1982 Stingray Starting Problems and plug/wire identification
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Joined: Jun 2013
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There is definitely voltage at the sending unit connector. At the connector I measure 12V on key turn. Once I connect the pump to the connector I don't measure any voltage on key turn. I measured that there is continuity across both terminals of the pump (should be ok since it's probably a coil....????) when it is hooked up or not. When I turn the key the continuity is still there so I'm shorted at key turn. This says to me that the relay may be dead? I figure I have voltage but not enough current supply to make anything of it at the pump.....?
I have jumped the connector all together with heavy gauge wires in order to test the connection and the same problem persists.
How do I identify the G terminal? I do not detect any continuity between the power wire (Tan/white) and any of the terminals at the check connector. I do detect that a few of the terminals at the check connector do have continuity to the ground wire at the sending unit connector.
I poured some gas into the TBI and lo and behold it fired up. It chugged for the few seconds it was awake, but it definitely was going.
Where is the fuel pump relay?
I have jumped the connector all together with heavy gauge wires in order to test the connection and the same problem persists.
How do I identify the G terminal? I do not detect any continuity between the power wire (Tan/white) and any of the terminals at the check connector. I do detect that a few of the terminals at the check connector do have continuity to the ground wire at the sending unit connector.
I poured some gas into the TBI and lo and behold it fired up. It chugged for the few seconds it was awake, but it definitely was going.
Where is the fuel pump relay?
Last edited by Igidy; Jun 14, 2013 at 01:30 PM.
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I ran a wire from the positive terminal to the G terminal of the check connector and nothing. No spark or any sign of anything..... I decided to go ahead and do a diagnosis check and I got a code 12. From my source I think that means "Diagnostic mode; no distributor signal to Electronic Control Module; System PASS" ????
From looking at the wiring diagram it doesn't seem like the check connector bypasses the fuel pump relay but instead just powers it up and runs through it to the Tan/White wire. From my research the fuel pump relay is behind the ECM? I guess I'll need to go ahead and access that and test and/or replace....?
From looking at the wiring diagram it doesn't seem like the check connector bypasses the fuel pump relay but instead just powers it up and runs through it to the Tan/White wire. From my research the fuel pump relay is behind the ECM? I guess I'll need to go ahead and access that and test and/or replace....?
Burning Brakes
Joined: Feb 2013
Posts: 1,062
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From: Burkburnett TX
I think its in the jack stowage compartment towards the front. Might have to pull the tray out to see it. I had a spare relay as the po of my car changed it and it matches the relay in that location.
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I can't find one locally so I'll have to wait a few days before I can replace it.... I've heard both battery case and jack compartment. If its the battery case then its behind the ECM...errrr hopefully it'll be by the jack.....
It was definitely a nice feeling when it kicked over and ran!
It was definitely a nice feeling when it kicked over and ran!
Last edited by Igidy; Jun 14, 2013 at 02:47 PM.
Thread Starter
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There's a good solid ground at the pump. I found the relay. It was just sitting there in the passenger side compartment. Any recommendations on how to test this thing? Which two pins do I power to flip the relay? I think i know the power side (red???). I'm guessing the dark green/white is signal? Not sure... any ideas?
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Melting Slicks
Joined: Jul 2005
Posts: 2,740
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From: Aurora Ontario
When testing for codes it will flash 12 three times then the codes. When its done it will flash 12 three more times.
So an example would be 12 12 12 55 12 12 12. In this example the code is 55.
You will notice the speed of the flashes is the same for 12. Flash pause then flash flash. 55 would be 5 flashes fad then pause the 5 more.
Check the two connectors on the driver side of the distributor. That's we're the reference comes from.
If the connections are good check the cap and coil. Make sure the ground rode is not missing off the coil.
So an example would be 12 12 12 55 12 12 12. In this example the code is 55.
You will notice the speed of the flashes is the same for 12. Flash pause then flash flash. 55 would be 5 flashes fad then pause the 5 more.
Check the two connectors on the driver side of the distributor. That's we're the reference comes from.
If the connections are good check the cap and coil. Make sure the ground rode is not missing off the coil.
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
Try running a ground to the pump as per ark vettes recommendation. Run a wire from the existing to any place on the frame. Out rule the ground.
I think the relay needs to be mounted. It may ground through the case.
I think the relay needs to be mounted. It may ground through the case.
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
Is this the relay in question? The new one has a schematic on the side...
Looks like 3 and 4 are the coil wires, signal in on 1 and switched between 2 and 5 depending on energized or not.
Problem is none of the pins are labeled.... If i had to guess the middle two turned sideways would be 3 and 4.... Dont trust my guess though, My schematic didnt make it any more obvious though.
Looks like 3 and 4 are the coil wires, signal in on 1 and switched between 2 and 5 depending on energized or not.
Problem is none of the pins are labeled.... If i had to guess the middle two turned sideways would be 3 and 4.... Dont trust my guess though, My schematic didnt make it any more obvious though.
