1G Fuel Pump Rewire Relay Question?

[TDC GSX]

Is this the correct relay for the rewire because when I plug the 20A fuse in with out turning on the car the fuel pump turns on??? I take the fuse out it turns off. I check my wiring and made sure that they are correct because with out them being correct the pump doesn't even run at all.

This is the one that I got at Radio Shack.

http://www.radioshack.com/product/i...uct+Type/SPST&fbc=1&kw=spst&parentPage=search

Thanks for the help.

Taylor

 

[femmeDSM]

That looks like the one I got.
However, I can't be completely sure, because I no longer use that one (it blew the first time I turned the car on. Great work, Radio Shack ). I went to AutoZone and picked up one of their basic 30A Auto Relays and am now using that one w/ no problems. Also, the one at AutoZone was like $2.99

Now on to why your fuel pump turns on with the car off....
Sounds to me like you have reversed two of the wires. Can you post a picture of the way you have it wired? Sometimes no matter how many times you "check" and "double check" the instructions, you miss something small that makes all the difference

On most typical relays, 85 is ground, 86 is trigger (to MPI relay -- black/white wire), 30 is input (from battery) and 87 is output (to fuel pump). However, I have seen some where 30 and 87 are reversed. Just FYI.

 

[spoolup]

It should have a single pole dual throw SPDT. Not single pole single throw SPST. With out seeing the schematic I can not say for sure and Radio Shacks site did not display it.

A quick easy test. Take the relay out and measure the resistance with a VOM (volt ohm meter) and see if you have a open or short (again with the relay removed) between 30 and 87 (or it may read 87A). If its open then you got a "suitable" alternate, if its a short then that's the problem and you have a common SPST relay used for alarm triggers.

Chances are you have the correct one (will read a open, since the other one is rarely used) and it is a simple miswire where the 12V source from the battery (the line you added with the fuse) is tied to a point directly across to the connected fuel pump. And only trouble shooting/retracing your install will find it.

 

[travislaw]

Is this the correct relay for the rewire because when I plug the 20A fuse in with out turning on the car the fuel pump turns on??? I take the fuse out it turns off. I check my wiring and made sure that they are correct because with out them being correct the pump doesn't even run at all.

This is the one that I got at Radio Shack.

http://www.radioshack.com/product/i...uct+Type/SPST&fbc=1&kw=spst&parentPage=search

Thanks for the help.

Taylor

Make sure you follwed the right directions for the fuel pump rewire. There are seperate wiring instructions between the GSX, and the other DSM models.

 

[TDC GSX]

Ok it seems that it is open when I put power to 30 and ground to 87. I scanned the back of the package to show you the schematic.

This is the way that I have my wires currently set up.
30 - Power with 20A fuse
85 - Ground
86 - To cars harness
87 - To Fuel Pump
87A - I don't have one on the relay as a visible plug.

Thanks
Taylor

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[spoolup]

To check continuity between 87 and 30 you want to remove the relay from all wiring and not provide any power AND use a VOM.

But it is good that it is open otherwise you would have made a direct short to chassis ground doing what you did (IE not good). And it appears you do have the correct relay and it also seems that the wiring is also correct. The next logical step would be that the relay is bad, however there is no way that the source voltage could get from 30 to the fuel pump turning it on since that path is open.

Maybe do as Femme did and stop by AutoZone and try a different relay. If it works then return the Radio Shack one and if it still acts up you can return either one you wish. But the way you have it, it SHOULD work.

Sorry I could not be of more help.

 

[TDC GSX]

Yes also my dad said maybe powering 87 from the batt and run power to the fuel pump through the 30. What do you think about that. We are going to try different ways do see how it works.


Thanks
Taylor

 

[jepherz]

Test it by running 85 and 86 to the battery. Either pole should work, but just for simplicity sake, put 86 on the (+) terminal and 85 on the (-) terminal. When the relay is energized, you should hear a click. This means it's turning on and off.

To wire it into your fuel system, you need to ground 85, hook 86 up to the stock fuel pump power line, 30/51 will connect to the pump power, and 87 will hook to your battery. Make sure to fuse this line as close to the battery as possible.

Relays are really simple. In your case, you don't have a "normally closed" pole. This is what others have mentioned, but in this case it is not necessary because you would only use it if you wanted the fuel pump to run when the car was off.....

 

[TDC GSX]

Thanks for your reply I was think about do it that way. I will put it in today and see how it goes.

Taylor

 

[spoolup]

It shouldn't really matter if the 12V goes to 30 or 87 and the pump goes to the other since there is no diode installed internal to the relay. At least according to the package but it wouldn't surprise me none knowing Radio Shack.

If there was a diode and it was hooked up backwards there is no way possible that the biasing voltage would be met and allow the pump to kick on as it was in your first post.

 

[jepherz]

Spoolup is correct. If you have no diode in a relay, it doesn't matter if you reverse polarity on the 85 and 86 pins, or on the 87 and 30 pins.

 

[TDC GSX]

Ohhh Ok I will try that then.

Thanks
Taylor