Jacki&GeneZ16

Victim: 1987 Automatic Convertible with 160K+ miles. Manufactured 10/86, Stock engine, Ignition, etc; The only real mods: the suspension for Autocrossing and no mufflers, just a Catalytic Converter for nice mellow louder sound - no resonance.

Problem/Test Results: I made it through the entire Code 54 FSM flow chart to the bottom with a digital volt meter instead of a test light, soooo.... the results was 0.01 DC volts. Does that low of voltage qualify as the Test Light being "On" therefore I need to change the Oil Pressure Switch? Or do I "back-up" 1 step and replace the Fuel Pump Relay also?

Situation: Using the 1987 FSM pages 6E3-A-60 (dated 4-4-86) & 6E3-A-61 (dated 4-24-86) these were my results:

BLOW BY BLOW (Flow Chart Results)

- Ign "Off" for 10 seconds
- Ign "On"
- Listen for In-Tank Fuel Pump
- Pump Should Run for 2 seconds After Ign "On"
Result: No

-Ign "Off"
-Using A Fused Jumper Wire, Connect Fuel Pump Test Conn. (per CF that was space G in the ALDL) to 12 volts
-Does Pump Run?
Result: Yes

-Ign "Off"
-Disconnect Fuel Pump Relay
-Probe CKT 340 (per CF that is the Orange Wire in Position E in the Connector to the Fuel Pump Relay) with a Test Light (I used my volt meter) to Ground
Result: Got over 12 volts = Light "On"

-Connect Test Light (my volt meter) between CKTS 340 (Orange wire) and 450 (Black w/white ground)
Result: Got over 12 volts = Light "On"

-Connect Test Light (my volt meter) between Harness CKT 465 (Green w/white wire) and Ground
-Ign "Off" for 10 seconds
-Note Test Light (my volt meter) within 2 second after Ign "On"
Result: Within 2 seconds over 12 volts for about 4 seconds = Light "On"

-Faulty Relay
-If Original Symptom was "Engine Cranks But Will Not Run" (yes that is so, but I can get it to runs when accelerater is pressed during cranking) Continue Test of Oil Pressure Switch
- Engine at Normal Operating Temperature
-Oil Pressure Normal
-Disconnect Fuel Pump Relay. Engine should Continue to Run, Does it?
Result: Yes

-Reconnect Fuel Pump Relay
-Ign "Off"
-Probe Fuel Pump Test Terminal (G in ALDL) with a Test Light to Ground
Result: 0.01 volts if that means Light is "On" then... per FSM: Faulty Oil Pressure Switch
OR
Result: If 0.01 would not be enough to Light a Test Light then... Fuel Pump Circuit OK

rodj

"-Disconnect Fuel Pump Relay. Engine should Continue to Run, Does it?
Result: Yes"
Show oil switch is all right, suplies power to pump direct bypassing relay.

Quick check , swap fan relay for pump relay (the same ) and see what you get. Assuming your fans work OK

DanZ51

.01 DC should be viewed as "background" voltage for anything less than electronic circuits (ecm signals). Electrical circuits (relays, lights, etc) need much higher voltage/amperage to operate.

Side note: I mentor young Army mechanics in their craft. Years ago the Army "upgraded" their toolboxes by dropping the old proven test light and adding a digital multi-meter. This has been a real PITA trying to troubleshoot light circuits as most issues are due to poor grounding. A multi-meter will show goodbattery voltage even though the resistance is so poor a test light will indicate a bad circuit.

PS. I replaced my oil pressure switch last year as I was having some flakey pump power issues. After searching for a loose/bad wire (intermittent problem) I finally gave up and replaced the OP switch. (It was cheap enough, I didn't care at that point). The flakey-ness disappeared. To access the switch I pulled the distributor cap for more room and put a wrench on it from the passenger side.

AGENT 86

Your testing has proven that your relay is bad and your oil pressure switch is good.

Jacki&GeneZ16

Fan is OK (fix that fusible link a few days ago) however, the Relay for the Fan (single fan on my 87) is not exactly the same, it has terminals for 4 wires with a blank space at the second position or B.

But since the connectors are the same and interchangeable I did swap them. Turned the key and ZIIIINNGGGGG! I heard the fuel pump when I turned the Ign "On"

So I suppose I'll buy a new Fuel Pump Relay?

Jacki&GeneZ16

Thanks, I'll treat the 0.01 volts as the Light "Off" and consider the OP switch as possible future replacement.

Jacki&GeneZ16

Thanks 86, I'll definitely buy a new Fuel Pump Relay today. I suppose after 21 years of service we can let that old relay retire to the trash.


This edit added late in the day after I installed the new Relay:

No codes, the old 87 is running fine now. Thanks to you all again!
Gene

DA1984VETTE

I have searched for this and didn't find what I was looking for. Could someone tell me where the fuel and fan relays are? I think the fan relay is the one by the wiper motor. I can't find where the fuel pump relay is. I have a FSM but couldn't find it under the fuel section. I just got it so I am trying to familiarize myself with it. The car is an 84, any help with pics would be helpful...thanks..

disregard this post here, I thought I posted a new thread..my apologies to the original poster...