1984 Carrera - no start

I have a "No Start" Problem 0n my 84' 911 Targa. No power to the fuel pump fuse. I jumped the fuse and can here the fuel pump humming but still "No Start" any ideas where to go from here?

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: 911 Carrera Engine Starting Troubleshooting

[Wayne 962]

The pump shouldn't run until the car is trying to turn over, so not having power to the pump when the key is in the ignition is typical. It sounds like your problem lies elsewhere. I'm going to copy your question to the technical forums, and perhaps the users there can offer additional assistance.

- Wayne

[DRACO A5OG]

Could be the Speed & Reference Sensor, check the OHMs there per Bentley Manual offered by our Host.

Sign up and search on how to install the new sensors, they are liken to a light bulb so do not twist them in. Ask me how I Know.

[kidrock]

I say, let's start with the basic stuff first. That means, we need to check for fuel and spark. Since you've already jumpered the fuse to the fuel pump, I'll assume you know how to already do the basic checks. Have you done this yet?

[djcdmv]

Originally Posted by DRACO A5OG

Could be the Speed & Reference Sensor.

This was the problem with my car that I bought last summer.

[kodioneill]

DME relay.

[ischmitz]

Basic checks as others suggested:

1. Turn ignition to ON and verify that the idle control valve is humming. This confirms that the DME is powered and no alarm unit is preventing engine the from starting.

2. Change the DME relay - this is a comon issue and you should have a spare in any case.

3. Check if you get spark. Use an old spark plug grounded to the engine while an assistant cranks. No spark could point to bad sensors (speed, reference) or a bad DME.

4. Use some starter fluid into the intake to compensate for potential missing fuel signals. If it starts with that but doesn't keep running you might have a bad DME (not the relay).

Alternatively, you can smell at the tail pipe. With missing fuel and working spark you won't smell raw fuel after cranking for 30 seconds. With missing spark but fuel you will smell lots of raw fuel. If one signal is present but the other isn't and you have confimed a good distributor and working fuel pump during cranking) you pretty much have narrowed it to a bad DME. If both are missing the sensors are more likely to blame.

Good luck,
Ingo

[Kidasters]

Does the car even turn over? It could also be the cylinder head temperature sensor. If the sensor isn't plugged in or is bad, the car won't start.

[Dynamik]

I had this same problem my old 84 Carrera. In my case it was a bad connection to the battery. I cleaned the negative terminal and it started right up.