OK here is a quiz for you 4runner geniuses. I need your help to save my baby-2000 4runner SR5.

This problem has been going on for a while, it comes and goes. The truck will start stalling out, sputtering along, then pick right back up. It is like the engine is being choked for gas. It never totally fails, I just lose all engine power for a second or two, then it picks back up. Then, the check engine light will turn on.

I thought the light might be for a gas cap, so I checked that first. Unscrewed the gap and hear a very noticeable "whoosh" air noise, like air getting sucked into the gas tank. After I adjusted the gas cap, the truck starts working as normal, runs great. For a couple weeks or so. Then the same problem. And the same fix has always worked as well - the gas cap trick, thus far, has worked every time (about five times).

I took it to a mechanic and they said the codes are for the throttle and I need a new throttle body for $1500 freakin dollars. I don't doubt the throttle could probably use replacin, but I don't think that's is what is causing this issue. If the throttle was the problem, it doesn't seem like it would be a problem that comes and goes. And why does the gas cap fix work?

Things I have replaced in the few years - fuel filter about a year ago, air filter recently, evap, O2, cat, timing belt, water pump, gas cap (about a month ago). Needless to say, I got a lot of $ into it. Think it could be fuel pump?

Really weird, me and my friends are stumped. I will probably try another mechanic and see what they say.

What was the code the shop had? I would also go to AutoZone or similar and have them scan it. Got to get that second opinion

You may want to check the roll-over valve(s) on the top of the gas tank. This will probably involve dropping the tank. I'd also check the cap. Not sure if it should be a vented cap or not.

If the TPS signal is irratic it will cause the problem you are taking about. In the years I have been working on toyotas I have never ever seen a gas cap or anything that is evap related such as rollover valves cause an intermittent driveability issue.

The shop you took it to is probably onto something with the throttle body. Maybe an entire TB is not necessary, try cleaning it really good or replacing the Throttle position sensor.

If that's the case, then why would the gas cap trick work?

verify all the vacuum lines are installed in the correct locations.
ive seen this happen before, but it was on a carb'd rig. improper tank venting was causing a vacuum in the tank, which the fuel pump wasn't able to overcome , it would end up starving the engine for fuel.

popping the cap off would fix it temporarily.


you could try just driving around with the cap loose, I suspect you wouldnt have that issue anymore. altho, that may lead to other CELS, but it would at least let you know you have a venting problem.

This is what I am thinking is going on. Can I do this on my own with limited tools?

I only meant that if you had a professional look at it and they came to one conclusion based off whatever it was they diagnosed, then maybe explore that before going down any other rabbit holes. People tend to go on safari and end up miles away from their target destination.

yes, I should have mentioned - I had the throttle cleaned recently. Doesn't seem like it would cause the vacuum whooshing noise or gas cap fix, and if throttle was truly failing, it would not work properly 95% of the time. I don't doubt I probably could use a new throttle, but I don't think that's what this is either. I am kinda wondering if the shop I had do the evap canister did not reconnect vacuum hoses correctly.

You are probably onto something there. It would be funny if it was pulling the tank into a vacuum like the previous posters suggested. I personally have never seen that happen but it is apparently most deffinately a possibility.

Good luck with the fix! Cheers!