GP controller?

[olivera149]

Cold starts in the morning are a pain, my WTS light stays on for about 12-14 seconds and it is getting to the upper 40s here at night and i just tested all of my GPs with a test light for continuity and all checked ok. I think i have the proper burn time, but after the WTS light goes off there is no clicking or cycling of the glow plugs, which leads me to believe the controller is about due.

If i follow standard operating precedure for start up; there is no clicks after WTS goes off and i get white smoke out of the tailpipe. So now i cycle the gp's for 4-6 times until i hear a click and then it will start up fine, but when i dont hear the gp's cycling it wont start and will smoke white out of the tailpipe.

I checked all the connections today for corrossion and dirt and all seemed fine, and ran some resistance tests with the battery unplugged, and all seemed fine, but is there any way i can test the controller? Winter is setting in quickly here in alaska, and i want to get the problem solved before i am working in sub-zero temps and the batteries only being at about 1/2 capacity with the winter. I have started my truck at -30F before after cycling 3 times w/ 15-40wt oil in the crankcase, so compression is not an issue, and also i have a pyro that i will never exceed 1100F. I just need some direction as to where i should check out as i am a novice mechanic with some background. Back in HS i took 3 semesters of auto and my teacher said i wouldnt need number 4 to pass the ASE exam and the accreditation would help finding a job in college, but i never took the test as i was a business major on a wrestling scholarship in college.

TIA

--Ryan

 

[Mr_Roboto]

What brand of GP's are in the engine? Many people have stated that a simple change from old GP's to new Beru or better cured their starting issues.

IMO, a continuity test will only tell you if the GP's are completely burned out (open). They will still test good using that method even if the coil is shorted out and not working.

 

[Builder Bob]

They will still test good using that method even if the coil is shorted out and not working.

Impossible, think about it!

Follow OHMs Law,
If the coil is shorted, current goes high, it will either blow the fusible link or the coil of the GP.
The GP coil is wire almost as fine as hair, it will blow open sooner the the fusable link.
The continuity test is always the best, there are 2 states for a GP, working or open.
Just like a light bulb!!

 

[Mr_Roboto]

Sorry dude, a actual resistance test is best. A continuity test only tells you if the circuit is opened or closed. It does not tell you if the GP has the proper resistance to heat properly and give the right feedback to the controller for it to operate properly.

A shorted coil only needs to pass enough current to light the test light to pass the test. Test lights are specifically made with very small bulbs that require little current to operate. It's like saying an A/C unit will work fine in a household circuit because a radio works in the same circuit fine. Even though there may be a 20 times difference in the current draw.

 

[Black dawg]

does it draw the volt gauge down while the light is on?

 

[olivera149]

i have motorcrafts in and the GPs were changed when i bought the truck 3 years and about 34,000 miles ago. I have been working construction in a remote site in alaska since May and came back this month and it was starting to act up and not make em click and the truck was fine before i left. It is drawing the voltage down, on the initial burn while the WTS light is on, but no clicks after the light goes off then my needle will move back towards the center.

Like i said earlier if i try enough times it will work properly

 

[Builder Bob]

Sorry dude, a actual resistance test is best.

Tell me then, what is the resistance of a good GP?
And why?
What is the allowable deviation?
And why?

The GP controller does not have a circuit that measures resistance, it has a circuit that measure the voltage drop across all of the GP's.

What is the resistance of a good GP?


give the right feedback

There is no feedback circuit, this 1990's circuit design, you are reading to much into this.

 

[Freight_Train]

oh no,Not this spit again!I vote for Resistance cause you can have a dead plug but still flow.Basic rule-Resistance equals Heat.More resistance more heat,Less resistance less heat.There can be a dead short causing low resistance and no heat.

 

[olivera149]

how can one go about doing a resistance test? Electricity has never really sparked my interest into learning more about it, but do i run it pretty much like a continuity test where i run off the positive-positive lead and touch the ground lead to the GP?

 

[Builder Bob]

If someone insists that an OHM meter be used, have at it.
Place one lead to ground and the other to the tip of the GP, with the lead removed of course.
Open or infinite = Bad
Continuity = Good
Now if you need further info, go buy a new GP, measure it, see what it reads.
What does it tell you? Nothing that my 25 years of experience can determine.

Remember the the resistance of the GP will vary with temperature, how much? who knows? Does it matter? No!

All that matter is that there are 8 good GP's in the circuit.

Now for the next issue,
Basic rule-Resistance equals Heat
More resistance more heat,Less resistance less heat
There can be a dead short causing low resistance and no heat.

