Pharaohabq Posted December 31, 2013 Share Posted December 31, 2013 Wow, have you tried lifting the flapper in the AFM to see if it'll turn on the Fuel pump? You should be able to hear it. I believe this is in the FSM... Quote Link to comment Share on other sites More sharing options...
Nightmare_Fairlady Posted January 1, 2014 Author Share Posted January 1, 2014 When it comes to electrical I honestly have no idea what to do, what do I need to check? Do I use a multimeter? Does the ecu need to still be hooked up while im testing? Quote Link to comment Share on other sites More sharing options...
superlen Posted January 2, 2014 Share Posted January 2, 2014 Nightmare, All you need to troubleshoot the fuel pump circuit is a multimeter, a jumper wire, and a copy of the schematic from the FSM. I've been designing an LJet digital/tuneable replacement ECU (HellFire) & have been wading through the FSM with regards to the ECU wiring/fuel pump workings so hopefully I can steer you in the right direction. First, The best page to find in the FSM is page EF-33. It's in the "Engine Fuel" section not the wiring diagrams section and it contains figure EF-45. If you have a paper copy, great, but if you are working from the pdf, search for EF-45 and you should come up with it. The fuel pump circuit for the early Zs isn't rocket science, but it's not straight forward either & it takes a bit of studying to get it clear in your head. All my notes below will refer to this page, so go find it first. For testing the FP circuit you can either have the ECU connected or not. The stock ECU does not control *any* part of the fuel pump circuit!! Strange isn't is? When you look at the schematic you will see a wire running to the ECU that *could* control the FP Relay but it's not even connected inside the stock unit. I think Bosch engineers had plans to use it, but never did. Anyway, don't get mislead by that wire. Just ignore it. FYI that wire runs to pin 20 on the ecu. Here are some key points to know: - The pump is only controlled by the FI Relay. - The FI Relay actually has two "relays" in it. Two coils, two contacts. They are both just housed in the same metal can and collectively called the FI Relay. - Two events can cause the pump to run. Either the key has to be in "start" position, or the key is on "run" and the AFM Vane is moved off of rest due to airflow. - Power to the FI relay comes from a fusible link which as we all know get flaky with age as the contacts corrode. It's always a good idea to verify your F' Links. Here's a cut/paste from a discussion where there are lot more details as we were troubleshooting the FI relay. There's more theory in that link, but the section below is a good easy first test procedure for you to follow. 1. With the key OFF. (note, it says OFF)2. Jumper +12V to P74 (pump should run - as P74 is the actual wire going to + side of pump)3. Jumper +12V to P36 (pump should run ) - tests one of internal coil/ contacts of relay4. Jumper +12V to P39 & Move AFM flap off idle (pump should run) - tests AFM contacts5. Now turn key ON & Move AFM flap off idle (pump should run) - tests the second internal coil/contact. 6. Now turn key to START (don't care about flap) (pump should run) - this tests the start switch it'self and the connection to the Relay. Hope this was helpful. Lenny Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.