Symptoms are the engine will turn over just fine, but even after 5 or 10 tries it still won't start. Up until recently it used to start on the first or second try, the problem seems to be getting worse, and it doesn't matter if the engine is hot or cold. The odd part is after several tries it may suddenly start, after which it will run & drive completely normally until you turn it off again. While it was failing to start I confirmed that I do have a spark on all four cylinders, using a timing light. A few years ago the main relay was apparently replaced, but the fuel pump is original. The car has 120,000 miles. Any ideas? Does the timing light showing the presence of a spark rule out the ECU? Could it be the fuel pump?

 

Three possibilities to investigate:

1) Main Fuel Relay (MFR) - This seems less likely since replaced fairly recently. You can rule out be carefully listening. When you turn keyswitch to On, you should hear soft clicks under dash, fuel pump in fuel tank buzz for 2-3 secs, and go off. Check Engine Light (CEL) should go off w/ fuel pump. If you get these, MFR is OK. If you don't hear fuel pump get an assistant to help and listen at fuel inlet to be sure no fuel pump buzz.

2) Keyswitch Assy - This initiallly seemed more likely, however you said you have spark. Generally, this defeats spark and is exhibited by no dash lights; Alt, Oil Pressure, and Check Engine Light. If these come on normally, then Keyswitch is likely OK.

3) Fuel Pump - If in 1) you hear MFR clicks, but no fuel pump buzz, try "hammering" the keyswitch on/off/on/off... until you hear (or not) the fuel pump come on. If this gets fuel pump going, engine will now start. However, a new fuel pump is indicated.

good luck

 

Thanks for the great suggestions. I decided to try a new MFR but that didn't help. The fuel pump is consistently making the sounds you described so I slightly loosened the fuel line where it attaches to the fuel injector rail. When I turned on the key gas sprayed everywhere, so I suppose that rules out the fuel pump as the culprit? I double-checked that I am getting spark to all 4 cylinders with an inductive timing light... is this sufficient to prove that? I also checked the ECU codes, and all I had was a 17 (i.e. the VSS, which I knew was bad). After i reset the ECU by pulling the neg battery lead for a few minutes, now the ECU LED comes on and stays on. Any ideas on what I should try?

 

Is the inductive timing light flashing when the car is having problems starting?

 

Yes, each time I did this test (2 different occasions X 4 cylinders) it would not start. I don't understand all that the ECU does, but is it possible that it is the culprit? Thanks again!

 

When was the last tune up done?

 

When no-start is present, are the Check Engine Light, Alt Light, and Oil Pressure light are coming on normally? Be sure the ignition switch is not intermittent. Check for 12V to distributor when no-start is present.

Generally, the timing light is a definitive indicator of spark, however I remember one case where timing light gave positive indication of spark and later events found either ignitor or coil was the problem.

From your description of hard starting/no starting and fuel pump working when no-start is present all suggests loss of spark somehow.

As Poorman suggests, all spark path parts need to be in good shape; plugs, wires, distributor cap, and rotor.

good luck

 

Yes, all the dash lights are coming on as normal. To give you an update... a friend suggested I reset the ECU and see if it would then record the error code of the underlying problem, so I pulled the backup fuse and waited a few minutes. I then tried to start it, and it fired up immediately. It ran as smooth as can be - no stumble, rough idle or anything out of the ordinary. I let it run another 10 minutes, then cut it off. I waited a minute, then turned it on and off successfully 5 more times over the next 10 or 15 minutes or so, each time it started immediately and ran very smoothly. And then on the next try, suddenly it wouldn't start again. I tried 3 or 4 more times with no luck, but the ECU didn't store any codes, at least not so far. The ECU LED just stays lit all the time. So it's very much an all-nothing-situation, which maybe points to an electrical problem...? If this is correct, does anyone have ideas what components would cause this all-or-nothing behavior? Could it be the fuel pump after all (i.e. a loose power connection)? I am inclined to think not, but I am no expert - and I still can't get my head around why the timing light flashed on all 4 cylinders when it wouldn't start, but the way it behaves seems to point to an intermittent problem with the spark…? Would a failing coil cause this (i.e. a weak spark), or the ignitor? Or something else???

 

Is this a manual or an automatic transmission?

Do you have a 12V test light?

 

A poor ground "could" casue this "intermittent problem with the spark". In the t-stat housing (lower hose) there is a ground cable I would also check-Clean-tight.

With this type of thing there are many "possible" causes, we are all asking questions to try to help narrow down the cause. So TX, PA and I are asking these to try to find the cause