Have a 1991 Buick regal,it stops charging wen I plug in temp/fuel gauge into the cluster,why would it do that?

It could be , but then again GM had instrument cluster problems back then . Bad stepper motors that controlled the gauges .An lighting problems as well . Go to a auto salvage yard an get a used one for $15.00 an see if it works .

There isn't any fusible links attached to the fuel pump relay.

The two fusible links on G.M. cars used to be behind the alternator. A heavy (appx. 10 gauge) wire on the alternator had a fusible link a couple of inches back from the bolt. Pull on wire to see if the link is burned out. The other link was attached to the starter soleniod . Same test.

common issue with these clusters, they short out... Need to replace it , but there are some people who can repair the one ya have but usually cost around 200$

Probably.
The volt gauge turns the alternator on once the engine is running. There could be a short in the circuit board inside the cluster.

If all voltages checked ok,then most probably its faulty instrument cluster board on which gauges are connected.Yes if cluster circuit board looks ok,then also it can be faulty.Somewhere there is minute short or burn on board then such prolem arises.
Also check the fuse box.One under hood and other under dash.Inspect each and every fuse and see if all are fine or not.
---------------For more troubleshooting on these cluster gauges i suggest you to refer the list of help links mentioned below.Its step by step instructions will help you to confirm the exact cause of problem in these conditions:---------
Click the link below:------

2004 Toyota Tundra: Oil Gauge and Temp Gauge Not Working?

http://howtobyme.blogspot.in/2012/05/2004-toyota-tundra-oil-gauge-and-temp.html

--------------

2005 Lexus SC430: Fuel Door, Dome light and Fuel Gauge Fuse Location?

http://howtobyme.blogspot.in/2012/05/2005-lexus-sc430-fuel-door-will-not.html
----------

Toyota 4Runner: Temperature Gauge Sensor

http://technoanswers.blogspot.in/2012/04/toyota-4runner-temperature-gauge-sensor.html
------------

Temperature gauge sits over half way mark?

http://schematicsdiagram.blogspot.in/2012/04/temperature-gauge-sits-over-half-way.html

---------------

Heater blows intermittently and temp gauge goes erratic?

http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html

----------

Temperature gauge does not move and no heat when heater is ON?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.html

-----------

2003 Pontiac Grand Prix: Erratic Fuel Gauge?

http://technoanswers.blogspot.in/2012/06/2003-pontiac-grand-prix-erratic-fuel.html

-----------

Temperature gauge keeps fluctuating up and down close to red?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-keeps-fluctuating-up.html

-------------

Temperature gauge on the dash quit working on Pontiac Grand Prix?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-on-dash-quit-working.html

---------------

Fuel gauge jumps from empty to full?

http://schematicsdiagram.blogspot.com/2011/12/fuel-gauge-jumps-from-empty-to-full.html

--------------

Gas gauge stuck on empty on 2002 Mercedes Benz 240c?

http://repairhelpcenter.blogspot.in/2012/02/gas-gauge-stuck-on-empty-on-2002.html
---------------

• Oldsmobile Temperature Gauge Lamp Switch?

-----------------

Fuel gauge drops to Empty?

http://technoanswers.blogspot.com/2012/01/fuel-gauge-drops-to-empty.html

----------------

Dodge neon gauges not working?

http://technoanswers.blogspot.in/2012/02/dodge-neon-gauges-not-working.html

------------

Temperature gauge went up?

http://schematicsdiagram.blogspot.com/2011/12/temperature-gauge-went-up.html

------------

Temperature gauge stays At cold on jaguar?

http://technoanswers.blogspot.in/2012/02/temperature-gauge-stays-at-cold-on.html
-----------

How to replace Instrument panel and dashboard on Toyota car?

http://repairhelpcenter.blogspot.in/2012/02/how-to-replace-instrument-panel-and.html

-----------

How to remove instrument panel on Chevrolet car?

http://technoanswers.blogspot.in/2012/02/how-to-remove-instrument-panel-on.html

-----------

How to remove control panel on Buick regal?

http://howtobyme.blogspot.in/2012/02/how-to-remove-control-panel-on-buick.html
---------------
These details will help.Thanks.

