Another fuel problem
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Racer
Joined: Nov 2015
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The evidence is that the strainer is 36 years old and the main pump seized. And the fact that your pump seized instead of the electric motor going bad (which is why it blows the fuse) is even further evidence.
My advice never varies: Never install a new pump without removing and inspecting the strainer/in pump tank. Almost 100% of them are clogged or have holes, at this point in time.
I have all levels of clients. Huge dollar people and super economy people. Therefore I sometimes end up doing things that I don't really approve of. I will install a pump without removing the strainer (or in tank pump.) I just won't warranty it.....
My advice never varies: Never install a new pump without removing and inspecting the strainer/in pump tank. Almost 100% of them are clogged or have holes, at this point in time.
I have all levels of clients. Huge dollar people and super economy people. Therefore I sometimes end up doing things that I don't really approve of. I will install a pump without removing the strainer (or in tank pump.) I just won't warranty it.....
Last edited by Kamilo77; Oct 10, 2017 at 11:39 AM.
Chronic Tool Dropper
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Look carefully at the wiring to the auxiliary air valve in the engine bay. The fuel pump relay supplies idle air when the engine is actually running, shutting it off when the key is turned off to make sure there's no "run-on" after the key is off. The wiring to that valve and the valve itself deserve a look. Damaged wiring with a short to ground will pop the fuel pump fuse and strain the fuel pump relay. Since you've replaced the main pump with new and still see the fault to ground, it makes sense to look at the other wiring.
A little troubleshooting: Disconnect the pump wiring and try and start the car with an 8-amp fuse in the fuel pump fuse position. The fuse will easily carry the load from the aux air valve, and is small enough to not risk wiring damage as you test. If the fuse blows, the problem is in wiring or the air valve and not in the pump itself. The CE panel connection for the pump itself is at terminal T5, while aux air valve output is at Q1. These are the connectors at the bottom of the CE panel. The aux air valve wiring passes through the 14-pin at the front engine bay through the front of engine harness, so you can pop that connector and the valve connector to meter the harness section of the wiring on its own.
For others with later cars, the heater for the oxygen sensors piggybacks on the fuel pump relays too.
A little troubleshooting: Disconnect the pump wiring and try and start the car with an 8-amp fuse in the fuel pump fuse position. The fuse will easily carry the load from the aux air valve, and is small enough to not risk wiring damage as you test. If the fuse blows, the problem is in wiring or the air valve and not in the pump itself. The CE panel connection for the pump itself is at terminal T5, while aux air valve output is at Q1. These are the connectors at the bottom of the CE panel. The aux air valve wiring passes through the 14-pin at the front engine bay through the front of engine harness, so you can pop that connector and the valve connector to meter the harness section of the wiring on its own.
For others with later cars, the heater for the oxygen sensors piggybacks on the fuel pump relays too.
Thread Starter
Racer
Joined: Nov 2015
Posts: 298
Likes: 47
Look carefully at the wiring to the auxiliary air valve in the engine bay. The fuel pump relay supplies idle air when the engine is actually running, shutting it off when the key is turned off to make sure there's no "run-on" after the key is off. The wiring to that valve and the valve itself deserve a look. Damaged wiring with a short to ground will pop the fuel pump fuse and strain the fuel pump relay. Since you've replaced the main pump with new and still see the fault to ground, it makes sense to look at the other wiring.
A little troubleshooting: Disconnect the pump wiring and try and start the car with an 8-amp fuse in the fuel pump fuse position. The fuse will easily carry the load from the aux air valve, and is small enough to not risk wiring damage as you test. If the fuse blows, the problem is in wiring or the air valve and not in the pump itself. The CE panel connection for the pump itself is at terminal T5, while aux air valve output is at Q1. These are the connectors at the bottom of the CE panel. The aux air valve wiring passes through the 14-pin at the front engine bay through the front of engine harness, so you can pop that connector and the valve connector to meter the harness section of the wiring on its own.
For others with later cars, the heater for the oxygen sensors piggybacks on the fuel pump relays too.
A little troubleshooting: Disconnect the pump wiring and try and start the car with an 8-amp fuse in the fuel pump fuse position. The fuse will easily carry the load from the aux air valve, and is small enough to not risk wiring damage as you test. If the fuse blows, the problem is in wiring or the air valve and not in the pump itself. The CE panel connection for the pump itself is at terminal T5, while aux air valve output is at Q1. These are the connectors at the bottom of the CE panel. The aux air valve wiring passes through the 14-pin at the front engine bay through the front of engine harness, so you can pop that connector and the valve connector to meter the harness section of the wiring on its own.
For others with later cars, the heater for the oxygen sensors piggybacks on the fuel pump relays too.
Thread Starter
Racer
Joined: Nov 2015
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Team Owner
Joined: May 2004
Posts: 31,166
Likes: 4,161
From: Philly PA
Did you get a fuel sample if the only change you made from a running engine to no was fill the tank then I would question the fuel maybe it has water in it
Putting in a new strainer is usually part of a pump replacement
Putting in a new strainer is usually part of a pump replacement
Chronic Tool Dropper
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Look carefully at the wiring to the auxiliary air valve in the engine bay. The fuel pump relay supplies idle air when the engine is actually running, shutting it off when the key is turned off to make sure there's no "run-on" after the key is off. The wiring to that valve and the valve itself deserve a look. Damaged wiring with a short to ground will pop the fuel pump fuse and strain the fuel pump relay. Since you've replaced the main pump with new and still see the fault to ground, it makes sense to look at the other wiring.
