1982 Stingray Starting Problems and plug/wire identification
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
Recommend getting both pump and sending unit? If so, both for an 85 or just the pump? seems I can only find the sending unit online... or possibly through a dealership.... maybe I can just pull it and inspect it. It really just acts like a conduit for the fuel between the pump and engine and the mechanism for measuring the fuel level, yeh?
here is the link to the "82 sticky" above....
http://forums.corvetteforum.com/c3-t...solutions.html
If you look under WEB SITES..."M" you will find info (a link) from another member on changing the fuel pump with an 85 unit. Just make sure you use "fuel rated hose" with the pump, as it has been know not to be the correct type of hose shipped with these pumps.
You can also look under PARTS in the "sticky" where you will find 2 part #'s for the 85 TPI fuel pump.
The sending units are available from many vendors here on the forum. The pumps should be also, but if you need one quickly, most likely your local auto parts store can get one in for you. From what I've read, it seems like the AC Delco and (or) GM pump is the one to use.
Good luck, hope you are running soon..............Tom
Thread Starter
Instructor
Joined: Jun 2013
Posts: 119
Likes: 3
Okay, new pump in and.... nothing. I have voltage to the pump connector. Is there an easy way to test the pump? Can I electrify it while it is out of the gas and see if it powers up or will that ruin it (or not work)? Bad luck with a new pump? I'll check my connector pins for proper fitment but I wanted to see if it is safe to bench test the pump out of the car.
Last edited by Igidy; Jun 13, 2013 at 06:19 PM.
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
Okay, new pump in and.... nothing. I have voltage to the pump connector. Is there an easy way to test the pump? Can I electrify it while it is out of the gas and see if it powers up or will that ruin it (or not work)? Bad luck with a new pump? I'll check my connector pins for proper fitment but I wanted to see if it is safe to bench test the pump out of the car.
Did you ever check out the ignition module, along with the rest of the ignition system?
You may have checked this already, just thinking out loud.....
BTW, what brand pump did you purchase? Is it the 85 TPI unit?
Thread Starter
Instructor
Joined: Jun 2013
Posts: 119
Likes: 3
I bench tested the pump with a battery and sure enough, it works. Connections, connections, connections....
It is a Precision brand for an '85. I'll check out my connections and make sure I'm hooked up correctly.
I have not checked the oil pressure sensor or ignition module.
It is a Precision brand for an '85. I'll check out my connections and make sure I'm hooked up correctly.
I have not checked the oil pressure sensor or ignition module.
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
If you have the voltage for a few seconds like you say, you should get action at the pump. Connections. Your on the right path! Check the ground on your sending unit and also check that silly noise filter that's in line with fuel pump in tank. If its bad, just bypass it as its not good for much anyway. (new sending units don't even come with it)
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Thread Starter
Instructor
Joined: Jun 2013
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I got the pump working by putting power into the connector outside the fuel tank so I know at least the in tank connections are good. I'm thinking its that out of tank connector. I'll take a look tomorrow
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
just a wild shot, have you also checked the fuel pump relay, which is also located in the ECM area? And that 20 amp fuse near the battery, make sure that inside the connector is corrosion free, pull the fuse to check.....it is probably something so simple, but yet hard to determine where.....
Melting Slicks
Joined: Jul 2005
Posts: 2,740
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From: Aurora Ontario
I haven't read your entire thread, but have you checked the 20 amp fuse and connector near the battery? Are your battery cables tighten, not loose? Have you checked the ECM connections and your PROM chip, that it is fully inserted? Have you checked your oil pressure sensor, as if it does not see 4 psi pressure upon start-up, it will disable the pump. Is the new pump with the new connectors properly seated?
Did you ever check out the ignition module, along with the rest of the ignition system?
You may have checked this already, just thinking out loud.....
BTW, what brand pump did you purchase? Is it the 85 TPI unit?
Did you ever check out the ignition module, along with the rest of the ignition system?
