Fiat Coupe Club UK

Fuel vapour lock?

Posted By: Anonymous

Fuel vapour lock? - 11/07/2018 12:24

Just over a week ago I had a great trip to the New Forest from Birmingham. The car (20vt) ran perfectly apart from a minor problem. After shortish trip from our hotel to the coast, the car was parked in the sun for about 45 mins and then refused to start. Battery must be good as it turned over well, but no go! After 3 or 4 attempts in fairly short order it fired and ran perfectly for the journey home. I then used it for a couple of short trips - no problem.

Then yesterday, after a run of about 55 mins. the car was again left in the sun. Half an hour later it refused to start again. This time, after several attempts, it would not go. I left it for an hour or so and it started after turning over a few times and ran well for the journey home.

Could this be a vapour lock? If so where in the fuel system could the issue lie and what could be the best cure?

Any help appreciated.

Chris
Posted By: Countrycruising

Re: Fuel vapour lock? - 11/07/2018 12:29

Sounds like early crank sensor failing, or fuel pump relays need re-newing or possibly the yellow connector of death is burning out.

These cars don't suffer vapour lock as the vapour is pulled through the engine on over run, keeps the planet green, apparently.
Posted By: Anonymous

Re: Fuel vapour lock? - 11/07/2018 14:01

Thanks.
Not as straight forward as I hoped - but it is a coupe!

I will get someone to look at these items.
Posted By: Anonymous

Re: Fuel vapour lock? - 12/07/2018 10:17

sounds exactly like what mine is doing!!
Posted By: Anonymous

Re: Fuel vapour lock? - 05/08/2018 10:23

I have used Multiecuscan to try and identify the problem and here is the result:
click to enlarge
Are these 3 problems related and is there just 1 fix for all of them?
Is it going to be relatively easy to fix them myself or do I need a specialist?
Posted By: DaveG

Re: Fuel vapour lock? - 05/08/2018 12:35

Either faults 16 or 05 will cause the engine to fail to start, both look to be intermittently faiing. 05 rpm sensor can cause engine to cut out whilst driving, but is relatively easy to replace, it's low down at back of block under starter motor, but 16 cam or phase sensor means that cam belt has to be removed and exhaust cam wheel removed for access to replace the sensor.

The other fault 89 refers to...
Originally Posted By barnacle
a short circuit in either the sensor or the cabling leading to it. The sensor is the atmospheric pressure sensor which is used to calibrate the mass air flow sensor; if it fails normal sea level pressure is used. The sensor is on the bulkhead near the centre, close to the brake fluid reservoir. It's a black box perhaps five by three by two centimetres.
Posted By: barnacle

Re: Fuel vapour lock? - 05/08/2018 15:58

Also, 16 or 5 can cause each other if one is intermittent as the ecu is looking for both signals to be present and in the correct phase to each other. So if one is coming and going, the ecu can't always tell just what is misbehaving.
Posted By: Anonymous

Re: Fuel vapour lock? - 06/08/2018 08:30

Thanks for all your input. I feel a trip to Motormech coming on!
Posted By: DaveG

Re: Fuel vapour lock? - 06/08/2018 08:48

So, you have faults that might have caused the failure to start, or might cause them in the future (plus the prospect of the engine cutting out when driving) but upon re-reading your first post, you say that both times it happened was after a short journey.

This can cause the engine to run rich at first and then if you stop the engine, it can get flooded with fuel, making it very hard to start some time later (even after several hours or overnight).

The key to knowing if this might be the case is whether the injector light stays on when trying to start: if there's a sensor fault (crank/rpm and/or cam/phase) then the light will come on and stay on and the engine won't start. But if it's only flooded, there will be no injector light.

See if you can reset the ECU to clear the faults and see if they re-appear when restarting, and if it fails to start, check for the injector light.

PS: The cure to start a flooded engine is to floor the accelerator (with ignition off) then keep your foot there and try to start: by opening the throttle you'll allow maximum air in and hopefully there'll be sufficient fuel still there to allow it to cough and splutter into life. You may however flatten the battery and set the alarm off in the process...
Posted By: Anonymous

Re: Fuel vapour lock? - 06/08/2018 19:08

Thanks DaveG. I will try this out next week after I return from a short break.
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