Fuel pump..

[9four4]

Are there two fuel pumps on a S2? Internal and external perhaps, or a primer pump and a fuel pump?.. or just a single external fuel pump and that is all?


Reason I ask, I have a non running 1990 S2 here. It has never run in my ownership, Im trying to resurrect it after 5years of sorn. It cranks but does not start. It's getting a spark and it does start if we spray some EasyStart into the airbox indicating all is well with the electrics, distributer, compression and timing etc.. However, there is no fuel at the rail at all.

I have had an auto-elec remove an old alarm/immobiliser as I thought that may have been the cause, this leaves only the factory Porsche alarm fitted (the alarm module has a 928 part no) with which I have done the alarm bypass trick by jumper-ing a relay and a couple of pins on the alarm module connector in order to bypass it and eliminate a faulty alarm from the process as this would prevent the fuel pump from powering up.

So my last port of call I think is the fuel pump itself.

Now.. the fuel pump does not prime until the engine cranks so I cannot listen out for it priming on ignition. I can jumper the DME relay and then turn on the ignition and I can hear a faint hummmm' from the rear of the car, its very faint. The fuel pump would be loud buzz should it not?

The chap who looked at it said (while trying to remember and scratching his head) the faint hummmm' I can hear will be the primer pump and not the actual fuel pump itself.

I am about to buy a fuel pump on ebay.. there are two types..

Dirty used things for over £50
New shiny ones for under £30

They both look different.. Is my guy correct- there are two.. or is this a case of used OEM and new aftermarket..?

I just want to know what pump to replace to get this car going? Sorry if I have not presented all the info in the correct order.. IF you can be bothered to read through, I hope you can offer some advice!

Thanks guys..

www.ebay.co.uk/itm/120703525426

www.ebay.co.uk/itm/250745678454

 

[bmnelsc]

Only one pump on an S2 AFAIK so if you are getting humming it is trying to run. Have you checked fuel filter also? Sitting for 5 years you may well have tank/pump/filter full of goo...

 

[9four4]

Thanks for that. My thoughts too regarding a blocked filter and a tank of gunk.. I will look into this. Thanks.

 

[PSH]

Hi

afraid I can't help with S2 fuel pump types but would add to what Bruce has said on fuel turning to goo......fuel does break down over time and turns to a kind of varnish....an easy check is to spill some and see if it evaporates....if it doesn't disappear reasonably quick then it won't fire up in the engine. I would be inclined to drain the tank and put some good high octane in to get the engine going..

hope you get her running soon...

Pete

 

[chrisg]

The 944's have two fuel filters, an internal tank one (purolator) that screws into the tank and an inline cannister one upstream of the pump.

So, fuel from the tank is collected from the tank through the conical purolator, drains into the pump then is pumped through the service part replaceable filter down the fuel lines.

Hope this helps,

Chris

 

[Waylander]

I had a an issue where the connection from the pump to the loom on the car was all corroded inside, as in your first picture.

car was running fine, put it in the garage and next day no start bit of checking later and that was the issue.

the pump should run for about 2-3 seconds when you turn the key to pressurise the system, and only continue to run when the DME sees rpm of 200 or more