bbrideau

Okay so, 91 3vz 5 speed sr5 economy has gone into the toilet. Truck is completely stock. Clutch was recently done and oil was changed that's about it. It has started to run rich ( can smell it in the exhaust) exhaust is whiteish at start up when cold and smells of fuel (i know that is normal on cold start up) Exhaust clears up but can still smell lots of fuel in the exhaust. It is not throwing any codes. Oil and coolant levels are all topped up and look fine. My guess is mabe the O2 sensors on the way out but i don't think that would account for the incredible loss in economy. I used to get about 400-450KM's to a tank, now it is more around the 250-300KM's to a tank. Any suggestions or ideas on where to start looking into this would be great. Thanks everyone.

TNRabbit

There's a test for the Cold Start Fuel injector; sounds like it could be leaking. Also, if you've never replaced the O2 sensor, it's done for.

When you say it's not throwing codes, DID YOU CHECK or are you saying there's no Check Engine Light? You can have cods without a CEL....

bbrideau

I checked for codes it flashed the all clear. I don't i know when if ever the 02 sensors have been changed as i only picked it up for the wife about a year ago. Will test csi see if that is the problem. Might as well change the o2 sensors as well seeing as i have no records of them being done. I do know the exhaust was redone a year or two prior to my ownership of the truck. Might have been changed then but probably not.

TNRabbit

Well, the O2 sensor is one of the most common culprits when a drop in fuel economy occurrs, if it can't be traced to anything else. You can find DENSO OEM replacements online for about $65. DO NOT use a Bosch. They seem to be shorter & tend to have issues playing nice with our Japanese trucks~

bbrideau

I dont use bosch anything nothing but issues with their products

JohnnyCanuck

Double what Rabbit said; denso only. Mine died 8 months ago and I haven't been able to replace it until this week; long story-read my truck thread. When the 02 sensor dies, ecu reverts to rich burn, my mileage was horrible, and the tailpipe was completely black. Driving back from the muffler shop on Tuesday - 20 minute drive - and the tailpipe is white-ish looking again, I'll check mileage on this tank.

bbrideau

i don't have any black smoke at all which is weird i thought rich conditions would be black smoke. but it might not be running that rich yet. can definitely smell fuel tho.

JohnnyCanuck

Use a multi-meter to ohm it out, you'll know for sure if that's what it is.