1,8 mx5 mk1 wont start

[rapidyellow161]

ok, last week I reversed out of our residents car park and it either cut out or I stalled it, and it simply would not start, it sounded like it was going to start but couldnt

anyway I ran the battery down trying, took it out and charged it over night then tried again next day, bridged the fuel pump pins on the diag and you could hear it hissing at the inlet manifold, I took off the fuel feed to see it was pumping, all ok, when I refitted fuel pipe I gave it another go and it started, and since then its been fine for a few days.

then this morning on way to work about a mile away it cut out on me, I pulled onto some grass outside somebody house it was on a country lane, it would not start, it has over 1/2 tank of fresh fuel.

So called the mrs, she came to get me, I tried to move the car on the starter as it was bit close to the traffic - we would not have moved it on the grass otherwise, and it started! so drove it home without issue, and went to work in the other car

so back home from work, tried to crank the 5 and its still no go, bridged the pump again and tried it, nothing, then when it had got a bit darker I put a plug attached to a large croc clip onto the engine, connect ht lead 1 and the spark is strong

when its trying to start theres a clicking sound on or near the inlet manifold, is it related?


whats likely to be wrong? can I still get a spark if the cam angle sensor is duff?

[Richyvrlimited]

You won't get a spark if the CAS (Cam Angle Sensor, it's actually a combined Crank and cam angle sensor on the MK1 MX5), is duff.

first port of call for me would be to source a 2nd hand CAS and see if that fixes it. It's not terribly common for them to fail, but it's not unknown.

If when it doesn't start you have spark, the CAS isn't your issue though.

[rapidyellow161]

I have tried to take the cas out today and I had to give up, theres no room for it to come out and away, and now I cant get it back in either, I can see that the drive dog only goes into the cam one way but I just cant seem to get it in

[Locknut]

Is this car fitted with the so-called "igniter" unit similar to the saloon cars? That means the coil is combined with the distributor so there is not a 5th lead going to the centre of the distributor cap. These units are prone to failure. Usually they will start and run for a while, then fail. Let them cool for a while and they will start again.

[fatjon]

If you bridged the pump and "nothing" the second time then I would assume it's the fuel pump. I am assuming by nothing you mean the pump did not run and you could not hear the hiss of fuel flow in the fuel rail?

I have had a fuel pump problem on my mk2 mx5 whereby I had to turn the ignition on and off several times to get it to start running to do the initial 2 second prime before the engine starts. Maybe they get a bit worn or gummed up. Anyway a new one fixed it.

I see nothing in any of this that remotely points to a diagnosis of a failed coil pack!

[Richyvrlimited]

Locknut said:

Is this car fitted with the so-called "igniter" unit similar to the saloon cars? That means the coil is combined with the distributor so there is not a 5th lead going to the centre of the distributor cap. These units are prone to failure. Usually they will start and run for a while, then fail. Let them cool for a while and they will start again.

There's no dizzy on an MX5.

The coils and the ignitor are integrated on the 1.8 versions, (thw 1.6 had a separate coil and ignitor). There are 2 coils that are shared between 2 cylinders (1&4 and 2&3) in a wasted spark configuration.

[Richyvrlimited]

rapidyellow161 said:

I have tried to take the cas out today and I had to give up, theres no room for it to come out and away, and now I cant get it back in either, I can see that the drive dog only goes into the cam one way but I just cant seem to get it in

Remove the cam cover, then you can remove the two bolts that hold down a half moon shaped piece, you'll then have full view of the CAS and the locating drive on the cam, removing the cam cover takes 5 minutes tops. - On reassembly put a small blob of gasket sealant (or bathroom if you've nothing else), in each corner of the humps for the cams/CAS. Oh, and do NOT overtorque the bolts, if you use the correct setting remember that they're in in/lbs NOT ft/lbs!!

I hope you marked the location of the CAS before you removed it. The orientation of the CAS sets the correct 'base' ignition angle, if it's wildly off you'll never get the car to start after you've re-assembled. If you've a timing light you can set the CAS to the correct position.

[rapidyellow161]

thanks, yes I went back to the car and removed cam cover, and the cap, all good!

just waiting for cas to arrive now