27 replies to this topic

[Mattnumber2]

In the USA so experienced mechanics are not available. My car will not start. It turns over, has a spark at all 4 cylinders, and plenty of fuel going to the carb. I've replaced the coil, distributor cap and rotor, plugs, and alternator (battery wasn't charging when it did run). The firing order is correct and timing is set up properly. I've checked the wiring half a dozen times, and everything is set up as it should. I've individually tested each plug, the coil, the leads, and the starter, and everything is functioning correctly. At this point I don't believe it can be an ignition problem, but I don't know what could be wrong with the carb if anything. After cranking the plugs are not wet but smell of fuel. The carb has 3in1 in the dashpot and has full in the float chamber. It is clean with no debris in the jets. The only modification to the car is a stage one kit from minispares. Any advice or direction for the next step would be greatly appreciated.

[Quinlan minor]

I know it's a completely basic question, but are the plug leads on in the correct order?

[Mattnumber2]

I know it's a completely basic question, but are the plug leads on in the correct order?

Yes 1342. 1st is top right.

[alpder]

Carb engine? If so, have you tried it with Easy-Start (or whatever the US equivalent is)? If it fires-up for a couple of seconds with that, then the problem is a fueling issue (maybe blocked inlet mesh, maybe failed/blocked 'choke').

 

If the distributor and drive have been significantly disturbed (removed and refitted) then the rotor could be in a random position so "1" won't necessarily be the same place as it was.

Edited by alpder, 28 March 2025 - 05:12 PM.

[Mattnumber2]

Carb engine? If so, have you tried it with Easy-Start (or whatever the US equivalent is)? If it fires-up for a couple of seconds with that, then the problem is a fueling issue (maybe blocked inlet mesh, maybe failed/blocked 'choke').

If the distributor and drive have been significantly disturbed (removed and refitted) then the rotor could be in a random position so "1" won't necessarily be the same place as it was.

Starting fluid doesn't do anything at all. The distributor hasn't been removed since it ran last. I double checked just in case and turned the crank to TDC on compression stroke and verified it was set correctly and pulley marks are correct as well. It is set to 5 BTDC as per Haynes manual.

[alpder]

This is baffling but with sparks at the plugs, and yet no life at all even with squirt, I'd still want to be absolutely certain that the timing is right by doing some really basic checking, just in case...

 

I would get it with #1 at TDC on the compression stroke. And, to be absolutely sure it was #1 (not #4) I'd visually check both #1 rockers are clear of the valves.

Then I'd pop off the distributor cap and see the rotor was pointing at the correct electrode.

 

It's probably overkill, but sometimes you just have to go right back to the start.

 

I'd also worry that since trying new parts didn't solve the problem... they may be causing a second problem and making it even harder to solve. Unless the old parts are clearly faulty, I'd refit them until the actual fault is found.

 

'93 I'm guessing has electronic distributor? But if not then points, gap, dwell, and condenser have to be suspects. Tho' if spark is strong... it's still probably not these things.

[Steam]

I would be checking the compression and making sure all the valves are opening correctly, resetting the valve clearances. Also double check you have fuel going into the cylinders.

[Mattnumber2]

I would be checking the compression and making sure all the valves are opening correctly, resetting the valve clearances. Also double check you have fuel going into the cylinders.

How do I check if fuel is getting into cylinders?

[bpirie1000]

Turkey baster drip it down the bores..

Have you checked compression?

Is the fuel old?

Does your firing order go clockwise or anti clockwise? If you are sparking at every plug then now't wrong with coil or points.....check your rotor arm rotation..

https://youtu.be/eqv...VEbJEfa_OU7cdj5

[Mattnumber2]

Turkey baster drip it down the bores..

Have you checked compression?

Is the fuel old?

Does your firing order go clockwise or anti clockwise? If you are sparking at every plug then now't wrong with coil or points.....check your rotor arm rotation..

https://youtu.be/eqv...VEbJEfa_OU7cdj5

It turns counterclockwise. I pulled the cap off the distributor and turned the engine to 5 BTDC and adjusted the distributor so the rotor points at cylinder 1. It is electronic so no points. Fuel is still good and clear. I'll check compression now.

[Mattnumber2]

So, the compression test went very poorly. 90 psi on 1, 30 on 2, 25 on 3, 85 on 4. Now it's a cheap tool that doesn't seat super well, so the numbers aren't likely correct, but it's obvious that 2 and 3 are bad. Now what do I do with that information?

[alpder]

If it's been standing a long time - or if you've been cranking a lot to try to start it - then the cylinder walls/rings may be dry. Try a little oil into the cylinders then test again.

 

If that seriously improves the readings, then chances are it's bore/ring issues. If it doesn't change things, then more likely valves or head gasket.

 

Two adjacent cylinders with very low pressure... a single cause for that would be failed fire-rings between them. But there could be other causes and before going mad and whipping the head off start with checking valve clearances.

 

by the way... compression test requires about 10 complete compression strokes plus holding the throttle open. Easy thing to forget if it's something you don't often do.

Edited by alpder, 28 March 2025 - 08:23 PM.

[lsto]

When you did the compression test how did you do it? Ideally you would do it with all plugs removed and the throttle wide open to get the best results.
As you said your results are quite poor. If 2 and 3 are bad it could be that the head gasket has blown between the two cylinders. Did you try squirting a little oil down the bores and trying the test again to see if it improves the figures?

[Quinlan minor]

So, the compression test went very poorly. 90 psi on 1, 30 on 2, 25 on 3, 85 on 4. Now it's a cheap tool that doesn't seat super well, so the numbers aren't likely correct, but it's obvious that 2 and 3 are bad. Now what do I do with that information?

Check for water in the oil.

If you can borrow a boroscope, have a look in cylinders 2 and 3. 

Check valve clearances and operation.

Head gasket failure is a possibility.

How was it running previously?

[Cooperman]

Whilst the cylinder pressures do look a bit low on 2 & 3, I would expect the engine to at least try to fire, especially if 'Instant Start' (or equivalent) was sprayed into the carb wit the throttle fully open.

Personally I suspect the timing is incorrect by at least 90 degrees.

Best plan might be to get it running, even if it runs badly, the address the compression issue. Re-set the valve clearances then re-time it.