No glow plug action again

[TronDD]

Glow plugs aren't working again. Same as last week, I get a split second of the wait to start light then just the after glow clicks. Truck doesn't start. This thing has never started more than once in a row since I've known it.

I checked the hacked plug on the intake, it wasn't grounding (or was bad). So I replaced all the plugs with my Motorcraft ones (except the one under the turbo). Test light will light up on the one in the intake.

Made zero difference.

If I bypass the controller by grounding the white wire, should I hear the relay click? Am I misunderstanding how the manual switch is wired in?

Also noticed, and not sure if it's new, the temp gauge will go all the way to hot while the key is in the on position. IS that telling the GPC I don't need the plugs?

Tim.

 

[argve]

No the temp gauge has nothing to with the operation of the glow plug controller. The controller measures a voltage drop across the big zig zag metal strip to determine if the plugs are hot. Now if you have bad connections (meaning dirty or such) then the controller can be fooled into thinking that the plugs are hot and they don't need to a full blast of current to heat up. So I would start by pulling off all the connections and checking them. Make sure they are clean and tight. Now grounding the white wire should make the relay turn on if the key is ON. typically I have found that bad connections are the number one problem if all the glow plugs are good. I had guys in the past send me their old bad controllers and I would clean the connections and install them on the Enterprise and it would work like a champ so I would recommend cleaning all the connection to where they shine. Then give them a little electrical contact grease to protect them from the elements.

 

[argve]

also the starter needs to spin these motors at a pretty good rate for them to start so make sure that it's working properly as well.

 

[TronDD]

Found a thread on FTE that outlines the steps for testing all the connections.

Right now the truck is on the block heater. Sounds like that is working, I can hear it sizzle. Hopefully I can start it and keep the batteries charged while I diagnose the root problem.

Tim.

 

[argve]

Cool keep us posted. I think there is a write up in the tech section here on how the solid state glow plug controller system works as well.

 

[TronDD]

When I started up after simmering on the block heater for a couple of hours, the glow plug system still wasn't working. I drove around to charge the batteries for a bit. Then I had to run an errand and since the truck was still warm, decided to take it out again. Glow plugs worked this time. And again in the parking lot of where I went.

Must be a loose connection somewhere. Probably the glow plug they stuck into the intake. It doesn't really thread in securely.

Tim.

 

[stumiister]

If you had the truck plugged in the gp's wont work since the controller is screwed into the coolant passage in the head.
It also sounds like you may have more than one bad gp. Have you tested the gp's themselves?
Have you thought about putting the gp system on a manual push button?

 

[icanfixall]

Mant times the glow plugs will not recieve enough power for them to operate. This is mainly because of the engine main wire harness plug is corroded up. Find the engine main wire harness plug on the passenger side of the engine. Open it up and look for crap. Your looking at the end with the two ywllow wires. Both those wires feed power to the controller. Ford felt two small wires are cheaper than one large wire... So does most of the electrical power companys but that another story. Its simple to modify these two wires. Just find a radio shop that installs car radios. But some 6 gauge wire and some crimp on lugs. Then cut loose those small yellow wires and run the new speaker wire you got at the radio sterio shop. You will never have a controller power issue again. Some feel they want a circut breaker in this mod. Its safer but not needed really. Many times that harness plug is melted and in worst cases it starts a fire...

 

[argve]

If you had the truck plugged in the gp's wont work since the controller is screwed into the coolant passage in the head.
It also sounds like you may have more than one bad gp. Have you tested the gp's themselves?
Have you thought about putting the gp system on a manual push button?

the truck in his sig says it's a 1991 which has the solid state controller not the old 6.9 system that uses all kinds of crazy stuff to determine if the glow plugs need to be turned on and for how long. The solid state controller uses a voltage drop across the glow plugs themselves to determine how long to burn the plugs. now with using the block heater it will shorten their action but will not keep it from even working at all. Because on the solid state it will always at least go into "after Glow" where the relay clicks on and off. But you are correct on the old "whizz bang" design of the older ones where it measures coolant temp and such. My 86 has the "whizz bang" system as I call it where it looks at this and that and is extremely unreliable or will stick on and toast the glow plugs while you are driving.... This is why mine has a manual control.

 

[Houndsman]

From my experience there is a relay next to the battery on the passenger side, mine has the starter wire the trigger for the starter and other on it, when I replaced my starter I also did that relay, thay relay puts power out to your GP's at least mine does. Before I go further check yours out?!!!

 

[Houndsman]

From my experience there is a relay next to the battery on the passenger side, mine has the starter wire the trigger wire and power to the gp and I bleaive the fule heater, and others. I found out thay a fusible link inside them witch mi e where bad so I cut the wires and went done and got the glass fuse holders and fixed the problem don't know if I did it the right way but it works now

 

[argve]

Houndsman that relay on the Solid state ones 87-94 IDI's is mounted on the glow plug controller on the rear center of intake manifold. Same relay but just mounted in different location. It's an all in one deal on the solid state controlled ones.

 

[Houndsman]

10-4 on that I know that but mine gets it's power when you turn your key forward and send power over that controller from the starter relay. I also bleaive the fule heater and others on it I would send add a pic but it dont let me do it from my iPhone idk why

 

[TronDD]

Glow plugs worked again today, 3 times.

I took a look at the harness connector at the passenger side fender. I can see a little distortion in the plastic from heat, but nothing alarming. I couldn't get the connector apart, but I didn't have good leverage. I'll try again to get it apart and check for corrosion and damage in there. I'll put rewiring the glow plug power on the todo list.

As long as the plugs keep working, I guess there isn't much I can do to troubleshoot. We'll see if it lasts this time. Meanwhile, I have bigger issues on the truck to look into.

Tim.

 

[Houndsman]

On my truck that where I had a problem, trace the wires make sure it's not gounding out any where, too but I did cut the wires going to that really where the feasible link was the stock one and replaced it with a glass fuse, and not she's all good, I would also cleans all your power connections even your Batteries, whis you the best of luck.