Relay Testing and Fuel pump help

[nefiwashere]

12 hours ago, SteveJ said:

There appears to be a significant disconnect between what I described and what you did.

For resistance, you should start with the lowest setting. That would be 200Ω and not 2MΩ.  This is important. In my previous post, I said I measured 78.7Ω across the coil. That would be 0.0000787MΩ, or on your display, 0.00MΩ. This is important. If the coil was shorted out, the resistance would be much less than 78.7Ω, but your meter would still give you the same reading as a good coil if you use the 2MΩ scale.

As for the test that you said failed, what were you using for your 12VDC source? Did you hear a click in the relay (possibly 2 clicks)?

Try this test: Put the positive from the 12VDC source on pin 95. Connect the negative to pins 94 and 96. Put your meter on the  200Ω setting and measure resistance across 91 and 97.

Here is the theory of operation for that relay:

If there is voltage across pins 95 and 94, the coil is energized, and the the contact near pin 96 closes. Now there should be voltage across pins 95 and 96, and the second coil is energized. That causes the relay to move the switch that connects 91 and 95 so that it now connects 91 and 97. This is all relatively binary. Either the circuit is open or closed. Either the coil is energized, or it is not. If there is a voltage drop, it could be from the contact between 91 and 97 getting pitted or dirty so that there is not good contact. This would act like a resistor in the circuit.

If the car runs, the relay works. However, the fuel pressure should not be at 48 PSI.

I think you're barking up the wrong tree.

attached pic of the values.   there are 2 different readings per test.  Used 2 meters to test with.   

95-91 and 93-92  my readings were very different between the 2 tests

still need to do the 97 to 91 test

[nefiwashere]

I had a 1976  combined pump and EFI relay that would overheat and have a coil go open circuit.  The coils were a little bit burnt.  You can peel the little tabs back and remove the cover.  After you finish the tests.  Good practice on meter operation and test procedure.

 
 

I did open up my fuel pump control relay last week and it looked nice and shiny on the inside. I could not see any damage.


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[Zed Head]

On 2/20/2019 at 4:31 PM, nefiwashere said:

attached pic of the values.   there are 2 different readings per test.  Used 2 meters to test with.   

95-91 and 93-92  my readings were very different between the 2 tests

still need to do the 97 to 91 test

Not really clear what you're saying here.  "my readings were very different between the 2 tests".   Are you saying that two different meters gave different results?  Or that the same meter gave different results?

And when you write "FAIL" you should still give the value of no or yes, or, better, the resistance reading.  You have no, FAIL, and resistance readings all blended together.

[Zed Head]

I converted your numbers in to yeses.  Everything looks right except for the fail.  That must mean that you had an open circuit on 95-96, meaning that the fuel pump relay would not get power.  I reread your first post and can't really tell what the problem is that you're trying to fix.  You said that you have a weird problem where the "new fuel pump was working".

	no power
95-91	Yes (yes)	No (no)	Yes (yes)
97-91	No (no)	Yes (yes)	No (no)
95-96	No (no)	Yes (???)	Yes (yes)
95-94	Yes (yes)

[Zed Head]

Sometimes a spec of dirt can get between the contacts in the relay.  I would take apart the pump control relay and apply power, then just watch to see if the 95-96 contacts close.  If they do close but there's no continuity then there's something in the way.  

You won't get shocked with just 12 volts.  Take it apart, check the contacts, hook up some power.

[nefiwashere]

So my excel spreadsheet matches each box when testing.

I used 2 different meters to test with to make sure I was getting same results.   on the resistance test ware i was getting  (meter1) 1.0 /  (meter2) 0.2 and 1.1 / 0.4        normal to get i difference like that?

The one that says fail. I got nothing no continuity at all.

 

as for the weird part.  when i replaced with new OEM fuel pump and let it idle for a bit than drove it around with no issues.    couple days later i started her up and drove it around but it started to stutter after about 1.5 miles of driving.   I than looked at the clear fuel filter and it was almost empty with 20psi fuel pressure, car would run but struggling .    after letting car sit for about 10 minutes i tried starting the car up and it cranked up fine. clear fuel filter started filling up with gas with 48psi fuel pressure.





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Edited February 22, 2019 by nefiwashere

[Zed Head]

The odd part is that you did get continuity in the "Not grounded" test, but not on the "Grounded" test.   Doesn't make sense that the contact would open just by grounding 96.  Unless it's a sporadic problem.

 

[nefiwashere]

The odd part is that you did get continuity in the "Not grounded" test, but not on the "Grounded" test.   Doesn't make sense that the contact would open just by grounding 96.  Unless it's a sporadic problem.
 

Not sure either. I’ll retest it.


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[nefiwashere]

so i did the retest on pins 95-96 with Ground,  it did fail again but it also did not.  what i noticed when touching the pins i herd it click and i was able to get continuity.    I than disconnected the power and connected it back.  first initial click as usual and tested it again, No continuity.     Moved the connectors around a bit and than another click. tested it again and i was able to get continuity.   

 

Is this normal?

[Zed Head]

1 hour ago, nefiwashere said:

Is this normal?

No. 

Soldering abilities at the Nissan factory weren't very good back then.  Broken solder joints and loose connections happen.  Some connections are soldered and some are staked.

Time to pry those tabs back and take the cover off.

[nefiwashere]

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[Zed Head]

Shiny.  Apply power, wiggle things.  The loose connection will show itself.