If all voltages checked ok, then most probably its faulty instrument cluster board on which gauges are connected. Yes if cluster circuit board looks ok, then also it can be faulty. Somewhere there is minute short or burn on board then such problem arises.

Also check the fuse box. One under hood and other under dash.

Inspect each and every fuse and see if all are fine or not.

---------------

For more troubleshooting on these cluster gauges I suggest you to refer the list of help links mentioned below. Its step by step instructions will help you to confirm the exact cause of problem in these conditions: ---------

Click the link below: ------

2004 Toyota Tundra: Oil Gauge and Temp Gauge Not Working?

http://howtobyme.blogspot.in/2012/05/2004-toyota-tundra-oil-gauge-and-temp.html

--------------

2005 Lexus SC430: Fuel Door, Dome light and Fuel Gauge Fuse Location?

http://howtobyme.blogspot.in/2012/05/2005-lexus-sc430-fuel-door-will-not.html

----------

Toyota 4Runner: Temperature Gauge Sensor

http://technoanswers.blogspot.in/2012/04/toyota-4runner-temperature-gauge-sensor.html

------------

Temperature gauge sits over half way mark?

http://schematicsdiagram.blogspot.in/2012/04/temperature-gauge-sits-over-half-way.html

---------------

Heater blows intermittently and temp gauge goes erratic?

http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html

----------

Temperature gauge does not move and no heat when heater is ON?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.html

-----------

2003 Pontiac Grand Prix: Erratic Fuel Gauge?

http://technoanswers.blogspot.in/2012/06/2003-pontiac-grand-prix-erratic-fuel.html

-----------

Temperature gauge keeps fluctuating up and down close to red?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-keeps-fluctuating-up.html

-------------

Temperature gauge on the dash quit working on Pontiac Grand Prix?

http://technoanswers.blogspot.com/2012/01/temperature-gauge-on-dash-quit-working.html

---------------

Fuel gauge jumps from empty to full?

http://schematicsdiagram.blogspot.com/2011/12/fuel-gauge-jumps-from-empty-to-full.html

--------------

Gas gauge stuck on empty on 2002 Mercedes Benz 240c?

http://repairhelpcenter.blogspot.in/2012/02/gas-gauge-stuck-on-empty-on-2002.html

---------------

• Oldsmobile Temperature Gauge Lamp Switch?

-----------------

Fuel gauge drops to Empty?

http://technoanswers.blogspot.com/2012/01/fuel-gauge-drops-to-empty.html

----------------

Dodge neon gauges not working?

http://technoanswers.blogspot.in/2012/02/dodge-neon-gauges-not-working.html

------------

Temperature gauge went up?

http://schematicsdiagram.blogspot.com/2011/12/temperature-gauge-went-up.html

------------

Temperature gauge stays At cold on jaguar?

http://technoanswers.blogspot.in/2012/02/temperature-gauge-stays-at-cold-on.html

-----------

How to replace Instrument panel and dashboard on Toyota car?

http://repairhelpcenter.blogspot.in/2012/02/how-to-replace-instrument-panel-and.html

-----------

How to remove instrument panel on Chevrolet car?

http://technoanswers.blogspot.in/2012/02/how-to-remove-instrument-panel-on.html

-----------

How to remove control panel on Buick regal?

http://howtobyme.blogspot.in/2012/02/how-to-remove-control-panel-on-buick.html

---------------

These details will help.

Thanks.

Faulty instrument cluster. GM has had many problems with their instrument clusters and this is one of them.There has been a recall untold,that if your vehicle is not over 7 years old and have less than 70,000 miles on it they will replace it at no charge.GOOD LUCK!! P.S. if they won't cover it then you can get one at www.Dorman.com .

4 resistors on the back of cluster bad get them at radio shack.