How to test fuel pump relay.

[Zackman]

Happy holidays folks!
I want to test a fuel pump relay, but the Convention on the relay is different from what I'm used to. It has two coil terminals and one common and one NO terminal.

I believe, if I'm right, I should put 12 volt power to the two coil tabs and see if I get power from the other two; is that correct?

Your input is much appreciated.

[Zackman]

THANK YOU SO MUCH FOR THE DETAILED EXPLANATION.
HAPPY NEW YEAR, WISH A HEALTHY AND HAPPY ONE FOR YOU.
ZACKMAN!

the 91 , car is the first car with a serperate fuel pump relay.
so is it really a 91>?
the way to tell fast is the ISC has 2 hot water hoses. (1990 does not)
i say this, because , many old cars have engine swaps,....
there is no convention, on these old jap cars. (no iso, no sae, rules on relays)

"i should put?"

do not hot wire this relay, if you do and the wire slips. 1/8" of and inch, bingo you just blew up a $400 ECU. fact.
do not hot wire ECU , or this relay, why are you doing that.?
please tell why , or the job, or the symptoms....
all this is easy if you have a voltmeter, got that? that is all it takes to find a problem here.
the schematic is on my schematics page

the relay is just a coil, and magnetic contacts, and is NO, normally open
2 pins have 12vdc all time key on.
the other coil (not 12v pin) is grounded by the ECU, cranking, or key for 3 second (not 89/90s they must be cranked.)
the ECU does this and holds the relay closed, running, full time.
unless the ECU THINKS it lost spark for any reasons. then cuts fuel.

if you hot wire the relay coil low side, say GOOD BYE ECU, and see the cloud of smoke.




the best test for the the relay is in the car.
not on a bench. (unless we do load testing on a bench)
in the car key on, and those 2 pins above, are 12vdc.

blk/wht and blue.black are hot, key on, 12vdc.
and so is the pink wire, after 3 seconds after key on.,
the output wire pink/blk goes to 12vdc cranking or for 3 second, key on,
the left rear tail light wire, (that loves to fail) is 12vdc on same wire.
the same below bumper. and at tank, 12vdc for 3 seconds, or cranking full time.

seen this yet.?
http://www.fixkick.com/INJECTORS/PUMP/dead-pump.html

see all this tests for 2door at end. see the 2 common failures. all killing the pump?
ground screw
and pink-blk, connector rust? end to end. it can rust.

---

on 2 doors, i start at the left rear tail light.
check for 12vdc on the pink black wire cranking
and clean the G402 ground first. nice and clean no rust.
if this wire fails to be 12vdc cranking (can drop to 11v due to starter load)
then its failing, 0v is failing, 1 to 9v.bad..10v marginal or in Alaska...battery drops due to super cold.
best is to do the test cranking, if car will not start. (you never said what it does or you are attempting to do?)

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i do not have the relay pin out drawings, (the FSM has this)
and never need it.
because the colors are all i need, and with that, i can see which pins is which, using the schematic above.

on a bench , the best tests is a large light bulb as a load, like an old good head light.
but i never do that , i test in car. (best test of any thing is on the car)

the main and fuel pump relays are identical, you can swap them,.

---

use needles (walmart leather ) to back probe that connector
if the pink black goes 12v cranking, then all that works. move on...
i can do that in 1min flat.
meter in hand.
ignore dots.. on wires. body -stripe colors matter.

[fixkick]

testing where
off car , or on car.?
on car is best. (real live testing under load, is best always)
off car is harder,
coil 120ohms.
contacts open and read infinity
12vdc applied to the coil pins, getting polarity correct. (some have clamp diodes inside the blow up, if reversed)
now the coil energizes and NO contacts read zero ohms
this is the rudimentry test.
we can do a full load bench test , too, using a large lamp.ask.

if asking for the pinout?
then the schematic above tells you which pins are which, easy. by color associations.

---

on car testing is even more easy
turn key to cranking, (closes for 3 seconds each keyon (not on some 89s) and full cranking and running.
relay closes. and its output pin will be 10 to12vdc. (warm whether high side, cold lower, as starter draws huge currents)
if that fails
we check for 12vdc across the relay coil cranking, if not, the ECU has issues, ask why. (or scan the ECU to see why)
keep in mind the ECU can cut fuel for many reasons.
the above is for dead fuel pumps. only. 0 PSI, or very low.