View Full Version : changed O2 Sensor, Now won't start. HELP!
05-29-2011, 09:17 AM
alright guys i need some help. bought this truck last july. has ran great since i bought it. the p.o. rebuilt the engine right before i bought it. its an 88.
the o2 sensor had been out of it since i bought it and the CE light had been coming on the whole time. so i put in a Beck Arnley splice in sensor in, the p.o. had but the plug off, and there was another splice in sensor in too. when i went to crank the truck, nothing. turns over like a champ but will not crank.
could it be coincidental that my fuel pump has gone bad at the same time and was throwing the code along with the bad o2 sensor? when i turn the key on i cannot hear it prime.
this is my dd and i need to try to get it running by tuesday.
05-29-2011, 10:00 AM
I think the issue is in the o2 sensor wiring I would replace the slice in sensors with plug in's or at least remove the aftermarket wiring from the harness and only use the new o2 sensor wiring
05-29-2011, 04:25 PM
the only aftermarket wiring is the new sensor, the old sensor that i took off was an aftermarket. the oe wiring is the same just no plug, it was cut off when i bought it.
i don't see how the o2 sensor wiring would keep it from cranking. the old sensor was dangling underneath the truck caked with mud and grime when i bought it.
can someone give me their :2cents: on my fuel pump suspicion. tomorrow will be the first chance i have to work on it. i will check fuses and i think there is a relay in there.
correct me if i'm wrong, the fuel pump is in the tank and the bed must be removed to get to it? once the bed is off is it a pain in the neck to change the pump, special tools etc?
05-30-2011, 09:23 AM
The sensor you replaced it with , was it a heated O2? the 88 truck had a heated sensor ( big black wire in the harness) if you cut it it will look like a radio antenna wire solid center with a braided ground around the outside. In order for the o2 to function the center wire must be spliced along with the outside wire. With that said if your truck craqnks but wont firs id say when you sspliced the wires you got one grounding out somewhere causing no spark issue.
05-30-2011, 09:38 AM
I agree with Yotaneck. Your truck should start, even without an O2 sensor. Un-wire what you just did and look for problems, isolate all those wires and try and start. If you think its the pump then check fuel pressure. I believe there is a pump electrical check connector somewhere, but its been a while since I have had a Toyota motor.
05-30-2011, 09:40 AM
Did you read what I posted on your thread on IH8MUD?
If the O/2 sensor wires ground out it can blow your main EFI fuse under the hood. Blown EFI fuse means no power to the fuel injectors.
This happened to me during a snow wheeling trip. As soon as the wires hit the exhaust and melted the fuse blew and engine died.
05-30-2011, 06:38 PM
blown efi fuse. wired it up again and still get check engine light though.
05-30-2011, 08:12 PM
Disconnect battery for 30 minutes.
05-30-2011, 08:13 PM
i'll try that i only did it for about 30 sec.
06-01-2011, 10:06 PM
give it a shot of starting fluid and crank it if it fires then shutsoff it is probley your fuelpump, just my 2cents
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