Hey guys,


So I tried to start the 914 and my fuel pump isn’t running or buzzing.

- Checked the fuel pump relay and both 15/30 amp fuses.

- Looked at ecu and looks ok

Found a loose green wire:

Click to view attachment

Can someone tell me what it is for? Ground to ECU?

This happened to me before when I get a low battery. Any ideas?

-Ed

Ok, so this is likely my problem. I just bought the battery today
Click to view attachment

See what happens after it is 100%



-Ed

That's the lead to the head temp sensor. That needs to be connected to run.

Where does it go? I don’t see any other loose connections...

Actually, I do not remember having issues with this. Ran fine before I even noticed it.


- Ed

Just wondering if the pic below is from driver side? If yes, the ECU normally on the passenger side just beside the battery tray and firewall. Head Temp Sensor should be by the #3 cylinder.

Click to view attachment

Click to view attachment

FYI... the relays on the relay board do nothing for the L-Jet system. Pull them and an L-Jet car will still run.

There is a double relay mounted close to the battery, usually on the support for the battery tray. The factory one is a metal can, the replacements are a black plastic box. One side of the relay hooks to the engine harness, and a single heavy red wire hooks to the positive battery terminal. The other side of the relay plugs in to the fuel injection harness. That is how the L-Jet receives power.

On the end of the engine harness that plugs into the relay board, there should be a loose yellow wire. That should be hooked to the right rear connection on the 4 pin plug that is on the left rear of the relay board. That tells the double relay you are cranking the car, and turns on the fuel pump. Once the engine is running, the air flow meter powers up the circuit to the double relay, keeping the fuel pump on.

Start with this. Pull the yellow wire off the starter. That way you can turn the key to the start position and not crank the car. Then turn the key to the crank position, and see if you hear the fuel pump running. Even if the whole L-jet harness is missing, you should hear the fuel pump.

If you don't then you have a problem with the power to the double relay. Check to see if the red wire is hooked to the battery.

If it does run, then turn the key on, and open the air flow meter with your finger. The fuel pump should run.


The wire in your picture doesn't connect to the L-Jet harness. It goes to the oil temp sender located on the bottom of the motor, in what we call the "taco plate" It is a round plate located under the dipstick. If you don't have an oil temp gauge, that won't be hooked up.



Also check to make sure there is a white wire from the L-jet harness connected to the negative side of the coil. That's how the computer knows the engine is turning. It gets a pulse down that wire from the ignition.

Check the grounds. They are under the intake plenum, just left of the motor's center line. They are hard to see, but they should have 3 spade connectors hooked to them. Two come from the white wires on the L-Jet harness, and one is brown and comes from the engine harness.

Start with that and let me know the results.

Clay

Ditch the 30amp fuse ,needs to be a 25 if I remember right,cheers.

If you are referring to the fuses on the relay board, well, they won't make a bit of difference. L-Jet doesn't use them.

Also note that L-jet does not "prime" the pump with a 1.5 second pulse when the key goes from "off" to "on" the way that D-jet does. L-jet runs the fuel pump when the starter is cranking, and also when the flap in the air-flow meter is opened.

--DD

Great advice Clay! Thank you for your detailed input. I learned more about the system. Battery 100%, but no buzz from the fuel pump.


Ok, so here is my progress with this. Followed your advice Clay and here are my results:

1. Pulled yellow wire, no start from pump.

So...

2. Checked the fuel pump relay (little black box by battery). Red wire leads to positive terminal is good. Checked the plugs, the black plug is getting signal, but I did not get a signal from this white plug:

Click to view attachment

Can someone tell me the function of this white and black plug?

3. Thanks for ID’ing the oil temp wire. I thought it was that one.

4. White wire hooking up to the coil is ok.


Checked if the fuel pump is getting juice, and looks good on that end. Right now I have a feeling the fuel pump relay or pump went to 914 heaven.


Any other tips let me know. I will try again next weekend.




-Ed

Fuel pump starts buzzing when the key is on position before cranking it Dave. Maybe wiring is switched.

Sounds like L-Jet is the most misunderstood of all 914’s. :

-Ed

The white plug feeds power to the FI system. If it is unplugged, the fuel pump should run when you turn the key to the start position. The engine won't run because the FI is completely disconnected.


Sounds like you have a bad double relay (the black box). If you buy one, make sure you get the correct one. I just had one fail on Betty's car, and they sold me the wrong relay.

Part number 0 332 514 120 is the correct relay. I got 0 332 514 121 and it doesn't work. The pinouts are different.

Click to view attachment

Click to view attachment

You need the relay on the left. The one on the right looks similar, but does not work in a 914 L-Jet.

The missing pin on the plug in the lower left (pin 85) is the ground for both relay coils. So nothing happens at all when you plug in the 0 332 514 121 relay.

Here's the one I bought for my L-Jet. Best price I found. I had to remove some of the black plastic to make it fit. Now I keep one as a spare.
https://www.autohausaz.com/pn/0332514120