PORSCHE 911 Carrera 3,2 1983 misfiring

[micky21]

Hi I wonder if anyone can help me I've not long owned Porsche 911 carrera 3.2 1983

I went for a drive in it today stopped off at a friends house Came back to the car started it up drove off stopped at the junction and it stopped running Started it up again And it just seem to run the rough and misfire all over the place any ideas

Micky

[smudger911]

could be a number of things

incorrectly reading fuel gauge
distributor, ht leads
dme relay
fuel pump
crank sensor or other sensor (cylinder head temp sensor)

might be a suggestion to head over to one of the other forums like Impactbumpers or DDK

[micky21]

Thank You for your prompt response just before this happened I just filled the tank to the top never done that before

Micky

[Stonic]

Hopefully you have not topped it up with diesel. if it was running fine until you refuelled it could be contaminated fuel but I didn't think that was a real issue in the UK or maybe the breather is blocked and causing a vacuum in the fuel tank preventing the pumps getting what they need. Take the fuel filler cap of and see if it runs ok when stationary. If I'd does, symphony a gallon out at without the fuel filler cap, take it for a careful drive, then again with the filler cap fitted. All low tech ideas but may save you worrying over the weekend. You could also try draining the tank and then putting in fresh fuel. Hope you get it sorted.

[Wozy68]

Stonic said:

Hopefully you have not topped it up with diesel. if it was running fine until you refuelled it could be contaminated fuel but I didn't think that was a real issue in the UK or maybe the breather is blocked and causing a vacuum in the fuel tank preventing the pumps getting what they need. Take the fuel filler cap of and see if it runs ok when stationary. If I'd does, symphony a gallon out at without the fuel filler cap, take it for a careful drive, then again with the filler cap fitted. All low tech ideas but may save you worrying over the weekend. You could also try draining the tank and then putting in fresh fuel. Hope you get it sorted.

Surely he'd notice. Large plumes of white smoke emitted from the exhaust whilst driving off the fourcourt is usually a big giveaway something's afoot.

[micky21]

Thank you for your help and tips I am not familiar with Porsches and your tips pointed me in the right directionI think I have found the problem

I checked out all the circuits of the DME relay and all seem to be working okay specially Earth and positive feed to pump when turning over engine was present

I managed to locate fuel pump and when cranking I had earth and positive feed at pump but the pump was not making any noise at all So would I be right in thinking that the pump is faulty

Micky

[smudger911]

micky21 said:

Thank you for your help and tips I am not familiar with Porsches and your tips pointed me in the right directionI think I have found the problem

I checked out all the circuits of the DME relay and all seem to be working okay specially Earth and positive feed to pump when turning over engine was present

I managed to locate fuel pump and when cranking I had earth and positive feed at pump but the pump was not making any noise at all So would I be right in thinking that the pump is faulty

Micky

Sounds like there is some light in the tunnel. Keep us posted on the end result...

[micky21]

Hi I have sorted this problem now
It wasn't the fuel pump in the end I spent some time trying to diagnose this thought I unplugged crankshaft sensor and speed sensor and checked for resistance I found there was no resistance on the speed sensor so I jacked the motor up and put on axle stands went to have a feel of the senses and found that the bracket has come loose the bottom bolt had fallen out and Swan in to the ring gear which grounded speed sensor down so fitted new sensor new boult to bracket set up now running fine

Thank you all for your help