Short Cycling Wait Light

[hounddog]

Changed the fuel filter yesterday. The wait light now only stays on for a few seconds compared to about 8 to 10 seconds. Also seems to want to start a little harder now. I was thinking maybe I cranked too long bleeding the system. Any ideas?

 

[hemichallenger]

That should not have caused a problem. You should check the glow plugs and controller. To check the glow plugs take each wire off and connect a test light to the positive battrey terminal and when you touch the end of the glow plug the test light will light if the plug is good. Make sure your light is 24v if your glow plug system is.

 

[doghead]

Ted, your post is confusing and contradictory to the TM's. Your post is telling him to test the glow plugs by suppling them with battery power(unspecified 12 or 24 volts) with a test light(and the comment about a 24 volt test light is irrelevant to the test). While actually powering them with a test light is a reasonable indication of a good or bad glow plug, using an ohm meter as called out in the TM is more definitive(very small range of readings is acceptable, with very little variation).

A simple test with an ohm meter is what the TM calls for. They need to measure 0-3 ohms.

In about 95% of all GP problems, I think about 95% of the time, the problems could be diagnosed and repaired by the OP, simply by reading and following the TM diagnostics, step by step. (rather than reading random responses from posters that want to help but are usually less than 100% sure of all the facts and rarely explain how to test the whole system.

Heres a good read on testing them. http://www.steelsoldiers.com/500489-post3.html

And yeah, you wussies/nubies that get hurt feeling when we say"do a search", this is exactly why we get tired of re-explaining and linking to old posts that TOTALLY covered a subject, over and over. No wonder the search function results are challenging to read through. (this comment was NOT directed to the OP or any one individual in particular) In the last thread that discussed how we could just ignore it and pass on, well If we do, the forums will be full of incorrect and useless crap! So ignoring it is NOT the best answer!

I think in this threads case, a simple link to a relevant thread would have sufficed, better than a confusing and incomplete answer.

btw, If you think I'm a jerk for saying all this in this thread, don't, I do it because I care about the site and it IS my job as a moderator to try to manage the site.

 

[hemichallenger]

I thought i was making it simple. Now i see i was not. The reason you need a 24 volt test light is a 12 volt
bulb last about 4 seconds. I was not trying to confuse anyone . I guess i have been doing
it wrong for the last 20 years. Live and learn. But if the test light does not light up the glow plug has no
ground and is junk.

 

[davidkroberts]

I use the TM because I have no idea what im doing.......

Makes things nice and simple.

 

[mistaken1]

I thought i was making it simple. Now i see i was not. The reason you need a 24 volt test light is a 12 volt
bulb last about 4 seconds. I was not trying to confuse anyone . I guess i have been doing
it wrong for the last 20 years. Live and learn. But if the test light does not light up the glow plug has no
ground and is junk.

Couldn't one use a 12V test light if one used a 12V power source for this quick check procedure?

 

[Hasdrubal]

Using a test light is both simple and fast...and since you only connect it to one battery, it is 12 V. I've always done it this way, its foolproof, it either lights or doesn't. Why would using an ohm meter be more definitive? If i didn't know better, I'd say that was confusing...

 

[doghead]

A test light bulb would light up with 0-1000 ohms(or more). The GP needs to measure 0-3 ohms to function correctly with the resistor on the firewall. Miss just one GP out of spec and your gonna ruin all 7 others.

Simply put, a test light will prove that electricity will flow through the GP. It does NOT mean the GP will produce the heat it is designed to make, or that the total resistance of the 8 GPs and firewall resistors will be correct, to have a properly functioning GP system.

So, if the test light does NOT light, the GP is bad.
If the light DOES light, it DOES NOT mean the GP is good(within spec and will work right with the other components in the cucv GP system)

With an ohm meter, if you read 0-3 ohms, your good.
If you do not, you need to replace the GP.

See the difference now?

 

[hemichallenger]

The only differnce is some people go by the book and some people do not. The out come will always be the same. The test light is the simple , easy and quick way. The tm is the other way. If you understand that a glow plug will heat up if it has a ground just like grounding a hot wire if it is good if it grounds. The test light does not show it is getting power it showes that it has a ground because you are hooking it to the positive side of your battrey. I guess it is so simple some people do not understand how it works. Checking them with an ohm meter only showes that you have a ground. No ohms - no ground. Test light no light no ground. Any one with spare time check it out and see for yourself.

 

[hemichallenger]

Forget to say but i am sure it is in the tm. If you have more than a couple
glow plugs bad you need to check the controller because it may have not
shut off when it should have and that will burn out more glow plugs.

 

[doghead]

Ted. in simple terms, the GP IS a resistor that is used to pre-heat an area in the engine.

The proper way to test and measure a RESISTOR, is with an OHM meter, NOT a test light. A test light only shows if you have continuity.

The key to a proper functioning heater element is the actual Resistance.

The only difference is some people go by the book and some people do not. The out come will always be the same.

Wrong!

The test light is the simple , easy and quick way. The tm is the other way.

OK I get it now, TM bad, test light good

If you understand that a glow plug will heat up if it has a ground just like grounding a hot wire if it is good if it grounds

Yes,but the actual amount of heat it can make, is Dependant on the correct resistance of the element(measured with an OHM meter, not a test light)

Checking them with an ohm meter only shows that you have a ground.

Absolutely incorrect

The reason you need a 24 volt test light is a 12 volt
bulb last about 4 seconds.

Huh? Are you saying a 12 volt bulb, will blow, with 12v applied and a GP connected in series?(as you said to do, to test the GP) .

That is incorrect

 

[doghead]

Forget to say but i am sure it is in the tm. If you have more than a couple
glow plugs bad you need to check the controller because it may have not
shut off when it should have and that will burn out more glow plugs.

A single bad or out of spec(working but wrong ohms) GP can cause the others to fail(wiith a stock CUCV GP system. A high restance(dirty or "bad") connection at the terminals, will do the same thing.

 

[hemichallenger]

Thanks for your input. I do understend how a glow plug works. I do change glow plugs in trucks almost every week. I do understand the glow plug controller also. I also understand
injection systems that is what i do. I build 60 series engines. Yes no book. I was not saying you or your books are wrong i was trying to make something easy for someone but now understand all i did was make someone else mad and that is not what i am into. Test a set both ways and prove me wrong. Then i deserve the crap.

 

[doghead]

Ted, I am NOT mad, so don't sweat that concern. This is just a discussion to me.

I do understand your intention was to simplify the testing procedure. I simply felt I needed to clarify some things especially since your posts were not 100% thorough(and therefore somewhat confusing). That's the beauty of the TMs, they cover every single step needed to 100% diagnose the GP system, therefore, there is no need to even understand why things do the things they do.(unfortunately, that may not really teach you anything), it just gets your issue resolved.


I don't have any bad GPs here now but, I have tested at least one GP that had way out of spec ohm readings. After replacing a full set of bad ones, I did indeed "test" them a bit. I did see one that would pass the "light test" and yet it would not create any noticeable heat(with it in my fingertips!) Should have You Tubed it! Mangus was here and did that with me, if you need a witness.(he was also suggesting the "quick and dirty" test method). I had all 8 GPs bad, that time. it was interesting to find 7 that were open circuited and one with a very high ohm reading.