weak spark

[GlenAM]

Well i went out today again and tried a few things. I checked out the vacuum hose in question. It looks like it went to the vapor cannister and yes it was disconnected and sucking air. I jury rigged it and patched it up. Tried to start it but nothing. I then decided to cut off the cat convertor. Years ago I had a car that wouldn't start and it ended up being a plugged cat. However after cutting it off today it didn't affect anything. Still won't start. I remembered that it did start once about six weeks ago but it stalled after about ten seconds. That is a fuel pump issue when the start up relay hands off to the oil pressure switch. I have since installed a wire directly from the battery to the fuel pump with a switch in the middle. However its of no use because we can't get the thing started at all. But I think that thing six weeks ago may be telling us we have an intermitant problem???

 

[DonTom]

Not sure what the letters CPS stands for.

Crankshaft Position Sensor. It automatedly sets the ignition timing in the vehicles that cannot be adjusted at the distributor. Or can your distributor be adjusted?

It's a common failure item. In OBD2 cars, it will set a code and check engine light. But yours is OBD1 if 1992 and I am not sure how well that works to detect it.

Is your check engine light on?

It will be code 19, if it detects it. See here.

And also see here.


-Don- Reno, NV

 

[GlenAM]

Crankshaft Position Sensor. It automatedly sets the ignition timing in the vehicles that cannot be adjusted at the distributor. Or can your distributor be adjusted?

It's a common failure item. In OBD2 cars, it will set a code and check engine light. But yours is OBD1 if 1992 and I am not sure how well that works to detect it.

Is your check engine light on?

It will be code 19, if it detects it. See here.

And also see here.


-Don- Reno, NV

I am sure mine doesn't have one. Yes I can adjust the distributor if you can ever get at the bolt that holds it.

 

[GlenAM]

When I try to start I have a check engine light but I also have two lights talking about the brakes. I think this thing has some kind of automatic emergency brakes. Any thoughts? Perhaps this brake thing prevents starting???

 

[udidwht]

With a TBI set up check your fuel pressure first otherwise you'll be pulling your hair out throwing parts at it. A 92 should have 9-13psi preferably 11ish.

Only the 94 and 95 years had fuel pressure of 26-32psi.

 

[jubileee]

I think cos stands for crankshaft or camshaft position sensor.
Don’t worry. Your engine has neither, Also, does not have vacuum advance on distributor. Ignition module takes care of timing advance.
As I posted earlier, change out the ignition module. Even if it isn’t problem, it’s good preventative maintenance on that old of system.

 

[jubileee]

that should be cps. Darn spell check

 

[Tulecreeper]

Not sure what the letters CPS stands for. Please inform me.

Crankshaft Position Sensor

 

[TheBar]

If you had a good spark, you sprayed ether down it, and your plug wires and timing are ok, all that is left to fire it is compression and valves. Compression is not likely to quit in all cylinders at once. When it started, ran for 10 seconds, then wouldn't restart could the timing chain have broken? If you can see any of the valve rocker arms thru the oil filler cap hole or thru the PCV valve hole in the valve cover, have someone crank it while you watch to see if the valves move.

 

[Ex-Calif]

If you had a good spark, you sprayed ether down it, and your plug wires and timing are ok, all that is left to fire it is compression and valves. Compression is not likely to quit in all cylinders at once. When it started, ran for 10 seconds, then wouldn't restart could the timing chain have broken? If you can see any of the valve rocker arms thru the oil filler cap hole or thru the PCV valve hole in the valve cover, have someone crank it while you watch to see if the valves move.

I'm with you on this.

My last gasp is that a spark under pressure reacts way different than a spark in free air. In other words if you are claiming good spark because it jumps a 20-32 thou gap in free air it could be completely breaking down in the chamber.

It not only has to jump the gap, it needs to be bright blue or hot white - not yellow.

I had a condenser fail on my Jeep and that took a long time to troubleshoot.

I have also had a cracked distributor cap that allowed a fault to ground.

Without diagnostics tools this is the point where I start throwing money at things starting with the cheapest thing.

I still am unconvinced it is fuel pump if the thing won't pop on ether/starter fluid.

