6 Star Posted October 26, 2022 Share Posted October 26, 2022 Vehicle: 1986 Subaru GL Wagon, Dual Range 5 Speed, Carbureted, Weber 32/36 Converted Issue: No longer getting Fuel Pump Signal to the Pump. It would be intermittent, but now seems to be consistent with getting no Signal. I've heard from @Gloyale that the 6 pin Fuel Pump Controller (Relay) only sends power to the pump when there is a Tachometer Pulse on the yellow wire... Is that Signal originated from the Distributor? Also I've heard from @GeneralDisorderin regards to the Controller, that: "The wire going to the pump is usually a blue with red stripe. The control unit will also have a yellow tach signal, black ground wire, and an ignition hot supply (white I think)." Background: The problem began intermittently... if I had an issue with the pump, I could either add Fuel directly to the carburetor to prime the system. Or, I could apply power directly to the Fuel Pump to also Prime the system. Occasionally I would have to do both in order to get the vehicle to run. Once the pump was working, it would not cut-out mid-trip. Not until the vehicle was turned off and then tried to be re-started later; would an issue happen, where I would have to do one off the pre-mentioned priming methods. Now the pre-mentioned priming methods no longer work... What kind of tests can I do to see what needs replacing? I'd like to have the wiring stay this way it was from the factory... however if not I could wire the fuel pump to a switch, racecar style... I'm not sure though; does the tach Signal increase/decrease pump speed based on engine speed? Thanks for reading, hope to keep my Wagon on the Road! Link to comment Share on other sites More sharing options...
el_freddo Posted October 28, 2022 Share Posted October 28, 2022 The fuel pump doesn’t change speed with engine loads. The tacho signal is from the dizzy, most likely a yellow wire. Check your fuses! If the fuse is good I’d be testing to see if the engine runs with a fused wire directly to the pump. If this works there’s possibly an issue with the “magic box” under the dash that gives power to the pump. If the engine won’t run but the fuel pump works with the direct power trick then it’s most likely a dead ignition module in the dizzy. Also a good idea to test the coil as when these die they also kill the ignition module. Cheers Bennie Link to comment Share on other sites More sharing options...
6 Star Posted October 28, 2022 Author Share Posted October 28, 2022 Thanks for the reply Bennie, I will have to do some more tests; but the fuel pump does still work when direct power is applied to it. (I take a 12v battery and use jumper wires directly to the connector at the pump.) If I prime the pump long enough it will send enough fuel up to the carb to run the engine for 30 seconds to a minute or so. During that time I'll listen to the Fuel Pump (which I hooked back up to the harness) however the pump is silent and not pumping, and the engine will shut down once out of fuel. I could try an ohms (resistance) test on the coil, however it seems to produce enough spark to run the engine... In the past I traded out my distributor for one from a parts vehicle, because the car would randomly die once warmed up. It was probably also related to the ignition module in the distributor. The "new" distributor cured that problem for the years since then, however now this one must be acting up now too. More testing to come! 1 Link to comment Share on other sites More sharing options...
el_freddo Posted October 29, 2022 Share Posted October 29, 2022 It sounds to me like there’s a wiring issue at play or the magic box is dead. Any rats or mice been active in the Subi? Cheers Bennie Link to comment Share on other sites More sharing options...
6 Star Posted October 31, 2022 Author Share Posted October 31, 2022 No mice activity that I could tell @el_freddo Wish I had more to report however life has been crazy for me at the moment, only have had time to do the minor upkeep on my hatchie to keep her on the road lately. She's the daily right now 1 Link to comment Share on other sites More sharing options...
6 Star Posted November 24, 2022 Author Share Posted November 24, 2022 @el_freddo What size fuse would be acceptable to run the fuel pump directly with a switch? Going to go that route until I can figure out the replacement of the oem electricals. Would it be a 15 Amp? Most of the fuses in the fuse box are that size... Link to comment Share on other sites More sharing options...
el_freddo Posted November 24, 2022 Share Posted November 24, 2022 I’d run a 15amp if it were me. You could try a ten amp and see what happens… Cheers Bennie Link to comment Share on other sites More sharing options...
6 Star Posted November 25, 2022 Author Share Posted November 25, 2022 7 hours ago, el_freddo said: I’d run a 15amp if it were me. You could try a ten amp and see what happens… Cheers Bennie Great minds think alike. I had an inline fuse holder, and it happened to have a 10 Amp fuse inside already. I set everything up and it's working like a charm, idling in the driveway. Will go on some test runs and bring some extra fuses and tools along just in case. 1 Link to comment Share on other sites More sharing options...
6 Star Posted November 28, 2022 Author Share Posted November 28, 2022 Update: I've taken the Wagon up to the Mountains, and to Work. So far the new set up with the fuel pump wired to a manual switch is working well. 1 Link to comment Share on other sites More sharing options...
el_freddo Posted November 29, 2022 Share Posted November 29, 2022 Now to work out what’s dead in the factory system and revert back to it for the built in fuel cut safety system in the event of a crash occurring. Glad to hear you’re mobile again though! Cheers Bennie 1 Link to comment Share on other sites More sharing options...
azdave Posted November 29, 2022 Share Posted November 29, 2022 A 10-amp fuse should be more than ample reserve for running the size pumps we use but the fuse is there to protect the wiring so don't run a 15 amp if the wire isn't rated for more than 10. My pump pulls about 4 amps. As for safety after a mishap, I often find it simpler to use an inertia switch to disable the pump in a crash. They are all over eBay for $10-$20. Just don't mount the switch where no one will ever think to look for it like Ford did for many years. In more modern vehicles, those impact switches are all part of the airbag/crash protection modules and can't easily be used like the style below. 1 Link to comment Share on other sites More sharing options...
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