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Flat 6

'83 SC won't start, not fuel

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Hey all,

So I had been driving my '83 SC on Friday but when I tried to start it yesterday it just wouldn't run.

I assumed it was a fuelling issue because I couldn't hear the pump running when the ignition was at the run position but I then remembered that it won't run on ignition due to the safety fuel cut-off valve.

I've spent some time looking at relay and wiring diagrams and concluded that I could at least test the pump by disconnecting the wire to the safety valve which is behind point 85 on the fuel relay.  So with that wire disconnected the pump runs when the ignition is at the run position.  I undid the union from the top of the fuel filter, switched on the ignition and out gushed plenty of fuel (captured in a tank via a rubber hose).  So no issue with fuel.

I don't think the safety value does anything other than cut fuel flow so with it out of the picture and everything else in place the car still isn't running.

Presumably a fail somewhere else.  What is most likely?  The engine kicks a bit when I try again after it has been sitting for a while but then just goes back to turning over.

V. frustrating when it's been running so well...

Al.

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Hi Al, 

so with the ignition on, go to the fuel meter and push it down, can you then hear the fuel pump cut in? If yes then good there. Also have you tried to swap the round fuel relay? If you don’t have a red one juts use a black one to test. 

If still on start, with the ignition on can you hear the high pitch noise coming from the high voltage unit on the left side of engine bay? If no then maybe a issue there. Also pull one of the plugs and then get someone to crank the car and see if you have a spark when placing the plug against negative bit tinware. Hold the plug with some insulated pliers for safety. If no spark then could link back to CDI, coil, dizzy cap, rota arm  if you have a good spark, then you need to start looking at fuel pressures, but you will need CIS gauges to test I wouldn’t start replacing bits until you can properly test as it’s will become expensive taking that route. Hope this helps cheers Paolo 

 

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Thanks Paolo,

I should have said, CDI is whining as per usual and I got a good jolt from one of the spark plug leads at the distributor when I removed it and bridged with a screwdriver (seems welding gloves are not good insulators...).

Could it be the dreaded WUR?

If it's fuel pressure why would there have been a change overnight? 

Al.

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I had similar symptoms in my ‘83 SC a few years back. After much faffing about, weeping and grinding of teeth traced it to the ‘green wire’, armoured pulse wire between dist and CDI.
Once that wire was replaced my problem was solved.


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I had similar symptoms in my ‘83 SC a few years back. After much faffing about, weeping and grinding of teeth traced it to the ‘green wire’, armoured pulse wire between dist and CDI.
Once that wire was replaced my problem was solved.


Sent from my iPhone using Tapatalk Pro

Correction... it’s a co-ax wire, not ‘armoured’!


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Thats the one BUT.......
The wiring harness on mine was not compatible with that replacement, it was all part of the engine harness on mine. I had to get a mini harness from ‘partsklassik’ (6-pin CDI harness, couple of hundred $$) that my mech fitted, it now has the connections to take that one.


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1488278a756423397e0c9ba1de00aaec.png


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5 hours ago, Flat 6 said:

Thanks Paolo,

I should have said, CDI is whining as per usual and I got a good jolt from one of the spark plug leads at the distributor when I removed it and bridged with a screwdriver (seems welding gloves are not good insulators...).

Could it be the dreaded WUR?

If it's fuel pressure why would there have been a change overnight? 

Al.

 

Hi Al,

As your SC is a 1983 model do you know if you also have a DME relay under your passenger seat as I have read they can course similar type of symptoms. Cheers 

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Thanks Guys,

Paolo, I don't think the SC had a DME relay even in its last year, isn't that part of the 3.2 setup?  Happy to be told otherwise!

Hickepa2 and Matt - my green wire has that same plug at the dizzie end but just disappears into the loom in the direction of the big multi-pin connector at the rear of the engine electrics panel.  Wonder if it goes to that multi-pin or does it just head forward and connect straight into the CDI unit in that six pin?

I'm at work now but will get a look at a diagram tomorrow some time and see if I can trace it.  Wonder if there is a test routine before I start shelling out on parts I probably don't need...again!

Al.

