Fuel Pump hot wired to ignition switch.

Gotta love that wiring . . .
Post Reply
NGinuity

Fuel Pump hot wired to ignition switch.

Post by NGinuity »

Hey everyone. Is there any particular "good" reason why the PO of this '82 2000 would bypass the fuel pump relay and wire the fuel pump straight up to the ignition switch, sharing the same pin as the ignition coil? They basically jumped the green/black wire that goes to the fuel pump from the relay, straight to the run circuit on the ignition. Here's some pictures..... maybe someone can take a crack at it:
Image
Image

Here's the lovely job they did patching it to the ignition harness that I just eliminated:
Image

Obviously, I want to fix it right, but I'd like to know the scenario I am dealing with first. I've got the battery disconnected and I'm addressing several terrible solutions that happened to this poor car right now.
User avatar
kmead
Posts: 1069
Joined: Sat Aug 02, 2008 9:24 pm
Your car is a: 1969 850 SC 1970 124 SC 85 X19
Location: Grand Rapids, MI

Re: Fuel Pump hot wired to ignition switch.

Post by kmead »

It should definitely be through a relay. Taking as much load off the switch as you can will allow the switch to live longer. It is a weak spot and the new replacement ones are not as good as the OEM version.

Whenever possible I like to go back to the original or improve on the design of what was done before. Depending on what the previous owners did, you may have a non fused condition.
Karl

1969 Fiat 850 Sports Coupe
1970 Fiat 124 Sports Coupe
1985 Bertone X1/9
NGinuity

Re: Fuel Pump hot wired to ignition switch.

Post by NGinuity »

Oh it's definitely not fused. I'm just hoping the relay isn't bad. Guess I'll find out tonight! :-) I was just wondering more or less if it's anything someone has done for any reason specifically.
wikkid

Re: Fuel Pump hot wired to ignition switch.

Post by wikkid »

You may find that the relay is not working. Or you may find that the pins relating to the AFM readings on the ECM are not making good connections. The PO may have hard-wired it to bypass a problem in the system that he didn't want to face, or didn't know how to address.

You are absolutely right that it needs to be fixed correctly. The fuel pump should not run when, for example, there is no signal made by the AFM that air is flowing through the intake. With the pump hard-wired to run any time the ignition is on, you risk getting fuel when you shouldn't.
NGinuity

Re: Fuel Pump hot wired to ignition switch.

Post by NGinuity »

Any advice on how to troubleshoot?
wikkid

Re: Fuel Pump hot wired to ignition switch.

Post by wikkid »

There are some really good fuel injection diagnosing/troubleshooting/maintenance guides available online. As the pump system, including the relays and the electronic control module, the air flow meter and the pump are all integral to this system, that's where you want to go to get a good overview and go through the steps.
Here's a good start, probably the easiest to read and digest, but not as technical as the Bosch guide, for example:
http://www.hiperformancestore.com/Ljetronic.htm
rlux4
Patron 2022
Patron 2022
Posts: 4211
Joined: Thu Jan 10, 2008 8:32 pm
Your car is a: 1982 2000 Spider
Location: Granite Falls, Wa

Re: Fuel Pump hot wired to ignition switch.

Post by rlux4 »

It is very common to find that a PO has bypassed the dual relay to get power to the fuel pump. Usually it's because they didn't diagnose the cause of the pump not running. If the green wire with a black stripe at the dual relay doesn't have 12V when the car is cranking it could be a bad dual relay, but it's more often than not that the dual relay isn't getting the 12V from one of the (4) sources. Here's a good trouble shooting guide to check for the problem once you've taken out the hot wire and made sure the original wiring is in place:
http://www.wcmotors.com/personal/Fiat%2 ... agnostics/
Ron
Ron Luxmore
rlux2n2@gmail.com
'82 2000 Spider: after 26 years between Spiders.
NGinuity

Re: Fuel Pump hot wired to ignition switch.

Post by NGinuity »

Gentleman, I thank you kindly. I'll troubleshoot and report back later! This is what I do instead of sleep these days.
NGinuity

Re: Fuel Pump hot wired to ignition switch.

Post by NGinuity »

Alrighty. I finally got the time to mess with this. After rewiring the ignition switch properly, and fixing two spots on the fuse block that were twisted together, the car appears to work normally... except the wipers don't work. I'll address that tomorrow.
User avatar
ga.spyder
Posts: 3478
Joined: Tue Nov 06, 2007 7:19 pm
Your car is a: 1982 Spider 2000
Location: Blairsville ,Ga.

Re: Fuel Pump hot wired to ignition switch.

Post by ga.spyder »

Ron Luxmore to the rescue...again.He diagnosed mine ,with the same issue, and helped me fix it over the phone! :D
Craig Nelson

1982 Spider 2000...pride and joy
1981 Fiat X1/9..gone but not forgotten
1976 124 Spider..the self-healer
2001 BMW 328ci daily driver and track car
Fling It Around Turns !
Post Reply