6.9 diesel won't start, 1984 F-250
- Thread starter Tomteriffic
- Start date
Tomteriffic
Registered User
Yes, it makes sense. if no fire in the wires going to the glow plugs means the glow plugs don't get hot and no start. I checked the bypass wire which I installed and with the ignition key on and the bypass switch on, I have fire going to the Relay. Which post on the relay exits to the glow plug wires? With a good test light, I can check it there too, and then keep going towards the harness until there is no fire. Point of no fire is the problem, right?
IDIBRONCO
IDIBRONCO
Yes, I truly believe that this is your problem. There is two large posts on your relay. One has a large wire that can be traced back to the constant hot side of the starter solenoid (relay) on the fender. The other large post on the glow plug relay has two smaller wires that go into a wiring bundle. These are the wires that power your glow plugs. First, I'd do a continuity check between the two wires at your relay and the wires that actually plug onto the glow plugs. Unplug the wires at both ends first of course. If there's no continuity, then you know that there's a break in between. Then you could do the same thing between both sides of the plug and the other end of the glow plug wires. If you have good continuity with low resistance, then the problem is in the plug. That's just a suggestion. The test light method will work just fine as well.
engineertppllc
Registered User
I think IDIBRONCO nailed it. His post is very well written. My pin and sleeve connectors were burned-up too. I spent lots of time cleaning and repairing the individual wire ends. Maybe, as you said, they should just be spliced together. Thanks BRONCO!
IDIBRONCO
IDIBRONCO
You're welcome. I know that splicing the two wires together is the easy way, but coming from my background of doing R&R on these engine for 6 years, I don't like that method. It makes it much harder to pull the engine out since you now have to fish the engine wiring harness out and put it back the same way. I know that you shouldn't have to pull the engine very many times, but it's still the way that I look at it.
Big Bart
Tow&Slow
Gents,
As I recall I had a similiar issue about a year ago. My glow plug light on the dash would come on for a couple seconds (Normally 10-15), go off, and then click click click click, I would hear the relay cycling. But I had a hard time getting it started at even 60 degrees. When it did it raced up and blew out white smoke from all the diesel that had injected but not burned from lengthy start cycles that did not start the IDI.
In one post it stated once the plugs are warmed by the controller for 10-20 senconds, then when warm cycle to not burn them up rather to keep them warmed. (So you hear click, click, click till you start or the key is turned off.)
In another post it was stated the relay is OHM sensitive. To prevent any electrical issues or fires it will not cycle for 10-20 seconds if it does not sense most of the GP's are in working order. (Or your wiring harness is bad, thus not conneted or grounded physically.)
My issue was I knew I had a bad GP wire (Frayed and broken in two.), but it was not causing any issues. But when a GP in another cylinder died (Might of been after two gave up.) the controller went to safe mode and did not cycle for 10-15 seconds. So the light came on, one-two, light went off, and click, click, click. Hard start followed by a nasty run up and smoke.
I pulled and replaced all my glow plugs (Only use Motorcraft according to this group. Aftermarket ones buldge and cause issues upon removal.), fix the bad glow plug connector, and the issue went away.
It could be your number 8 plug that you did not get to, is also bad. Thus 2 bad GP's, now a OHM reading your controller does not like. (Perhaps 3 or 4 if your wiring is failing.)
Now keep in mind I could start my truck with long cranks but not sure if it would have below 50 degrees. So start with the GP's. If your GP relay issue is gone but still no start. Look for a air leak.
You metioned a new fuel filter, you may have introduced a air leak. There are lots of strings on air leaks (Common no start or delayed start issue.) but as mentioned above look for a diesel leak at all lines and injector lines. The return lines/cups often start to leak over time. Usually you can see dirt that has collected on the diesel that is leaking out. As mentioned above you can bleed off air by cracking the injector lines at the injectors. Loosen all 8 nuts and turn the motor over till you see the bubbles gone or diesel coming out. Tighten the lines and try to start. If it starts and runs good you have a air leak, likely from a bad filter o-ring, the little sensor on top of the filter housing, the bottom part of the filter with the waste valve (If factory its there, some aftermarket replacments don't use it, so yours may be gone.), or one of the in or out fuel lines. Just from applying pressure or by leaning on something. (These trucks are up there in age.)
