Won't start 1 hour after use - but fine when cold

crisplex · Post by **crisplex** » 01 Feb 2017, 03:37

My volvo 850 starts fine first thing in the morning but if I drive it for any distance and then leave it for an hour or more it won't start. It will then start if I use jump leads and rev the other engine. The battery is fine however because it's brand new and it turns over fine but does not ignite.

Strangely if I try to start it a few times and then leave it for 15 minutes it might start.

I expect it is a relay but can you advise which ones it could be. Or if it's some other cause.

thanks

alex

Post by **erikv11** » 01 Feb 2017, 07:31

Check the positive battery cable near the post. Does the cable get warm when you drive the car? It is common for the connection to deteriorate there, which would cause what you describe. When the cable heats up resistance goes up. This would kill your battery more quickly than normal, too.

I would also check the fuel pump relay at the dash under the cowl. Try using a jumper there.

Post by **rspi** » 01 Feb 2017, 08:59

Could also be a bad ECT.

Post by **rspi** » 01 Feb 2017, 09:00

Is it cranking?

Post by **abscate** » 01 Feb 2017, 12:55

Hot crank/no-start is classic fuel pump relay failure.

Diagnose, don't throw parts. In this case, try a jump wire at the relay when the car exhibits symptoms.