Sorry FreightTrain,
all wrong,
Less resistance more current, more current = more heat.
Dead short = maxi heat.
Study up, P= I X E

 

[Mr_Roboto]

*Edited to remove an inappropriate statement made in the heat of the moment*

I personally have abandoned the bastardized 7.3L IDI system and gone to manual control and dual coil GP's. My trucks are for commercial use and they need to start EVERY time.

The following is a quote from this thread:http://www.oilburners.net/forums/showthread.php?t=13412&highlight=resistance It specifically addresses why the "test light" test is not definitive.

"The resistance in ohms will increase rapidly with temperature....You can get up too 5 or even 10 ohms if it was recently running and as high as 15-20 ohms on a hot engine.

Here is a post which includes the info re GP ohms.

If you have 2 or more bad GPs, the controller may not cycle at all.

Two problems that occur with the solid state ( 1987 to 1994 IDI engines ) GP systems. If a GP burns out ( circuit resistance goes up ), the controller cycles the GPs at a faster rate which doesn't let them get to max operating temp. If 2 or more GPs fail, the controller may not cycle the GPs at all ( very rapid or no clicking heard ). When you check the GPs, use an ohmmeter. A high resistance ( not necessarily burned out ) GP can cause circuit resistance to go up and the controller will then cycle the GPs too fast. You probably will not find this problem with a test light. Resistance spec for GPs = .5 to 1 ohm cold. Second problem. A poor controller ground ( black wire attached to valve cover stud ) will cause the controller to leave the GPs on longer, often damaging or failing them. If you are having mulitple GP failures, I would check closely the controller ground. Now the confusing part. Bad ground --> longer GP on time ( slower cycling ). Burned out GPs --> faster cycling If you have both situations, it may appear that the controller is cycling the GPs at the proper rate. Bad ground slows it up while the burned GPs speed it up ---> normal cycling. The system acts/sounds like it's working normally, but you have a hard starting concern.
DieselDon"

 

[Mr_Roboto]

Olivera, to test the resistance of the GP heat coil, you set the DVOM to Ohms and put one lead on the GP tip where the wire hooks, and the other lead to the base of the GP, or any other good ground. It does not matter which lead (red or black) goes to which part.

 

[Builder Bob]

Thanks Roberto, for the personal attack!

To prove my point, I will trade you 4 new GP's, for 1 that has "A high resistance ( not necessarily burned out )".

Lets say 4 x normal!


Do you accept the challange?

If you lose you will write an apology, to the members of Oilburners

The reason you will lose is that JUST DOES NOT HAPPEN!

GP's are Open or Good,
Do you accept the challange?

Your documentation lacks credability, just another posting by those that do not know electricity.

Lets go!

BB

Now where did Frieght Train go?

 

[Agnem]

Bob,
Welcome to OB. Glad you made it over. However, we do things a bit different here, and unlike over at TDS, I get to do more than just complain, I can actually stop this nonsense. If you want to argue with somebody, take it off line. I don't think the rest of us are really interested in this petty dispute. We've been solving glow plug problems here for a long time before your need to be the only correct person came on the scene. Just present your opionion, and that's the end of the story. Everybody has one, and everybody likes to be right about it, but in the end, folks that are wrong will figure it out, and their opionion will change. There's no need for your effort to change it forcibly. Use the PM function if you can't see your way to letting this thread take a more civil course.

 

[olivera149]

i want to keep a user friendly version start-up with no ill effects for my brothers and father who will be using my truck when i leave for boot camp (BC) this fall and want them to use the truck and haul with it, so i want to keep the ford solid state GP system and just make sure everything will work for them, it will be kept at my dads home nearby and he will make sure it stays running until i can get mil leave and drive it down to wherever i am stationed after BC. When i am gone at BC it will be used as a garbage/ scrap hauler as we are constantly battling home improvement at my dads house and i am working on and off allowing enough time to train and help my Pops out. I am not working now(just got done putting in 115 HR work weeks), since May, but allowing 4-6 hours of training now.

If something major comes up i have the time to take care of things, but other than that i am focused on my goals in the military and helping my dad out when possible, but i want to start diagnosing the possible causes as soon as possible.

Havent done a resistance test yet, but every time i go to start my truck the interior lights will dimn, so at least the GP starting circuit is taking power, but i want to atleast try the resistance test to confirm some people's beliefs and disbeliefs, i need help as i dont know much about electricity, but measurements, wrenches and torque i can handle, so any help is greatly appreciated by myself and further on my family.

--Ryan