fuel pump not working on first key position

Gotta love that wiring . . .
antonisorphanou
Posts: 6
Joined: Mon Mar 26, 2018 1:57 pm
Your car is a: fiat spider 1981

fuel pump not working on first key position

Postby antonisorphanou » Sat Mar 31, 2018 11:54 pm

hello guys,
have an issue with my spider 1981 and I need your help to resolve it.

The fuel pump does not receive 12v on first ignition position but receives 12V on the stating second ignition position.
I have checked the relay connector and it properly receives 12v.
I opened up the plastic relay casing and I can see one of the two relays closing on the first ignition position BUT the fuel pump does not receive 12v. I can see the second relay closing and the fuel pump receiving 12v only on the second ignition position.
Is this a case of a bad relay or is it anything else I should check? I have ordered a new relay....so lets see...

appreciate your help on this

spider2081
Patron 2024
Patron 2024
Posts: 2967
Joined: Fri Jan 27, 2006 11:45 pm
Your car is a: 1981 Spider 2000
Location: Wallingford,CT
Contact:

Re: fuel pump not working on first key position

Postby spider2081 » Sun Apr 01, 2018 9:42 am

With the key in the 1st position (run) of the ignition switch, the fuel pump circuit is through the AFM's fuel pump switch. Are you opening the flap in the AFM when measuring the fuel pump voltage??? The the dual relay connector with the white wires in it has a wire # 36 that goes to the relay terminal 86b. This wire/terminal should have 12 volts when the ignition switch is in (run) and the AMF flap is open. Terminal 86b energizes the fuel pump power relay in the dual relay

The AFM needs to have its electrical connector plugged in and the flap physically open for the fuel pump to run.

antonisorphanou
Posts: 6
Joined: Mon Mar 26, 2018 1:57 pm
Your car is a: fiat spider 1981

Re: fuel pump not working on first key position

Postby antonisorphanou » Mon Apr 02, 2018 2:58 am

thank you for your reply spider2081

well I finally understood the issue, yes you were right on target to point to the AFM switch;

The previous owner had rewired (closed/shorted) the AFM fuel pump switch and I would hear the fuel pump working on the first ignition position. Actually as I found out, the car is originally intended to turn the fuel pump on on the second switch ignition (cranking the engine) and after that the air flap turns the AFM fuel pump switch on to keep the pump going. (That is a safe way to run the fuel pump).

Changing an intermittently faulty fuel pump and the AFM (pin-7 of the AFM connector was not making proper contact due to an on AFM connector damage, made the car running like a charm again.


Return to “Electrical Issues”

Who is online

Users browsing this forum: No registered users and 63 guests