Squiddy

This is for my 92 3.0

I am getting increasingly strong gas smell in the cab and under hood, the latter mostly in the passenger side close to the firewall. Have looked and looked and can't find any leak. Seems worse when truck has been sitting, much less when driving. Running fine. Mileage seems normal. A few years ago replaced hardware between tank and engine, fuel lines seem fine.

Since I can't find any leak of the fuel lines going into the engine, thinking this may be a bad EGR? Anyone got any bright ideas as to a) what it is and/or b) how to sort out?

Thanks

gottadog

iTrader: (3)

There is a regulator under the plenum that is known to leak.

scope103

You're probably smelling excess fuel vapors coming from the charcoal canister. The canister is "emptied" through the Thermal Vacuum Valve, which is notorious for breaking.

I would start with tracing the vacuum line from the canister to see if it goes to the right place. Follow with hooking that line to known good vacuum (might make it idle poorly, but it's just a test). Then use the FSM to check the Canister itself.

good luck!

Squiddy

Charcoal = EGR, right?

sb5walker

Most common fuel leak spot on the 3VZE is the fuel pulsation damper, a little disk with a plastic cap stuck on the back end of the passenger side fuel rail. It's dangerous because it drips fuel onto the intake manifold, where it can create some good-size pools, then overflows onto the exhaust crossover which ignites it. Some very nasty fires have started as a result.

Usually manifests as a fuel vapor smell in the cab.

Check for it by jumping +B & FP in the check connector and turn ignition on (but don't start it). That will run the pump and pressurize the fuel rails. Just reach around under the back of the plenum on the passenger side, inboard of the valve cover. About an inch inboard of where the passenger side heater hose comes out the firewall, also a couple inches down and a few forward. Probably a good idea to locate it before pressurizing the fuel lines.

They're pricey for their size - about a hundred bucks. Try 1sttoyotaparts.com, but I couldn't find the damper in their catalog, so you have to search by the part number. There are reports of aftermarket parts not fitting, so best to go dealer on this item. (Aftermarket not much cheaper, anyway.)

See this great thread for part numbers and tips on replacing:
https://www.yotatech.com/forums/f116...ner-v6-186626/

Don't forget to get new copper/aluminum crush washers.

It's like a shock absorber for fuel pressure. Evens out the spikes & drops in pressure as injectors open and close, so the fuel metering remains accurate.





Thanks to various yotatech members for these photos - please forgive; I didn't track which was from whom .


Other somewhat common leak spots include injectors (including the cold start injector), the rubber portion of the fuel return line (connects to the fuel pressure regulator which is front end of driver side fuel rail - it runs to the middle section of the return line which is steel). If new copper or aluminum crush washers were not used on both sides of a banjo fitting when fuel line segments were disconnected, then the joints can leak. There are rare reports of the fuel vapor recovery canister leaking, but that isn't common.

DO NOT IGNORE GAS SMELLS - FUEL SMELL MEANS FUEL LEAK! There are MANY sources of ignition on a vehicle. No one who has ever witnessed a fuel-fed vehicle fire would ever drive a vehicle with a fuel leak. https://www.yotatech.com/forums/f116...ew-one-222309/

And no, charcoal canister & EGR are completely different.

Squiddy

Sb5
Thanks so much for details -- huge help and exactly what I needed!

Squiddy

Sumbitch. It is indeed the fuel pulsation damper ... looks cracked and can feel gas. Waa.

Squiddy

PS what moron of an engineer puts this stuff where you have to pull the plenum off? Criminy!

sb5walker

Yeah, and it's SO fun to take the plenum off! I think you can leave the throttle body attached, and leave most of the tubes of the passenger side attached, and sort of flop it over. I THINK I've read suggestions of that nature, but I haven't yet tried that technique - I pulled everything off when I changed head gaskets. You'll have to disconnect the EGR valve somewhere, and probably the PAIR tube to the exhaust also. Good luck!

EDIT: also, many people find it a lot easier to remove the hood when removing the plenum - it's easy to do.

