Catalytic converter or fuel pump maybe???

I've got a problem that I cant figure out. I have a 2003 tundra v6 2 wheel drive that started having issues idling then misfiring then wouldnt run at all. Weve changed spark plugs, wires, the fuel filter and it's still acting like it's not getting gas. It drive like brand new for about a mile yesterday then it just died and wouldnt run again. What else could it be? We thought fuel pump or catalytic converters but were not sure. HELP!!

 

Test for fuel pressure before you break out the parts cannon. You want to have at least 35psi to the rail (ideally a little more than that).

What have you done to rule out/test the coil packs?

 

I'm trying to hunt down a fuel pressure gage right now. To test the coil packs I unplugged one at a time while running and engine completely dies on each one. That'd rule out coils right?

 

Do you have a scan tool that can read fuel trims? Those can tell you a fair bit and at least point you in the right direction. Also they can tell you which cylinders are misfiring, if it's one bank or two etc.
For example, if it's one bank only misfiring, makes it unlikely to be fuel pump or a dirty MAF.

 

The other thing I noticed is you said it ran fine for a mile or so, then started playing up? Is that every time?
O2 sensors (or cats for tha matter) don't really operate until warmed up, so the system ignores info from the sensors until they do.

 

I don't have a scan tool but when it was just started acting up I was able to get it to the auto parts store and they said all cylinders were showing.Yea it ran fine just for a minute. But that's not all the time either.

 

I got a fuel pump but just trying to make sure before I bust into it.

 

I think that's a viable test, yep.

The reason he's saying this is simple: The O2 sensors aren't being read/used used for the first 1-2 miles of driving, IIRC. Therefore if it runs fine for that period of time, your issue is probably the O2 sensors.

If the fuel pump you bought is a store brand, DON'T DO IT! If I had a dollar for every person that's shown up here with a store brand fuel pump that was either DOA or died within the first year, I'd have enough to buy a couple of premium 4-packs of beer. It's one of a couple places you always go with the OEM brand or OEM part (fuel pump, starter, O2 sensors, timing belt, lower ball joints, are a few big ones you should never use aftermarket parts with).

Test for fuel pressure before you replace the pump. The vast majority of times it is NOT the fuel pump.

 

If fuel pressures turn out to be fine, a scan tool will be useful. They are not too expensive now. Even the cheaper ones will give you O2 sensor info and fuel trim info. I'd also not trust a parts store probably. Did they show you the codes or just tell you? I just would not expect BOTH upstream O2 sensors to go down at the same time.
Unmetered air can give similar symptoms to a lack of gas, because that's essentially the net result, a non stoichmetric mix. Those would come from vacuum leaks, manifold leaks, dirty MAF sensor. Vacuum leak often improves with increased RPM. Dirty MAF often gets worse.

 

Well I was unable to get a scan tool. I'm way out in the country and no way to get one currently. I cleaned maf with maf cleaner. But I unplugged the O2 sensors and tried starting and it would just crank. Plugged them back in and it'd start just same rough idle. Same with maf sensor. That'd rule out of sensors right? .I appreciate all the feedback. I'm trying to do anything to get this truck running good again as it's my daily/only driver.

 

No, I don't think that's a valid test.

Really, only the upstream sensors would have any impact on how the engine runs. The upstream sensors are measuring the combustion mixture as it leaves the cylinders, effectively telling the ECU what fuel/oxygen ratio it detected, so the ECU can then adjust fuel trims based on the volume of air the MAF says came into the engine. Sadly, I think a lot of people think those sensors are just government EPA control, but the upstreams 100% serve a purpose, monitoring to make sure the engine runs optimally, never rich or lean. Running rich or lean could lead to the engine stumbling.

Look, it could be anything. It could be your timing is off. It could be you have a vacuum leak, hoses tend ot crack after 15-20 years. It could be the ECU is getting bad info from the upstream O2 sensors, which is why Fragman wants the scanner to see fuel trims (basic scAmazon cheapo scanners often show long/short term fuel trims). It could be you're not getting sufficient fuel (but I'm extremely skeptical it's the fuel pump). Based on what you said about the coil packs, I don't think it's the coils either.

I'm not as familiar with the V6 you've got. I think it's only got one upstream O2 sensor. I'd be really tempted to pick up a new genuine Densor brand upstream from the store and install it. If you can't get Denso, Bosch could do the trick but probably not going to be much cheaper. I don't trust any other store brands, aftermarket parts are fucking garbage these days. But really, I want to see fuel pressures, while idling, and when you press the pedal. That's going to rule out a HUGE possible culprit.