ulysses76

I have a tremendous amount of respect for this forum and have been using it religiously for the last 4 months. I read my newbie rules and watched the sheep video so please don't think that I'm just posting to post.

I have 96 SR5 6cyl, 150K that I purchased about 5 months ago. When I first got it the car ran perfect but was throwing a front O2 sensor cel. Replaced it, cel went away and the car ran like crap. I started tracking mileage: 14.6 is the city average right now. I try not to travel to far with it, the one time I did: 21.2 mpg. The symptoms have changed over time. Originally I was getting a gas smell in the cab, loss of power under load and a very obvious misfire.

Changed the 3/6 ignition coil
Tested the other 2, they came out fine
New plugs
Checked the wires
Cleaned MAF(used MAF cleaner)
New PVC
Used propane to check for vacuum leaks
Cleaned the throttle body

Obvious misfire gone, gas smell in cab gone, runs marginally better. The car runs great in open loop for the first 30 seconds to minute its up. Everytime I start it, I check the power in that small window of time. Engine sounds great and it feels like I could drag race it. Then once it hits closed loop the engine noise changes, it almost sounds like my old 88 4 cylinder. The more it warms up the less power it seems to have. So:

New cat
New fuel filter

No help, just louder. Now I've noticed a gas smell coming from the rear drivers wheel after my 5 mile commute home. A week ago I was ready to pull the plenum and swap all of my injectors but now with this smell I'm wondering if a leak or bad gasket could be my problem. Here's the other issue. I live in DC and do not have a driveway, so the work I've done has been on the street. Changing the cat was a little dicey with the occasional car driving by. I would like some better perspective before I drop the gas tank and start looking around.

My question/s is/are, what would cause the smell and effect driveablity? Is there an easy way to test fuel pressure on the 3.4?(I saw the write up with the guy who tapped the line and I'm not sure that my skills are there)

I've been using this forum everyday for the last 4 months and it's awesome. Thanks

Justin

dubbsbetty

iTrader: (2)

Hello Justin, my name is Justin, and congrats on your first post here at yotatech, amazing forum for sure! I'm not sure about the 3.4 but is there some sort of valve or pressure release on the fuel rails or are they completely covered by the plenum? If you can find a valve like a schrader valve or a point where you can tee into a fuel line with a fuel pressure gauge you could check for the proper fuel pressure to determine if the fuel trim is running rich or not, sounds kinda like it. Maybe a scan tool? If you can find a test point make sure to depressurize the fuel system first, lol. An overly rich air-fuel mixture will cause rough engine response and driveability issues

J2F42C

I'd start with looking at the fuel pressure regulator, it is located behind the intake plenum, to the right and back of the throttle body. Pull the vacuum line. If you smell gas, or if gas comes out, that is the culprit.

BTW, there is no pressure valve on the fuel rail for the 3.4. You have to buy a special adapter or make one yourself.

ulysses76

The front of the fuel rails are barely accessible under the front of the plenum. I checked for a schrader but didn't see one. Haynes has an illustration for the 3.4 that looks like it has an inlet for it but cant track it down.

ulysses76

Thanks, I'll give this a try this afternoon. Would that cause a gas smell by the gas tank/rear wheel?

EDIT: I went to pull the vacuum line and it's almost like it's welded on. I'm going to yank it later but first I'm going to pick up some vacuum line at Autozone. The regulator itself is completely rusted over. I'm guessing replacement requires removing the plenum. Back to the question above-if the regulator was shot, would this cause the gas smell at the rear of the car? or am I looking at replacing gaskets as well.

Evilmunkey

um thinking on the fuel smell in the rear of the vehicle, might also want to check the evap lines to the charcoal canister under the vehicle, which last I remember is under the backseat/trunk area. Also might want to check the tank's filler neck the new ethanol/gas mixed fuels like to eat away at rubber components in some cases.

J2F42C

I need to read with a more clarity next time.

You can check the regulator, and pull off the vacuum line, but since the smell is coming from the rear, check the filler neck. You may want to look at the gas cap as well. Then work your way back to the front of the car.

