I have a start-up dilemma with my '93 7.3L. glow plugs check out, are new, and carry the current. Batteries are strong. All connections cleaned and strong.
I still need to plug the truck in to get it to start without cranking on the starter. the weather has been in the mid 40's and warmer.

I have also noticed my truck's acceleration will occassionally burst forward on me after coming to a stop or making a sharp turn. The burst happens although the accelerator pedal is steady.

I am wondering where to begin on the start-up dilemma. I've read through various threads here and other sites. there have been mentions of potential air in fuel line, but i've read in my manual that my truck is equipped with an automatic fuel system bleeding mechanism.

I am clueless how to remedy this. I would love for the truck to start on its own accord like it should. I do not have a desire in burning out the starter. i am also unsure that the acceleration is or is not related to starting up. could be separate.
any insights, guidance or helpful information is valued.

m

 

mijale,
Welcome to FTE and the IDI forum.

Does your volt meter drop several volts while the glow plugs are heating?

If the engine fires right up when it is plugged in, but has to crank when starting with just the glow plugs I would still be looking at the glow plug system.

What brand of glow plugs are in it now?

Do you notice the surge being worse at lower fuel tank levels?

 

My voltage meter on the dash does not drop or increase during the 'wait to start' cycle.
the glow plugs are motor craft. the engine does fire up when plugged in and has to crank, crank, crank, when working just with glow plug cycle.

I also have been perusing the forum and found why the burst is happening. I am usually in the lower ends of a fuel tank during this time.

 

Since the glow plugs draw about 200 amps when they are heating, if your volt meter does not move I would guess that they are not working.

Do you hear any clicking of the glow plug relay?

This is a picture of the late model glow plug controller/relay with the cover removed.
Controller is under the relay and powered by the small wires on the relay terminals.



With the key in the ON position, use a piece of wire to short the white wire terminal to ground.
The relay should click when you do that.

Use caution, the battery terminal has battery voltage at all times.
The ignition terminal has battery voltage when the key is in the ON position.

If the relay does not click when you ground the white terminal, check for voltage at the battery and ignition terminals.

If you have no power, there is a connector on the passenger side of the engine where the engine harness plugs into the chassis harness.
Check that connector for signs of overheating or corrosion inside the connector.

 

i appreciate your attention dave. I am unable to locate what the picture shows to be able to test as you have pointed out.
I am fresh to the diesel, and am blindly feeling my way around here.
I wonder too if what i am looking for may be different in my truck than what you have pictured.

m

 

Thats the glowplug relay.It should be under the hood faceing up.I really dont know that year.I get a surge some times when i shift into second,and sounds like it smooths out or got a drink of some good fuel.Then it just runs normal again.Iam thinking air is getting sucked in the fuel lines some were or fuel pump coming loose.New fuel filter can help.If you can start your truck with about 1/2-1 FL OZ cup of diesel on cold start then its Glowplugs or Fuel pressure.Dont use starter fluid.Check for some sort of temp sensor for that year.

 

The glow plug relay is mounted on the back of the intake manifold right next to the firewall.
Remove the air cleaner, it is in the center of the rear of the engine.

There will be a plastic cover over the top of the relay to protect the wires from accidental contact.
Squeeze the sides of the cover to release it from the relay, there are arrows that show where to squeeze embossed in the cover.

Also remember if the battery cables are on the batteries, there is voltage and a lot of amperage on the terminal marked battery on the relay.

A wrench or screw driver shorted to that terminal and another metal item will weld or burn holes in it.

 

thanks dave. the clicking sound happens when i ground it to the block. there is no change in the voltage on the dash meter for the battery as this happens. not sure that there would be.
I noticed the air filter having an oily residue along the bottom, on the screen for the air flow intake, and on the bolt bottom holding the entire apparatus together. is this normal?

appreciating the guidance. what next captain?

m

 

There should be a drop in the volt meter, the glow plugs draw about 200 amps when they are heating.

