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Old 01-11-2009, 12:36   #1 (permalink)
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1987 3.8L T-Bird- no power to fuel pump

I have power to the fuel pump relay connector but no power to the fuel pump when the relay is hooked up. I have replaced the fuel pump, relay(twice) and relay connector. The inertia switch is not tripped.When I unplug the relay and jump the connector, the fuel pump works. When I have plugged in two new relays, the pump does not work. What am I doing wrong?
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Old 01-11-2009, 16:18   #2 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

So what's your problem ? Are you saying the pump will not come on when you turn the
key on to start the car ? Need more info. Does the engine run then quit ? When does the pump not work ?
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Old 01-12-2009, 06:24   #3 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

The car ran with no problems one day but not the next day. I turned the key and it just kept turning over. It did not fire at all. It had spark so I started checking for fuel problems. I sprayed starting fluid down the throttle bodt and it fired briefly. I turned on the key several times and found that the fuel pump was not coming on. I checked the inertia switch and it was not tripped so I replaced the fuel pump relay. I turned on the key and no fuel pump. I removed the relay and turned the key on and jumped the connector and no fuel pump. I could hear it click but it would not run. I pulled the fuel tank and removed the fuel pump. The strainer was off the pump and laying in the fuel tank. I applied 12 volts to the pump and after a couple of tries it started running. I installed a new fuel pump and screen filter and when I turned on the key the fuel pump did not come on. I checked the inertia switck again and it was not tripped, it was in the down position. I pulled the relay to jump the connector and the fuel pump will run. I replaced the relay again and also installed a new connector. When I turn on the key the fuel pump still does not come on.
Any suggestions would be greatly appreciated.
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Old 01-12-2009, 09:34   #4 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

Your barking up the wrong tree. It's your E.C.M. that turns the pump on when the key is turned to the start possition and cranked. The pump runs for one second. When the engine starts the tachometer pulse proves the engins is running and the pump relay is
energized restarting the pump and keeping it on. You have to find out if you have reference voltage to the ecm. ( 5 volts ). then you have to find out if you have 12 v. to the relay from the computer. I'd say you don't.Then you have to find that wire to make
sure there is no opens in it if you don't find 12 volts. Unplug the computer harness and
plug it back in. could be corrosion. That simple. If all else fails you need a computer.
Have you checked ALL fuses ? Substitute a known good computer and see what happends but it had better be the same.
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Old 01-12-2009, 11:55   #5 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

I appreciate your help. I checked the fuses before I started. I checked the owners manual to identify the fuel pump relay fuse and it did not list it so I pulled each fuse under the dash and visually inspected them. Are there any fuses in the engine compartment? Anyhow the fuses must be ok and I must be getting 5volts to the ECM because I have 12 volts at the relay. There are four wires to the relay. The yellow is hot all the time. When I turn the key on the brown wire and the red wire have 12volts. There is also an orange wire with a blue stripe that goes to the fuel pump. When I jump the yellow or red wire to the orange/blue the fuel pump works. The fuel pump must be grounded seperately? Before I posted my problem I read on a different post that it might be a problem with the small ground wire off of the negative battery terminal. My negative cable with the small ground wire wasn't in the best condition so I replaced it when I was installing the new pump, relay, etc. I have the fuel line disconnected from the fuel filter because I wanted to pump gas through the old filter before installing a new filter in case I kicked up any sediment from dropping the tank. I did not realize the pump only ran for 1 second when the key was turned on. I thought it ran for a few seconds, I was probably missing it. I will install the new filter and try it.
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Old 01-12-2009, 13:36   #6 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

The pump relay for the engine run is grounded through the computer. Make sure all grounds that you can see are clean and is good shape. some engines prove the " run "
through the charging of the alternator. Computers don't pop over night, but i've seen it
happen. I'd be looking at bad grounds. One thing i forgot to mention. The battery has to
be at full charge. The fuel pump will not work at 10 volts but the starter will. Good luck.
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Old 01-12-2009, 16:58   #7 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

Thanks for the advice, I'm going to check grounds while the battery is on a slow charge overnight. I think I'll remove the panel and check the connection at the ECM while I'm at it. I'll report back when I have more info. Thanks again.
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Old 01-13-2009, 12:53   #8 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

No luck! The battery has a full charge but it won't start. It will fire if I spray starting fluid but it won't start. The ground connection at the ECM looks good. It is grounded to the body at the ECM and is clean and tight. I checked the connection from the ECM to the pump relay and it looks good. There are a yellow and a red wire out of the ECM to a connector and out of the connector with a yellow, a red, and also a tan wire. I unplugged the connection and reconnected it. The compartment that houses the ECM looks clean it is pretty well protected, no dirt. Any suggestions?
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Old 01-13-2009, 18:02   #9 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

The ground for the pump is made INSIDE the E.C.M.. You will never see this that is why i
suggested try a known good computer, as in switch it. You will have no choice but have
them put a scanner on it. DO NOT throw parts at it. Have it checked buy a dealer or
someone that has the tools and KNOWS what they are doing. Has anyone checked the
ignition switch ?
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Old 01-13-2009, 21:07   #10 (permalink)
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Re: 1987 3.8L T-Bird- no power to fuel pump

The ignition switch has not been checked. Is the car able to be scanned ? Did I erase the trouble codes when I disconnected the battery to charge it?
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