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Sounds the same as mine then Al, integral part of the engine harness. From memory (I’m a wash it and drive it merchant, so tech nous is limited), two of the six pins are the centre (pulse) wire and shield wiring of the green wire. How easy or not it would be to splice these into the connector I have no idea?
What testing can be done I’m not sure, it was Jonny Hart of classic retrofit fame who pointed me in the direction of the green wire at the time, I believe he frequents this parish on occasion and definitely knows the CDI as well as anyone, might be worth an enquiry??


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If you want to test the green wire. Check resistance between pins 7 and 31d on the 6 pin plug.  Should be 600 ohms or there abouts when connected to dizzy.  Have a good waggle and check it doesn't change the reading.

You could also pull the injectors out and check fuel is making it to the injectors.  Put the injectors into some plastic bottles, switch on the ignition and lift the air flow sensor plate and the fuel should flow. The bottles should be equally full. 

Confirm you’ve got fuel and a spark first and then start looking further - good luck. 

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This sounds a lot like my SC's starting issues. It either starts on the first cylinder or cranks and cranks without firing. I have (I think) traced it to the starter solenoid. Yellow wire from ignition switch when on 'start' fires the solenoid to turn the engine but another output of the solenoid sends volts Via the thermoswitch to the plenum injector to start the engine, after that airflow lifts the CIS plate and the car runs. 

In my car, no voltage ever reaches the thermoswitch so I assume the solenoid is faulty or the wire is broken, no time so far to check it out....!! 

I think that is my issue, maybe yours?

Chris.

 

 

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10 hours ago, Ringo911 said:

 

Hi Al,

As your SC is a 1983 model do you know if you also have a DME relay under your passenger seat as I have read they can course similar type of symptoms. Cheers 

No babee, not on a 3.0

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Simple 6 pin CDI check.

In your case the CDI is making the whining noise.  This confirms is that its internal power supply is working. 

To check that it is seeing the distributor signal, crank the car over whilst watching the tacho.  If the tacho is totally dead then it’s either that green wire or the CDI itself that has failed.   Do the resistance check as Northy suggested.

 

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1 hour ago, Jonny Hart said:

Simple 6 pin CDI check.

Do the resistance check as Northy suggested.

 

Which was a direct quote from you, Jonny 👍

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Thanks Gents,

When I am cranking the engine, the rev counter gradually builds up until about 4000.  Does that tell you anything?

A.

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7 hours ago, Flat 6 said:

Thanks Gents,

When I am cranking the engine, the rev counter gradually builds up until about 4000.  Does that tell you anything?

A.

4000 RPM?  You sure about that?

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Hi Jonny,

Didn't take an accurate note I must admit but it climbed gradually the more I cranked and then settled at a max of let's say 3000-4000.

I've just tried again to take a proper note but it is now not climbing at all.  The tacho is not totally dead in that it is lifting maybe 2mm from rest but not getting beyond '0'.  

And I've just taken that resistance reading.  With my meter set at 200 I'm getting a reading of 0.7.  I take it this means the wire is broken?

If so, do I have to buy one of those looms that takes the replacement green wire Matt sells or if there an alternative just to replace the green wire all the way to the connector?

A.

 

Meter reading low res.jpg

Pin low res.jpg

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Any further advice on this Gents?

I'd like to get this sorted in anticipation of a long hot summer ahead!...🤔

Al.

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ok 1st basics...did you try to see if the pump work by it self? Jump fuse number 6(from the windshield ) with no.3-4 where there is always power.If you can hear the pump --pump is not your problem.

2nd.once you eliminate this--saying pump is working..go to the engine and behind the air both is a safety roll over Bosh plug -on the pic .Disconnect it and put the key on --you should be able to hear the pump If yes this plug is kaput.You can drive like this ,just do not leave the key on(light on dash only) so the pump is not running .

 

 

try it and let me know

 

Ivan

 

 

sensor fuel pump.JPG

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Can be................isnt that engine from a 3.2?

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nope this is 91SC from behind, you silly;-) Carrera does not have ..for example an airboot;-) and air decelerator and auxiliary air regulator...........should keep going;-DD

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