VSV ticking and startup problems

For the past 6 months or so my 1995 3.4 has been making a terrible ticking noise which I've found is coming from the vsv on top of the evap canister. No CEL coming on. Ive hooked up my scanner and nothing is coming up. In the past year its also been struggling with some power issues. Within my 2 years of owning this truck I've put in a new fuel filter, new fuel pump, new front and rear o2 sensors (denso), new plugs, wires, and boots, new iac valve, new pcv valve, new battery, and alternator. After just recently doing my fuel pump and o2 sensors the truck has really started ripping again. I'm actually able to climb some highway hills at a decent speed haha. But now the ticking sound is still driving me nuts. I've tried swapping that vsv purge valve for another oem from a 4runner, but it still kept making that awful noise. Also tried replacing all the vacuum lines. The only thing that made it stop was when i unplugged the harness. Then the CEL came on. So i plugged it back in and the light eventually went out but now im having cold startup problems. I have to give it some gas to get it to start up and i have to keep my foot on for a while or it will stall. Also noticed whenever i remove my gas cap it makes a violent hissing sound like air is being trapped in the tank.

 

Vapor pressure sensor

 

Does your gas cap have a vacuum relief valve in the middle of cap?

 

Does my 95 have a vapor pressure sensor? I though only the newer style canisters had those. (The Square ones) I think my cap is a vented one ill get a picture of it.

 

Does the gas cap vent work?
Other than sucking on it I don't know how to test the vacuum relief valve in the cap.
The vapor line from gas tank to cannister hose may have become damaged or clogged. Try blowing it out with gas cap off.

 

I'll try putting an air compressor to it. Is it dangerous blowing compressed air into the fuel tank or will it vent out if i have the cap off?

 

I wouldn't use an air compressor.
I would disconnect the hose from line and attach a clean hose to blow through by mouth to check for clogging.
If it is clogged I would then use the compressor at 10-15 lbs to try blowing it out.

 

I disconnected the rubber vent line and blew compressed air through the hard line with it disconnected from the canister. Didn’t see any crap come out of there. Also blew air through the tank side and replaced with a new rubber hose. Tried to start it up with everything back together and still wouldn’t fire up. I did notice the exhaust is leaking on the inlet side of the muffler, but that shouldn’t cause idle and startup issues being that far down the pipe right?

 

An exhaust leak won't cause hard starting.
I'm gonna do more research on the old style round charcoal cannister to see if I can find the FSM reference.
Will post link if found

 

Thanks man. I've been looking for vacuum leaks but haven't found anything yet.

 

https://www.tacomaworld.com/attachments/charcoal-canister-pdf.1344462/
Hope this helps if I did it right. LOL
Also found 1995 3.4 vapor pressure sensor is located on fuel tank but looking for FSM on that.

 

I have a picture of the top of tank when i had the bed off to do the fuel tank. I don't think I have a vapor pressure sensor. I'm also second guessing my evap vacuum line routing. When I changed my canister I put one in from a 3.0 v6. I still have my old one, im going to compare them. I thought they were the same...

 

Dude
Your brake fluid is filthy.
I have concluded you need a new EVAP VSV if you can find one.

 

If the vapor pressure sensor isn't on the gas tank look by brake booster and master cylinder.
Then again it may not exist at all on a 1995.

 

Someone said it might be my EFI relay. Do you know how to test a relay? I’m going to look at getting a new vsv tomorrow. Still no luck finding a vapor pressure sensor on this old truck haha

 

Well if it starts and runs with the gas cap off the EFI relay would be ruled out by my way of thinking.
That is if the hiss when removing gas cap is pressure and not a vacuum caused by gas cap vacuum vent being non functioning.

 

the VSV valve on my 96 3.4 purges automatically when the pressure in the tank increases due to it being hot outside. Take the pressure off the tank by taking the gas cap off and I am sure that the clicking will go away unit the pressure in the tank builds up again.

 

Interesting, so it could be as simple as replacing my gas cap with one that vents properly.

 

Gas cap vent is one way only.
Allows air in to replace gasoline consumed by engine and prevents tank implosion due to vacuum created by gasoline cooling. I guess it could cause a gasoline starvation issue.
The EVAP VSV can dump way too much gas vapor causing rich a/f mix flooded if not working properly.