You may have checked this already, just thinking out loud.....
BTW, what brand pump did you purchase? Is it the 85 TPI unit?
Even if the oil pressure sensor senses no oil.The pump should still buzz when you turn the key to on. You should still get a prime pulse from the injectors. The oil sensor kills fuel supply after cranking.
Running power to terminal G bypasses the fuel relay and I think the ECM.
You can determine if its ignition related by pouring a bit off fuel down each TBI. See if it starts and runs for a few seconds.
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
I thought he already verified he had prime pulse voltage at the connector by the tank? That would eliminate the fuel relay, ecm, pretty much everything forward of there correct? I'm still thinking bad connection right there at the sending unit plug.
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
It sounds like every connector should be cleaned including the connectors on the ECM. Then there is the distributor reference signal to consider as well. If there is a problem in the distributor the car may not start if gas is poured down the TBI's but it would be nice to know it does. I know if you disconnect one of the two wires on the driver side of the distributor the injectors will not fire....I know this because I have left it unplugged accidently.
FWIW terminal G is the top right on the plug.
Last edited by jdp6000; Jun 14, 2013 at 09:42 AM.
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
Isn't one of the three wires in that plug back there a permanent ground? I believe the middle one is sending unit and the other is power. Do we have a good ground to the pump? Just thinking here....
Melting Slicks
Joined: Jul 2005
Posts: 2,740
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From: Aurora Ontario
I just know that once the fuel pump is energized the signal has to go back to the ECM. The ECM has to sense the signal to fire the injectors. The ECM also has to sense multiple other signals to start. So just because one wire has power at the pump does not mean the others are sending the signals needed.
If there is no prime (buzz for 2 seconds) there is no signal. If there is no buzz from the pump chances are the ECM is not reading energized. It will not fire the injectors. The buzz at start I think is controlled by the fuel pump relay. Once started the ECM takes over.
Jim
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
With voltage should come pump running regardless of what else could be wrong. Why isn't that voltage getting to the pump? I really don't think the ecm in an 82 receives any feedback from the pump itself....its a far more simple system than that. The prime pulse is sent at the beginning to both pump and injectors regardless of if either is actually doing anything. I verified that with noid lights while chasing my own problem. The ecm just needs parameters met to keep 12volts fed to the pump via the relay. If 12v was there for a prime pulse, the relay is working.
Melting Slicks
Joined: Jul 2005
Posts: 2,740
Likes: 3
From: Aurora Ontario
With voltage should come pump running regardless of what else could be wrong. Why isn't that voltage getting to the pump? I really don't think the ecm in an 82 receives any feedback from the pump itself....its a far more simple system than that. The prime pulse is sent at the beginning to both pump and injectors regardless of if either is actually doing anything. I verified that with noid lights while chasing my own problem. The ecm just needs parameters met to keep 12volts fed to the pump via the relay. If 12v was there for a prime pulse, the relay is working.
Somehow something tells the pump to turn to maintain pressure.
I'm not going to argue with you. It's not our car. Feom my experience to many posters jump steps and look for an easy fix. In my opinion step one is to see if he can power up the pump through terminal G. Second is to see if it will run by pouring gas down the TBI's. this will tell me a lot.
Burning Brakes
Joined: Feb 2013
Posts: 1,062
Likes: 28
From: Burkburnett TX
No arguing intended :-). I have the schematic in front of me...the return to the ecm is from the fuel pump relay itself. Only letting the ecm know that the relay is energized or not. We will get this car running one way or another!
Melting Slicks
Joined: Mar 2006
Posts: 2,248
Likes: 67
From: Warrington PA
Finalist 2020 C4 of the Year - Unmodified
great thread here with tons of troubleshooting info, will have to reread many times and try to sort things out, and add it to the "sticky" for sure. I think if this 82 owner did what jdp6000 (Jim) suggested from the beginning, about terminal "G" and pouring gas down th TB's, what Arkyvette said about getting it to run will be accomplished......