Cutting out when cold

[rustynuts]

Right, I replaced the fuel pump as suggested, and the situation is much improved, but not quite right still.

Car is no longer stumbling or stalling, but is still a little down on power.

Mechanic says he used a timing light and it was all over the place, timing moving from aboiut 7 degrees to 17 degrees, like the timing belt was loose. There is also a noise from the engine that he diagnosed as a belt slapping its housing. All popints at a loose timing belt, but on investigation, the belt is tight.

So, in the absence of it being due to a loose belt, the only other cause I can think of for fluctuating timing is the cam position sensor.

great news about the pump, going to do mine 2morrow
Has anyone ever had one of these fail on them?

[K10]

Bad news. Started the car this morning, and it acted just as before. Looks like it wasn't the fuel pump then. Will get the pressure measured again and see whether that's right now anyway.

[Fergus]

May as well get a leak down test done as well.

[rustynuts]

Bad news. Started the car this morning, and it acted just as before. Looks like it wasn't the fuel pump then. Will get the pressure measured again and see whether that's right now anyway.

BUGGER,keep going mate,you,ll get there in the end.

[fabfiveferg]

Christ dude I've been watching this thread avidly. You poor fucker.

My head would have exploded by now.

Sorry I have no assistance to offer but hope you get it sorted soon. God knows you desrve it.

You've also made me mention Christ and God. Neither of which I believe in

[K10]

You're right Fergus, a leakdown test is prob a good idea, I've been telling myself it's not anything like that (wishful thinking), but it's time to stop spending money if that is the problem.

Next suspect is the timing, will get it done properly. Any sign of that gun?

[Fergus]

He's not back from Australia yet, should be back sometime this week though.
I'll text you when he returns.

Perhaps it may be better to just go buy another engine ? Think it's around 500 sterling....how much have you spent on it so far ?

Would/could it be a 'Shortnose crank keyway' problem ?

[Steve]

before doing anything else I'd do what Bill Cardell suggested. All you need is a long screwdriver or a stick.

[K10]

Will do, but no time at the moment, over the weekend, I will get the fuel pressure checked again and do that check on TDC, I'll also take off the crank pulley and make sure the keyway is OK.

A few more things, then if it doesn't behave, we'll be having an MX5club barbecue in my front garden (she's got a half a tank in her).

[K10]

Just chatted with mechanic, he did short those terminals when checking the timing, so as I see it, 3 options

- Keyway fecked
- Cam position sensor fecked
- pulley starting to fail (rubber inside it), so timing is actuall OK, but marks look off

Do these cars have a crank position sensor (is there something reading off the flywheel)?

[Steve]

CAS (Crank Angle Sensor) ... roundy thing beside the coil at the back of the camcover. Just one bolt to remove (read the notes on CAS o-ring renewal before you take it out.. especially the bit about making aligning marks).

[K10]

But is that not a cam angle sensor? Is there one on the crankshaft.

[Steve]

Yes, but it is both the cam & crank position/angle sensor as they are related.
No specific CPS on a mk1 (think there is one on a mk2 tho.. )

[K10]

Cheers, thanks, just wanted to be sure there was only one sensor - wouldn't make sense to have 2 - they are both connected by the belt anyway. Duh.

Forgot I still have your coilpack, will get it in the post ASAP.

[K10]

Just stripped the timing belt and all that gear from the front of the engine.

The timing was way out, spark was timed roughly (it varied a bit) 16 degrees BTDC.

The reason is that the keyway in the crankshaft nose has worn, possibly due to the crank end nut (holding the pulley and key tight onto the end of the shaft). Unfortunately the pulley seems to be made from harder steel than the crank. Which is a pity, as the crankshaft was then the one that got eaten.

You can see the keyway on the crank is elongated (apologies for the bad pic).



Wheaeas the keyway on the pulley is fine (the key is in this pic too, and that's pretty much disintegrated).



So, the proposed fix is to use a new woodruff key with some chemical metal, screw it all up tight with some thread seal in there and let it all set. It's not the most professional sounding of fixes, but the only other answer is a new engine.

Does anyone have any links to and previous fixes for this issue, I remember there were a few on the UK MX5oc, but I'm no longer a member.