but what puzzled me is no codes...and specifically, no codes that the vehicle failed the leak test.

It seems that 'Yota messed up in the declaration they made in respect of emmisions for a range of vehicles from 96-98. It also seems that from real world testsing, the EVAP system and leak test DO NOT FUNCTION as expected on these vehicles. Hence, system will malfunction, release hydrocarbons into atmosphere and NOT THROW A CODE or MIL lamp to alert driver

Net result is class action lawsuit and Toyota being forced to extend the Emmisions system warranty to 150,000 miles or 14 years.

According to the link from Tundra Solutions (http://www.tundrasolutions.com/forums/4runner/69530-1997-4runner-evap-warranty/) , my vehicle is covered and I also determined that the syptoms are a strong smell of fuel and often, zero stored or pending codes.

I am scheduling a service visit now, I am armed with details of the warranty extension and I will update you all with my findings.

David

[97kurt]

Is the EVAP cannister on the drivers side front?

[nrgetic99]

Yup,

Between battery and brake booster server bolted to DS inner fender.

Black plastic box about 4 x 4 x 10 with two round domes on top and a host on vacuum lines.
The purge valve is the solenoid valve mounted to the back of the cannister, not the one on the engine side of the cannsister or the one up on the firewall.

David

[ecchamberlin]

Wow

This is exactly what mine was doing in the desert the past few months(110+ degrees F). It was so bad that I would have to open the gas filler cap at each stop to release the presure. The Land Cruiser I was with and one of the FJC's had the same problem. Hell, I bet I release a lot more hydrocarbons with this problem than a gas can without a CARB spout.

THe smell is very strange. At first I thought it was a hole in my gas tank and then I thought it was my trans burning up. I had me baffled until we stopped and turned the rigs off in a tight canyon. Then I could hear the gas cap hissing. The smell is very localalized to the gas door area. This is great information. Thank you.

So do we have to wait or what is the action we can take right now?

[ecchamberlin]

I just read the thread on Tundra Solutions. Does not seem to cover my year. I wonder what that means for my issue. I do not want to continue to vent that crap out into the atmosphere.

[nrgetic99]

UPDATE :

Dropped off at stealer this morning. It was like pulling teeth to get the service writer to write down what I said. She kept just writing 'customer advises emmisions system not working' :roll:

I finally got here to write down verbatim what I said after telling her I could come around desk and type myslef if she had a comprehension issue :D

Then I informed her about the extended warranty and she first said I would have to prove it then said my vehicle was not covered then after I showed her the documents she said well, if it is not covered, I would be liable for any and all costs.

At this point I got the Service Manager and as of right now, they are going to hook up the EVAP system diagnostic tool and run a full leak test and system test. IF they do not find a problem, I will be out the $86 for that test :chair:

If that happens, I will pay, take it to another dealer and get their opinion without telling them about the first guys.

My expectation is low at this point...

David

[MTL_4runner]

David, I'm sorry you're going through all this mess with the EVAP system and yes it can be a serious PITA to fix those because it often requires hooking up to the dealer's diagnostic (simple OBD readers don't have this ability) and a smoke machine to find any leaks in the system. You might try replacing the purge control valve to see if that helps you with the noise you've been hearing because to me it sounds like the valve is sticking open when it really should be shut. The purge valve should only open when the engine its at full operating temps and the engine is under heavy load (such as when starting from a stoplight or passing on the highway).

[nrgetic99]

Wow and double wow !

Got truck back from dealer after spending $86 and being told the EVAP system was functioning fine and also getting ablank stare when I said Purge valve SHOULD NOT RUN ALL THE TIME :shake:

I open hood when I get home and look at the valve from the other side of the engine bay and it hits me ! The aftermarket siren that is installed there is physically touching the case of the valve.

The valve is rubber isolated from the vapor cannister as a result of TSB where owners complained about a ticking noise from under the hood. So, I gently bend the siren brackets a hair and the instantly, the valve stops running. Jump in the car and the noise has stopped.

I then go and gently push the siren onto the case of the valve and the valve cranks up and the noise is back !!!

So, inadvertently, the siren was providing a hard mechancial and electrical connection from the purge valve to the firewall and the sound I was hearing was the pulsing of the valve vibrating essentially the entire firewall...no wonder it was loud.

Also, from my research, purge valve is permanently hot, switched ground so if the siren touched it , the body as grounded and the valve ran. I was so elated to find that and the fact I knew why I was having the issues helped out the pain of the $86 at the stealer..hey, look at the upside, I know my EVAP system is working fine.

How did the siren end up touching the valve ? I had to have a new fender about 4 months back after a landscaping truck did a nice hit and run in a private parking lot (police could nothing, truck left scene) and the body shop must have accidentally tweaked it or R&R'd it when replacing the fender.

Really does wonders for your peace of mind knowing you can diagnose such a problem and inspite an idiot tech telling me "they all do that" (where do they learn that line as they all use it), fixing the problem.

Now onto the fun stuff, need a waterpump so that is next..got the parts on the way, will do water pump, timing belt, tensioner and probably #1 idler this week.

David

[MTL_4runner]

David, glad you that figured out. :thumbup:

[nrgetic99]

Did you see my PM ??? Do I need to remove radiator to replace water pump and timing belt ??

Thanks

David

[MTL_4runner]

Did you see my PM ??? Do I need to remove radiator to replace water pump and timing belt ??


David, I don't have any PMs from you, but I had trouble with my email a few days ago so if it went that way it might have been lost.....so I apologize if that was the case. To answer your question, no you don't need to remove the radiator to do either of those items although it can give you alot more room to do the job. If you decide to leave them in (which I usually do) then just cover the radiator with a few sheets of cardboard because it's very easy to accidentally cause damage in the process.

[nrgetic99]

You know, it was an email not a PM, my mistake.

Thanks, I will have a look at it. I took the rad out for my 93 and it made things a ton easier.
I will intentionally do it over two evenings (I have a well lit, warm garage). Strip and replace water pump first night. New belt etc and re-assemble following evening.. I am too old to do what I used to do which was stay up, often until 1 or 2 am until it was done.

David