1989 740 won't start

tamaralc · Post by **tamaralc** » 28 Nov 2012, 20:10

1989 740 turns over will not start. replaced rotter cap & button ,spark plugs ,wires ,fuel pump relay , support relay ,crank shaft position sensor ,checked spark plug #1 it is getting gas ,the spark plugs are getting spark ,any ideas?

Post by **billofdurham** » 29 Nov 2012, 12:27

Welcome to Matthew's Volvo Site.

There is a radio noise suppression relay on the coolant reservoir which can go bad and cause a variety of symptoms including no start. There should be two identical relays on the bracket. One is the noise suppression relay which actually controls the injectors and the other is the coolant fan relay. You can switch them over to see if you do have a faulty relay.

The 1989 740 should be fitted with an On-Board Diagnostic (OBD) unit which can be used to read diagnostic trouble codes. Does your car have this unit? Look behind the left strut tower for this:

740 OBD unit.pdf: (396.4 KiB) Downloaded 115 times

If the unit is there instructions for its use are pinned at the top of the forum.

Bill.