Fuel Pump works only when Using OBDII tool?
Thread Starter
Teching In
Joined: Jul 2015
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Fuel Pump works only when Using OBDII tool? Hi Guys,
My car did not start today (I recently rebuilt it, and it has been running, and never had any start up issues) but today was unique. I went to go start the car and the fuel pump didn't prime. I tried again, and nothing happened. (everything else was working as usual). So I began troubleshooting, I checked the fuel pump fuse underneath the hood and it was good, I swapped the relay with the A/C one right next to it and nothing happen still. So I went to autozone and got a diagnostic tool to see if it would give me any errors. but when I turned the key to the "acc on" position, I heard the fuel pump prime! I disconnected the diagnostic tool and turned the key again, and nothing. I plugged the tool back in, and it works. How can this be? what can I do to relieve this problem??
Thank you in advance,
2000 Manual Trans Am
My car did not start today (I recently rebuilt it, and it has been running, and never had any start up issues) but today was unique. I went to go start the car and the fuel pump didn't prime. I tried again, and nothing happened. (everything else was working as usual). So I began troubleshooting, I checked the fuel pump fuse underneath the hood and it was good, I swapped the relay with the A/C one right next to it and nothing happen still. So I went to autozone and got a diagnostic tool to see if it would give me any errors. but when I turned the key to the "acc on" position, I heard the fuel pump prime! I disconnected the diagnostic tool and turned the key again, and nothing. I plugged the tool back in, and it works. How can this be? what can I do to relieve this problem??
Thank you in advance,
2000 Manual Trans Am
Thread Starter
Teching In
Joined: Jul 2015
Posts: 30
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Thanks for the conformation guys! Last night my friend brought that up as well and I thought he had a good point. Now that you, both, said that as well also makes me feel more confident. Does anyone know where the ground should be? I can look in my Haynes manual, but if someone knows off the top of their head then that would save me some time!
Thank you!
Thank you!
Thanks for the conformation guys! Last night my friend brought that up as well and I thought he had a good point. Now that you, both, said that as well also makes me feel more confident. Does anyone know where the ground should be? I can look in my Haynes manual, but if someone knows off the top of their head then that would save me some time!
Thank you!
Thank you!
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Thread Starter
Teching In
Joined: Jul 2015
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Thank you guys so much for the info. jrpimp00 I rebuilt the entire engine, so everything was disconnected. My freeze plug was leaking on the rear Driver side cylinder head (where those grounds are) and I must of loosened the ground or something when I was trying to pop out the freeze plug. I will check this weekend, and update you guys on the results. It may solve the issue!
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In for an update, my car has a similar issue but not quite the same. Fuel pumps prime but won't attempt to start unless OBD scanner is plugged in.
Not a high priority deal because I use a scanner for certain gauges like fuel level, fuel trim, timing and temp readings.
Not a high priority deal because I use a scanner for certain gauges like fuel level, fuel trim, timing and temp readings.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Poked around and found a misplaced chassis ground while I was doing the ABS delete, line lock install, and manual brake conversion. Then found a DS head ground on the block and extra ground on the head.
Fixed those and relocated the extra ground circuit to connect: front block, rear block, PS head, shock tower, and battery ground in trunk.
Removed scan tool and she fired up. Didn't realize how picky these cars are about ground locations.
Fixed those and relocated the extra ground circuit to connect: front block, rear block, PS head, shock tower, and battery ground in trunk.
Removed scan tool and she fired up. Didn't realize how picky these cars are about ground locations.