Fuel Pump - Need Help, trying to fire up my barn find for first time...no fuel Options

[willimac]

I'll try to keep the story short. I have a '74 1.8 L-jetronic 914 that I rescued from a barn in central Wisconsin almost 3 years ago. It had sat for over 20 years and become a palace for generations of barn mice, who built nests in every available cavity. Since then I've been sporadically cleaning it up, vacuuming mice and their nesting material, dropping the engine, dismantling and rebuilding it, cleaning up rust, shopping new parts (alternator, starter, stainless fuel lines, seals and gaskets) re-boring the cylinders, splicing chewed-through wiring, etc... finally got it put back together this week and am having trouble with the fuel delivery. The fuel pump does not turn on.

There is power to the double relay switch - terminal 86a checks out with the ignition switch on start, zeros out in "on" position , and AFM resistance checks out. The terminals at the fuel pump plug read zero volts unless the ignition is turned to "start" and the AFM is propped open - in which case it reads 7 - 8 volts.

Don't know what to do---is there a way to test the pump to see if I need to replace it? Why would only 8 volts be making it to the terminals for the pump? Is this possibly a problem with the double relay switch?

Any help would be greatly appreciated...I feel very close to bringing this one back from the dead.

[timothy_nd28]

yep, the bigger black wire with red stripe is the fuel pump wire. So you have no voltage on pin 88D by either attempting to start the car or moving the AFM flap?

If this is the case, lets check the voltage at pin 88y. You should have a solid 12volts from this pin to the negative battery post. If you have 12 volts on pin 88y then continue with this step. Put the meter leads on pins 88y and 88d with the voltmeter set to DC. If you read anything between 0 and 12volts DC on the meter while starting the car, then you have a voltage drop across the points within the relay. 0 volts across these two pins indicates that you have zero loss across the points. 12volts would mean that the relay isn't pulling the points together

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[willimac]

yep, the bigger black wire with red stripe is the fuel pump wire. So you have no voltage on pin 88D by either attempting to start the car or moving the AFM flap?

If this is the case, lets check the voltage at pin 88y. You should have a solid 12volts from this pin to the negative battery post. If you have 12 volts on pin 88y then continue with this step. Put the meter leads on pins 88y and 88d with the voltmeter set to DC. If you read anything between 0 and 12volts DC on the meter while starting the car, then you have a voltage drop across the points within the relay. 0 volts across these two pins indicates that you have zero loss across the points. 12volts would mean that the relay isn't pulling the points together

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Correct. No voltage at 88d moving AFM flap, .03 volts trying to start the engine (might as well be 0 volts, no?)

Yep, solid 12 volts at 88y, without the key in the ignition.
Solid 12 volts between 88y and 88d with ignition key off.
solid 12 volts with ignition key "on".
10.5 volts with the engine cranking.

So there is a voltage drop across the points within the relay. What does that mean?

BTW I am so glad that you chimed in on this post...I'm awestruck by how helpful you've been to others on the site, and have learned so much from reading those threads. THANK YOU.