Tenshieternal

My '82 928 as been running for a couple of weeks no issues then yesterday I started her up to put nose in first in the driveway did some interior work. I was going to go to the store and she wouldn't start. check the plugs for flooding, nope, all dry. Too dry, so I checked the fuel pump and it wasn't pumping. I'm not getting any power to the fuel pump.

I've tried three different relays and tried the jumper trick still nothing. I put in the fuel pump from the 84 that I'm rebuilding and didn't need for the moment and still..... nothing. What else could prevent the pump from getting power? Unless I have the worst luck with four bad relays and two bad fuel pumps.

Thanks for any ideas as to what could be causing this.

Dave928S

Power from the 30 bus line goes via fuse 22 to the 30 terminal on the relay, then through the contacts in the relay to terminal 87, and then to the fuel pump. By jumpering 30 to 87 you take the coil circuit (which switches the relay) out of the list of possible problems.

I assume you've checked the fuse ... if not check fuse 22.

If still no go check that you have power to the fuse, and then to the relay (terminal 30), using a multimeter.

If you do have power to that point, then you need to follow the circuit through to the fuel pump (with the jumper in place), checking down the line until you find where you don't have power.

Tenshieternal

I'm at my day job right now so I'll get back to work on it late this afternoon.

I didn't check the voltage at the fuse to the relay yet. The idea of a broken wire in the circuit is a pain in the ***, that's why I was wondering if there is something in between like a fuse-able wire link or device that may prevent power from getting through.

Dave928S

Nothing like that ... only what I've already mentioned.

BTW didn't mention one of the obvious things ... you should also check grounds. If you find you have voltage to the pump (and the pump is good), then you need to continue to the end of the circuit, which is the ground.

Just be methodical in following the circuit, and checking connections and voltage as you go, and you'll find it.

I'd be guessing a loose badly connecting fuse, a bad ground, or another loose/corroded connection is more likely than a break. Edit: just saw jp's post ... I've had overheated pump fuses, and no starts, in both my cars from poor contact.

jpitman2

I recently has some adventures in this area - relay failure initially, swapped it out, problem came back.Jumpered the relay socket, saw a spark out of the corner of my eye----fuse 22! It now has one of my blade fuse adapters fitted, and is good - see my thread on 'converting bullet fuse board to blades' . I believe the relay was killed by excessive current caused by poor contact at the fuse, now shows 7A.
I have an 80 model CE board for testing blades, and its fuse 22 position is well burned, as is the fuel pump relay socket heat damaged.

Make a relay jumper with male blades at each end of a wire (needed for good contact), jump the relay socket; if still no pump, check the fuse. If still no pump, then go looking for a wire break. If you can beg/borrow/steal a network tracing tool, put it in tone mode, connect lead to the +12V lead at the pump (removed from pump), and check if you get tone up at the CE board - if not try to follow the wire up the car from the back (via tone) until it stops - the break...
Mentioned the blade fuse thing to a mate yesterday - he laughed and told me a story - as a young man with mates travelling in a VW combi, they had an ignition fuse problem; one of the guys had teeth braces with ~3/8" rubber bands on them; problem solved by running one of these bands top->bottom of the fuse holders.
jp 83 Euro S AT 54k