1Blue720 Posted August 28 Report Share Posted August 28 Hey! I've found these forums to be super helpful in the past, so I thought I'd make a post. I've got an '86 720 (blue exterior and interior) but recently it has been a little funky. Usually, it warms up at around 2k rpms, then drops to around 700-800 for it's normal idle. The past couple days, it just won't drop from the 2k rmps. I've driven it around the past couple days and other than that it's been fine. For a bit of background, it's got about 241,000 miles on it and I (and the previous owner) use it as a daily driver. I just replaced the head gasket a few weeks ago as well as thermostat, thermostat gasket, exhaust manifold gaskets, and intake gasket. I did the oil pan gasket a while back and it has a new clutch too. It's been running super smooth up until this point, and still runs and drives. Thank you so much! Quote Link to comment
720_Jeff Posted August 28 Report Share Posted August 28 Thinking, most will want to know the answers to these questions. Air cleaner, has one or two wing nuts/fasteners on the top, or just one in the center, assuming the original air cleaner is on there. Does it have a weber? One wing nut/fastener in the center of the air cleaner lid, at least, original carburetor style carburetor. Could have been replaced with a cheap chinese knockoff. Two wing nuts/fasteners, probably TBI Looking at your vehicles in the profile section, this maybe a 4x4? I believe most '86 4x4's, at least the ones I've seen, are the Throttle Body injection. I think those are at least some of the preliminary questions folks will ask, before making too many suggestions. Quote Link to comment
1Blue720 Posted August 28 Author Report Share Posted August 28 Yes, it has the original air filter (one wingnut) but not original carb. I'm not sure what carb is on it, the previous owner replaced it and I don't have many details. It's also had an EGR delete (by previous owner). I've been thinking of upgrading it to a Webber but haven't gotten around to it yet. I messed with the carb a little bit after putting it back on when I did the head gasket, but it's been running just fine up until now. It is a 4x4 and 2.4L engine - I should have included that in the original post. Quote Link to comment
datzenmike Posted August 28 Report Share Posted August 28 1/ Warm it up and take the top off the air filter and look. The choke flap should be vertical and fully open like this... Not partly closed or fully closed... 2/ Have a look at the fast idle cam when warmed up. If it's in this position hold the throttle at lease 1/2 open and use a pencil to push and rotate it clockwise. If it simpy stuck this should dislodge it. 3/ use a flashlight and look down the secondary and see if the throttle plate is fully closed. It should be but a piece of almost anything may have blocked it from closing fully. 4/ Find the BCDD on the valve cover side of the carburetor. It's the protruding roundish thing with 6 Phillips head screws. In the center is a rubber plug. Remove it and turn the screw under it counter clockwise 2 full turns. Take for a drive see if the idle lowers. If no change return the BCDD 2 turns clockwise. 3 Quote Link to comment
1Blue720 Posted August 29 Author Report Share Posted August 29 4 hours ago, datzenmike said: 1/ Warm it up and take the top off the air filter and look. The choke flap should be vertical and fully open like this... Not partly closed or fully closed... 2/ Have a look at the fast idle cam when warmed up. If it's in this position hold the throttle at lease 1/2 open and use a pencil to push and rotate it clockwise. If it simpy stuck this should dislodge it. 3/ use a flashlight and look down the secondary and see if the throttle plate is fully closed. It should be but a piece of almost anything may have blocked it from closing fully. 4/ Find the BCDD on the valve cover side of the carburetor. It's the protruding roundish thing with 6 Phillips head screws. In the center is a rubber plug. Remove it and turn the screw under it counter clockwise 2 full turns. Take for a drive see if the idle lowers. If no change return the BCDD 2 turns clockwise. Thank you so much Datzenmike!!! I'll give this a try and let you know how it goes! Quote Link to comment
1Blue720 Posted September 3 Author Report Share Posted September 3 On 8/28/2024 at 1:22 PM, datzenmike said: 1/ Warm it up and take the top off the air filter and look. The choke flap should be vertical and fully open like this... Not partly closed or fully closed... 2/ Have a look at the fast idle cam when warmed up. If it's in this position hold the throttle at lease 1/2 open and use a pencil to push and rotate it clockwise. If it simpy stuck this should dislodge it. 3/ use a flashlight and look down the secondary and see if the throttle plate is fully closed. It should be but a piece of almost anything may have blocked it from closing fully. 4/ Find the BCDD on the valve cover side of the carburetor. It's the protruding roundish thing with 6 Phillips head screws. In the center is a rubber plug. Remove it and turn the screw under it counter clockwise 2 full turns. Take for a drive see if the idle lowers. If no change return the BCDD 2 turns clockwise. I think I've got it pretty much fixed!!! The fast idle cam gets stuck every once-and-a while but it's going like it usually does! Thank you Datzenmike!! Quote Link to comment
datzenmike Posted September 3 Report Share Posted September 3 Spray it down with WD-40. 1 Quote Link to comment
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