91 Camry won't start

Determine if its fuel or electrical first. Remove a plug wire and short to block to see if there is spark, if spark its fuel related, ex pump , filter, or a control piece. Electrical could be coil, etc.

If they were original equipment,..dont fret too much,..at least you'll not be bothered by them for another 13 yrs+

I was to replace the

wouldn't

Sounds suspicious. As Mark said, try and determine the fundamentals for engine operation ie spark, fuel and air. Spark: crank the engine while a helper checks for spark. Best way is to place a screwdriver up the spark=plug boot. Then hold the driver handle so the metal shaft is about 1/2 inch from the chassis. A decent spark will jump that gap easily. Colour should be blue.

Fuel: undo the fuel line at a point you can see easily. Only a few turns may suffice. Turn ignition on and check for fuel leakage. Make sure the ignition leads are secure in their holes, so there is no chance of a fire.

Air: check the filter for cleanliness. Make sure there are no airleak points or loose clamps near the throttle body.

If all these check out,..buy a workshop manual and check the ignition timing. You may also check their ways of checking for fuel and ignition (buy the book first :-)

NB: If the ignition base-timing is correct,..the cam-belt must be OK with respect to having jumped a tooth. The dissy is driven off one of the cams.

If these all check out,...its time to wonder about the ECU mixture control (injector timing open-shut period),...or maybe some other reader will have an idea of where to go next?

Jason

If still no-go

Is there a possibility of a fuse alowing it to crank and not fire. Also look for broken wires mainly around the distributor.

Jason, great tip on testing the spark. There is NO sparks. so go-ahead and replace the ignition coil? Where is it located?

Has anyone used the OBD? How reliable is it?

Thanks for the great tips and I'm determined to fix this problem myself after being ripped off by a repair shop recently.

No spark ? Before replacing anything I suggest you get a manual Haynes is pretty good. It could be allot of things but start by measuring voltages to the coil and of the coil or you may just be replacing allot of parts, not the right way to go.

The ignition coil is part of the distributor. To carry out any fault diagnosis you will need a workshop manual and an ohm meter which covers quite a wide scale. A digital multometer for about $15 or so should be OK.

The distributor has 2 sets of pickups which feed small voltage impulses to the igniter which is mounted on the firewall. The igniter's job is to amplify the small signal pulses synchronised with each cylinder's power stroke commencement (or there abouts. The actual ignition timing is 10 degrees BTDC) to full 12v peak coil power-switching pulses. So there is a loom between the dissy and the igniter which contain wiring to and from the igniter. The coil is in plain site once the dissy cap is off and the cover removed.

There is a connector for the pickup coils,..but you may have to remove the ignition coil to measure its continuity ie Coil primary and secondry : 0.3 to 0.6 ohm and 9k to 15k ohm. The coil has 3 contacts when viewed as installed. Both Primary and Secondry resistance is measured with respect to the +ve terminal which is the lower RHS one. The other Primary contact is the lower LHS,...the Sec (spark output) is at the top edge.

Pickups : unplug the dissy's rear connector (closest to firewall) There are

4 contacts laid out left to right as G+ G- NE- NE+ Make sure the connector tab is at the top for correct orientation. Ohm measurements are : G+ and G- 185 to 265 ohm

NE+ and NE- 370 to 530 ohm

You will need a manual to do these measurements, if you are not experienced with this type of work.

Jason