I'm restoring an 82 spider . Being in New Zealand the wiring has been hacked several times by the RHD conversion wizards and PO 's. It seems the Fuel pump has been directly connect to the "brown wire " junction block and the previous brown wire to the fule pump relay persists .The terminal from the relay that was meant to be connected to the pump is now connected to the in line fuse which feeds back into the relay ?? . Can anyone help me here.? Has the PO done this to bypass a faulty relay ? Is it safe to have the fuel pump "hot wired "like this ? IS the way to test the fule pump relay
I'm aging rapidly on this one- Thanks Chris
FUEL PUMP RELAY Puzzle
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blusmith
- Posts: 82
- Joined: Sun May 29, 2011 3:00 am
- Your car is a: 1982 124 spyder
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wizard124
- Posts: 752
- Joined: Mon Oct 29, 2012 9:27 pm
- Your car is a: 1980 124 spider FI
- Location: Sheridan, WY exSan Rafael, CA
Re: FUEL PUMP RELAY Puzzle
From adifferent thread:
Re: 81 FI Harness
by wizard124 on Thu Apr 25, 2013 8:45 am
spider2081 wrote:
88a powers the fuel pump switch in the air flow sensor.
It would be very strange to have power to the fuel pump and not to the injectors as the same part of the relay set is common to both the pump and injectors.
If you are sure you have no voltage at the injectors (with ignition switch in "start or run") and your fuel pump is working I think a previous owner has modified the cars wiring.
wizard124 wrote:
From my Fiat FI Manual......
"With the engine running and ignition switch released, current no longer flows from Terminal 50 (ignition switch) to energize the fuel pump relay. Current from the closed contacts of the power relay flows thru the closed contacts of the fuel pump switch in the air flow sensor to the fuel pump relay, keeping the relay energized."
Since your engine dies shortly after starting. It seems to me that the power and fuel pump relays are working properly. My take is, the fuel pump contact in the air flow sensor is not closing. This contact should close once air is pulled thru the air flow sensor during the starting process. If it does not, the fuel pump relay opens and the fuel pump stops.
A more thorough discription:
Terminal 15 of the ignition switch stays hot in RUN and and Start (pink/black wire to relay connection 86c). This wire powers the power control relay in the relay set. When closed, this relay energizes the injectors and ECU. Since your engine starts, this power control relay is working.
Once the key is out of the Start position, terminal 50 is cold (red/black wire to terminal 86a). 50 powers the fuel pump relay and cold start circuit. With the engine running and air being sucked through the Air Flow Sensor, its closed switch now energizes the fuel pump relay. The same power control relay is still closed that powers the injectors and ECU.
Since you have now swapped the relay set, I'll try to convince you to do the diagnostics I supplied earlier. The black plastic cover of the AFS is stuck on with silicone and removes easily. Inside you will see the contacts that should close with the slightest movement of the flap. If the flap is stuck or the contacts worn or mis-aligned, the fuel pump does not run and the engine quits. Which sounds exactly like the problem you describe. If the PO has messed with the original wiring, then all bets are off. The diagnostics will tell you if this switch is working.
I am not making this stuff up I am giving you info from Fiat manuals that I own. Just trying to get you on your way
'80 spider FI, SnugTop hardtop
From what you describe, it does sound that the current wiring bypasses the fuel pump relay. Perhaps the switch in the Air Flow Sensor went bad, so it was bypassed. Is the fuel pump still fuse protected? That would be my biggest concern. I may have read somewhere that the reason for the switch in the AFM is to prevent a fuel spill in the event of an accident.....if the engine quits, so too does the fuel pump.
How different is the rest of the wiring from the Fiat diagrams? Could be that if you returned the relay and pump wiring to spec, you could be giving yourself a headache somewhere else!
Re: 81 FI Harness
by wizard124 on Thu Apr 25, 2013 8:45 am
spider2081 wrote:
88a powers the fuel pump switch in the air flow sensor.
It would be very strange to have power to the fuel pump and not to the injectors as the same part of the relay set is common to both the pump and injectors.
If you are sure you have no voltage at the injectors (with ignition switch in "start or run") and your fuel pump is working I think a previous owner has modified the cars wiring.
wizard124 wrote:
From my Fiat FI Manual......
"With the engine running and ignition switch released, current no longer flows from Terminal 50 (ignition switch) to energize the fuel pump relay. Current from the closed contacts of the power relay flows thru the closed contacts of the fuel pump switch in the air flow sensor to the fuel pump relay, keeping the relay energized."
Since your engine dies shortly after starting. It seems to me that the power and fuel pump relays are working properly. My take is, the fuel pump contact in the air flow sensor is not closing. This contact should close once air is pulled thru the air flow sensor during the starting process. If it does not, the fuel pump relay opens and the fuel pump stops.
A more thorough discription:
Terminal 15 of the ignition switch stays hot in RUN and and Start (pink/black wire to relay connection 86c). This wire powers the power control relay in the relay set. When closed, this relay energizes the injectors and ECU. Since your engine starts, this power control relay is working.
Once the key is out of the Start position, terminal 50 is cold (red/black wire to terminal 86a). 50 powers the fuel pump relay and cold start circuit. With the engine running and air being sucked through the Air Flow Sensor, its closed switch now energizes the fuel pump relay. The same power control relay is still closed that powers the injectors and ECU.
Since you have now swapped the relay set, I'll try to convince you to do the diagnostics I supplied earlier. The black plastic cover of the AFS is stuck on with silicone and removes easily. Inside you will see the contacts that should close with the slightest movement of the flap. If the flap is stuck or the contacts worn or mis-aligned, the fuel pump does not run and the engine quits. Which sounds exactly like the problem you describe. If the PO has messed with the original wiring, then all bets are off. The diagnostics will tell you if this switch is working.
I am not making this stuff up I am giving you info from Fiat manuals that I own. Just trying to get you on your way
'80 spider FI, SnugTop hardtop
From what you describe, it does sound that the current wiring bypasses the fuel pump relay. Perhaps the switch in the Air Flow Sensor went bad, so it was bypassed. Is the fuel pump still fuse protected? That would be my biggest concern. I may have read somewhere that the reason for the switch in the AFM is to prevent a fuel spill in the event of an accident.....if the engine quits, so too does the fuel pump.
How different is the rest of the wiring from the Fiat diagrams? Could be that if you returned the relay and pump wiring to spec, you could be giving yourself a headache somewhere else!
'80 spider FI, SnugTop hardtop
http://s940.photobucket.com/user/a7ewiz ... t=3&page=1
http://s940.photobucket.com/user/a7ewiz ... t=3&page=1
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blusmith
- Posts: 82
- Joined: Sun May 29, 2011 3:00 am
- Your car is a: 1982 124 spyder
Re: FUEL PUMP RELAY Puzzle
Thanks that helps . The wiring is not as spec and I guess he has bypassed the relay . The AFM switch tests out OK I will try it back to spec 'because it should be safer. If this fails I will get a new relay set . Thanks again
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blusmith
- Posts: 82
- Joined: Sun May 29, 2011 3:00 am
- Your car is a: 1982 124 spyder
Re: FUEL PUMP RELAY Puzzle SORTED
New dual relay and restoring the wiring to "as spec" What fooled me was the out feed to the fuel pump was a B/W instead of the specified G/B . Wiring diagrmas show B/W is the fused feed to the relay so I was never going to get it right> go figure. Thank God someone invented an ohmeter . Chris