tasdeviltoyota

hey just looking for help with my 94 4runner 3ltr v6 it starts up fine runs for a min then shuts itself of wont start again unless i cycle the key tried replacing the ecu from another 94 v6 4runner hasn't helped, I've got good fuel pressure Ive swapped and replaced every fuse and relay ii can find with new ones, the egr valve has been replaced, throttle position sensor replaced, fuel pump is working correctly, ignition timing is spot on. dizzy is a second hand replacement with good points and new rotor as original one seized, Ive got injector pulse, has good earths, alternator is charging and apparently running fine, only error code the diagnostics is pulling up is a 21 code (oxy sensor) it was disconnected to pull the gearbox back and replace clutch and was as far as i know plugged back into the wires it was previously connected to (it was pulling up the 21 code for ages before it was disconnected, prior to this problem i had issues were it wouldn't start on the key but replacing the ecu has fixed that (had to roll start it for ages before that) does anyone know what would be causing the computer to shut the engine off after 1 minute every time its started or has anyone else had similar problems

RJR

So, can you reproduce this problem by simply starting it and letting it idle in your driveway for 1 minute until it shuts off? Is it always the same length of time? When it shuts off, can you always restart it (by cycling the key) and have it run for another minute before stopping? Does it shut off cleanly, or sputter its way to a stop?

If it sputters to a stop it's probably because the fuel pump is cutting off. Try jumpering Fp to B+ on the diag connector and see if it runs longer. Also, you can just connect a voltmeter to Fp in the diag connector and watch it while the engine is running. It should read +12V. If the voltage goes away beforethe engine shuts down, you know it's a fuel pump power issue. If the voltage drops to 0V after the engine shuts down, the fuel pump control is working as it should.

If it stops cleanly, most likely either the ignition or the fuel injectors are shutting off. First thing to do is to find out which one, so you can narrow your search. When it shuts off, try starting it without cycling the key. While cranking it, monitor the ignition (inductive pickup from a timing light on the coil wire should do it) and/or the pulses going to the injectors. One or the other will likely be missing - that'll tell you where the problem is. Then maybe we can talk further about why.

tasdeviltoyota

yes problem can be reproduced over and over and over again can sit at idle for 1min or can hold revs for 1 min does the same every time and will start again and do the same as soon as the key is cycled, have had voltmeter on fuel pump its working properly, it stops clean each time but if holding a couple of revs on it the revs will die down slightly before it shuts of, just waiting on battery to charge to go and check if injector pulse is missing after if shuts of or if no signal on coil lead, will update results soon