Sean092 Posted March 9, 2017 Report Share Posted March 9, 2017 I'm new to this forum I've been reading around to see if anyone happened to have the same issue I'm having but haven't had much luck I recently bought a 85 720 2wd and it ran ok but started having problems idling it funds fine when cold but after it warms up it will die unless I keep my foot on the gas I turned up the idle speed to keep it running but now it idles pretty high then drops down when warmed up it runs but not well I've replaced my fuel filters made sure the choke is working right and checked to make sure the fule cut off solenoid has power but its wired funny and I'm not sure exactly where it is so posed to be wired to does anyone have any ideas on what to could be going on? Quote Link to comment
datzenmike Posted March 9, 2017 Report Share Posted March 9, 2017 Do you have an O2 sensor in the exhaust manifold? Turn ignition on off on and off (don't start). Listen near the carb you should hear a soft click from the idle cut solenoid. This would shoe that it's getting power ... at least. Quote Link to comment
Sean092 Posted March 9, 2017 Author Report Share Posted March 9, 2017 I believe so but I'm not positive I'm pretty new to this there was something in the manifold but the wire was cut Quote Link to comment
Sean092 Posted March 9, 2017 Author Report Share Posted March 9, 2017 I checked the solenoid and it clicks and I've also tested it with a light tester to make sure Quote Link to comment
datzenmike Posted March 9, 2017 Report Share Posted March 9, 2017 If you have a non operating O2 sensor then the mixture cannot be regulated with feedback from it when the engine is warmed up. When the engine is cold it runs in open loop mode. This is a pre set mixture for warm up. When warmed up the O2 sensor detects the oxygen content in the exhaust and the ECU adjusts the carb to tightly control the mixture. This is called closed loop operation. Quote Link to comment
Sean092 Posted March 9, 2017 Author Report Share Posted March 9, 2017 Ok I have a book on the truck but sadly can't find it what wire does the o2 sensor connect to? Quote Link to comment
datzenmike Posted March 9, 2017 Report Share Posted March 9, 2017 I think it's a Green wire that eventually ends up into the ECU under the drivers seat. If disconnected it needs to be connected. Quote Link to comment
Sean092 Posted March 9, 2017 Author Report Share Posted March 9, 2017 Ok thank you I'm not sure that there is anything under either of the seats but I guess I could double check Quote Link to comment
datzenmike Posted March 9, 2017 Report Share Posted March 9, 2017 Does the carb have a round electrical connector with about 6 wires? If so you have the ECC carb with O2 sensor. Quote Link to comment
Sean092 Posted March 9, 2017 Author Report Share Posted March 9, 2017 Yes I have an ecc I should have mentioned that Quote Link to comment
datzenmike Posted March 9, 2017 Report Share Posted March 9, 2017 The connector is thought to be problematic with the wires breaking internally and loosing connection. Sometime wiggling the connector makes the connection and it improves the idle. Narrows the problem down. Quote Link to comment
Sean092 Posted March 9, 2017 Author Report Share Posted March 9, 2017 Ok I can try that does the connector serve a specific purpose or would I be able to remove it and just solder the wires together? Quote Link to comment
datzenmike Posted March 10, 2017 Report Share Posted March 10, 2017 You couldn't remove the carb if you did that. I'm saying it's a possible source of problems. Quote Link to comment
Sean092 Posted March 10, 2017 Author Report Share Posted March 10, 2017 That's a good point I have a 84 that I'm using as a parts truck that has a Webber in not sure on the model but would there be any benefits on swapping them? Quote Link to comment
datzenmike Posted March 10, 2017 Report Share Posted March 10, 2017 I'm not partial to the ECC... to complex, too much can go wrong and too hard to figure out and fix. All you need is the power for the choke heater and idle cut if it has it. Quote Link to comment
Sean092 Posted March 10, 2017 Author Report Share Posted March 10, 2017 That's for the ecc right?or the Webber? Quote Link to comment
datzenmike Posted March 10, 2017 Report Share Posted March 10, 2017 I assume the Weber on the '84 has and electric choke? connect to the BLUE wire If it has an idle cut solenoid, connect that up to the RED wire. Quote Link to comment
Sean092 Posted March 10, 2017 Author Report Share Posted March 10, 2017 Yes it has an electric choke and ok thank you I'll try swapping them out and see what happens Quote Link to comment
Sean092 Posted March 10, 2017 Author Report Share Posted March 10, 2017 Do you know of a site with a vaccume line diagram? Or do you possibly have one? Quote Link to comment
datzenmike Posted March 10, 2017 Report Share Posted March 10, 2017 Only have the '84 from the FSM. Quote Link to comment
Sean092 Posted March 10, 2017 Author Report Share Posted March 10, 2017 Ok thank you Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.