No fuel pressure on 87 T-Type

[Jeasen]

Car was running. Shut it off to go do something. Came back to start it and it would not start. After doing some checking I found no fuel pressure. Checked further and found that the fuse for the fuel pump was blown. Put in new 15 amp fuse and still no fuel pressure. Checked fuse again and it was blown. We changed a broken shifter cable yesterday. Could we have shorted a wire under the console that finally worked thru today? If not, does anyone have any idea where to look for the problem?

 

[Jeasen]

Ideas? Anyone!

 

[blackbuick87]

Pump could be seized causing blown fuses. Also could have a wire grounding out anywhere from the relay to the tank.

 

[Jeasen]

Blackbuick87, thanks for your thoughts. If I unplug the fuel pump by the tank near the rear bumper then I should be able to tell if it is the wiring from the relay to the pump or the pump itself. When unplugged if a fuse don't blow then I guess it is the pump. Could the relay be bad? If the fuel pump is served through a relay then maybe the wire is bad between the fuse and the relay?? Or is the fuse between the relay and fuel pump? Does anyone know where the fuel pump relay is located? I guess I could run a hot wire to the connector by the rear bumper and see if the fuel pump runs? This is my sons car and I would like to get it out of my garage. My 86 T-Type has been setting out in the rain for the last two days and I am not happy about that. Other ideas? Anyone??

 

[6=8]

I think your Idea about attempting to start the car with the fuel pump unplugged is a good step. Once you try it and if the fuse blows, then wiring damage is suspect. If it only blows with the pump pluged in, then the pump is probably at fault.

Once you try this, then you will have a better understanding which way to go (Hotwire it or look for shorts in the area you worked last.)

I bet it's the pump. Not much warning when they go!

 

[Nick Micale]

Did you check if the pump runs when wired direct with the connector behind the alternator?

 

[SilverSleeper]

If the pump is suspect, you dont really want to test it with the direct connection behind the alt do you? Unless you fuse your jumper wire when you do that, it could cause a nasty problem I would think.
Whenever you are dealing with a possible shorted wire, you really want to fuse any kind of test wire when applying power.

 

[Jeasen]

Thanks everyone for your replys to this post. I did some further checking and here is the deal. I unplugged the connecter for the fuel pump at the back bumper. Installed a new fuse and turned on the key. The fuse blew. I then left the connecter at the rear bumper unhooked and unplugged the wires going to the fuel pump relay. Installed a new fuse and turned on the key. The fuse did not blow. I then back probed the connecter at the fuel pump with a meter hooked to the positive terminal of the battery. 3 of the 4 wires shows a ground. From what I can tell from a wiring diagram from GNTTYPE.org only one wire should be grounded. So I am back to my original thought which is, my son grounded the wire leading to the fuel pump when installing a new shifter cable. He did remove and reinstall the console. He claims that there were only wires going to the lights in the console visible when the console was removed, but I don't think so. Am I on the right track? Any thoughts, anyone?? Does anyone know the routing of the wire from the fuel pump relay to the fuel pump?? Does it run along the transmission/drive shaft hump under the console. Thanks for your help.

 

[Nick Micale]

Originally posted by SilverSleeper
If the pump is suspect, you dont really want to test it with the direct connection behind the alt do you? Unless you fuse your jumper wire when you do that, it could cause a nasty problem I would think.
Whenever you are dealing with a possible shorted wire, you really want to fuse any kind of test wire when applying power.

Guess all the years I have been working on these car I was not doing it right?

Use a lighter gauge wire for power if a "nasty problem" is a concern, or jumper back at the tank connection.

 

[SilverSleeper]

Didnt mean to step on anyones toes there Nick.
I was just asking, not telling.
I have burnt up quite a few things by not fusing power supply wires.
I was just merely suggesting it to be on the safe side.

 

[Dan Thompson]

You might want to try a Caspers Hot Wire kit.

Did you try making contact, don't connect them, between the black wire from the underhood light to the black wire behind the alternator? As soon as these touch the fuel pump start running.

 

[Racetronix]

A hotwire kit will not solve the problem as it takes power from the factory harness to trigger it. The factory wires run down the driver's side inside the car. They do not run inside or under the center console. Based on your tests the feedline from the relay to the pump is shorting to ground.

Unplug the oil pressure switch behind the turbo and see if the fuse still blows. If not then the oil pressure switch is grounding out. If the fuse still blows then it is the feedline between the relay and the back of the car.

View this diagram here to see the color coding of the wires that lead from the FP relay to the pump. The feedline is divided up into multiple sections with, four connectors inline before it reaches the fuel pump. See if you can isolate the damaged section. Hopefully it is not the aluminum wire as it can not be soldered.

If you need to replace this wire, contact me and I can provide a harness to replace / bypass this faulty wire.

Good luck!

Jack
Racetronix
www.racetronix.com

 

[Nick Micale]

Originally posted by SilverSleeper
......
I was just asking, not telling.
I have burnt up quite a few things by not fusing power supply wires.
I was just merely suggesting it to be on the safe side.

Since the simple things are done first, see if the pump runs at all.

I would just momentarily touch the hot wire to get power to the pump connector. If no sparks fly, then leave it to see if the pump does operate. Possible it is frozen and not running?

 

[UNGN]

Originally posted by Jeasen
Does anyone know the routing of the wire from the fuel pump relay to the fuel pump?? Does it run along the transmission/drive shaft hump under the console. Thanks for your help.

It doesn't run down the console. Take off the door sills and look there.

 

[Racetronix]

Originally posted by Racetronix
The factory wires run down the driver's side inside the car. They do not run inside or under the center console. Based on your tests the feedline from the relay to the pump is shorting to ground...

If what I posted above checks out but the feed wire seems to be grounded you can unplug the sending unit and the the connector in the trunk near the driver's side wheel well. Unplug the FP relay. Probe for continuity between the grey wire going into the relay socket and body ground. If you do not get continuity once the connector in the trunk is unplugged then the wire running outside the car to the sending unit connector is shorted. If it shows continuity then the wire running inside the car / engine compartment is shorted to ground. Hopefully this will not be the case as finding a short inside the car’s wiring harness can be a PITA.

Jack
Racetronix

 

[Jeasen]

Thanks everyone for your replys to this post. I will not be able to try your suggestions until tonight. I will let everyone know what I find out.

 

[Jeasen]

Well after considerable messing around we fiddled with the wires on the front of the motor. Just wiggled them around especially the oil pressure sending unit wires and the car runs and is not blowing the fuse any more. We tried to check the wiring and replaced the relay for the fuel pump and nothing seemed to work. I guess it is in the wiring harness around the point where the oil pressure sending unit wire enters the harness. I can't understand why we had this problem. And why the car ran and then started blowing the fuse but I guess it is how a electrical problem works or don't work. Anyway, I want to thank everyone for their help. You can't beat the Buick community bar none.
Jim

 

[Jeasen]

Well the fuel pump fuse did not blow for about one day and then it started again. After checking out the oil pressure sending unit wires and finding nothing we removed the connector from the sending unit and found that the terminals on the sending unit were loose. We replaced the oil pressure sending unit and it is working fine. No blown fuses. The oil pressure light worked right so we did not think the sending unit was bad. Live and learn I guess. I just thought that I would let everyone know what the problem was. Maybe it will save someone else much time if they have the same problem.
Jim

 

[6-b-kwik]

i had the same problem first time it was a relay for my hot wire kit.then on the second time the same problem hapened it was my ecm so u might wanna give that a look? lata greg