Oh, and watch you don't drop something into the intake(!) https://www.yotatech.com/forums/f116...a-love-242550/

Squiddy

Ended up having my mechanic do it.
Stoopid valve with plastic piece = $170
Various gaskets = $20
Labor = $210
Not wasting my entire day = PRICELESS.

Outsane

one day I'll learn this

Squiddy

Mind you, $400 for fixing a 10 cent piece of plastic. grrr.

On other fronts, now that it's fixed, my gas mileage seems to have gone to pot. Any ideas? Could it be as simple as a misdirected vacuum hose during repair?

rworegon

A vaccum line could have been misrouted. Still a small leak wasting gas? Have you changed your morning warming-up-the-rig routine due to colder weather?

Gevo

I didn't want to start a new thread..

My symptom, yesterday when starting car in parkign lot at work in the afternoon (parked under shade) I smelled gas. Then, the whole way home it was kind of there. At stops and starts I could smell it more. I got home, popped the hood and couldn't tell anything other than from the passenger side I could smell the fuel. It was faint, and more or less faded within the few minutes I was looking around. I checked the best I can with a flashlight to see if I can see any moisture anywhere or leaks. Nothing. But of course we can't easily see the fuel rail on that side.

This morning, I started up... no smells, went to the hood, no smells, and pretty much no fuel odors like yesterday. Now, I thought it could be the charcoal canister.. i was hoping it was... but I doubt it, all of the hoses going to it are new and I'm certain they are connected correctly. Charcoal canister was checked just a couple weeks ago when I bought it as a used item to replace my old one.

So, intermittent fuel odors on passenger side... Other than the pulsation damper (which I assume wouldn't create an intermittent issue) what else is going on there that I can't see?

once I get to my handy dandy little swivel mirror I will be able to check under the plenum a bit better. I'm here to ask what else should I be looking for when turning the fuel pump on and checking for leaks? Other than the obvious fuel line-fuel rail-injectors... ?

scope103

Get some buff-colored paper towels; with the fuel pump on (as described by sbwalker) slide the paper towel under the damper (and elsewhere) to look for leaks. Incredibly, gasoline is so "clear" that I have a tough time seeing it on a good white paper towel, but the cheap buff colored ones will look wet for a few seconds before the gasoline evaporates.

Mine was the FPD, rather than the evap canister, as I had suggested earlier above. Since gasoline evaporates so quickly, the slightest breeze can blow it away and you might not smell it. So a slow leak might seem intermittent. Worth checking for, anyway.

Gevo

That is a good idea! Just dropped the truck off for new carpet (finally), will test it tonight after engine cools.

Gevo

Update: Fuel smell has not repeated itself since that one and only time. I can't find any fuel coming out of anywher ein the system, and can't smell it. Car is running well, I'm getting about 14.3 mpg mixed driving. No fuel droplets from bottom, no visible fuel leak markers.

I don't like to leave a potential problem alone.. especially dealing with fuel.. As much as I can understand form teh damper, it really can't leak sometimes and not others.. if it leaks it can only get worse.. right? So, any ideas? Was it a phantom fuel odor that followed me from downtown LA to the valley?

Bills86e

The Other Thing = the three tubes under plenum ctr passenger side get mixed up - misrouted,to the three vsv hoses. two are EGR and third is fuel regulator, when the plenom is re-attached.
accounts for bad mileage & fuel smell also.

Gevo

Bill, my hoses are routed correctly. 14.3 mpg seems to be about the avg these engines give. And, I have yet to experience the fuel odor a second time. If there was a mis-routed vac hose I would think the problem would be more persistent?

perhaps I didn't understand you well enough.

pixelsilver

I had an '89 4Runner (3VZE) with leaky injectors. Toyota dealer didn't even catch it when I took it to them. Ended up diagnosing (it got worse...aka obvious) and replacing them myself.

Now I have a 95 Tacoma (5VZFE) and I occasionally notice what I can only best describe as an elusive natural gas odor. I seem to notice faintly in the cab when I come to a stop after exiting the freeway. When I get home and check under the hood it's even more elusive but still seems to be there faintly.