Rembrant Posted January 20, 2019 Share Posted January 20, 2019 He hasn't said what engine he has so could it be the choke relay for a 351 4V engine? the 1986 EVTM shows a group of relays in the 5.8L 4V carburetor circuits but isn't clear on their locations. I think Lebaron nailed it... If you do a search on choke relay, a couple different old threads pop up, and they're all in reference to a 351 4bbl engine... Pics of the same relay in this thread below: https://www.ford-trucks.com/forums/1146787-carb-choke-problems-2.html Link to comment Share on other sites More sharing options...
donaldb Posted January 20, 2019 Author Share Posted January 20, 2019 I think Lebaron nailed it... If you do a search on choke relay, a couple different old threads pop up, and they're all in reference to a 351 4bbl engine... Pics of the same relay in this thread below: https://www.ford-trucks.com/forums/1146787-carb-choke-problems-2.html Interesting, the factory carb has been replaced with a regular Holley, requiring 12v for the choke. The relay in question I would guess with pretty good confidence is factory since it is using the same color and shape rivet to hold it on as the other one. If it warms up in Missouri today I'll see if I can get the wire colors. Thanks all who commented. Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 20, 2019 Share Posted January 20, 2019 I think Lebaron nailed it... If you do a search on choke relay, a couple different old threads pop up, and they're all in reference to a 351 4bbl engine... Pics of the same relay in this thread below: https://www.ford-trucks.com/forums/1146787-carb-choke-problems-2.html First, what do those yo-yos on FTE know? Oh wait! I recognize some of them. Ok, so it is probably the choke relay, although there does seem to be some discrepancy with the wire colors - both in the FTE thread as well as here. Further, the EVTM contradicts itself. The schematic above is from the 1985's page for 5.8L carb circuits in the Electronic Engine Controls section. Note that it says the connection goes to Page 15. The schematic below is from Page 15, and it clearly says only the 4.9L engines have a connection to the carb circuits on the Electronic Engine Control page. All else go directly to the choke. Hmmm, can't be both ways. But, let's assume that's what it is. Then why is the relay buzzing? I'd say there's a problem with the alternator's stator output. If you look at the schematic you'll see that the stator isn't grounded, and that it relies on the diodes. I think one or more of the diodes are blown. Link to comment Share on other sites More sharing options...
donaldb Posted January 20, 2019 Author Share Posted January 20, 2019 First, what do those yo-yos on FTE know? Oh wait! I recognize some of them. Ok, so it is probably the choke relay, although there does seem to be some discrepancy with the wire colors - both in the FTE thread as well as here. Further, the EVTM contradicts itself. The schematic above is from the 1985's page for 5.8L carb circuits in the Electronic Engine Controls section. Note that it says the connection goes to Page 15. The schematic below is from Page 15, and it clearly says only the 4.9L engines have a connection to the carb circuits on the Electronic Engine Control page. All else go directly to the choke. Hmmm, can't be both ways. But, let's assume that's what it is. Then why is the relay buzzing? I'd say there's a problem with the alternator's stator output. If you look at the schematic you'll see that the stator isn't grounded, and that it relies on the diodes. I think one or more of the diodes are blown. Gary think you are right about the diodes. Is the diode set replacable on Gen 1 alternators? Thanks Link to comment Share on other sites More sharing options...
Gary Lewis Posted January 20, 2019 Share Posted January 20, 2019 Gary think you are right about the diodes. Is the diode set replacable on Gen 1 alternators? Thanks Yes, it is. But you might want to upgrade to a 3G. Link to comment Share on other sites More sharing options...
vjsimone Posted January 21, 2019 Share Posted January 21, 2019 Gary think you are right about the diodes. Is the diode set replacable on Gen 1 alternators? Thanks donaldb, photo those wires and connector if you can. Link to comment Share on other sites More sharing options...
donaldb Posted February 2, 2019 Author Share Posted February 2, 2019 donaldb, photo those wires and connector if you can. Finally warmed up to get out there and look at it. It is exactly as Gary's wiring diagram shows above. 2 black ground wires, Yellow, gray with with white, and white with black. Thank you all for the help Donald Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 2, 2019 Share Posted February 2, 2019 Finally warmed up to get out there and look at it. It is exactly as Gary's wiring diagram shows above. 2 black ground wires, Yellow, gray with with white, and white with black. Thank you all for the help Donald Welcome. Have you figured out why the relay was buzzing? Link to comment Share on other sites More sharing options...
donaldb Posted February 7, 2019 Author Share Posted February 7, 2019 Welcome. Have you figured out why the relay was buzzing? As you said alternator. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 7, 2019 Share Posted February 7, 2019 Welcome. Have you figured out why the relay was buzzing? And, more specifically, blown diodes. That would give alternating current to the relay's coil, causing it to alternately pull in and then drop out, creating a buzz. Thanks for confirming the theory. Link to comment Share on other sites More sharing options...
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