won't start when hot
 

05 BCGT. If it is driven for 45 - 60 minutes and then parked in the sun and left for a couple of hours, it won't start. It will go into the ignition cycle (i.e. crank) briefly and then die before starting. This ONLY happens when the temperature and humidity are high and ONLY after a longer drive. The only error code I get is "crankshaft position sensor" which I replaced recently, but still get this error under these conditions.

If the car is allowed to cool for 3 or 4 hours, it starts repeatedly and runs perfectly. It is worth noting that both batteries are new and no trouble lights appear. I suspect a faulty wiring assembly somewhere.

Has anyone else experienced this problem and if so, what was the fix?

have you checked the ground that goes to engine block just below the water pump ?

Thanks Peter for your insights. I will check the ground this afternoon and report back.

Thanks for that insight also. I was aware of that problem with wire corrosion. However, the drain "pocket" was dry and we carefully checked the drain holes by testing with water. Everything drained properly and we couldn't find any sign of corrosion. We'll check again.

I understand the car has two fuel pumps. Further I believe one starts the car and then 20-30 seconds later the second fuel pump takes over. If I had a fuel pump problem, wouldn't it throw an error? I ask because yesterday, after several tries, I did get the car to start when hot but it only ran for about 20 seconds and then died. Repeated attempts to start after that failed. No error codes were found on a high-level scan. As I reported earlier, when the car cooled down (after a 40 minute trip in the rain on a flatbed), it started perfectly.

if you feel it could be a fuel pump problem remove the two relays and jump them, they are in the trunk on the left hand side, when you say it won't start is it cranking ?

Yes, it goes into the start cycle and turns the engine over for 1-2 seconds and then dies.

1-2 secs is not right,pull the fuel pump relays and it should continually c rank from what i remember,have you had any Kessy codes and have you checked the wiring at the bulkhead on left,there is a little black cap that sits on the connector and the o2 wires are routed real close,its the mains feed from starter.

Thanks again Peter. I don't believe we've had any KESSY codes. My car doesn't have the keyless start option and when the condition happened, I tried both keys just to make sure it wasn't key related. I also tried turning the keys to the left (emergency switch over of batteries) but I didn't hear the relays switch over which suggested the starter battery had full charge. Prior to driving the car, it had been on a CTEK charger for three days. We'll check the wiring on the bulkhead. I assume you are referring to what we call the Firewall? I'll pass this along to my tech as I'm not at the car right now. I'll report back.

it may not have keyless start but it has Kessy control unit, look under the carpet of drivers side (LHD) and see if you have any dampness down there.it is hard to get to by the way.

That sounds to me like a fuel pressure check valve failure not a pump failure.

Please, please tell me I don't have to remove that floor liner (under the carpet) on the driver's side. I have read the procedure and it is a brute of a job. :eek:

Thanks for joining in. If this was the case, wouldn't we get an error code?

Further research indicates I was incorrect on my understanding of the two pumps. The manual says, "...no fuel pressure sensor. The pumps are independently operable from the master ECM-pump one operates as the main pump and pump two comes in with engine load increase".

Still searching for solution. Ran a 2 1/2 hour VAS 5054-A diag session. I no longer see the "crankshaft position sensor" fault. In fact, we couldn't find any faults other than the TPMS fault (I had disarmed the subsytem). Mechanical investigation revealed a broken tab on the connector to the right hand fuel pump. We cleaned the terminals and reconnected. I'm also changing the fuel filter. I'm still trying to get a repeat on the "hot-no start" condition and will report my findings. If anyone wants more agonizing detail, PM me.