Ωhm

Oil Pressure Gauge has nothing to do with C101, but the Coolant Temperature Gauge/Bulb does.

Cluster swap should have no affect on charging voltage. Check the condition of Fuse Link A (BLUE) at the starter relay stud.

Vanilla Black Cow or Boston Cooler?

If they're reimbursed for the repairs, I'd stay away.

Measure Starter Relay coil in ohms and divide that number into Battery/Applied Voltage or I=V/R.

Fuel Pump Relay (Bosch cube) coil draw = ≈160mA

When LOGGED-IN. Go to upper right hand corner of screen. Click on Username. Click on Account Settings. Find and click on Signature. Add your vehicle information here (YR, ENG, TRANS, etc, etc) then click on SAVE. This helps everyone. This information will be available every time you post.

Using a voltmeter or 12vdc testlight (preferred) check for B+ on the following pins (use battery negative terminal for ground): D1_5: B+ (Hot at all times) D2_4: B+ (Hot during KEY ON/CRANKING). D1_6: KEY ON (B+ (Hot for 2-3 seconds)) or CRANKING (B+ (Hot during CRANK)).

Check that hose for the Fuel Pump Pressure Regulator for fuel. Sure is close enough.

Been a long time and don't think I could ever find the two that I had. But the best one of the two was the one that someone made in metal shop (high school). Somewhat involved but kind of a simple project, if you got access to the machine tools on hand.

Myself, I'd deal with @cruiser54. Wouldn't want no metal filings in my intake manifold unless you remove and steam clean it.

Welcome to the CC forum.

Hot going to the Fuel Pump Relay is RED. The Fuel Pump circuit itself is ORANGE (ORN). Things that splice off of this circuit may have a tracer. FYI MJ_1987_Electrical_Manual_1.pdf

Okay thanks. I'll forget LOW/HIGH. RED usually means BATTERY FEED (Hot at all times).

So its a boneyard golden nugget?

Took a visit to NickInTimeDesign and sure enough "ECU CODES". No listing for "Fuel Pump Relay", but that could be just Website needs updating. Arrow down might mean LOW whereas arrow up might mean HIGH. Thank for opening up these new headaches for me. When you say "bypassed the relay" do you mean that there's a jumper wire in place of the relay? Also found this under RENIX PARTS SUGGESTION: Intake Manifold Air Temp Sensor (IAT) The stock IAT sensor has been long discontinued so we will need to adapt a similar sensor instead. – GM part 213-190 will replace it but requires the intake manifold port to be retapped to 3/8″NPT (stock is 1/4″NPT) and replacing the pigtail connector as well. This will update the sensor to a currently used part with the correct resistance range. @eaglescout526 Is this true, no NOS IAT sensors? @PhilisDiller 1987 MJ 4x4 Shortbed 4.0 5 speed manual

ECU code; interesting. I noticed a down arrow next to the word relay. Are there more ECU codes under that?

I don't get REM "throwing a code". Keep this high on your list. Yes it would be.

1969 Boss 429 Shotgun

Been thinking, you may not be able to hold proper intake manifold VAC if the EGR valve is unseated (leaking) somehow.

ADD A SIGNATURE: When LOGGED-IN. Go to upper right hand corner of screen. Click on Username. Click on Account Settings. Find and click on Signature. Add vehicle information here (YR, ENG, TRANS, etc, etc) then click on SAVE. This helps everyone. This information will be available every time you post.

That air freshener did it use Scratch "N" Sniff technology?

If that's a cube relay being used as a bypass jumper, which could be wired using the NC contacts, then its a very expensive jumper wire.

Engine manifold vacuum (VAC) reading at idle should be between 18-21"hg. Now if engine runs rough due to excess of fuel or weak secondary ignition (unburnt fuel) I guess your VAC readings could be possible. I know you know your running RICH so where could the fuel be coming from? I think you asked this in your 1st posting, so if your not leaking fuel from the INJ's, Fuel Pump Pressure Regulator, EGR valve or the Charcoal Canister, maybe weak spark at idle. IDK. I don't like the VAC reading so I would also check MAP wiring. Color Codes: C218_A - BRN W/TR C218_B - VIO C218_C - RED W/TR DVOM w/MAP disconnected, harness side. C218_A - Continuity to GND C218_C - KEY ON; MAP supply; 5vdc

RICH is a cool burn. LEAN melts metal. With KEY ON only, note the BARO reading. BARO-MAP=VAC.