Lastly check your lift pump to see if it is delivering fuel to the fuel filter to make sure it works. Another common issue when trucks have starting or performance issues.
As I recall I had a similiar issue about a year ago. My glow plug light on the dash would come on for a couple seconds (Normally 10-15), go off, and then click click click click, I would hear the relay cycling. But I had a hard time getting it started at even 60 degrees. When it did it raced up and blew out white smoke from all the diesel that had injected but not burned from lengthy start cycles that did not start the IDI.
In one post it stated once the plugs are warmed by the controller for 10-20 senconds, then when warm cycle to not burn them up rather to keep them warmed. (So you hear click, click, click till you start or the key is turned off.)
In another post it was stated the relay is OHM sensitive. To prevent any electrical issues or fires it will not cycle for 10-20 seconds if it does not sense most of the GP's are in working order. (Or your wiring harness is bad, thus not conneted or grounded physically.)
My issue was I knew I had a bad GP wire (Frayed and broken in two.), but it was not causing any issues. But when a GP in another cylinder died (Might of been after two gave up.) the controller went to safe mode and did not cycle for 10-15 seconds. So the light came on, one-two, light went off, and click, click, click. Hard start followed by a nasty run up and smoke.
I pulled and replaced all my glow plugs (Only use Motorcraft according to this group. Aftermarket ones buldge and cause issues upon removal.), fix the bad glow plug connector, and the issue went away.
It could be your number 8 plug that you did not get to, is also bad. Thus 2 bad GP's, now a OHM reading your controller does not like. (Perhaps 3 or 4 if your wiring is failing.)
Now keep in mind I could start my truck with long cranks but not sure if it would have below 50 degrees. So start with the GP's. If your GP relay issue is gone but still no start. Look for a air leak.
You metioned a new fuel filter, you may have introduced a air leak. There are lots of strings on air leaks (Common no start or delayed start issue.) but as mentioned above look for a diesel leak at all lines and injector lines. The return lines/cups often start to leak over time. Usually you can see dirt that has collected on the diesel that is leaking out. As mentioned above you can bleed off air by cracking the injector lines at the injectors. Loosen all 8 nuts and turn the motor over till you see the bubbles gone or diesel coming out. Tighten the lines and try to start. If it starts and runs good you have a air leak, likely from a bad filter o-ring, the little sensor on top of the filter housing, the bottom part of the filter with the waste valve (If factory its there, some aftermarket replacments don't use it, so yours may be gone.), or one of the in or out fuel lines. Just from applying pressure or by leaning on something. (These trucks are up there in age.)
Lastly check your lift pump to see if it is delivering fuel to the fuel filter to make sure it works. Another common issue when trucks have starting or performance issues.
Big Bart
Tow&Slow
One more thing gents, I have a 88 7.3.
I saw above someone suggested the relay works differnet between 6.9's and 7.3's.
But the fact two relay's later still no power to the GP's would suggest the relay is sensing a bad OHM reading and not giving power.
Above it was mentioned to jump the relay to see if you get power to the GP's, if you do then the relay is choosing not to power them. So likely a wiring issue, #8 is bad too, or you are getting a false positive from a marginal or dead GP.
I saw above someone suggested the relay works differnet between 6.9's and 7.3's.
But the fact two relay's later still no power to the GP's would suggest the relay is sensing a bad OHM reading and not giving power.
Above it was mentioned to jump the relay to see if you get power to the GP's, if you do then the relay is choosing not to power them. So likely a wiring issue, #8 is bad too, or you are getting a false positive from a marginal or dead GP.
Similar threads