 

[GlenAM]

I think cos stands for crankshaft or camshaft position sensor.
Don’t worry. Your engine has neither, Also, does not have vacuum advance on distributor. Ignition module takes care of timing advance.
As I posted earlier, change out the ignition module. Even if it isn’t problem, it’s good preventative maintenance on that old of system.

Thanks for your suggestion. I think its good and I will get a new one although I have no idea how to change it?

 

[GlenAM]

I'm with you on this.

My last gasp is that a spark under pressure reacts way different than a spark in free air. In other words if you are claiming good spark because it jumps a 20-32 thou gap in free air it could be completely breaking down in the chamber.

It not only has to jump the gap, it needs to be bright blue or hot white - not yellow.

I had a condenser fail on my Jeep and that took a long time to troubleshoot.

I have also had a cracked distributor cap that allowed a fault to ground.

Without diagnostics tools this is the point where I start throwing money at things starting with the cheapest thing.

I still am unconvinced it is fuel pump if the thing won't pop on ether/starter fluid.

Thanks for your thoughts. You have been down a lot of roads. I have noticed that when it is turning over the distributor cap wobbles a tiny bit although the clamp is tight.

 

[GlenAM]

Last summer I bled the brakes and topped up the master cylinder. That was around the time that I couldn't start it any more. When I turn the key to start I get two warning lights on the dash both saying brakes. Does anyone know if there is any kind of a circuit that prevents starting if the computer thinks you have no brakes?

 

[TheBar]

Thanks for your thoughts. You have been down a lot of roads. I have noticed that when it is turning over the distributor cap wobbles a tiny bit although the clamp is tight.

Not good. I think Ex_Calif may be right about your spark. Sounds like you have wear on the distributor shaft which would affect your spark. A new distributor on RockAuto.com isn't that expensive and after 31 years it might need it.

 

[udidwht]

I would pull the distributor and check for a broken and/or cracked relocator. Put the engine at TDC #1 prior to removal of distributor.

 

[Ex-Calif]

Thanks for your thoughts. You have been down a lot of roads. I have noticed that when it is turning over the distributor cap wobbles a tiny bit although the clamp is tight.

Not good. I think Ex_Calif may be right about your spark. Sounds like you have wear on the distributor shaft which would affect your spark. A new distributor on RockAuto.com isn't that expensive and after 31 years it might need it.

I would pull the distributor and check for a broken and/or cracked relocator. Put the engine at TDC #1 prior to removal of distributor.

Wow! Yes - all of this.

First step is to remove the cap and crank the engine. Look for wobble in the dist rotor shaft.

While not cranking (of course) you can try to wiggle the shaft. It sound bent or worn. The cap should definitely not be wobbling.

If/when you remove the distributor you have to allow for the lower helical gear to align it correctly. Get the rotor positioned directly at a spark wire post. Make a distinct mark across the base of the distributor onto the fixed metal of the engine usually in line with the vacuum advance module.

As you draw the distributor out the rotor will turn. When it stop turning mark or note the position of the rotor. You have to start the distributor back into the hole with this offset so it lines up perfectly after it is seated. The vacuum advance module should line up perfectly with the line you made is step one.

 

[GlenAM]

Thank you for all your help. I have an ignition module on order and I will be inspecting the distributor next time I am out there.

 

[GlenAM]

Well I went out again. This time I installed a new AC DELCO ignition module. I also tightened the distributor cap and now there is no wobble. Although I have good spark and good gas it still wouldn't start. I tried for about an hour. I have pulled the distributor and I am going to install a new ignition pick-up coil. Some of the sites on the net suggest this could be the culprit. Don't know what else to look at.

 

[GlenAM]

Ihave come to realize that I probably have a bad flooding problem. I can see a pool of gas down the throat. Apparently it is quite common and I need to put a new kit in the TBI and perhaps also new injectors.

 

[DonTom]

This time I installed a new AC DELCO ignition module. I also tightened the distributor cap and now there is no wobble. Although I have good spark and good gas it still wouldn't start.

Have you checked the engine compression? I once had a GM engine with cam lobes ran all the way down and would not even move most of the valves. There was a run of cams that were made way too soft, but I think that was back in the late 1980's.

If an engine has the correct fuel, compression and spark at the correct time, it must run. There is not that much to check for an engine that will not run. Just three things, but they have to be tested correctly.

First step is to check those three things the best you can.

-Don- Auburn, CA