Car cranks but won't start

Technical Area Engine, Transmission, Exhaust etc
1

My car cut out on me while driving. I assumed it was the fuel gauge reading incorrectly but I was skeptical because I could hear fuel in the tank. So I topped it up anyway and the car started but after about a mile of driving it cut out again and now will no longer start.

I have no spark or fuel as far as I know and an engine management light doesn’t show on the dash. However, I do have a battery light. Fuel pump does not prime unless I bypass the relay but even with the fuel pump priming it still doesn’t start (probably because I have no spark).

I assume it’s something to do with either the main relay or the CAS. How would I test the relay is bad for sure?

I get continuity on these 2 pins (I’m not sure if that means anything… i don’t have much experience with anything electrical )

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2

If you look really closely at the relay, moulded into the plastic can you see the works “Coil”, “NO” and “COM”? What age & spec car is it?

3

I can see an “A” and “4”. It is a 1993 S-Special Import. Also the relay is a Denso B6S8

4

Do you have continuity across the other 2 pins? Is it a 1.6 or a 1.8?

5

I don’t. Just the two pictured

6

If you can get hold of a 9v battery and some wire, apply 9 volts across the pins with continuity observe if the relay clicks. If it does click, with the 9 volts still applied, check for continuity across the other 2 pins.

If I had to guess, I be suspecting a failed CAS.

7

Don’t have a 9v battery, however I plugged in the relay while the car was cranking and the relay does click.

8

Is it a 1.6 or a 1.8? You can either try throwing a CAS at it at this point or I can walk you through some more tests.

9

it’s a 1.6. Any test would be helpful, just don’t wanna buy a CAS and find out it was just the relay

10

To confirm, you’ve called it the main relay, but it’s the fuel injection relay that you’re testing from the fuse box under the bonnet.

11

that’s right, yes

12

With the ignition on, have you got battery voltage at the B+ terminal in the diagnostic box under the bonnet. If you have, you can be quite confident that the relay is good.

13

Okay so, I ran to the shop and got a 9v battery. with the relay powered I have continuity in the other 2 pins. I’m going to assume that means the relay is working fine?

14

I’d still check for battery voltage at the B+ terminal in the diagnostic box next. At least you’ve got a spare battery for your smoke alarm now.

15

Yeah, I have voltage at the B+ terminal

16

My next test would be to check the the voltage remains at that terminal during cranking. It’ll drop a bit depending on overall battery condition. Then I’d check for battery voltage at the Red/White (or White/Red, can’t remember which) wire at the CAS with the ignition on.

17

Just as an aside. I had a ‘crank no start’ with no fault code and wasted money on crank and cam sensors.
My best buy was a can of Holts Easy Start. Spray it into the inlet side for a few seconds and turn over the engine. If it runs for a few seconds that eliminates the ignition side and shows up fuel side as the problem.

18

The white/red has 12v. I unplugged the cas and plugged it back in and the car started for a second before dying. I can’t replicate.

Also to note, the tachometer doesn’t move when cranking, not sure if that means anything

19

Tried this but didn’t fire

20

It’s not just a poor connection at the CAS is it? I’ve known wires to break in the actual connector, hidden by the waterproof seal.