Ωhm

Time to add more request to the request. Ballast resistor resistance. Like mentioned above remove one wire and measure resistances. Re-read request (post #1). HOrnbrod you want 1.6Ωs?

I'm making a a$$umption here, I'm using 1.1ohms for the ballast resistor, unless I know of an exception (HOrnbrod again). Too keep this simple, voltage reading are fairly consistence between meters, ohmmeters are not. Ohmmeters rely on the condition of the internal battery. Maybe the results could ask a question: "What are the ohms at the ballast"? But yes, you're right about this.

Yes, I've been vague about the voltage measurements. Keep in mind I understand what I'm saying, that don't mean others do. Let's clear up the voltage measurements. One voltmeter needed. Battery voltage to be taken at the battery, using both battery posts (terminals may be dirty). If no post is available, connect VM to terminals. As for the ballast resistor voltage, connect one lead to one terminal of the ballast and the other lead to the other terminal of the ballast. Across the ballast. Polarity doesn't matter, what I need is the number. Voltage drop at the ballast and knowing ballast resistance, one can determine current flow thru the ballast. Since the ballast is in series with the fuel pump and current flow is the same in a series circuits, we now know fuel pump current. Using fuel pump current and battery voltage minus ballast voltage drop, one can conclude fuel pump running resistance. This resistance value is what I'm trying to tie into fuel pump health. Everyone punch holes into this. I know I'm leaving a bunch of open ended variables like different voltmeters, ambient temp, fuel density, fuel rail pressure (HOrnbrod), altitude, is it raining, etc, etc. As for engine at normal operating temperature, some will be and other won't. But I have one constant, engine running at idle. So any and all value will reflect this, engine running and at idle. Numbers that fall out of this yet undetermined window, could show as a problem.

2 measurements. Battery voltage and voltage across the ballast (when hooked-up). No one needs to crawl under their vehicle.

I've adjusted request/data form for multiple vehicles. Good point. Re-read request (post #1).

Thanks for helping me tune-up my request for information. Re-read request (post #1).

Big mistake on my part. I'll edit request and drop renix only.

I need a project so I'm looking for some information. I'm interested to see if I (we) can determine fuel pump health by using the fuel pump ballast resistor. What I need is two (2) voltage measurements, one (1) resistance measurement and type of fuel pump, if known. Requirements: Any 4.0L and those still using the fuel pump ballast resistor. Conditions: Engine running @ idle. Measurements taken: 1. Battery voltage. 2. Voltage across the ballast. (polarity doesn't matter). 3. Ballast resistance measured in ohms. Also include type of fuel pump. IDK is good for 'I Don't Know'. Example: 1. 12.70 vdc 2. 3.00 vdc 3. 1.1 ohms 4. Type of fuel pump if known, otherwise use IDK. 5. Vehicle: MJ88, XJ89, TJ90, MJ89-RED, MJ89-YELLOW (examples) I'm not sure where this will lead or what results I can conclude, but I think its worth a shot. I'll post results later if enough data is supplied. Thanks, in advance to any and all that participate.

HOs have DTCs. That's everything you ever need to know.

Did you put a timing light on it?

The distributor has no "fire the coil" gadget in it to rotate. Timing uses TPS, MAP & RPM's.

If your base timing is correct at idle, your flexplate show good. Keep in mind rotating the dist will NOT change timing. It will only change Dist indexing.

Since you now have a extra distributor cap, cut the window in it and verify rotor tip position again. Trailing edge of rotor should be at Number#1 tower. Otherwise suspect MAP sensor.

Yes, REM could help with A/F. It would just take driving time, adjustment, more driving time. O2 would determine Open/Closed Loop (14.7:1) while Fuel Trim (FT) would show Rich or Lean direction.

My DVOM (Fluke 77 first edition) has what's known as a bar graph below the numeric digital display. This digital bar graph has a considerably faster update rate (simulating analog) then the numeric display. Use this feature if equipped on your DVOM. Analog meter would be your best choice though.

Did you reuse the fuel pump tank/sending unit gasket? If it is new, then maybe the wrong one, not thick enough.

Your quick Pete.

If you jump the pump you still need to a ground side to the circuit.

I get all mixed up unless things are real simple. Too hot?? Too cold?? Which one?

Check hose for blockage between the radiator cap and the coolant overflow bottle. Suspect radiator cap.

First test with any module is the smell test. Sometime the nose knows.

Might be road test time. CC might require a load. Also, I see you got three adjustments on the CC module to toy with.

Check out page 20 (4 speed transmission) in the 88 electrical manual. There's mention of a Cruise/Trans switch. Not exactly sure yet how it works, but it's tied in with the servo vacuum dump valve and the brake torque converter. Shows connector C260.

Good looking (mj)eep. Whatever it takes, fix that passenger her side door. If mama ain't happy, no one's happy. Any technical questions should be posted under MJ TECH. More eyes on the topic. Something is wrong with your grill, I'm not sure what it is, maybe some else can help here.

C253 colors do match the Cruise Control harness side. Is it possible that the steering column/stalk has some hidden wires? If you got the CC switch you should have the wires somewhere.