Congrats for changing the cat in the DC streets. I lived on 25th and K, and if I even had the hood open, the landlord threatened to have me cited.

ulysses76

Didn't have a chance to really look into it. The vacuum tube that led to under the upper plenum felt like it was glued on and the valve itself was rusty as hell. Let's say there is no gas smell tomorrow when I pull the line, is there another way to test the regulator?Do you think this could effect performance? Now that the regulator has been brought to my attention, I'm curious to see if the smell is an entirely different problem.

J2F42C

Without a tester, not that I am aware of.

When the gas cap fails, it usually causes a CEL, and the 4runner could run rough.

A friend had a Ford where the filler tube had a small hole in it at the neck and wrecked havoc on the EVAP until we finally found it. I cannot remember if it caused a CEL to come on or not.

dubbsbetty

iTrader: (2)

If the regulator is faulty it could let the system run completely rich and therefore smell like fuel, but if it's the rear( i missed that one too) probably the gas cap, can set a dtc like J2F42C said.

ulysses76

sorry for the delayed response: here's what i've got so far: pulled the vacuum line for regulator and smells a little like fuel. i had to wait until i got some replacement line because the rust had connected itself to the tube. The regulator is completely rust covered. I'm going to replace it. When I pull the plenum, I'll multimeter the injectors as well.

I'm curious to see if a bad gasket on the fuel tank would cause these bad performance issues.

As far as the smell in the rear goes: I crawled under the back and took a look. The gas inlet has a housing around it that I can't seem to access, that is until it comes down about 20 inches and turns towards the front of the car. The plastic/rubber hose looks to be in good condition. The only thing that has me wondering is where it meets the tank. There is about a 1/4 inch gap all of the way around where the bracket meets the tank. It almost looks like it's removed itself. I wanted to get some opinions before I yanked it.

Evilmunkey

in order to really check the gasket where the filler neck attaches you have to drop the tank (recommend doing it when on E) also it will give you a better look at the rest of the system in that area.

ulysses76

One more quick question about the regulator. I found this test on Ytube:
http://www.youtube.com/watch?v=AKtR_yF7bi8

The line is clearly holding a vacuum, mine doesn't do that. I pulled the tube and waited a few minutes, revved a couple of times and no suction. Just for anyone that might not remember the line leads through the bend between the two plenums and into the air box on the intake hose. Should I have noticeable suction there?

93toyrunner2

Before you drop the tank, check to see if you have an inspection port under the back seat, just above the tank. I believe that it is almost triangular in shape, and has three Phillips screws holding it down to the floor. Lift up the bottom of the seat above the tank, pull the carpet back and see if it is there. My 2001 and my 93 both have this, opposite sides of the truck.

ulysses76

Thanks for the tip about the inspection panel. Now I cant unsee what's there.
I can only imagine that either the gasket is bad or there's a hole in one of the lines.



Could this be the culprit of my performance issues or did I just add something new to my checklist?

J2F42C

I think given that situation with the tank, the fuel pressure regulator is not the culprit. I believe you should have vacuum from the line to the FPR.

Other than using a gauge to test the FPR, I know no other safe way to test it. And take auto repairs on YouTube with a grain of salt.

j2the-e

Your best bet here is to get a scanner that streams live data. You can watch your o2, maf and fuel trim readings as it switches to closed loop. Doing anything without a scanner is a useless waste of time and you will end up wasting money throwing parts at it. Based on what you've done so far though, my next suggestion would be to pull the purge hose from your intake and make sure there isn't liquid fuel in there, but, you really need to check your data list, that will help point you in the right direction. Also, in order to reset the ecm's learned data parameters(fuel trim, timing) after any repairs, you need to disconnect the battery.

93toyrunner2

I would suggest starting here with removal and replacing everything that is corroded, new fuel sending unit & gasket, new pressure line and purge line. May want to check the copper lines that run along the rail for their condition as well. I was able to remove and replace mine with a little metal trimming around that area, enough to get the cover through. Once done, I covered that area with a piece of sheet metal cut to fit.

ulysses76

I ordered the fuel pump mount bracket and the gasket online. Once i get it, I'll drop the tank and replace it. The rest of the lines look good.

lekiboy

hi,
i am just wondering, can i check and pull out the fuel pump from this inspection panel? thanks a lot!