fuel pump relay
fourwheelin_78
03-28-2004, 04:51 AM
97 regal fuel pump relays burnin up....any ideas why?
Mr_D
04-26-2004, 11:46 PM
97 regal fuel pump relays burnin up....any ideas why?
The only way to burn a relay is to run too much current through it.
A vehicle with a fixed input voltage like 12 volts isn't likely to have too much voltage. So the problem has to be too much current draw through the relay.
If the pump turns hard it would draw more current than normal and this could damage the control relay.
A 2nd possibility is a a short to ground in the wiring (or the pump) that feeds the fuel pump. Either condition could also draw excessive current and damage the relay.
Use a multimeter and read the current through the relay. That will tell you if the current is excessive. The relay should have a spec on it for max current such as 15 amps or so. Compare that to how much is going through it.
These vehicles do appear to have a 2 speed circuit for the fuel pump. Low speed runs through a resistor. Assuming the circuit is properly designed, one could surmise it could run in either speed indefinately.
The fuel pump is located in the fuel tank. I have the schematic but there's not much to it. Just a couple relays, it appears one turns it on or off and the other selects the pump speed by driving the pump directly, or through the resistor which lowers the pump speed.
Does the pump continue to run (make a slight buzzing nose in the vehicle rear) while the vehicle is turned off?
One last idea, the schematic shows it has a 15 amp fuse. If the fuse isn't blowing I would wonder why not. The fuse should blow if it drew too much current. Make sure the fuse hasn't been replaced with a larger one. Also make sure it has the correct rated relay installed. A 15 or 20 amp unit should be fine. That's all there is. It's a fairly simple circuit. I may test mine and meausure the current to have a baseline to compare to.
Mr_D.
Electrical Engineer
The only way to burn a relay is to run too much current through it.
A vehicle with a fixed input voltage like 12 volts isn't likely to have too much voltage. So the problem has to be too much current draw through the relay.
If the pump turns hard it would draw more current than normal and this could damage the control relay.
A 2nd possibility is a a short to ground in the wiring (or the pump) that feeds the fuel pump. Either condition could also draw excessive current and damage the relay.
Use a multimeter and read the current through the relay. That will tell you if the current is excessive. The relay should have a spec on it for max current such as 15 amps or so. Compare that to how much is going through it.
These vehicles do appear to have a 2 speed circuit for the fuel pump. Low speed runs through a resistor. Assuming the circuit is properly designed, one could surmise it could run in either speed indefinately.
The fuel pump is located in the fuel tank. I have the schematic but there's not much to it. Just a couple relays, it appears one turns it on or off and the other selects the pump speed by driving the pump directly, or through the resistor which lowers the pump speed.
Does the pump continue to run (make a slight buzzing nose in the vehicle rear) while the vehicle is turned off?
One last idea, the schematic shows it has a 15 amp fuse. If the fuse isn't blowing I would wonder why not. The fuse should blow if it drew too much current. Make sure the fuse hasn't been replaced with a larger one. Also make sure it has the correct rated relay installed. A 15 or 20 amp unit should be fine. That's all there is. It's a fairly simple circuit. I may test mine and meausure the current to have a baseline to compare to.
Mr_D.
Electrical Engineer
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