86 Cherokee w/ 2.8L Where do I connect to diagnostics?

I was given a 1986 Jeep Cherokee w. 2.8L v6 and was told it was in perfect condition. They were wrong. It was a mess. It got 9 mpg, dash wireing had been cut and spliced incorrectly, vacuum lines leaked or were plugged and there was sand in the fuel bowl of the carb. It had a current inspection sticker, but I highly suspect it was bought illegally. Needless to say, when I attempted to get it inspected, it flunked inspection miserably. Since then I have fixed the above list of problems, and after I rebuilt the model 2SE Rochester carb. it runs smooth, but I still smell strong gas fumes under the hood and while driving with the A/C on and it still only gets 10 mpg. One side of the purge canister smells of gas fumes, but there is no liquid in it. I need do a diagnosis of the engine. The Jeep repair manual talks about a D1 and D2 plug either on the firewall or LH fenderwell on California engine, but this is not the California version, and I can find nothing there to connect to. I also do not know if there is an OBD1 connection somewhere on the vehicle. I read about using the check engine light to get a code, but I can not find anything in the Jeep manual as to where the check engine light is located. I replaced all the instrument/dash lights and nothing lights up when the key is turned to the on position except the seat belt light and clock. 1. Could someone tell me where the check engine light is supposed to be? 2. Where do I connect to do a diagnostic on this Cherokee and what do I use to test it. 3. Where is the o2 sensor. The book mentions removing the o2 sensor before removing the exhaust manifold on a 4 cyl engine, but says nothing about the O2 sensor on a 2.8 V6. One mechanic told me it looked like it may not have an O2 sensor, but the auto parts house had one in stock when I gave my make and model to them. I have been all over the exhaust manifold and tail pipe and found no O2 sensor. I have also look on the firewall and fenderwells for a D1 or D2 connection, but found none...or am I suppose to use a OBD1 tester and connect somewhere else? Any help would be much appreciated. My inspection sticker ran out and I want to be sure everything is right before I try again for an inspection sticker. Thanks and God bless. James G.

The check engine light should be on in the dash when u turn the car on for a few seconds. possibly when u rewired everything, the bulb might have shorted out or who ever gave it to you purposly burnt it out to geta current inspection sticker. as far as codes and such, i know nothing, but i do know that if the engines vac lines arn't hooked up right or they leak, it will run aweful and have very poor milage. good luck with that! john

ok I have one of these.

There is no on board computer. Everything is hard wired.


No O2 Sensor either. To diagnosis this year you have to do it the old fashion way.

If its back fuel milage you are getting I would suggest a compression test to start. If you are getting good compression the check to see if the plugs are all good.

If they are good then there are a few other items such as air filter, Improper settings on Carburator, Maybe a semi clogged Cat. Converter

Would help if you have accesss to a scope to hook up to it. If you want to you could do a test on the exhaust fumes to see if its running rich or lean which could help with the carb settings.

I have tried, but after 5 tries, this 2.8L will not pass inspection. It read more than double the legal output on HC and CO. I had the converter checked and was told it was clean. When I received it, numerous vacuum lines under the hood and wires under the dash were cut, plugged or rerouted incorrectly. If you have a 2.8L could you please send me a hi-resolution digital picture of a "top-down" view of the the engine with the air cleaner on and especially, one with it off. You can also contact me at 281-463-1302. I have a couple of vacuum diagrams, but there are things on it such as some next to the carb which is called"orifice" which I have been unable to find. My Jeep gets only 10 mpg, smells strongly from under the hood of unburned gas al the time. It has a 2bbl Riochester VariJet II carb which is one of the suspects for causing theproblems. I rebuilt it and the engine runes smooth, but there still has to be something wrong to cause such problems. I bought a new charcoal filter which I have not installed because the gas smell is NOT coming from the old one, but from somewhere around the carb. I have not tested the EGR valve so it may be bad, but most of all I don't trust him. A couple of good photos showing the vacuum lines and any advice you have would be greatly appreciated. Thanks, James




ok I have one of these.

There is no on board computer. Everything is hard wired.


No O2 Sensor either. To diagnosis this year you have to do it the old fashion way.

If its back fuel milage you are getting I would suggest a compression test to start. If you are getting good compression the check to see if the plugs are all good.

If they are good then there are a few other items such as air filter, Improper settings on Carburator, Maybe a semi clogged Cat. Converter

Would help if you have accesss to a scope to hook up to it. If you want to you could do a test on the exhaust fumes to see if its running rich or lean which could help with the carb settings.