C4S wont start

[dave993cars]

Hi

Long story, but I will keep it short, my Carrera 4S has been in dry storage in my garage for over two years with my son in law starting the engine every month to six weeks up until six months ago, the battery is on a trickle charge and the petrol has been topped up with new fuel, the DME is OK but when I try to start the car it turns over but won't fire up, it is a 1998 with only 36,000 miles on the clock, can anyone point me to the possible problem, thanking you all in anticipation.

Dave S

 

[D Ward]

Have you got a spark, if so could be the fuel pump packed up because of sitting idol for so long

 

[John Maddox]

You say the DME is ok but is the relay actuating it ok. A common fault - do a search for details. I think this controls the fuel pump as part of the function.

 

[harry]

Check DME and if it fails, I would change battery. I had mine on trickle charger and eventually battery failed. How old is the battery anyway. If it is over 3 it may be the battery failing to hold charge and not the DME.

 

[dave993cars]

Hi Thanks for the replies, I took the DME relay from my 944 (same as 993, I think ?) and tried it in the C4S (also tried 993 relay in 944 and it worked OK) the battery is only 6 months old as after the long time laid up the original was starting to fail, where is the fuel pump and how can I check if its not working, I can't hear it running, there is no smell of petrol from the engine (as you would expect if it was getting fuel and no spark) I have not checked for a spark. Any ideas. Dave S

 

[2QIC2C]

Sounds like an immoboliser issue. Could be cutting the fuel. Give H&P a call and they should be able to help.

 

[D Ward]

the fuel pump is under a cover plate just behind the front boot floor pan, if you jack the front of the car and slide underneath the car you should be able to see the cover plate. Easiest way to see if pump is running is to switch the ignition on remove the dme relay and bridge the terminals underneath with a jump wire then you should hear the fuel pump running, if not its probly the pump is stuck, sometimes a tap on the pump with a soft hammer will get it going again. If your not sure which terminals to bridge, u can just remove the top from the dme relay and manually move the contacts together with a cocktail stick or similar

 

[dave993cars]

ORIGINAL: 2QIC2C Sounds like an immoboliser issue. Could be cutting the fuel. Give H&P a call and they should be able to help.

I thought this at first as the battery in the fob was not great, but I used my other fob with new battery and it seems to operate OK (it is standard Porsche factory fit no mods). Dave S

 

[dave993cars]

ORIGINAL: D Ward the fuel pump is under a cover plate just behind the front boot floor pan, if you jack the front of the car and slide underneath the car you should be able to see the cover plate. Easiest way to see if pump is running is to switch the ignition on remove the dme relay and bridge the terminals underneath with a jump wire then you should hear the fuel pump running, if not its probly the pump is stuck, sometimes a tap on the pump with a soft hammer will get it going again. If your not sure which terminals to bridge, u can just remove the top from the dme relay and manually move the contacts together with a cocktail stick or similar

Thanks I will try and check to-morrow or Tuesday, I have a spare DME relay already bridged as I have had problems with my 944 (assuming it is the same DME relay) in the past, it was a get me home solution to the DME problem. Regards Dave S

 

[clyde]

Assuming the battery is turning it over adequately, fuel and spark are the obvious two to ensure are okay before going any further. Might be easier to pull a spark plug to check for fuel rather than getting underneath at this stage and you can then check for a spark if fuel before putting the lead back on. As you say I would normally expect a strong petrol smell from the exhaust if it is getting fuel though, so it does appear that this is the culprit. Once you have ruled these two out it is probably a job for a specialist as you're then into faulty mobiliser, dme or some such malady.

 

[clyde]

ORIGINAL: dave993cars (assuming it is the same DME relay) Dave S

It is the same Dave. You've probably got 993 part numbers in both your cars by now as the 944 numbered ones (also fitted to 993s) were prone to failure.

 

[Porker993]

Yes, and intermittent failure at that. So it's no use saying "my DME relay worked fine in such and such a car". The only solution is to buy a new DME relay (993 part number) and keep a spare. It's £35 well spent.

 

[dave993cars]

ORIGINAL: D Ward Easiest way to see if pump is running is to switch the ignition on remove the dme relay and bridge the terminals underneath with a jump wire then you should hear the fuel pump running, if not its probly the pump is stuck, sometimes a tap on the pump with a soft hammer will get it going again. If your not sure which terminals to bridge, u can just remove the top from the dme relay and manually move the contacts together with a cocktail stick or similar

Hi Porker993 I did as D Ward suggested and still no joy, with the Relay bridged out it would seem that this is not the problem, I take what you say on board and will purchase a spare DME Relay. Dave S

 

[D Ward]

The pump should run when you bridge the dme relay, even if the relay is faulty, so it sounds like your pump is faulty. Have you checked to see if you have a postive power supply up to and into the dme relay

 

[Porker993]

ORIGINAL: dave993cars Hi Porker993 I did as D Ward suggested and still no joy, with the Relay bridged out it would seem that this is not the problem, I take what you say on board and will purchase a spare DME Relay. Dave S

OK dude, the one and only time my 993 didn't start in 9 years of daily use was DME relay, so I guess I'm a bit biased ! Good luck with getting it sorted.

