cruiser54

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Pin 30 of the fuel pump relay receptacle? The flat 6 wire connector on the passenger inner fender. Unplug and check the connections. Solid orange wire is fuel pump power.

Ever seen this?

Brown wire at the ignition switch is likely melted as well as the switch being bad.

I've only done exactly what you're asking about 4 times. Works fine. Use the Renix intake gasket and match port both the intake manifold and head to it. Intake won't need much. Head will need more but it's cast iron. Do it first. Scribe the gasket on to the head. Start at a 45* angle and go in about 1/4". Taper in to the head from there a few more times. I have photos.

Change the oil and filter as suggested. What brand oil filter are you currently using? I'm also betting your radiator is clogged up since it gets hot on the highway even with cold ambient temps. New radiator is only $100.

Hmmm. Good idea. Last I heard the Renix pump doesn't ground at the tail lamp. Driver's side inner fender under a sheet metal screw. Time to start chasing the power. Is there power at the resistor? How much?

Hmmm. Good idea.

Nice pic!! Where'd ya get it? LOL. Snag the one below if you want. First place to look. It's okay to bypass the resistor also. Fuel pump relay could be it also.

I disagree that a bad O2 sensor does not cause a wonky idle. Quite common actually. For the Renix years, 87-90, the O2 sensor has 3 wires, 2 black and 1 orange. The orange wire (largest gauge of the 3) is the 12-14 volt power that comes from the O2 sensor heater relay on the passenger side firewall, and that powers the internal heater in the sensor so that the sensor can work at idle, and almost immediately after start up. Loss of that power will hurt gas mileage even with a good O2 sensor. One of the black wires is a common ground for the heater power and O2 signal to the ECU, so a poor ground will give a voltage feedback from the heater power input, to the ECU causing poor mileage even with a good O2 sensor. The third wire, also black is a voltage feed wire, 5 volts, from the ECU to the O2 sensor. The O2 sensor is an O2 concentration sensitive variable resistor. At optimal O2 concentration the 5 volt input feed to the O2 sensor drops to 2.45 volts due to losses across the O2 sensor to ground. That same wire if disconnected from the O2 sensor will read 5 volts constant to ground. At idle that voltage should read 1-4 volts oscillating quickly back and forth roughly once every second. At 2000 rpm it should run between 2 and 3 volts max, and is optimally running between 2.3 and 2.6 volts at 2000 rpm (in park). A digital meter can NOT be used for reading the O2 sensor voltage, but it can be used to test the ground and the 12-14 volts to the heater and the 5 volt feed from the ECU with power on and engine off. You must use an old style analog meter with the needle gauge on the display to see the voltage swing back and forth with the engine runing. If the O2 sensor readings are not right, say they read 4 volts or 1 volt steady, you have a problem. BUT before you blame the O2 sensor make sure it has good wiring, and make sure the proper voltage is feeding it, by turning power on, engine off to read the engine off voltage feeds (12-14 volts on the orange wire, and 5 volts on one of the two black wires), and ensure the ground wire (power off) reads less than 1 ohm to the battery negative post. A leaky exhaust system or leaky fuel injector(s), or bad compression, bad rings or leaky valves, bad plugs, wires, cap, rotor, HV coil, and so on, or combination of these, can also cause a lean or rich condition that gives you high or low O2 sensor readings that are not the O2 sensors fault, so try and verify those other items also before buying parts like an O2 sensor to fix your problem.

I might be able to help but I have no late model wiring diagram. Bzzzzt is the sound shorted out electrical stuff makes......

Can't imagine how I drove those twin stick transfer cases all those years with no indicator lights.

Bzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzt.

woohoo!! You old fart. I have 11 grandkids, one more on the way, and 2 great grandkids with another on the way.

See Post 5......

Agreed. Just a note here: to those using the shout-box, don't expect any good advice from it.

Me too.

That would be them, my dumb @$$. Whoops..... Hopefully others see this and see the importance of completing the first few Tips right off the get-go.

The ones in Tip 10?

Yep.

Thanks for posting that for him!! I've got Tip #28 written and published here on CC and also on my website. Tip 29 and 30 in the works. Tip 1 has an addition in the Comanche section at the end thanks to Hornbrod.

Alright, you're off the hook......

Doesn't the lever on the floor indicate enough for you?

Yes.

You can just change the nipple in the oil filter adapter and use a Napa 1515 oil filter. Nipple is about $6 at the dealer.