Isuzu Diesel won't Start

[aware]

Hi!

I traded some work on a Nissan for an Isuzu Diesel but it won't Start. I have to use starting fluid ( I know, a big no, no) to start it.

So I checked for power to the glow plugs and there was 4 1/2 volts. One glow plug had 0 continuity and the others? Who knows if they are bad - the continuity reading kept going up and up and up!. So I bought 4 new glow plus, expecting to fire it up.

No go.

Still won't start.

What else could be causing this problem?

It's a 1981 Isuzu I-Mark diesel with 120,000 miles. Runs good! (I know, not an SUV or truck but the same engine as the truck.

THANKS in advance!

Ben

[amigo-2k]

I see you already posted your question here:

http://www.4x4wire.com/forums/showfl...=5&o=1&fpart=1

You should have better luck posting there.

[Cat Fuzz]

If the engine is too worn out, it won't start. Diesels rely heavily on compression and heat for combustion. If the engine is worn badly, you won't get enough compression for combustion. Glow plugs are only helpers in getting a cold engine started, they have nothing to do with how the engine runs once its started. You could also have a bad glow plug relay. I would think you should be getting 12+ volts at each glow plug. If not, check the wiring and relay. Also, if there is one wire to each glow plug, that means that the glow plug is grounded by it being threaded into the engine, if the threads aren't clean, you might not be getting a good ground there, or there might be grounding wires or straps missing from the engine to chassis.

If you're reading 0 on an ohm meter, from the glow plugs postive wire to ground, the glow plug is shorted.

Thats all I can think of, for now.

[2000izusu]

we start trucks with cummins and detroits all the time (in cold months) at work, in less than 10 degree weather, with either. i know i know my work needs block heaters. now these are the big diesels with out glow plugs. so just a little shot in the intake while somebody cranks is enought to fire it off. i think as long as you don't over due it you won't blow the motor. i also hear that is how they start excavation equipment in the field when no elec is around for a block heater. but as for your problem i would start with the glow plug system. i don't know if 81 has a glow plug module but you can start there or the relay like cat fuzz suggested.

[aware]

Hi everyone and thanks for the answers!

Here is what I found:

Rechecked voltage at glow plugs using a digital voltmeter and it showed no voltage - however, it blipped for a second as it if WAS going to show voltage. (Here is where an analog voltmeter would be handy)

Checked backwards to the wires to the relay, same thing.

There was voltage to the relay.

Then I noticed (with someone else turning the key) that the relaly only went on for half a second, so no wonder the glow plugs didn't warm up.

I unplugged the sensor with no change.

So I put 12 V at the relay to energize it and still didn't have voltage at the plus BUT I did at the relay. Come to find out the plug-in connection near the bar going to the glow plugs was corroded. Cleaned it and now I have 12 V at the glow plugs.

In reading, I also found out why the relay was shutting down. The system monitors the amperage/voltage to the plugs and if it's not right, it cuts off. SO with only 4 1/2 V initially and zero later, it cut off the relay. As soon as there was sufficient voltage at the bar, the relay stayed on.

If a glow plug burns out, it's possible the system wouldn't work!

I believe the 2 small wires that go to the bar monitors the voltage or amperage. Sort of looks like a bus bar used for amp readings.

Another thing, is that there is 12 V to the glow plugs only for the period of time the light is on, then it goes to 7 volts through the second relay.

I read that the on time is 180 seconds. Not sure if that is true but my glow plugs stay energized after the engine starts. Haven't measured it yet because I'm afraid they'll burn out!

Does anyone know if that is correct?

Several websites verify this: http://rubyenterprises.indianyellowpages.com/glow-plugs.htm for one, Apparently this is 3-phase heating.

See page 38 here: http://www.adpdist.com/beru_glowplugs_application_na2004.pdf#search=%22is uzu%20glow%20plugs%20%22180%20seconds%22%22

Maybe it depends on the type of glow plug.

ANYONE?

THANKS!

Ben

[aware]

Hi everyone and thanks for the answers!

Here is what I found:

Rechecked voltage at glow plugs using a digital voltmeter and it showed no voltage - however, it blipped for a second as it if WAS going to show voltage. (Here is where an analog voltmeter would be handy)

Checked backwards to the wires to the relay, same thing.

There was voltage to the relay.

Then I noticed (with someone else turning the key) that the relaly only went on for half a second, so no wonder the glow plugs didn't warm up.

I unplugged the sensor with no change.

So I put 12 V at the relay to energize it and still didn't have voltage at the plus BUT I did at the relay. Come to find out the plug-in connection near the bar going to the glow plugs was corroded. Cleaned it and now I have 12 V at the glow plugs.

In reading, I also found out why the relay was shutting down. The system monitors the amperage/voltage to the plugs and if it's not right, it cuts off. SO with only 4 1/2 V initially and zero later, it cut off the relay. As soon as there was sufficient voltage at the bar, the relay stayed on.

If a glow plug burns out, it's possible the system wouldn't work!

I believe the 2 small wires that go to the bar monitors the voltage or amperage. Sort of looks like a bus bar used for amp readings.

Another thing, is that there is 12 V to the glow plugs only for the period of time the light is on, then it goes to 7 volts through the second relay.

I read that the on time is 180 seconds. Not sure if that is true but my glow plugs stay energized after the engine starts. Haven't measured it yet because I'm afraid they'll burn out!

Does anyone know if that is correct?

Several websites verify this: http://rubyenterprises.indianyellowpages.com/glow-plugs.htm for one, Apparently this is 3-phase heating.

See page 38 here: http://www.adpdist.com/beru_glowplugs_application_na2004.pdf#search=%22is uzu%20glow%20plugs%20%22180%20seconds%22%22

Maybe it depends on the type of glow plug.

ANYONE?

THANKS!

Ben

[Cat Fuzz]

Sorry, I only have a general knowledge of how diesel engines work.