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Glow Plug Issue

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Old Dec 7, 2017 | 07:49 AM
  #1  
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From: Kentwood, La
Glow Plug Issue

I have a 1995 7.3L F250 daily driver. When I got the truck the glow plugs were not warming up, so I bought a new relay and put it on. Same problem. Both relays go off almost immediately after coming on. Because of that, I keep the truck plugged in at night, and it never gives me any problems since I live in mild temps. However, it has been colder than normal and I would like to figure out what is going on with it. I left it plugged in last night, and it still wouldn't crank this morning.

I have in the past, with another 7.3 jumped from one relay terminal to the other to heat the glow plugs when the relay failed. With the other, It would at least arc and get warm. Neither relay that has been on this truck has even arced.

Thanks in advance,

Tyler
 
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Old Dec 7, 2017 | 07:53 AM
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From: Bahstun
time to ohm out the glow plugs, you might have a lot of them burnt out
 
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Old Dec 7, 2017 | 07:59 AM
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Sounds like he's not even getting power to the gpr.

Check with a multimeter and follow until you get voltage.
 
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Old Dec 7, 2017 | 08:04 AM
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It is getting enough power for the gpr to make the typical "click" when the key is turned on. I will check it with a multi-meter though if that helps.
 
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Old Dec 7, 2017 | 08:43 AM
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Are you arching the big terminals?
 
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Old Dec 7, 2017 | 08:45 AM
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Yes, except with this truck they don't actually arc
 
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Old Dec 7, 2017 | 08:50 AM
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Humm, the one wire is always hot meaning its connected directly to the battery, have you made sure you aint got corrosion on the + side the battery connection?
 
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Old Dec 7, 2017 | 09:33 AM
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To me, it sounds like most of the glow plugs are burned out. Do as Knottyrope said in the first reply. Or check them with a test light by clamping the lead from the test light to the positive side battery post, the touch the pin to the glow plug with the tip of the test light. Ig the light comes on, the plug is probably good. No light the plug is bad. You can do this by unplugging the harness from the valve cover gasket. There are 2 plugs on each side. The pin layout is glow plug-injector-common-injector-glow plug, so you would touch the outer most pin on each plug with the test light. If you find the plugs bad, replace with the Motorcraft ZD11 plugs only, or you will be replacing them quite shortly.
 
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Old Dec 7, 2017 | 11:55 AM
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From: Bahstun
problem with a test light is that it might light up when GP is bad


GP take about 10 amps and many test lights use a fraction of that current to light up
 
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Old Dec 10, 2017 | 06:23 PM
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You NEED to use VOLT meter
 
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Old Dec 10, 2017 | 06:59 PM
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"Both" relays? There's only one. If you have more than one relay in the GP circuit, some previous owner has hacked something.
 
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Old Dec 11, 2017 | 07:51 AM
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From: Kentwood, La
Both relays, as in the one I took off, and the one I replaced it with.

Thanks guy, I will try to pull the valve covers this weekend and ohm out the glow plugs. I will post the results when finished.
 
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Old Dec 11, 2017 | 08:34 AM
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From: Bahstun
don't have to pull covers to ohm it out, just pop the connectors off
 
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Old Dec 11, 2017 | 08:58 AM
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I still don't think he's getting voltage to the GPR.....
 
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Old Dec 11, 2017 | 02:10 PM
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From: Bahstun
Originally Posted by Jarrett Campbell
I still don't think he's getting voltage to the GPR.....
very possible


Mine did that last year and with a wire brush on GPR post, it worked fine again and I have a spare GPR now.
 
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