fuel pump still not working

[24flys]

ok,

my 72 still won't start. I'm beginning to think it doesn't like me anymore! I've put a new fuel pump relay in it, unstuck the throttle valve, etc. it gets spark because it wants to fire with starting fluid. I can hot wire the fuel pump to the battery and it pumps, but the injectors won't spray,even after I cleaned and tested them. I also tested the pressure sensor and it is good. Does anyone have any advise, I'd like to drive this thing again someday!

scott

[John Rogers]

If the injectors won't fire then the injector points may be stuck shut? I'd recommend pulling the distributor and checking them and the regular points both. The FI points won't last long if the car is not used and they were in the closed position when stopped. You have gotten a copy of the FI trouble shooting article from the PP site here haven't you??? Good luck

[24flys]

I do have a copy of the trouble shooting article but I'm not very good with these cars. I know where the points are in the distributor but where are the regular points?? can I "unstick" the points or would I have to get new ones??

[mejulihn]

As one who has personally overlooked the obvious...just a helpful suggestion: have you checked to make sure the three-wire plug for the FI trigger points at the back/bottom of the distributor is plugged in?

[This message has been edited by mejulihn (edited 05-29-2001).]

[bowlsby]

There may be other things to check. The ECU is central to getting the injectors to fire.

The ECU gets its power from the regulator plate connector on the FI harness. Check the integrity of the regulator plate connection.

Check fuses on the regulator plate.

The trigger points tell the ECU when to begin firing the injectors - the sensors TS1, TS2, MPS and TPS, tell the injectors when to stop firing. Check all of those if you haven't already. The car wont start if there is a problem with the TS2 (cylinder head temp sensor).

[pbanders]

Hi, you sent me some email regarding your problems, I'll reply here.

I agree with Bowlsby's suggestions. You need to do signal tracing to verify that the fuel pump circuit and basic injection circuits working properly. Here are some suggestions on what to expect and what to do:

1. Turn the key to "on". +12V is supplied to the fuel pump. Ground is supplied to the fuel pump for 1.5 sec by the ECU, then it goes open. This is to pressurize the fuel system before starting, without the pump continuously running and creating a fire hazard. A check valve in the fuel pump keeps the pressure up after the fuel pump stops running. If the fuel pump doesn't run, trace the circuit, verify the ECU is getting voltage. If the ECU doesn't supply ground to the fuel pump, you may have a bad ECU. Swap with new/rebuilt to check, or rent the VW 1218 tester from Pelican Parts to test it and verify.

2. Turn key to start - fuel pump should run during cranking. Use a multimeter to verify that the pump is running (+12V across the input) while cranking. If not, trace the circuit, verify the ECU is getting voltage. If the ECU doesn't supply ground to the fuel pump, you may have a bad ECU. Swap with new/rebuilt to check, or rent the VW 1218 tester from Pelican Parts to test it and verify.

3. Go to your local Checker/Kragen and get a "noid" light for Bosch injectors, plug it into one of your injectors. Crank your engine while someone looks at the noid light to see if you get injection pulses. If not, check your trigger contact points in the base of the distributor. Make sure the connector is in place. You can check the points by removing the distributor from the car, they alternately supply ground when the distributor shaft is turned. Check the wiring harness to make sure you have continuity on the trigger contact terminals.

4. If your fuel pump is working, and your trigger contacts and harness appear to be OK, yet you have no injection pulses, you may have a bad ECU. Swap with new/rebuilt to check, or rent the VW 1218 tester from Pelican Parts to test it and verify.

Brad Anders

[24flys]

I did some checking last night and found several things wrong.

1. I have no power to the fuel pump but it is constantly grounded.

2. the ecu is not getting power from the relay board. I have continuity from the power relay(pin 87) to the fuel pump relay(pin 85) and from the power relay(pin 87) to the top right spade where the fi harness plugs in. I don't have continuity from the power relay(pin 30) to fuel pump relay(pin 30), also none from power relay(pin 30) to #16(12v power from relay board) or to #24( 12v power) at the ecu.

3. I found a ground with another set a wires mounted to the car by the top left of the relay board. the other end of this ground is not attached to anything, I don't know where is goes.????

so right now I know I don't have power to the ecu and I have a ground that's not connected to anything. Anyone got any ideas???

I put a pic of the relay board and ground here also, hopefully it will come out.

scott

IMG SRC="http://www.pelicanparts.com/ultimate/image_uploads/relay board.jpg">

[bowlsby]

Hmmm...

Does the relay plate have a voltage source?

Check it by verifying that your heater blower fan operates...

Check the fuel pump and main power relays...(I think you did that already?) Those pin cavity contacts on the relay board for the relays look pretty corroded as well.

Replace the ignition switch? If the switch is bad, the starter won't even crank over.

No clue as to what that stubby cable is attached to the chassis ground.

Have you checked to see if the ECU gets voltage? Check it at the FI harness connector on the harness, harness detached from the ECU, at terminals 16 and 24. You should have constant voltage there when the key is in the on position. If voltage is there, then the probnlem is in the ECU or downstream of the connector. no voltage at the connector, the prblem is upstream of the ECU connector.

[This message has been edited by bowlsby (edited 05-30-2001).]

[Dave at Pelican Parts]

Brad, you've got the fuel pump wiring a little off there.

The pump itself always has a ground. The ECU provides a ground for the fuel pump relay. This ground completes the circuit through the coil of the relay, causing it to connect its pins 30 and 87 together, sending power to the pump.

Right idea, but the wrong circuit...

--DD