Trouble shooting FI double relay

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BammBamm
Posts: 240
Joined: Fri Jul 31, 2015 1:23 am
Your car is a: 1982 Pininfarina Spider
Location: az

Trouble shooting FI double relay

Post by BammBamm »

I think my double relay has gone bad. It won’t start the fuel pump from the run spot on ignition. From the diagrams it appears the fuel pump part should engage from terminal 86a and 86b. Does that mean there should be continuity between the two?
Bill Woodbury
Design Engineer
Zero Shock Seating
1982 Spider 2000
18Fiatsandcounting
Posts: 3798
Joined: Fri Mar 15, 2019 11:23 pm
Your car is a: 1969 and 1971 124 spiders
Location: San Francisco Bay Area

Re: Trouble shooting FI double relay

Post by 18Fiatsandcounting »

(Bamm)^2, there's a pretty good document on diagnosing the dual relay, and if you PM me your email address, I can email it to you.

-Bryan
spider2081
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Your car is a: 1981 Spider 2000
Location: Wallingford,CT

Re: Trouble shooting FI double relay

Post by spider2081 »

It won’t start the fuel pump from the run spot on ignition.
For the dual relay to power the fuel pump with the ignition switch in the run position the flap in the air flow meter needs to be open.

Dual relay terminals 86a and 86b are connected together through a steering diode and a fixed resistor. I think to get any continuity between the pins the meter would have to be set to Diode check and then it might indicate with the red meter lead on pin 86a and the black lead on 86b. Reversing the leads the meter should indicate an open circuit.

My experience has been the female pins in the dual relay loose their tension and become intermittent more often than the relay fails.
Unplugging and plugging in the relay a few times often gets it working again.
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