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I'm going to stop using the term B+. My meaning was for Battery Voltage. The ECU receives Battery Voltage from the Fuel Pump Relay for the INJ Feed circuit. The 88 Electrical Manual should have the same set up as your 90. _mj1988electricalmanual_1.pdf

C201_C11 & C201_D10 both are INJ FEED circuits for the ECU. B+ from the Fuel Pump Relay.

No need if properly bypassed. When disconnected should see NO voltage.

With B+ on C157_F connect connector back up. Disconnect C139 at the Fuel Pump and measure for B+ at C139_C. If circuit test good measure for continuity between C139_A and a good ground. Looking for ≈0_Ω.

Doors aren't the best place for grounding. Use under the dash and on the medal. Should see some grounding lugs there. Make sure Fuel Pump Ballast Resistor is good and correctly connected or properly bypassed. Measurement takes into account the Fuel Pump Relay is still jumpered.

With Fused jumper wire jump Fuel Pump Relay Pins_30(1)&87(4) again. Listen for Fuel Pump. If no Fuel Pump action, disconnect C157. With jumper still in place measure for B+ on C157_F(ORN), engine or IP side of harness.

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)).

I was just thinking swapping relays is a method used for troubleshooting. Your testing on the D1_D2 connector should have proved out the Fuel Pump Relay. Maybe cleaning the coil contact did more good for ya.

This makes me wonder.

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)).

Make sure you got full swing on your throttle plate or its not loose, in the throttle body. You'll need to look. Could just be a mechanical issue.

Get back here to Detroit. They got these street corner pharmacies that will sell you things call “Happyoids”. Then, you may think your flying back to Atlanta, when your really driving.

@Barnes2001 Need to know here.

@BlueJeans KEY OFF. Depress brake pedal. Using T/S SW set to RH side, can you turn OFF the RH rear bulbs? Try same thing for the LH side.

Do the Brake Lights work?

Fuel trim numbers, both long or short, do two (2) things. Add fuel or subtract fuel from the INJ PW time. 128 is the centering point for this decision. Numbers less than 128 take time OFF the INJ PW (engine running RICH, calls for less fuel), while numbers greater than 128 add time ON the INJ PW (engine running LEAN, calls for more fuel). Your fuel trim numbers tell me your engine is running RICH and fuel trim is calling for less fuel. NOTE: Your numbers are well within the range of authority for the ECU and would be considered normal. Back to guessing again since you don’t seem to be running LEAN, check your fuel pressure gauge for accuracy. If your gauge checks out good, than I’m barking up the wrong tree.

No. Using REM what are your ST&LT fuel trim numbers? My guess is your running LEAN or you got a faulty fuel pressure gauge.

Green Left: OFF Green Right: TEMP

Is that as low as you can go on the adjustment?

Yeah, I’ve witnessed that ON/OFF highway stunt. Flying down the highway, being instructed to exit highway, drive through downtown small town just to be told go back on the highway. What a joke.

Just spent two days trying to figure out exactly how the navigation system works on a 2013 Ford Flex (SYNC). Seems great for getting me to the house across the street, but for long trips (one state to another) SYNC has a mind of its own. How do you deal with your vehicle navigation systems? Do you just OBEY it? Is it smarter than us? Can you custom make a high mileage trip simply?

Should be close enough. Best we can do. MJ_1987_Electrical_Manual_1.pdf

Under normal engine operations, the fuel pump current, flows through the ballast resistor causing a voltage drop to the fuel pump motor. Now when engine is at WOT the O2 Heater relay is activated (O2 Heater OFF) and this will bypass the ballast resistor and apply full battery voltage (B+) to the fuel pump motor (max current). During a WOT condition there is really no need for a O2 Heater, but there is a need for max fuel pump.

Running engine without the ballast resistor just means more fuel through the fuel return line. Pressure will stay the same. EDIT: I was thinking you had RENIX fuel pressure regulator.

Welcome to the CC Forum.