Volvo 850 starting problems when hot

[Adam850]

I have a 1996 Volvo 850 estate. The car starts fine when cold, but does not want to start when hot. It feels like its fuel starved. When it finally starts, it runs beautifully. The problem was intermittent at first, but now it is constant. I am thinking that it could be bad fuel pump relay, but the check engine light does not come on. Would the computer store codes without the check engine light coming on. Volvohelp.com also suggests that it could be a bad crank sensor, but the car runs fine. Where is fuel pump relay and crank sensor on Volvo 850 (non turbo)? Is there a way to check them? Does it make sense to invest in code reader, will it show codes despite not having check engine light on?
Any suggestions to solve this problem would be welcome. Being on tight budget I am reluctant to go to the dealer to solve this problem.
Adam

[warthog]

Adam,

most likly culprit is the fuel pump relay. Position 103 in the relay section of the fuse box under the bonnet (you'll need to take the whole fuse box top off to find the relays).

When the car is hot and it doesn't start, can you hear the fuel pump run for a few seconds on switching the ignition on? If you can then it's probably not the relay. I don't know whether a bad relay just at startup would trigger error codes (low fuel pressure) but a crank position sensor fault should.

There are two sensors of engine position, one just above the flywheel indicating crank position, and one on the distributor end of the camshaft showing camshaft position. It's this one that from earlier posts can develop faults leading to poor starting, but with this you just wouldn't get a spark rather than no fuel.

Fuel pump relays are available from many non dealer places such as GSF and Euro and cost around £20

[Adam850]

Warthog,
Thank you for reply. Please see my follow-up message with more info.