[T3] Fuel Pump relay not energizing

Daniel Nohejl d.nohejl at gmail.com
Thu Feb 23 13:28:31 PST 2017

I've had several ECUs which were unable to ground the fuel pump. Jim was able to repair at least one of them but not all. I forgot exactly what it is that goes bad (resistor, transistor, or some such thing) but it's a fairly common failure. Either way, jumping the pump relay to ground is the easiest workaround. As you've obviously already noticed, when you do this the fuel pump runs constantly once the key is on but the car will run just fine. I daily driven for months at a time like this though not everyone will recommend doing so for safety reasons.

> On Feb 23, 2017, at 15:27, Dorough, Don CIV, NPPSC N3/PSD Pensacola <don.dorough at navy.mil> wrote:
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> I've got a 1970 Fastback with the original fuel injection still on it.  
> I bought the car not running and I’m trying to get it running.  
> For some reason the ECU is not telling the fuel pump relay to energize then the key is turned on.  Therefore no fuel pressure, no start.
> Fuel pump is good, relay is good, fuse is good.  I can actually manually energize the relay/pump by applying the "ground" to the relay that would normally come from the ECU and the car will start and run.
> My question is why is this signal not coming from the ECU and what does the ECU check for before it will energize the fuel pump relay?  I'm thinking there is a problem somewhere else and not in the ECU.
> Thanks,
> Don
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