92 corolla fuel/ignition switch problem - Toyota Nation Forum : Toyota Car and Truck Forums

simmre · 01-31-2012, 02:49 PM

hi guys. just joined. hope i can get some help here. what i have is a 92 corolla dx with a 1.6 and an automatic. i bought the car with a blown engine, as i had a fresh one to put in. after the engine swap, i had to change the fuel pump because the car had sat up for a couple of years. after cleaning the tank, i installed the pump wit a new strainer, and also a new filter. the car crank and ran fine until a short time ago. now, the pump doesn't come on when the ignition is switched on. it will only come on if i bump the starter and release the key. i've checked every fuse, as well as swapped out the pump relay with a known good one. still the same thing. when i run a hot and a ground directly to the pump, i can crank the car. thinking the new pump was faulty, i replaced it. same thing happens. i checked for voltage at the pump harness, and can only get it when i bump the starter, and release the key. could this possibly be a bad ignition switch??????? i'm stumped.

bakwoods · 01-31-2012, 04:37 PM

Please clarify you "bump the starter and release the key" because I'm trying to imagine that. You smack the starter with a stick? Or are you cranking the car and it'll crank but not fire.

Get a friend and step by step:
1. Remove the back seat and undo the plugs to the fuel gauge float AND pump
2. With a test and multi-meter both the plugs for voltage at different states.
3. Whats the voltage when the car is in ACC? Check all pins, one should have a constant 12V
4. What is the voltage when the car is in ACC? Use you're test light to see the voltage pulse. You'll notice the light flickers when cranking, 15-20 seconds of cranking you'll see the light flicker.
5. The relay that you plugged in, did you check the voltage on those pins? What are the readings?

simmre · 01-31-2012, 06:17 PM

by bumping the starter, i mean turning the switch over just enough to rotate the starter as if bringing engine to tdc. on the fuel pump connector under the seat, 0 volts in the acc position, 0 in the on position, 10 volts when cranking over, and 13 volts for about 1 second after releasing the key. on the sending unit connector, 13 volts on the yellow with green stripe, and 4 volts on the yellow with the red stripe. this is in the on position. 0 volts in the acc position. voltage drops to 9 volts when cranking. this was with the fuel pump unplugged. its the same with the pump plugged in, but like i said before, the pump only comes on when the key is released from the starting position. as for the relay receptical, there was 13 volts on 2 of the spaces. this did not fluctuate when cranking. i don't know if you're familiar with noid lights for checking the power to the fuel injector harness, but i used one, and have power to each injector plug.

bakwoods · 01-31-2012, 07:13 PM

Quote:

Originally Posted by simmre

Fuel pump
0 volts in the acc position
0 in the on position
10 volts when cranking over
13 volts for about 1 second after releasing the key.

Float/Gauge
this is on the off position
13 volts on the yellow with green stripe
4 volts on the yellow with the red stripe.

this is in the on position
0 volts in the acc position
voltage drops to 9 volts when cranking.

as for the relay receptical there was 13 volts on 2 of the spaces. this did not fluctuate when cranking. i don't know if you're familiar with noid lights for checking the power to the fuel injector harness, but i used one, and have power to each injector plug.

Well the good news is that the injectors have power. My concern is if it's a relay issue, because it would seem to be that the power is not being directed properly. If you can wait till Friday I'll actually get my exact voltages since I'm replacing my fuel pump since it crapped out. I jumped it via jumper cables. It works on 12V directly, but not when it's priming or cranking. Obviously it's a bad pump. If not, then it looks like I'm in the same boat as you lol.

simmre · 02-05-2012, 08:29 AM

changed ignition switch. still the same. my search for answers continues.

90 GP · 02-05-2012, 08:59 AM

If you turn key to on the pump will not run. You have to be in the start position and cranking to have it run. That is the way it is designed. From what I read on this forum it has to get a signal from distributor ( via it's rotation) to engage it. In the on position there is a way to jumper connections at the diagnostic connector to test it but otherwise if not cranking/engine running it won't operate. Maybe someone can chime in on exactly what to jumper at the diagnostic connector if you want to put a pressure gauge with banjo bolt adapter to hook it up to the fuel rail for a pressure reading. If you determine it's not fuel related read Rogue Moog posts on (Tach needle spins while starting) for some electrical wiring issues to check into that could be affecting it not running.Have you tried squirting some starting fluid into throttle body to see if it would run till it's burned up? If so that would verify if fuel or ignition related.