Brad Huff

I purchased 2 of these V8 Miatas 2 summers ago. They are both 5.0 conversions with slightly hopped up engines that were built using Martin's design. One of them has the fuel pump circuit under the control of the Ford ECU. The other one, I shall call the "Red Car", was wired as per Martin's conversion manual. In other words, the fuel pump runs any time the key is on. Just like the old days with carbureted engines and electric fuel pumps. I have decided to rewire it so it too will be under control of the Ford A9L based ECU. In preparation I connected my breakout box and checked for voltage between pins 37 and 22. I do have proper voltage there. The problem is is that there is voltage there all of the time. From what I understand the voltage should be present initially for a couple of seconds and then disappear if the engine does not start. This is basically a priming function. I have checked for the usual problems with circuit traces and have replaced all three electrolytic capacitors on the board. The problem still persists. I have previously posted about this and have gotten 2 responses for which I am grateful. Before I throw in the towel on this computer I am wondering if I should try to reflow the solder joints. I did some resistance checks between the base of the capacitors and a point on the associated traces and from what I can see everything is ok. However, I realize that this is a multi layered board. I suppose that it is possible that there might be insufficient solder flow to the middle sections. Should I reflow my solder joints or just replace the ECU? I have a "Hickock 453 TFI Intermittent Ignition Analyzer" that is also showing a flickering "No Computed Advance" led. It does not seem to vary with RPM. Don't know for sure but I wouldn't guess that is normal either. Sorry for the long winded post but I wanted to give as much information as possible. -Brad

Brad Huff

Ok guys. Here is a response to my issue. A guy from the EEC.org forum gave me something to go on so I thought that I would repost it here for those that may have similar problems in the future. The voltage checks with a DVOM between pins 37 and 22 gave me a false reading. Apparently there is insufficient circuit loading from the DVOM to accurately read the situation. I got the reaction that I was hoping for when I wired my low voltage test light to pins 37 and 22. The ECM provides the proper priming voltage and then shuts off as it should. So much for always using a higher impedance meter to check a circuit. The low impedance test light saved the day. The fuel pump relay coil will be similar. Now to rewire the setup. Right now this car has Martin's jumpered fuel pump circuit.