Are you sure the glow plugs are good?
Check for voltage on the glow plug terminal of the relay when you trigger the relay.
I have seen a couple relays that did click, but did not put through any voltage from the battery terminal.

The oil residue is from the CDR.
It should be serviced every other oil change.

Remove the CDR from the back of the intake throat and soak it in a pan of solvent, I use gasoline.
Aggitate the gasoline inside the CDR every couple minutes, then dump out the gasoline in the CDR and then stick it back in the pan. Look for pieces of black rubber when you dump the gasoline out of the CDR, if present it would be part of the diaphram which means the CDR needs replaced.
When the inside of the CDR looks clean, dump the gasoline out and lay it aside to dry.
Never used compressed air to dry the CDR, diaphram damage will result.

 

Are you sure the glow plugs are good?
I have checked them with a basic current light. the engine turned off, the key in the off position. Mitchell manual suggested. Another way? Different voltage gauge?


CDR
Means...? Is this the filter, or something other?

today, i drove a short distance (a mile or so). turned off engine and heard a whirring sound. popped the hood and it was coming from beneath the air filter/intake. i took the screw out and the circular mechanism beneath was spinning. I could not start the truck while this was happening. it went on for about a minute, and once it stopped, the truck fired right up.
something wrong here/is this normal for something? it is the first time this has happened.

i will check to see that a current is leaving the relay wire for the glowplugs. FYI; i do not hear the click when the key itself is turned on alone in sync with the WTS light. I hear a click in sync with the ABS light however.

i am unable to do check ups until the weekend. I appreciate this.

m

 

if you have a multimeter you can take one probe to the glowplug tip and the other to a good ground,with the engine cold they should read less than 1 ohm, any reading above that and it most likely bad (the bad ones i found on my truck were wide open I.E. infinate resistance)one bad plug reading open can screw up the whole system operation.

 

alrighty. here is the input having been able to check out this weekend.

using a standard voltage light: all gps check out (positive terminal to exposed gp tip withm engine cold and key turned off) they are beru.
relay clicks on when key is turned on, and i hear it click well after the wts light goes out. (i see no change in the voltage on my dash during any of this)
relay clicks when white wire is grounded. (again, no change in voltage on dash)
gp wire, ignition wire, and bettery wire show current with same standard voltage light.

i am now having startup trouble when engine is warm.
didn't want to start after sitting for about two hours. plugged in for thirty minutes, and it rough started. had to plug in after work earlier in the day after sitting for about 4 hours, and before that, roughm crank start for lunch.

i like my truck.

m

 

Does your truck have a turbo?

I am not understanding the "circular mechanism beneath the air cleaner was spinning"

When you checked the glow plugs with a test light, the wire was removed from the glow plug, correct?

Near the dip stick you should have a connector where the engine harness plugs into the chassis harness.
Two large diameter yellow wires are on one end of the connector.
Inspect the connector for signs of overheating.
If it does not look like it has melted some, try to unplug it, inspect for corrosion and then reconnect it.
The large gauge wires in that connector are power to the glow plug relay battery terminal.
Any corrosion there would limit the power to the relay.

With the engine being hard to start warm, I am starting to think you may have air intrusion problems with the fuel system.

 

i'll check on the turbo..
'the circular mechanism' is what i find beneath the airfilter atop the engine. A circular screen with a heavy duty nut/bolt in the center. the center of this nut/bolt has threads for the lock bolt that holds the entire air intake together and in place.
the spinning was coming from beneath the air intake. the entire truck was in 'freeze'. would not turn over, start until the spinning stopped.

i will check the wiring as you mention.

appreciated
m

 

dave sponagle:
i removed my cdr and it has no diaphram. nothing, just a pipe. maybe thats why i'm using oil.
i kept wondering why you keep insisting that i wash it every oil change, and i would just wash the pipe. i think i'm missing parts.
john