 

[D Ward]

ORIGINAL: Porker993

ORIGINAL: dave993cars Hi Porker993 I did as D Ward suggested and still no joy, with the Relay bridged out it would seem that this is not the problem, I take what you say on board and will purchase a spare DME Relay. Dave S

OK dude, the one and only time my 993 didn't start in 9 years of daily use was DME relay, so I guess I'm a bit biased !  Good luck with getting it sorted.

Your quite correct, It often is the dme relay that causes issues. but the dme relay is only a electronic switch and by removing the top and manually operating the contacts the op can diagnose if his fuel pump is working or not, before he has to buy parts he may not need. Which is why I also suggested the op checks to make sure he has a postive supply up to and into the dme relay, if he hasn't got power up to that point he needs to be looking back down the circuit to see why there is no power going up to the dme relay Some garages like to just change bits here & there at customers expense till they find the problem I always find it cheaper to work through the problem till you find the exact fault then repair or replace whats at fault, so your not spending out on parts you dont need

 

[A Ward]

Just been reading through the posting - have you checked the actual fuses to see if you have a blown fuse? If the pump has siezed of become stiff due to lack of use (sitting unstarted for 6 months) - it could be that this has caused a scenario where it has tried to draw to much current and therefore blown the fuse. Thus removing your power supply - obviously if you have a multmeter then you can remove the DME relay and check at the terminals on the board...but if you don't have access it may be worth having a quick look at your fuse panel. Obviously if your fuel pump has siezed (which I'm not saying it has) - it could be down to the fact that the fuel pump has water contamination - and this is one of the potential pitfalls of leaving the car standing in one place for long periods of time - EU law allows up to 5% ethanol to be blended with fuel - which helps increase the octane rating - the pitfall is that ethanol is hygroscopic and thus absorbs water. Not an issue if you are using the car frequently but definitely a potential problem if you store for extended periods of time. Water will seperate from the fuel and settle to the lowest point of the tank and therefore directly at the point where your fuel pump draws from. So potentially your problem could be the non-combustibility of water rather than an electrical issue...or if water has been drawn into the pump you could be looking at corrosion issues. I hope that this is not the case - but it would be worth checking out as it could cause further problems if not addressed. I believe you can purchase test kits to see if water is present - but it is definitely one of the things I would be checking for if you have no joy with the other suggestions. Hope you get it sorted

 

[dave993cars]

ORIGINAL: A Ward Just been reading through the posting - have you checked the actual fuses to see if you have a blown fuse? If the pump has siezed of become stiff due to lack of use (sitting unstarted for 6 months) - it could be that this has caused a scenario where it has tried to draw to much current and therefore blown the fuse. Thus removing your power supply - obviously if you have a multmeter then you can remove the DME relay and check at the terminals on the board...but if you don't have access it may be worth having a quick look at your fuse panel. Obviously if your fuel pump has siezed (which I'm not saying it has) - it could be down to the fact that the fuel pump has water contamination - and this is one of the potential pitfalls of leaving the car standing in one place for long periods of time - EU law allows up to 5% ethanol to be blended with fuel - which helps increase the octane rating - the pitfall is that ethanol is hygroscopic and thus absorbs water. Not an issue if you are using the car frequently but definitely a potential problem if you store for extended periods of time. Water will seperate from the fuel and settle to the lowest point of the tank and therefore directly at the point where your fuel pump draws from. So potentially your problem could be the non-combustibility of water rather than an electrical issue...or if water has been drawn into the pump you could be looking at corrosion issues. I hope that this is not the case - but it would be worth checking out as it could cause further problems if not addressed. I believe you can purchase test kits to see if water is present - but it is definitely one of the things I would be checking for if you have no joy with the other suggestions. Hope you get it sorted

Hi I have been away so i am no further forward than I was on Sunday, but due to your post I had a quick look to-night, I checked fuel pump fuse (No 26) but its OK, I though I could hear the Pump, but it was coming from the front bulkhead in the tyrewell, I presume it is the ABS pump, I have a multimeter and will have a good go at it at the weekend, any other thoughts would be appreciated. Dave S

 

[bernard tester]

Have you checked to see if you have a spark yet? just pull a ht lead off and pop in a spare plug make shure you have a earth and get someone to turn the key while you look! if there is no spark it could be the speed/reference sensor. Berny.

 

[dave993cars]

ORIGINAL: bernard tester Have you checked to see if you have a spark yet? just pull a ht lead off and pop in a spare plug make shure you have a earth and get someone to turn the key while you look! if there is no spark it could be the speed/reference sensor. Berny.

Hi Didn't get to the fuel pump to-day but I did check for a spark, (first top spark lead left hand bank) and guess what I have a spark, seems it is a petrol problem, I have brake pads on the wifes Golf to do tomorrow before I check the fuel pump, will keep you informed. Dave S