I know from previous post the relay ground is controlled by the computer.  This one is strange works fine some times and others not.

 

Well, I thought I had it, I swapped the heater fan relay and fuel pump relay and the fuel pump worked just fine yesterday.

 

I went to start it this morning and it would not start.  I dropped the kick panel, Computer and just moved the relay and it started and ran fine for 3 hours.  I stopped for gas about an hour into the trip and it started right back up.

 

Now sitting in the driveway for a while, I was cleaning it and then went to start it, no joy.  

 

I removed and jumped the relay and it runs fine.  

 

Wiring or Computer?  Anyone have the wiring manual or a good way to check this?  Looks like you'd have to drop the complete dash out to really get at all the wiring.

 

Thanks, 

Larry

Is the plug cruddy looking inside? Could just be a loose terminal in the plug.

 

I would think the problem is near the relay or in the connector if wiggling or moving the relay makes it work again.

I suggest you at least use a test light to verify that power is getting past the relay when the trouble is occurring. If power is okay there then check for a bad connection at the connector between the relay and the pump.

Yep, Load, Ground, Power.  

 

I"m going to get my meter out today and take some voltage readings under load.  I also remembered the PO had bypassed the ignition SW with 3 on off switched which I removed and put back on an Subaru Ignition SW so I'll double check that as well.  The connector looks clean and contacts are in good condition.

 

Thanks Larry

Back probed the plug

11.5 volts on both sided of the control coil, = missing ground

11.5 volts on the input side of the fuel pump switched contact.

 

I hit the yard today and got a couple of Subaru fuel pump relays, newer ones and plug one in.  It started right up.  Hopefully it is a solid fix.

 

I believe the relay did it.  2nd day in a row with many start and stop cycles, has worked each time.

Edited April 29, 201510 yr by lmdew