Riskyrunner

Hi thanks in advance for looking to help the new guy....
So I have had my 4 runner for a year now and in love with it...
It is the 94 3.0 V6 180 + thousand miles... Automatic.

Recently this summer I went to a small mud hole to play around like any other day... Well upon leaving my rig started to sputter and cough as if the distributer was wet. It continued to do this for a week.
I then changed plugs wires and distributor no dice.

At that time it was sputtering at 2000 rpms and had a top speed of 55 mph

The next week I took it to my buddy who works at the toyota dealership they scoped my motor and tranny and it came back amazing. They replaced my maf
New timing belt and water pump. With no change to the sputter.

2 weeks later I started to mess with my fuel system even after my fuel pressure test came back good and within good limits.
I replaced my fuel filter and I had all my power back with no sputter and no cough. 5 days later the problem was back...

I'm at my wits end and it's winter here in Oregon and would love to play in the snow with my runner please give me guidance?

Just a recap of what's new
Distributor
wires
spark plugs
maf meter
fuel line from tank to motor on passenger tire
3 fuel filters
New sock for fuel pump
Countless bottles of sea foam and premium gas

Thanks again
Risky Runner

saurkraut

I see you have replaced the filter 3 times. Did this fix the issue every time?

scope103

There's a tiny screen in the top of the injector. If you knocked some crud loose while changing a filter (or otherwise) it could intermittently block an injector. Just a thought.

RJR

Have you or anyone else checked for diagnostic codes? Hopefully the people at the Toyota dealership started there.

I would be suspecting a bad signal from either the VAFM, TPS or ECT to the ECU. Anyone of those signals being erroneous can cause the fuel-air mixture to be wrong and result in misfiring.

Riskyrunner

Every time I've replaced the filter it has corrected the problem... My power returns no sputter or anything. But the problem always returns within a week or a couple days...

Riskyrunner

I think this is a great idea... Please don't think I'm questioning it just playing the devils advocate but, if an injector was clogged would it stay that way? Or would the problem be before the injector hence the filter changes helping the problem for a short fix... I'm only asking because I've done research and the injector system seems like a pain to get to?

Riskyrunner

Yes both toyota and I have both checked codes. I've checked diagnostic jumper codes and toyota used the dealership scanner.... No codes were thrown at all which baffles both our minds the only codes stored are the two from once me pulling tps and another from me pulling the vaf or maf meter sensor plug while at idle... Other than that no codes have ever come across even in the time I've owned the vehicle...



And just an update but I bought a new fuel pump from jc Whitney a denso replacement part with new sock.... It seems to have helped with the sputter. It will do a max speed of 60mph and sputter at 2500 then kick up and sputter at 3200.... I also took an volt meter and tested the maf and tps and both were within operating limits for the 3vze... Still puzzled. My buddy at toyota says some toyotas just have gremlins and take awhile to fully diagnose i hope this isn't the case.

RJR

Since the problem goes away every time you replace the fuel filter, and then comes back in a week or so, it sure sounds like you have crud in the tank that is fairly quickly plugging the filter. You might want to pull off the tank and give it a good cleaning.

Have you dissected any of your old fuel filters to see what they look like inside? That can be instructive. I had a '76 Ford pickup once where some kids discharged a dry chemical fire extinguisher into the tank. Took several fuel filters and finally dropping the tank to get all of that yellow powder out of the system. Fortunately no harm to the engine that I could ever detect.

oldblue

I'm with RJR, sounds like a dirty fuel issue.

joel1952

ANY UPDATE?
Just because a new filter fixes the problem doesn't mean the fuel is dirty. It could just mean that the problem is intermittent.

When replacing the fuel pump, did you carefully inspect the tank for contamination?

The way to test for clogged fuel filter is check fuel flow from the return line. Plenty of flow indicates the filter is ok. Pressure must be adequate, as well. This can be tested by hand...your thumb over the end of the return line will stop the flow with medium hard effort. Hard to "gauge it" that way, but 80 psi is equal to 5-10 lbs of "thumb" pressure

I don't know the exact hose connections and such in the tank, but did you verify that the connections are tight? A small leak there would lower the pressure.

I have a similar intermittent problem in a 94 T100 and am in the process of T-ing a pressure gauge into the fuel line.