Unwanted immobilisation

[Rob Cowell]

Just had a call from Mrs Cowell. The 120 is refusing to start. Engine turns over. Red light showing a car and a key on the dash. Can't picture that one. She assures me the handbook says this is an immobiliser issue.

So assuming Britannia Rescue can't start it and dump it near the house I'll have this to look at tonight / tomorrow. Any suggestions of where to start? Electrics not my strong suit, but I can work a multimeter.

Ta

 

[Chris]

First thing I'd do would be to get out, lock it with the bipper and leave it to set. About a minute or so. Then unlock with bipper and try again.

 

[Rob Cowell]

OK. Diagnosing problems on the phone with someone who isn't used to working through issues.

Immobiliser light only flashing when key is out. Which I think is normal behaviour.

So right now I'm in a won't start, no clues scenario. I've never had a diesel engine that didn't start, so still very open to suggestions.

Have tried the out, lock, unlock. And also pulling the ECU fuses in case reseting that helped. Before I deduced the immobiliser light wasn't on with the key in the ignition.

 

[Chris]

Ahh, I see. Have you told her to grip the wheel with both hands and scream 'Start you Mother F*****R!!!!!'

If it turns over but won't start it's really only two things. Fuel and air. Unless she has parked in a vacuum then fuel is the most likely thing. Either no fuel or the fuel cut off solenoid is stuck on open. As to the cause of that - well quite possibly the immobiliser. Can't remember enough about my 120 to narrow it down any further Rob

 

[Rob Cowell]

So the breakdown fella came out, gave it a squirt of 'Easy Start" and it started. Have just driven 45 minutes home, running smoothly. Stopped. Immediately tried to restart and no joy. I did buy a can of Easy Start on the way home so might get it going again, but what is this likely to be? Breakdown fella suggested maybe fuel pump. Would this be the case? Would it run fine once started, but not start? Now off to check the manual to find out where the fuel pump is and hope it's not in the tank.

 

[Chris]

Sounds as though fuel is draining back to the tank. Maybe a an air leak, slit hose, loose fitting. When you spray the EZ start in it fires and runs long enough to pull fuel up. Next time it won't start pump the fuel primer plunger on top of the fuel filter til it goes stiff then crank it.

 

[Rob Cowell]

Thanks Chris. Needed to get Mrs Cowell to turn it over while I primed the filter, but it started. Any secrets to finding a hole, or is it just close inspection?

 

[Chris]

Rob, never heard of this on a 120 series. Could be anywhere from the pump to the tank. Look where there are joins and clips. So from the pump to the filter and from the filter down the bulkhead. After that it's a dry day, torch and feel you way along. Do NOT pressurise the fuel line with air to see where it's leaking as you can blow the filter off the end of the pick up in the tank. Could also be negative pressure in the tank. Air has to get in to replace the fuel that has been used. If the valve letting air in is blocked and the pressure is reduced in the tank, it may just be enough to suck fuel back. Next time you stop, release the filler cap and leave it loose. When you come to start it next time, if it fires up, it may be that simple. It's a case of narrowing the potential.

 

[Rob Cowell]

Well with the filler cap off it starts, no priming. Although turns over for longer than it has needed previously. Cap doesnt seem blocked. I can suck air through it one way, which I think is correct. Would be sucking into the tank. So I'm guessing a little leak somewhere and removing all pressure from the tank is enough to get it going. At least I think I can drive it for a bit now and rumour has it, it might stop raining before Saturday afternoon so I can have a better look.

Thanks again Chris.