Hi Folks,

I've got a '76 2.0L and I'm getting no power to the Fuel Pump. Car was running fine when last parked, now won't start. I've been troubleshooting and can report the following:

On the Relay board...
1. 12V at Pin 30 on fuel pump relay
2. 12V at Pin 85 on fuel pump relay (should be ground, right?)
3. Ground at Pin 86 on fuel pump relay (should be 12V, right?)
4. Pin 8 on the 14 pin connector reads 12V.
5. No 12V at Pin 13 on the 14 pin connector
6. No power at the 25A terminal (13S)
7. For ground, I'm using pin 10 on the 14 pin connector that attaches to the relay board.
8. On Main Power Relay on Regulator board, checked Pin30, have 12V. Checked Pin 87 when key is turned, nothing...

I swapped out the Relay board with another one that was loaned to me and get the same results.

I also tried pulling the ECU and checking the cable connector, but it is bundled and connects INSIDE the box. ECU grounds at the 3-post connector on engine block seem good too.

Any ideas why Pins 85 and 86 would seem reversed on the Fuel Pump Relay?

Anything else you might recommend?

Thanks,
Jason

Do this and you'll have your answer. http://members.rennlist.com/pbanders/FPChecklist_frame.htm

Thanks!

It looks like there is supposed to be more when I click the link. It just has a short statement about follow these flow charts... Do I need a special viewer? Maybe it's an old link?

It is not clear in your post if you have checked the fuel pump to see if it has failed. If you haven't, you should do that first to see if it is a current flow issue or a pump issue.

I dealt with this problem a few years ago. I spent a fair amount of time troubleshooting a suspected current flow problem that didn't exist. It turns out that the problem was the pump. The pump was actually failing intermittently so be aware that that is a possibility.

First, can you jumper the fuel pump?
Second, is there a fuse for the fuel pump on the relay board??

Rich

Jason

There should be 12v on the 25 amp fuse, it come from battery on pin#12 feed from
the battery. Check your +battery post that all the red wires are connected.

Larry

Thanks guys.

Have been trying to go through Brad Anders debug guide. So far, everything checks out, until I get to the ECU harness. This is a 76, so there is no connector on the outside of the ECU, just a gang of wires that goes into the ECU through the bottom.

I have checked the power at the fuse on the Relay board and there is no power taht I can measure. I have checked on 3 different relay boards. There is power coming from Pin 12, 14 and 8.

Going to try and find a wire long enough to hotwire the fuel pump now...

Hot-wired fuel pump, nothing. Did connect a "light probe" between the battery wire and positive terminal on fuel pump and light comes on, so grounding through the pump. Also disconnected ground and ran same light probe to ground wire and light comes on, so looks like fuel pump is dead.

But why would we not get power at the fuse on the relay board?

Did you whack it gently with a hammer?

Do you have battery on the 25 amp fuse? There is a red wire from pin#12 directly
to the + battery post. This wire may be broken off.

Call me I drew out how it works and I can explain it to you.

Larry

I have power at Pin 12

Hah, Hah! Yes, used a rubber mallet... :-)

Quick lesson on how it works.

1. Turning on key supplys power to the coil to the power relay #85 on the relay board which operates it.

2. This supplys power from pin #14 (14 pin connector) to the power relay #30
to #87, which supply power to #85 on fuel pump relay and I terminal on 4 pin
terminal to ECU.

3- The ECU now grounds pin # III which is connected to #85 on fuel pump relay
which now operates it. Pin #30 which has battery on it now supply battery
on #87 which goes to the fuel pump on #13 (14 pin connector) to the plug
in connectors to the fuel pump.

Got it! I'll have to digest that in a bit. I ran out of "work on car" credits and have bloodied my hands up pretty good digging in the engine compartment today.

Goign to go ahead and order a fuel pump (or look for one used). Maybe its just that and will be a quick swap out out next weekend.

Thanks for all the pointers so far. I'll post back when I get any change in status.

So again, have you tried to use jumpers on the fuel pump to see if it works?

Yep, darn thing won't spin-up. Ran 12V straight off the battery and also confirmed good ground. Was really expecting it to work.

Working on a sourcing a replacement now and will retest once it arrives. :-)

Thank You everyone for your help! It turned out to be the fuel pump!