A little troubleshooting: Disconnect the pump wiring and try and start the car with an 8-amp fuse in the fuel pump fuse position. The fuse will easily carry the load from the aux air valve, and is small enough to not risk wiring damage as you test. If the fuse blows, the problem is in wiring or the air valve and not in the pump itself. The CE panel connection for the pump itself is at terminal T5, while aux air valve output is at Q1. These are the connectors at the bottom of the CE panel. The aux air valve wiring passes through the 14-pin at the front engine bay through the front of engine harness, so you can pop that connector and the valve connector to meter the harness section of the wiring on its own.
For others with later cars, the heater for the oxygen sensors piggybacks on the fuel pump relays too.
A little troubleshooting: Disconnect the pump wiring and try and start the car with an 8-amp fuse in the fuel pump fuse position. The fuse will easily carry the load from the aux air valve, and is small enough to not risk wiring damage as you test. If the fuse blows, the problem is in wiring or the air valve and not in the pump itself. The CE panel connection for the pump itself is at terminal T5, while aux air valve output is at Q1. These are the connectors at the bottom of the CE panel. The aux air valve wiring passes through the 14-pin at the front engine bay through the front of engine harness, so you can pop that connector and the valve connector to meter the harness section of the wiring on its own.
For others with later cars, the heater for the oxygen sensors piggybacks on the fuel pump relays too.
Team Owner
Joined: May 2004
Posts: 31,166
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From: Philly PA
FWIW you should check the voltages at the connectors to the air valve and the temp sensor.
The connectors look the same but do different things.
With the key in the run position you should find the following
The air valve connector runs on 12V.
The temp sensor runs on 5v.
if these are connected backwards then you also need a new air temp sensor as the 12v has fried it.
BTDT got the t shirt.
NOTE after verifying these connectors see if the engine runs without blowing the fuse
The connectors look the same but do different things.
With the key in the run position you should find the following
The air valve connector runs on 12V.
The temp sensor runs on 5v.
if these are connected backwards then you also need a new air temp sensor as the 12v has fried it.
BTDT got the t shirt.
NOTE after verifying these connectors see if the engine runs without blowing the fuse
Thread Starter
Racer
Joined: Nov 2015
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If your delayed "fuse does not blow" is in response to the steps I shared, the problem looks like the aux air valve -- disconnected, the fuse doesn't blow. Leave the aux valve disconnected this time and start/run the engine. If all is well, the aux air valve is likely what was taking out the fuse.
Thanks for the help I'm so relieved.
Thread Starter
Racer
Joined: Nov 2015
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Guess I misunderstood you initially. Haven't had much time to tinker, Unplugged the air pump, and ofcourse, starts up fine once the fuel made its way to the motor. Started up again a few times after that. Fuse is fine. I don't see any immediate issues with the wiring so prob the pump itself is done.
Thanks for the help I'm so relieved.
Thanks for the help I'm so relieved.
Ordered a used auxiliary air valve from 928intl. Swapped it in about 20mins. She fired right up! Had a bit of a sticky lifter seemed like from the passenger side of the motor. Noise went away once warms up hope it stays that way.
Chronic Tool Dropper
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Great news! Sometimes we get to take a few laps around a problem before it comes into close focus.
Clean and flush the old pump with ATF, and leave it in a ziplock bag in ATF while stored. The pump depends on fuel for cooling and lubrication. ATF is an easy corrosion-preventer for storing used-but-still-serviceable fuel pumps.
Clean and flush the old pump with ATF, and leave it in a ziplock bag in ATF while stored. The pump depends on fuel for cooling and lubrication. ATF is an easy corrosion-preventer for storing used-but-still-serviceable fuel pumps.
Thread Starter
Racer
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Originally Posted by dr bob
Great news! Sometimes we get to take a few laps around a problem before it comes into close focus.
Clean and flush the old pump with ATF, and leave it in a ziplock bag in ATF while stored. The pump depends on fuel for cooling and lubrication. ATF is an easy corrosion-preventer for storing used-but-still-serviceable fuel pumps.
Clean and flush the old pump with ATF, and leave it in a ziplock bag in ATF while stored. The pump depends on fuel for cooling and lubrication. ATF is an easy corrosion-preventer for storing used-but-still-serviceable fuel pumps.
Minutes ago I just put the gauge cluster back on after fixing the voltmeter bulb to get and putting a new stalk combo in so I can have a horn again. After starting just fine for the last year and a half once I fixed the last issue, it dies.
I'm not hearing the fuel pump. So I check my fuses (1981) and my #22 has popped. I start thinking this is familiar, I unplug the auxiliary air valve thinking, there's no way this used part went to s* already did it? After I unplug the valve connector it fired up ran for a second then died.
I am deflated. Quite literally every time I fix one thing, something else goes wrong, this has been the project from hell.
Burning Brakes
Joined: Dec 2001
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From: Baltimore Md 21212
I am pretty sure the fuel pump requires a 25 amp fuse. I know earlier in the thread someone recommended trying an 8 amp, but I believe they did so knowing that 8 amps was way less than required and would blow before damaging anything else for testing purposes.
https://www.928gt.com/t-81fuse.aspx
https://www.928gt.com/t-81fuse.aspx