'75 2.0. Just put in a new bosch fuel pump (and filter) because the old pump started making a lot of noise and I assumed it was dying. The PO had removed the black/red wire that goes from the + on the pump to the relay board and instead ran a red +12v wire to somewhere that kept the fuel pump running at all times, even if the car didn't start.

With the black/red wire connected now, the pump runs for 1 second or so before cutting off as it should. However, I can't get the car to start. (No issues previously). Feels like it's being starved of fuel. At one point I got it running for a solid 6 or 7 seconds, but it was close to stalling the entire time and the fuel pump stopped running after the initial 1.5 seconds or so. Shouldn't it have been running even if the car stumbling?

If I recall the ECU in my car is from a '74 or a '73. (came with this when I bought it). Engine had been rebuilt and smog stuff removed. Any chance the ECU not being the correct model is the problem here?

I haven't had time to check for a crimped fuel line under the tank yet, but doubt that's the issue given all was good prior to replacing the pump and rewiring it. Really feels like the pump just isn't staying on long enough for it to run.

Here is my experience: I installed new SS fuel lines in my stock '73 2.0 and a new fuel pump relocated to the firewall behind the passenger seat. My rubber fuel line under the tank was kinked and so I had no fuel to the pump. Wouldn't start. I pulled the tank, installed "loops" of fuel line under the tank, re-installed the tank, blew air thru both fuel lines to check there was no kink; put gas in the tank and after a little coughing and sputtering it runs fine.

It totally could be a kink in the line and will check for that tonight, but given I didn't have to pull on the lines that hard to change the pump I'm kind of doubting that's the issue.

Seems odd that the pump didn't keep running when the engine was running, albeit very badly. Shouldn't it have stayed on?

Yes, the pump needs to run when the engine runs. There is a flow chart that makes it easy to diagnose the FP circuit. Unfortunately, I can't offer it to you because it went with my computer when the HD crashed. Someone here will pointe you to it. Kent

Fully understand that the pump runs only briefly at startup and then when the engine is running. My question is how well the engine needs to be running for the pump to run, and would an ecu from an earlier car make any difference?

Assuming you're running Fuel Injection, the ECU will only run the pump when it detects the secondary contacts on the distributor opening and closing.

If the PO rewired the fuel pump to run all the time, it is plausible that the contacts on the distributor aren't working or aren't connected. But if they're not working, the FI shouldn't work either. Hmmm...

Stock FI with no issues (that I'm aware of).

Although it appears as if the ECU doesn't drive the FP when the car is running. This could be why the PO rewired the FP to run all the time.

You will have to dig deeper to find out why the ECU isn't powering the FP during starting.

I would start by putting your voltmeter on the front-left pin to the ECU on the relay board. This is the FP relay signal. It is opposite of operation: 0V = pump running; 12V = pump not running. Measure from the front-left pin to chassis ground. It is good to have someone else turn the key so you can keep the voltmeter on the front-left pin the entire time.

Have your friend turn on the ignition (verify 1.5 sec of pump operation), then crank the engine. The front-left pin should be:

0V when key is turned on for 1.5 seconds, then go to 12V.

When key is turned to start, the pin should go from 12V to 0V (pump running).

Thank you! I'll check it this afternoon an report back.

Turned out to be a kinked fuel line.

Original wiring back in place. The original fuel pump relay was bad which must have caused the PO to run a 12v wire directly to the feul pump. So much effort when he could've just tested another relay! Glad to have the wiring corrected!