Hard starting 7.3
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Senior User
Joined: Jul 2009
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Hard starting 7.3
I read through the glowplug sticky and tested my system. I have an 89 7.3 with a good glow plug system (and 8 new zd9 berus and about 9v at each connector with the key on). Wait to start light comes on for 8-10 seconds as it should. I can hear a click but no where near as loud as on my 86 f350 with the 6.9 (with the zd1a plugs). It takes 10 seconds of cranking to start my 89.
The truck has no air intrusion but is hard to start cold even at 90 degrees outside. The truck does not smoke whatsoever and makes good power - also starts up great once its warm. Could it still be the injectors or ip? Maybe the little brass valve on the top of the ip? - I might pull and clean that.
Is there something I'm missing here - the problem just feels like glowplugs despite the system appearing operational.
Thanks
The truck has no air intrusion but is hard to start cold even at 90 degrees outside. The truck does not smoke whatsoever and makes good power - also starts up great once its warm. Could it still be the injectors or ip? Maybe the little brass valve on the top of the ip? - I might pull and clean that.
Is there something I'm missing here - the problem just feels like glowplugs despite the system appearing operational.
Thanks
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Joined: Jan 2012
Posts: 359
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From: Harrisonburg, VA
IIRC the voltage to the GP's are suppose to be 12 at each one but Im not sure if i do remember correctly. If that is the problem, you might just try cycling the gps twice and then see if they are hot enough to get that ol girl to start.
How sure are you that you have no Air Intrusion?
If you have an aid that can start it while your hitting the schrader valve, and you get fuel right at the start then I doubt you do have air intrusion issues.
Just a couple quick shots in the dark here.
How sure are you that you have no Air Intrusion?
If you have an aid that can start it while your hitting the schrader valve, and you get fuel right at the start then I doubt you do have air intrusion issues.
Just a couple quick shots in the dark here.
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Can anyone confirm the glow plug voltage to be 12? Bad relay maybe? - It works just the same if I jump it with a screwdriver. Looked at a glowplug today (forget what brand) and it said 10.5 volts on it. Is this a max or min or recommended?
Cycling plugs twice seems to help so the potentially low 9v could be the culprit?
If anyone has a working system and can check voltage at their bullet style glowplug connector (years 1987+) that would greatly be appreciated.
The truck used to stall out at stops and have injector clatter/chatter sometimes - these issues have since subsided/gone all together. 154k miles on injectors and ip - truck is plenty powerful (compared to my other idi with similar mileage) and is now even better with a sidewinder turbo. Got 18mpg highway with 4.10s a zf5 and 4x4. Just got 15 mpg now with the turbo
- mostly 40-60mph but I was pulling up through the Appalachian mountains.
Thanks
Cycling plugs twice seems to help so the potentially low 9v could be the culprit?
If anyone has a working system and can check voltage at their bullet style glowplug connector (years 1987+) that would greatly be appreciated.
The truck used to stall out at stops and have injector clatter/chatter sometimes - these issues have since subsided/gone all together. 154k miles on injectors and ip - truck is plenty powerful (compared to my other idi with similar mileage) and is now even better with a sidewinder turbo. Got 18mpg highway with 4.10s a zf5 and 4x4. Just got 15 mpg now with the turbo
- mostly 40-60mph but I was pulling up through the Appalachian mountains.Thanks
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Joined: Dec 2011
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From: Rockland Ontario
I can't confirm it, "yet' but when i get a chance, I'll test the voltage.
Having said that...your glow plugs should have 'full" battery voltage to them.
Have you checked the condition of your batteries.
Having said that...your glow plugs should have 'full" battery voltage to them.
Have you checked the condition of your batteries.
Senior User
Joined: Dec 2011
Posts: 484
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From: Rockland Ontario
Well, I went and tested one, it was at 9.6 volts, energized.
Battery voltage was at 12.4.
These are about one month old. i suppose there's a voltage drop as the plug heats up.
Mines a 1990, and I have the bypass, push button to turn them on.
Battery voltage was at 12.4.
These are about one month old. i suppose there's a voltage drop as the plug heats up.
Mines a 1990, and I have the bypass, push button to turn them on.
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