720_KID Posted October 13, 2013 Report Share Posted October 13, 2013 Alright first off, i have an 86 720 TBI. the problem here is that when i start up my truck it idles at 3k then it slowly start to rev higher and higher. i checked if anything was disconnected on the throttle body but it was all connected properly. started it again and it still was idling high. I honeslty dont know what can be the problem causing this, anyone know what it might be? Quote Link to comment
jesusno2 Posted October 13, 2013 Report Share Posted October 13, 2013 Air leak somewhere or the idle controller is stuck. Quote Link to comment
720_KID Posted October 13, 2013 Author Report Share Posted October 13, 2013 I just checked the computer for codes because the sensor light was on, and i got two codes 12 & 24, i don't know what they are because the sticker was ripped of the computer. Quote Link to comment
datzenmike Posted October 13, 2013 Report Share Posted October 13, 2013 12 ..... afm air flow meter 24...... neutral and clutch inhibit. Quote Link to comment
720_KID Posted October 13, 2013 Author Report Share Posted October 13, 2013 so im guessing its code 12 then huh. where would that sensor be located at? Quote Link to comment
datzenmike Posted October 13, 2013 Report Share Posted October 13, 2013 It's on the throttle body. I would check that the throttle cable is not too tight or that it is returning fully to the idle position. Quote Link to comment
720_KID Posted October 28, 2013 Author Report Share Posted October 28, 2013 Well it turns out it was the whole throttle body that was causing the high idle. But I encountered a new problem now. It was driving fine for a week until I turned it off and I tried to turn it back on but it just wouldn't fire up. I noticed that the fuel pump relay didn't kick in. I tested the relay and apparently it was in good working condition. I honestly don't know what to do now. Any suggestions? Quote Link to comment
elmerfudpucker Posted October 28, 2013 Report Share Posted October 28, 2013 Before you got started, did you go thru and clean all your grounds and fuse box? Quote Link to comment
DaveZilla Posted October 28, 2013 Report Share Posted October 28, 2013 I'd also agree to check your wiring connectors, a loose or dirty connector can really mess things up... not to mention it sux to go out and buy what you think will fix it just to find out it's doing the same thing still... Quote Link to comment
720_KID Posted October 28, 2013 Author Report Share Posted October 28, 2013 I removed every fuse and relay I could find to check if they were ok and they were, but I didn't clean them. I have not checked the grounds, I will get to that later on today. Quote Link to comment
elmerfudpucker Posted October 28, 2013 Report Share Posted October 28, 2013 Grounds, that is the fun part, I will be going thru all connections this winter, most issues will correct themselves after that, or at least give you a clean slate to help chase them down. Quote Link to comment
datzenmike Posted October 28, 2013 Report Share Posted October 28, 2013 Well it turns out it was the whole throttle body that was causing the high idle. But I encountered a new problem now. It was driving fine for a week until I turned it off and I tried to turn it back on but it just wouldn't fire up. I noticed that the fuel pump relay didn't kick in. I tested the relay and apparently it was in good working condition. I honestly don't know what to do now. Any suggestions? . The front of the carb has a small round window to show the fuel level. Simply look and see it you are getting gas. Pul a plug and stick an old plug in the end. Lay on a grounded surface and watch while you crank. Does it spark? Quote Link to comment
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