Some like it hot

[Gsmack]

It's time for me to call out for help.

intro been driving BXs for 13 years now, only main car I've ever owned, currently in possession of 7 bxs, currently none are going
My daily driver has decided to have a rest, well it decided to have a rest half way up the Hume hwy between Melbourne and Sydney, for those that know the road, its long, boring and breaking down on it is an expensive exercise.

Car gets hot and cuts out, won't restart. Because it was dark, found the problem quite easily as moving some wires near the battery created great sparks. The wire that runs from positive battery to fuel relay had worn through and was shorting out.
Got the car back to Melb, fixed it, all good.....
Nah, still cuts out when it gets hot, double checked fix, all good, started investigating further a field, checked dissy and rotar, look ok, rotar could do with a sandpaper, but no arcing in the cap, plus it was replaced three years ago.
Moved on to coil, resistance increased significantly when hot, right new coil that will fix it, nah....
Found the narrow heat range where it cuts out, checked water temp sensor, removed them didn't change it, wondered if when the fans come on, it's creating a short elsewhere ... nah...

Running out of ideas, started down the cranke angle sensor route, however it's a tri with a be1 gearbox and a jetronic ecu...so nah...

Help, other ideas please, what else could have been damaged by the fuel line being shorted? Never had the problem before it stopped dead on the Hume.

Thanks
Gamila

[NeilGP]

Does your BX have an ignition module?
I have experienced that these fail they usually work well from cold, but mis-fires and cut-outs when hot.

[Gsmack]

Yes I had one, I had wondered about that, is there anyway of testing or just replace and try?
Are the ignition modules th same for jetronic and montronic?

[motorgnome]

Yeah..My first reaction was ignition module. When it wont go, does it have spark at the plug leads?

[Kitch]

When you say 'it gets hot' do you mean once it's warmed up to temp, or it's getting too hot? And I'm guessing we're talking about the coil here?

I'd be thinking of eliminating a damaged fuel pump relay, seeing as silly buggers have been going on with the wiring to it. If it's just a standard 4 pin relay, I'd run it until it starts playing up, then remove the relay and bridge the main wires and see if it makes a difference.

[bouncy]

Any old school guys around your area who have an ignition module tester.. I still have mine and was often used to check these modules out..

[Gsmack]

No, car's not getting 'to' hot, fault kicks in just as the fans kick in roughly, and that's working fine, it's also got the best radiator in it that I've ever had in a bx. Also nearly winter here, air temp is dropping so it's not an overheating issue.

Coil has already been replaced with a new one, and is reading better.
I'll check if there is spark when the fault is present.

Also good idea re fuel relay, I had wondered, good thoughts for testing it.

[Tim Leech]

My 19GT did the same thing, would run fine until it was warm, turned out was a tired dizzy cap and rotor arm!

[Gsmack]

Travelling for work, so sorry for the delay in replying, troubleshooting is always hard when ones nots with the car.
Re ignition modules, are they the same between the jetronic systems and the montronic systems?

[Dragon Man]

it sounds just like ignition module issues to me. i have an old Fiat Panda 4x4 (i have a few actually) and many of them have this issue. they are a pain in the ass and i always carry a spare in each car.
the ignition module replaces the points. using a magnetic/hall sensor in some ways its loads better as you never need to replace or adjust points. but they do have this issue of just dying. it happened to me on the motorway back from touring around Scotland in my 91 panda 4x4 sisley. i had no spare at the time so had to be recovered some 400 miles back home hahaha

most of the time you can adapt other ignition modules from other cars to fit yours (my current one is using one from a BMW!
they all work the same, mostly just using 4 or 5 wires. a ignition live, an earth to the - side of the coil, an earth and the rest go to the hall/magnetic sensor.

heres a picture i did of the panda 4x4 ignition module as they are well known for failing over in Fiat land.



hope this helps!

[Gsmack]

So a bit of an update. Turns out my fuel pump wasn't getting enough power as it hot got, so by the time it cut out it was down to 11v, traced that problem back to a faulty regulator in the alternator, which failed as it got hot.so new alternator has been got and 13+v gets consistently to the fuel pump.
Replaced dissy cap, new spark plugs because they were very unhappy - probably due to the fuel wire constantly shorting out to ground.

Definitely seems the reason the car stops is because of lack of fuel, if one uses aerostart one can keep it running.

The problem is getting worse, as in it needs less heat now before it cuts out.
I've tried keeping the temp of the ignition module down, with an ice pack and also measuring its temp, didn't make any difference, plus I've already swapped it out once and the problem didn't change at all.

Fuel pump got replaced last year, I'd like to test it to see how much fuel it pumps when cold vs hot.
Does anyone know what pressure it should be running at or how much fuel it should pump per minute?
Thanks

[Kaapelimies]

3 bars with a 4-point injection. L/min no idea, but several

[TizzyD]

This might be just a dumb suggestion but could it be fuel vapourisation ? I see you're in Australia, could they be adding something to the fuel over there which is boiling off at a low temp (or boiling off at a temperature below the normal temperature of the engine bay) that then starves the engine when hot ?

[assembled]

1. What is your battery voltage when motor is running? Should be 13.7-14.7V, higher when charged.
2. You can test fuel pump output by unplugging return hose and measuring fuel flow. It should be a couple of liters per minute.
3. Pump should work well even with 11V supply you have mentioned. When engine is being started, battery voltage can normally drop to 9-10V and pump must still be able to deliver sufficient volume and pressure.

[Gsmack]

So fuel probably isn't vapourising as it's currently winter, plus the car had driven about 80km on this tank before the problem started. I have undone the petrol cap just to make sure I'm not getting a vapour lock. No change.

Today I've cleaned all the inlet side, so air filter, maf sensors, throttle body. No change.
But the problem does now turn up after about 8 mins, also the car cuts out when nearly 'hot' when the door is slammed, any door.

Tomorrow is fuel pump and filter, thanks for the ideas re volume of fuel.

Any knowledge here around the symptoms of a failing catalytic converter? Do you have them in the uk?

Thanks