Fuel pump issues, no power to pump Options

[Tab914]

Hello all,

Well took the teener out today to start my summer driving. Charged the battery and car started on first cranks. Let the car run for a bit, turned it off and turned it back on. Pulled out of the garage and took pictures to get a new insurance policy and let the car sit for half an hour.

Here is where the fun begins. Go to start the car to put it back in the garage and......nothing. Don't hear the fuel pump buzz when I turn the key. Push the car back in the garage and start testing.

The car is a 1974, 2.0lt d-jet.

Direct power to the pump shows that pump works.
Jumping the relay shows that power from the relay board will reach pump.
When pump is running while jumping the relay, the car cranks but won't start.
Then, when checking the main power relay, looks like I am getting no power to the relay board.
Swaped out the computer (brain) for another and still no power to the relay board.
Tried jumping the wires at the relay under the passenger seat and still nothing.


Been going over and over the electrical diagrams and getting nowhere.
Got tired and can't think anymore.

Very frustrating after having the car start right off the first crank.

Is there something simple I am not thinking of?

Thanks in advance to whoever can help. Appreciate all answers / suggestions.

Will check tomorrow after a nights sleep.

Cheers,
Dominic. (IMG:style_emoticons/default/beer3.gif)

[Tab914]

Well the flow charts are great. From isolating the problems to the right steps to troubleshoot them.

Got the car running again after doing the following.

Checked and cleaned connections of red wires running from the + battery pole.

Using the charts I established that I was in fact getting power to the relay board. (good)
After pulling the plug on the board (the one closest to the firewall) I found a bit of corrosion there so cleaned that off while I was at it.
After following the charts and doing the tests I found that I wasn't getting any ground to the fuel pump relay (relay 75) and that that is why it wasn't working.
Looking at the trace on the relay board for that ground I found that it went back to the five wire plug at the back of the board marked with roman #s I - II - III and IV on the relay board chart and that it trace to the pin marked III
These wires go back to the ECU. After pulling the ECU and checking continuity in the wires I found everything to be OK there. Reconnected the ECU, checked its ground at the back of the engine along with the injector grounds and made sure those were clean and tight.
Cleaned the connection at the plug marked with the roman #s and I think that that is were my problem came from. Bad ground connection at pin marked III was preventing relay #75 (fuel pump relay) from working.
If I look at the relay board chart properly it looks like relay #75 is the only relay that grounds at that point. (must be a reason) Anyway........

Put that plug back in and car started on first crank.


All of this to say that it was a grounding problem between the board and the ECU. Took a while to figure out but lucky that all components work.

Needless to say that those charts worked wonders. Couldn't have done it without them.

Hope this and the chart will help others and save some time finding the problem.

Thanks to Dave Darling, Eric Read, EJM, Sir Andy and Brent D. for all your help and suggestions.

Cheers everyone (IMG:style_emoticons/default/beerchug.gif)

Dominic.