Starting problem.

[jaed_43725]

I am new here and new to diesels. I did search as much as I could find. My problem is my 88' When I turn the key to let the wait to start light come on it only comes on for a very brief second then I hear clicks. I checked the glow plugs and they are all good. I checked the plug controller and plug solenoid and they are all checked good. According to the Chiltons Manual its the coolant temperature sensor that I have to get. But when I went to Advance Auto Parts to get one I was unable to match the plug to anything on the engine (a 2 wire plug). And it says its on the front left of the engine (around the A/C pump area as far as I can tell) and all I see are 2 different sensors that use a 1 wire hookup. I don't want to start unnecessarily replacing parts.

I am sure the diesel vets around here have seen this a million times. Any info you have is greatly appreciated.

 

[Shadetreemechanic]

temp sensor wouldn't cause the gp light to go out in under a second, but bad glow plugs would.
How did you check them?

 

[jaed_43725]

Checked them with a multimeter. It tested that I am getting 6 volts to the plugs and when it clicks the multimeter pulses with it.

 

[Shadetreemechanic]

You are getting voltage to the plugs, but they ain't working. To test the plugs put your multimeter on the resistance setting and check the glowplug to ground. I forget the exact number, but you should show continuity with some resistance. What I think you will find is that several of them show an open circut. These are burned out.
The glowplug controller sets the glow time based on the resistance it senses in the glow plug circut. It can tolorate one or two bad glowplugs, but after that the resistance builds really quickly and the controller cuts power to the circut quickly.

 

[jaed_43725]

ok,i see. so a water temp sensor isnt the brains of the thing. there is actually a gp controller. is the gpc the gp solenoid?

 

[Andylad13]

the brains of the glow system is resistance. when the plugs are on, resistance builds up in the wires and the controller tells them when to turn off based on that resistance. when you have bad glow plugs they show up to infinant resistance, making the glow time very short if not at all. you need to ohm the plugs by removing them and putting the multimeter on ohm setting, put the neg on the threads of the plug, and the power on the bullet connector part of the plug. good ones will show a .2 reading. bad ones are higher than .5 ish. when i had bad ones they ranged from 1.5-12. sounds like you have atleast 3 bad ones.

 

[jaed_43725]

ok, that makes sense. i will be doing some testing soon then. would anyone know what the chiltons was talking about then,about the water temp sensor? thanks for the help.

 

[Redneck]

ok, that makes sense. i will be doing some testing soon then. would anyone know what the chiltons was talking about then,about the water temp sensor? thanks for the help.

Isn't there something to do with overall engine temp that regulates when/if/how long the GP's come on for? Maybe that's the reason for checkin it?

 

[4x4TruckinGirl]

Sounds like GP issues or controller issues. The GP controller is kinda hard to test I think, or maybe I just had no luck. If you do have a few bad plugs, you oughta just replace all of them with the motorcraft ones. On your 88 they should be easy to change, since you don't have a turbo on....

 

[icanfixall]

The glow plug controller is a solid state type and its located behind the intake manifold. The air filter housing needs to be removed to see it. I'm with others. The plugs have failed and just replacing the bad ones is not the best idea but will get things right... For a while. Don't replace with Autolites or Champion brand plugs.... Those will burn out and swell up. Then the heads need to be removed to get them out. Motorcraft Beru ZD9 are about the best for these trucks. Figure to pay around $9.00 or $10.00 per plug and shop around... Ford wants more than $25.00 per plug and we all know they can be found cheaper than that. Be careful removing the old set. They could be tuff and don't pull too hard. Post back is you find a stuck plug. Mant here can tell you how to easily get them out. Welcome to the site too....

 

[RLDSL]

For one thing, it would greatly help if you fill in your signature with some information about your truck. Not so much for this, but other things.

There are temp sensors but they are more related to the cold start advance and high idle speed switch. The one under the filter with 2 prongs would be that one. The two temp senders in the drivers side head are for gauge and overtemp warning.

With an unknown, I would be inclined to go ahead and replace the set of glow plugs with a new set of Beru plugs. It would bring peace of mind and you'd have a known starting point.

As far as the chitlins manual, if you know someone with a parakeet, you could donate the pages to sanitation collection, otherwise, you can usually find the ford manual in print or CD on ebay etc, much better.