mx71 Posted October 3, 2017 Report Share Posted October 3, 2017 I went to get my 85 KC 4x4 smogged, and it didn't pass. Apparently it's missing an air injection pump and it was high on CO emmissions. 1. What's an air injection pump, and why would someone remove it? Also, where can I get one? 2. What would cause CO emissions to be high? Max is 1.2, and it tested at 7.5 on high idle. 1 Quote Link to comment
G-Duax Posted October 3, 2017 Report Share Posted October 3, 2017 The smog pumps blew air into the exhaust manifold to help burn up any unburned fuel. They were crap, as was the whole concept, and thankfully modern cars (and really old ones) don't have that crap. If your 720 has a carb, check it for too high of fuel level, causing an over rich mixture at idle. When was the last time you did a good tune up? Plugs, rotor & cap, plug wires, etc.. My late 86 had fuel injection, so no damn smog pump. 1 Quote Link to comment
flatcat19 Posted October 3, 2017 Report Share Posted October 3, 2017 CO emissions being high is normally from a running rich condition. How are your ignition parts? Lean out fuel mixture to pass after knowing you have good spark. 1 Quote Link to comment
racerx Posted October 3, 2017 Report Share Posted October 3, 2017 I went to get my 85 KC 4x4 smogged, and it didn't pass. Apparently it's missing an air injection pump and it was high on CO emmissions. 1. What's an air injection pump, and why would someone remove it? Also, where can I get one? 2. What would cause CO emissions to be high? Max is 1.2, and it tested at 7.5 on high idle. ...smog pump. 1 Quote Link to comment
racerx Posted October 3, 2017 Report Share Posted October 3, 2017 I went to get my 85 KC 4x4 smogged, and it didn't pass. Apparently it's missing an air injection pump and it was high on CO emmissions. 1. What's an air injection pump, and why would someone remove it? Also, where can I get one? 2. What would cause CO emissions to be high? Max is 1.2, and it tested at 7.5 on high idle.[/...u in Calif? If failed don't u have to take to a ref? 1 Quote Link to comment
G-Duax Posted October 3, 2017 Report Share Posted October 3, 2017 He's in Idaho. OP, You look to have a Cressida, right ? 1 Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 I haven't done a tune up, but this truck had been cared for. All the wires/distributor cap look recent, and the plugs look good. It's possible it's running rich as it smells rich idling. How ouwld I check the fuel level? Is there a float adjustment? Are there jets to adjust? It's an early Motorcraft carbed, which is essentially a Holley made licensed version of the Weber 32/36. G-Duax..Cressida? You mean a Toyota Cressida? What do you mean by that? 1 Quote Link to comment
racerx Posted October 4, 2017 Report Share Posted October 4, 2017 He has a 85 kc 4 x 4, not cressida 1 Quote Link to comment
flatcat19 Posted October 4, 2017 Report Share Posted October 4, 2017 Mx71 is the body code of one generation of Cressida. 1 Quote Link to comment
datzenmike Posted October 4, 2017 Report Share Posted October 4, 2017 The Z series engines in the 720 did not use an air pump. So who ever told you that is wrong. Instead one, or in the case of the 4x4s, two pipes were run from the exhaust manifold to the air filter. At the air filter end are one way reed valves. Each exhaust pressure wave is followed by vacuum wave. The vacuum waves are used to suck in air through the reed valves which prevent reversal of flow. The oxygen rich exhaust is then fed through the catalytic converter and 'burned'. High CO levels means your choke may not be shutting off. You mentioned a fast idle? When warmed up you should not have a 'fast idle'. When warmed up take the top[ off the air filter. The choke plate should be fully open like this... not like this or part way.... 1 Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 It doesn't idle high, I just failed the CO limit on high idle, or around 2500 rpm. It passed on regular idle. One thing I did when I bought it was that I had hooked up a wire from the choke to the idle cut circuit which is always on, so maybe that's my only problem?I hope it's that simple. It's at a shop right now, so I left a message for them to check on the choke and not having an injection pump. 1 Quote Link to comment
datzenmike Posted October 4, 2017 Report Share Posted October 4, 2017 If idle passed then not the choke. One or two wing nuts holding the air filter on??? If one wingnut, do you have an O2 sensor in the exhaust manifold? 1 Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 Haha, the air filter is rigged. It’s essentially an air filter housing with a round air filter zip tied to the carburetor. I think it’s essentially the Weber set up without the metal clips. https://imgur.com/gallery/13VHu 1 Quote Link to comment
datzenmike Posted October 4, 2017 Report Share Posted October 4, 2017 There's your problem. The AIS is gone. Plus who knows what jets the Weber is using. The Z24 engine is pretty clean running if everything is on and working. 1 Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 What’s the AIS? Air injection system? Is that what that open port is on the front? 1 Quote Link to comment
datzenmike Posted October 4, 2017 Report Share Posted October 4, 2017 No I already explained how it works on the stock air filter. You no longer have this. 1 Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 Gotcha. Also, I do have an O2 sensor on the lower end of the exhaust manifold, yes. 1 Quote Link to comment
datzenmike Posted October 4, 2017 Report Share Posted October 4, 2017 Well that question was before it was known that you don't have the stock carburetor. Doesn't matter now. That Weber is going to have an impossible time trying to get the same emission readings as the stock (electronically controlled carburetor) ECC system carburetor. The ECC system uses a solenoid main jet that varies the air/fuel mixture to keep it near stoichiometric or (14.7) tightly controlled by feedback from the O2 sensor. 1 Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 If the diagnosis doesn’t look good, do you think I’d be better off getting a Hitachi on eBay for it? Quote Link to comment
datzenmike Posted October 4, 2017 Report Share Posted October 4, 2017 Depends on the smog check. If it has to be stock then it has to be. If it has to pass a visual it has to be. Get one from another '85 720 in a wrecking yard. Quote Link to comment
racerx Posted October 4, 2017 Report Share Posted October 4, 2017 Did it pass before? What was done different? New carb? If new weber, I don't think they will pass. Heard there's no more smog legal 32.36 weber. 1 Quote Link to comment
Charlie69 Posted October 4, 2017 Report Share Posted October 4, 2017 Well that question was before it was known that you don't have the stock carburetor. Doesn't matter now. That Weber is going to have an impossible time trying to get the same emission readings as the stock (electronically controlled carburetor) ECC system carburetor. The ECC system uses a solenoid main jet that varies the air/fuel mixture to keep it near stoichiometric or (14.7) tightly controlled by feedback from the O2 sensor. My Weber 32/36 passes emisions fine every 2 years on my 86 720 2wd. But mine is a real Weber and I still use the EGR during emission testing. I can not help you trouble shoot the Motorcraft carb. Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 I've only had this for a few months. No idea if it passed before. If you spend at least $300 in emissions related repairs (other than re-installing parts that have been removed such as air injection pump or EGR valve), then you qualify for a waiver. This is the first emissions test I've done since I've had it and they're required every two years. It does appear to still have the EGR. 1 Quote Link to comment
datzenmike Posted October 4, 2017 Report Share Posted October 4, 2017 Check the wrecking yards for another '85 and collect al the missing parts. 2 Quote Link to comment
mx71 Posted October 4, 2017 Author Report Share Posted October 4, 2017 No 720 in wrecking yards here. There's only a few wrecking yards within 50 miles of here, and people tend to drive cars here in Idaho until they won't drive anymore, and just about nobody lives here, so it would have to be eBay. 1 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.