Last edited by Arkyvette; Jun 14, 2013 at 03:45 PM. Reason: photo
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
HA! Its the Airtex 1R1327... Also fits the HVAC blower relay system... and not surprisingly its cheaper to buy as an HVAC relay vs a Fuel Pump relay... silly Corvette Tax.
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I checked the relay and it's good. It energizes the tan/white like it should.
On key turn, I get 4.5 mV to the pump.
Also, on key turn I measure a pull of 1.75 amps. Using a power supply I measure that the pump comes on at very little voltage and approximately .75 amps. Seems like the 1.75 amps should prove to turn the pump.
I hooked the pump back up to the car and with my hand on the pump I turned the key and could not feel any bit of vibration in the pump. Hrmmmmmm.... It seems like the prime pulse should be a pretty strong fluid pulse yeh?
I figure that the pump would work with 4.5 mV and 1.75 amps and that it would make a pretty good pulse. I could easily feel it vibrate at about .75 amps. I still think a prime pulse would be pretty strong.....
On key turn, I get 4.5 mV to the pump.
Also, on key turn I measure a pull of 1.75 amps. Using a power supply I measure that the pump comes on at very little voltage and approximately .75 amps. Seems like the 1.75 amps should prove to turn the pump.
I hooked the pump back up to the car and with my hand on the pump I turned the key and could not feel any bit of vibration in the pump. Hrmmmmmm.... It seems like the prime pulse should be a pretty strong fluid pulse yeh?
I figure that the pump would work with 4.5 mV and 1.75 amps and that it would make a pretty good pulse. I could easily feel it vibrate at about .75 amps. I still think a prime pulse would be pretty strong.....
Last edited by Igidy; Jun 14, 2013 at 05:50 PM.
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
Is it possible the connector you added for the pump itself is bad? I find it very rarely but sometimes a circuit cant carry current. This can be damaged wiring holding on by 1 thread or a bad splice somwhere, like maybe where you spliced in the connector? We test those on aircraft with a load light. Something like a tail light for light current loads, up to a fog light or headlight to really test the current capacity of the circuit. If it glows nice and bright, your wires are generally in good shape. If it barely glows, could be 12 volts with not enough current. The pump will jump pretty good when first turning on if your holding it. The prime pulse lasts about 3 to 4 seconds on my car. So what happens when you feed manual 12 volts into the sending unit connector? Does the pump run then?
One more thing... Just because a relay clicks and allows voltage doesnt mean its allowing all the current through. I think about how many Ford starter solenoids I have had that would get dirty contacts and not allow enough current through to start, but would click and allow 12 volts.
One more thing... Just because a relay clicks and allows voltage doesnt mean its allowing all the current through. I think about how many Ford starter solenoids I have had that would get dirty contacts and not allow enough current through to start, but would click and allow 12 volts.
Last edited by Arkyvette; Jun 14, 2013 at 05:58 PM. Reason: one more thing...
Thread Starter
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If I feed 12V to the sending unit connector (throughout the entire sending unit harness down to the fuel pump) I get a very strong pulse. This to me says that the connections are in good shape. Also, when using my power supply I am using the sending unit connector.
Also, using my power supply I measure .7 - .8 V and .75 - .8 amps for the pump to kick on. Remember that when using my ammeter I measure a 1.75 amp pull to the pump on key turn.
The low voltage (4.5 mV) is sort of a weird one....
Also, using my power supply I measure .7 - .8 V and .75 - .8 amps for the pump to kick on. Remember that when using my ammeter I measure a 1.75 amp pull to the pump on key turn.
The low voltage (4.5 mV) is sort of a weird one....
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
I would wire a load light in place of the fuel pump and compare its brightness level from your power supply vs the car supplied pulse power.
Just be very careful with these tests around a fume filled gasoline environment.
Just be very careful with these tests around a fume filled gasoline environment.
Thread Starter
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Joined: Jun 2013
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From the wiring diagram it shows that after the relay the routing is to the Oil Pressure Switch, ECM, Fuse, and then pump.
Is it possible that the Oil Pressure Switch or ECM are drawing current and preventing the pump from getting its proper power?
Also, is there a fuel cut-off (for accidents, etc) on this vehicle?
Is it possible that the Oil Pressure Switch or ECM are drawing current and preventing the pump from getting its proper power?
Also, is there a fuel cut-off (for accidents, etc) on this vehicle?
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
No fuel cut off.
Answer to a couple of questions.
The pump when it kicks in makes sure there is 9-13 psi of fuel to the rear TBI.
The injector prime pulse, a noise you have not heard yet comes from the injectors and is triggered by the ECM.
Pull the ECM and clean the connectors. Look for burn marks on them and on the circuit board.
Answer to a couple of questions.
The pump when it kicks in makes sure there is 9-13 psi of fuel to the rear TBI.
The injector prime pulse, a noise you have not heard yet comes from the injectors and is triggered by the ECM.
Pull the ECM and clean the connectors. Look for burn marks on them and on the circuit board.