Fuel pump problems

elwood-914 · 12-10-2003, 06:49 PM

Help!

I can't get my car to start! I don't hear the couple of bumps telling me that the fuel pump is working. I swapped relays, then with the key on I get no voltage at the fuel pump connector. Any ideas from the experts? Thanks

elwood-914 · 12-10-2003, 07:26 PM

Now what? It just started. I had to have it towed home last night. There must be something intermittent, a short maybe. I am now leary to drive it since I don't want to be stranded. Any thoughts?

3D914 · 3D914's Garage

elwood,

Remove the relay board cover (if you have one). Locate the white connector with four sockets in it.

One socket has two wires (upper-right of connector - we'll call this A)- this is the main switched power for the ECU.
Lower-right of connector is starter/fuel-pump wire (we'll call this B). Lower-left is fuel-pump wire (we'll call this C).

With a volt-meter connected to a ground, have the positive lead handy.
Turn the key On (but don't start it).

Check A - it should read around 12v.
Check C - it should read around 12v. You should hear the fuel pump.
To check B - have someone crank the car. B will only get 12v when cranking the starter. It also sends 12v to fuel pump when cranking, so C will stop reading volts when cranking.
After cranking, C should return to 12v.

If all is well with these checks, verify that the connector on the fuel pump is not loose or dirty. Since it hangs down from the pump, I've had mine just barely connected before.

Good luck,

elwood-914 · 12-10-2003, 08:23 PM

Gereld,

Thanks for the reply, I'll check things out tomorrow. Thanks a bunch.

mathews2001 · 12-11-2003, 12:40 PM

Where would a PO have likely put an aftermarket fuel pump? The car is a 1974 that was converted to carbs.

M. Hendrix · 12-11-2003, 02:42 PM

Under/Aft of the fuel tank.

M

mathews2001 · 12-11-2003, 02:49 PM

Normally accessible from the top or under the car?

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Under. Also check the stock location, underneath the passenger's side of the engine bay. Also check inside the front trunk in the "out of the way" corners.

--DD

mathews2001 · 12-12-2003, 01:26 PM

Thanks. I think the issue is the many crimp and spade connectors I see for the wiring. I hate those things. They are loose and flaky.

3D914 · 3D914's Garage

Good job Mathews2001,

My 914 experience has only reaffirmed my belief that solving most problems is 90% correct diagnostics, and the rest is relatively easy.

How is going Elwood914 - any luck yet?

elwood-914 · 12-13-2003, 12:43 PM

Hi Gerard,

Things are checking out fine. I had the voltages you discribed. Yesterday I drove it to work and on the way home it acted like it was running out of gas, I pulled over and I swapped relays with a relay without a cover and activated the relay by hand and I heard the fuel pump going. It started right up and got home just fine. Bad Relay?? I havent put the other one back in yet. I'll keep putzing with it. Thanks.

3D914 · 3D914's Garage

Sounds like it. Also check the connection sockets on the relay board where the relays are inserted. Moisture can get trapped and cause intermittent connections that break down when things heat up.

Good luck.