Car wouldn't start yesterday, now it's fine (Fuel Filter?)

Try a filter as said, sounds like fuel starvation.

Simon said:
Fuel pump could be shagged as it ran dry. Very small chance of this though.

The inside of the tank will be spotless. Most fuel pumps will recirculate the entire contents of the tank twice through a fuel filter twice in a minute. There is no dirt.
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All of the fuel tanks i've been inside recently have had some form of crap in the bottom of them. God knows what it is but it definetly exists.

And using for example and uprated Walbro 225l/hr pump will only shift 4.25l/min then its going to take a good while longer than a minutes to recirculate the contents of the tank to the rail and back. Unless its one of the crappy newer in tank regulator designs and even then it'll still take a good chunk longer than a minute.
 
Why haven't you changed the fuel filter yet? Sounds like it needs a new one to me.
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Basically, I listed the things I thought may cause it, and did them in order of difficulty until the problem seemed to go away.

However, yes Fuel filter is the next thing I'm going to do. Sadly I don't think I'll have time for at least 2 weeks, so it'll have to sit at home on a battery conditioner and I'll use the motorbike. . .
 
AtomicBanana said:
Basically, I listed the things I thought may cause it, and did them in order of difficulty until the problem seemed to go away.

However, yes Fuel filter is the next thing I'm going to do. Sadly I don't think I'll have time for at least 2 weeks, so it'll have to sit at home on a battery conditioner and I'll use the motorbike. . .
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I've found fuel filters differ widely in difficulty. My fiat and Rover were a doddle, but the Nissan was a real PITA. I had to remove loads of parts to get to it.
 
Right. Before doing any more blind guess I decided to get an LED to read out the error codes from the car (http://www.mx5oc.co.uk/forum/forums/t/204.aspx). I got 2, oxygen sensor, and water thermistor.

I tested the voltage output of the oxygen sensor and it seemed normal, so I'm going to hold fire on that. I've ordered a replacement water thermistor. This is the one at the back that feeds into the ECU, so seems promising as a likely culprit.

So fuel filter is out of the equation for now, and my current plan of attack is:

Water thermistor > oxygen sensor >>> Coil Pack > Fuel filter

Fingers crossed, aren't cars just so much fun sometimes? ;)
 
Erm, thanks for that.

The sensor feeds information directly to the ECU, and it's used among other things to control the choke. In the MX5 workshop manual I have it suggest this sensor is used by the ECU quite a lot, and it recommends replacing it if you have any suspicions about it (like, say from the fault code generated). Good chance it's either causing the problem, or masking it.

I think you're assuming it's the themostat that's used to control opening/closing of the different water loops around the engine/operating the fan. That's a seperate one, and there's actually 3 water temp sensors:

1 at the front (controlling which route the water takes, controlling the fan)
2 at the back (1 feeds the dash temp gauge, and the other is used by the ECU to control choke etc)
 
If you do end up changing the fuel filter, it's not difficult. The hardest part is getting the rubber pipes disconnected from the old filter. Then just jam a Biro in them to stop fuel ****ing all over you :)
 
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