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mphilleo

New 720 Owner in Need of Help with High Idle

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The 80 model is wired differently. I think power for the choke heater comes from the farthest left hand side of the fuse box. The rear most one. 

 

The choke heater relay needs a charging alternator to send that power to the choke heater. If low alternator output, the relay usually buzzes. The choke heater is located up under the dash on the passenger side just above the kick panel.

 

 

If you can't find or fix the problem just connect the Blue choke heater wire to the Red idle cut wire at the carburetor. The idle cut is switched on and off by the ignition so it will work the same.

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Thanks Mike, you sure know these things. Boy what a complicated choke!  Tempted to hook up a cable..The idle cut wire is also referred to as anti dieseling wire I believe, it's the only other wire at the carb and I did jumper to it yesterday when testing.  I'm away from the truck now but I don't recall any fuse in the rearmost slot, and I also looked between the glove box and kick panel and didn't see any relays.  I'll have another look on Tuesday.  Thanks and Happy New Year!

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The '80 was a one off 720. There is a lot of differences to the '81 and up including the fuse box.

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Hi Mike. Got to work on the 720 today. Running pretty well with the choke wire jumpered to the idle wire. I have power to that rearmost fuse but still can't locate the relay. Nothing above pass kick panel. I read something about one being behind the glove box or console? Like to find it.

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Progress!  I bought a factory, 1980 only 720 service manual.  The choke relay is one of the two attached to the fuse panel, and the fuse is indeed the rearmost.  What I found was, the previous owner added an electric fuel pump (the mechanical one is still on the engine, disconnected), and ran it off of the input wire to the choke relay, thereby disconnecting power to the relay.  I jumpered it back and got power to the choke.  The remaining question is: should I power the fuel pump like it was (straight off the 10 amp relay fuse), or splice into the blue choke wire (thereby sharing the relay with the choke), or from another location?  

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Yea I see a lot of unplugged holes and missing lines. I would suggest finding a donor or parts car and put it back together because you still have stock carb. or weber and remove. If you look at my 85' fuel issue post. we kinda went over most of the lines and i have many pics posted.

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Use you 1980 Factory Service Manual (FSM) as the 85 post will be completely different.  Different engines and carbs not to mention wiring vaccum diagrams.  It is like Mike said 1980 720 is a 1 off.

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