Fuel pump problem
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- Posts: 6
- Joined: Tue Feb 11, 2020 10:15 pm
- Your car is a: 1979 Fiat Spider 2000
Fuel pump problem
The previous owner hotwired the fuel pump to a keyed wire on my '82. I'm trying to fix this properly so it will run when the AFM door opens and closes the microswitch that should then send power to the double relay and then down the green/black wire to the pump positive terminal. So far I've replaced the double relay and pulled the cover off the AFM, and removed the hot wire to see if the pump will run with the key on and the contact in the AFM closed- it will not. I am afraid to connect a test light to anything with the computer connected...how can I safely determine if I'm getting power at the switch in the AFM with the key on, and also at the relay? I have applied power to the green/black wire at the relay (with the computer disconnected just in case) and the pump runs so I know that wire is ok at least from the relay to the pump. The AFM has a sticker on it showing it was overhauled in the past and the switch terminals look clean, so it seems like I'm either not getting power to the relay or there's no power at the AFM switch.
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- Patron 2024
- Posts: 3015
- Joined: Fri Jan 27, 2006 11:45 pm
- Your car is a: 1981 Spider 2000
- Location: Wallingford,CT
Re: Fuel pump problem
First I think the Bosch fuel injection troubleshooting guide recommends using a test light for many of the voltage tests in the L-Jetronic system.
With the top removed from your AFM use the test light or volt meter to check for power at the fuel pump switch in the AFM. AFM pin 39 is is the power from the dual relay to the AFM fuel pump switch. With the top off the AFM you can also check for power out of the fuel pump switch on the green/black wire pin 88d.The dual relay has 4 power pin inputs. They are the solid brown wire pin 88z "Hot all the time" (not fused). The pink/black wire "Hot in start or run"pin 86c, the red/black wire hot in "start"pin 86a and a brown/white wire "hot all the time", pin 88y fused, wire with an inline fuse behind the fuse panel.
If you don't have power on the green/black wire when the fuel pump switch contacts are closed check the brown/white wire's in line fuse.
Note there is a single spade connector in the green/black wire located above the driver side kick panel near the hood release lever. I connect a test light there and move the vane on the AFM to check the fuel pump switch in the AFM.
With the top removed from your AFM use the test light or volt meter to check for power at the fuel pump switch in the AFM. AFM pin 39 is is the power from the dual relay to the AFM fuel pump switch. With the top off the AFM you can also check for power out of the fuel pump switch on the green/black wire pin 88d.The dual relay has 4 power pin inputs. They are the solid brown wire pin 88z "Hot all the time" (not fused). The pink/black wire "Hot in start or run"pin 86c, the red/black wire hot in "start"pin 86a and a brown/white wire "hot all the time", pin 88y fused, wire with an inline fuse behind the fuse panel.
If you don't have power on the green/black wire when the fuel pump switch contacts are closed check the brown/white wire's in line fuse.
Note there is a single spade connector in the green/black wire located above the driver side kick panel near the hood release lever. I connect a test light there and move the vane on the AFM to check the fuel pump switch in the AFM.
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- Posts: 6
- Joined: Tue Feb 11, 2020 10:15 pm
- Your car is a: 1979 Fiat Spider 2000
Re: Fuel pump problem
I have been looking for the in-line fuse on the brown/white wire- I have the console and most of the interior out, but I can't find it.
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- Patron 2024
- Posts: 3015
- Joined: Fri Jan 27, 2006 11:45 pm
- Your car is a: 1981 Spider 2000
- Location: Wallingford,CT
Re: Fuel pump problem
The brown and white wire come from C17 a 4 cavity junction connector located on the driver side of the car above the black plastic kick panel. the inline fuse holder has a brown/white wire attached to both ends it is usually located behind and above the mounted 12 fuse fuse panel, sort of hanging in the wiring. It could have been removed in the previous wiring modifications. If it was removed you could confirm bu testing for voltage at he dual relay pin 88y Pin 88y should have a brown/white wire on it.
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- Posts: 6
- Joined: Tue Feb 11, 2020 10:15 pm
- Your car is a: 1979 Fiat Spider 2000
Re: Fuel pump problem
spider2081- genius! Not only did I find the fuse by your description, but it was blown. I replaced it- and now the pump runs with the key on but without the AFM switch closed. What could cause that?
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- Patron 2024
- Posts: 3015
- Joined: Fri Jan 27, 2006 11:45 pm
- Your car is a: 1981 Spider 2000
- Location: Wallingford,CT
Re: Fuel pump problem
that sounds like someone bypassed the an =ofuel