[alfaaddicted]

Hello further to my earlier problem in my 89 S3 Spider which wouldn't start I thought I'd sorted it with the fuel injection relay and main relay , the car started and ran well but then I found that when the engine was warmed up it won't start . If I leave it 10 minutes it'll start again ,all the pumps do their stuff and you can hear them power up but all it does is churn over.
The summer season will be over before it gets out of the garage.
Thanks for looking

 

[sloboy89]

I would confirm spark first. If no spark, then test the flywheel sensors.

If you have spark, then move back to the fuel system where there are a couple of possibilities. First, it might be a bad pressure regulator. Second, I had an issue once where the in-tank pump had failed mechanically such that it was spinning but not pumping at all. A broken stepped hose on the fuel sender could possibly do the same thing. Depending on the level of gas in the tank, the main pump may be capable of delivering fuel without the assistance of the in-tank pump.

 

[alfaaddicted]

Yes tested the spark and plenty when not starting, would the flywheel sensor only work when the engine is cold?
Also the engine will run until turned off but only won't start if it's turned off but run happily until then

 

[sloboy89]

I have had flywheel sensors that would work intermittently before complete failure (not sure if it was temperature related, but doubtful). But if you have spark while it is not starting, it is almost certainly a fuel issue (and not the flywheel sensors).

Pull the vacuum hose from the top of the fuel-pressure regulator and see if there's any gas in it. There should not be. If there is, you likely have a bad pressure regulator. But even if not, that does not necessarily mean the pressure regulator is good.

Can you test the fuel pressure? Typically, this is done by disconnecting the hose to the cold start injector and hooking up a pressure gauge to that hose. (Clamp the hose and use eye protection before disconnecting).

With the pumps running, the fuel pressure should be about 35 PSI. If the fuel pressure is too low, it could be a bad pump (main or in-tank).

 

[David O'D]

Alfaaddicted, if I'm not mistaken, a dodgy coil on its way out might keep up when cold / cool, but falter when hot. Swapping with a known good coil is the easy test.

Good luck!

David OD
Laguna CA

 

[alfaaddicted]

Thanks I guess I've got a lot to look at , I did wonder about a coil , I'm beginning to wonder why I like Alfas!

 

[sloboy89]

Thanks I guess I've got a lot to look at , I did wonder about a coil , I'm beginning to wonder why I like Alfas!

Alfas are like a new puzzle every day!

 

[sepehr]

Maybe the cold start injector is active when it's not supposed to be?

Something you can try:

Warm up the engine, then shut it off. Unscrew the cold start valve from the intake manifold and point it into a bottle.

Crank the engine and see if it's spraying. It should only spray fuel when the engine coolant temperature is below 35C, and then for no more than 8 seconds at a time.

Obviously have a fire extinguisher on hand.

 

[pantera928]

Yes tested the spark and plenty when not starting, would the flywheel sensor only work when the engine is cold?
Also the engine will run until turned off but only won't start if it's turned off but run happily until then

I am not sure what you mean to say in this post. Care to clarify?

 

[alfaaddicted]

I am not sure what you mean to say in this post. Care to clarify?

The engine cuts out when it gets up to operational temperature i then tested for a spark of which there was a strong spark.
The engine will run without any problems until it is turned off but if you immediately try to restart it whilst at operational temperature it won't again until the engine temperature has dropped, then it will restart.

 

[pantera928]

The engine cuts out when it gets up to operational temperature i then tested for a spark of which there was a strong spark.
The engine will run without any problems until it is turned off but if you immediately try to restart it whilst at operational temperature it won't again until the engine temperature has dropped, then it will restart.

Got it now. I think someone mentioned a flaky coil but that would not give you spark.
Doe it run well as it is getting up to temperature or is it dodgy?
Do you have the L-jetronic troubleshooting guide that is on this forum?
I am wondering if a temperature sensor could cause this although I have never seen that.
Still thinking....

 

[alfaaddicted]

Yes it runs absolutely fine and shows no signs of cutting out or stalling or misfiring.
It seems to be a temperature related problem but the engine keeps a good steady temperature and doesn't get too hot either.

 

[zedsn]

Have you pulled and inspected your spark plugs to see if they are wet in your no start condition?

 

[alfaloco]

Pull the connector off the CTS, coolant temp sensor, spray sensor and plug with electronics cleaner, then reconnect. The CTS is a key input signal to the ECU for both startup and running conditions.

 

[David O'D]

Alfaaddicted: I'm beginning to wonder why I like Alfas!

Well it's just part of the fun with cars so full of 'personality'. All of us prefer minimal headaches and the car running (almost) all the time. . . .

Pantera928: I think someone mentioned a flaky coil but that would not give you spark.

Greg, is it not true that a marginal coil will sometimes perform when cool, but stumble when hot? Pretty sure I've read of that behavior in several places -

David OD
Laguna CA

 

[alfaaddicted]

Well I managed to get an hour on the spider today , no further on I'm afraid but when it stops I've discovered the plugs spark and they are bone dry so whatever is happening is turning off the fuel supply when the engine is warm .
I'm wondering if to replace the under floor pump

 

[alfaaddicted]

Certainly got me stumped 🤔

 

[zedsn]

Your spark plugs are suppose to be dry and not wet so your pump may be in good working order. My next step would be to add a gauge to the fuel line before the injectors to see if you still have good fuel pressure when the car does not start. Also, get ahold of a multi meter and check the ohms on the coil to make sure that it still has 1.5 if my memory serves me right when the car won't start. Intermitent no start problems are hard to remedy sometimes because the car does come back to life on its own. Lastly, have you tried jumping the main fuel pump relay behind the back seat to see if your car starts then on your hot no start? You can try these next.

 

[jayhunt]

Try disconnecting a hose from the air intake duct near the fuel injection plenum.
When the engine is warmed up, but won’t start, spray starter fluid into that port while cranking the engine.
If it starts and runs fine, then you have a fuel related issue.

 

[pantera928]

Alfaaddicted: I'm beginning to wonder why I like Alfas!

Well it's just part of the fun with cars so full of 'personality'. All of us prefer minimal headaches and the car running (almost) all the time. . . .

Pantera928: I think someone mentioned a flaky coil but that would not give you spark.

Greg, is it not true that a marginal coil will sometimes perform when cool, but stumble when hot? Pretty sure I've read of that behavior in several places -

David OD
Laguna CA

You are correct regarding flaky coils but in this case, I believe he says that he is still getting spark unless I am mistaken