I have one of those voltmeters you plug into your lighter socket. Resting, it indicates the battery(s) level at 12.4 volts. At the battery terminals, my multimeter measures 12.67 volts. Sitting in the truck and turning the key on to activate the glow plug relay, the voltage drops anywhere from .6 to .7 of a volt. I seem to remember that last winter, the drop was closer to a full 1.0 volt. The reason I ask is the truck is hard to start even with two new batteries, two new battery warming blankets and the block heater plugged in.

Question: Does anyone know what the voltage drop/draw should be if all 8 glow plugs are good and all are activated?

 

 

Numbers look good, what's the voltage when cranking. With new batteries and assuming good connections I'm suspecting just an old worn out starter, especially in cold climates. Does the truck spin over fast and has the starter ever been replaced? Been there done that on both trucks.

 

Thanks John, your voltage numbers at the batteries are almost identical to mine so it looks like some of my GP's are not working. BTW - just read your post on Super Sport tire chains. Hard to find them where I live. I'm heading to Denver in the Spring. Any place/chain store you know of that carries them there?

Jim, I haven't noticed the voltage when cranking. However, it does seem to turn over fairly strong and I attribute that to the new batteries. Starter seems to work fine too as it cranks over strong although my guess it's the original starter ... at least I haven't replaced it in 5 years of owning this truck. It's just that it takes me about two to three crank cycles to get the engine fired up. The first crank cycle (or sometimes two cycles) last about 10 seconds. I stop there because I don't want to overheat/harm the starter. The truck usually starts about 5 seconds into the second (or sometimes third) crank cycle. Lots of white smoke (doesn't happen when it is warm out) but it's hard to tell if that is caused by the cold temps (about 10* F today) or something else. I can hear the fuel pump priming so I don't think it's a fuel issue. Once it does start and warm up, runs like a champ.

 

My voltage drops about a full volt when GPs are on. Other voltages reported above are similar. A tenth or so difference between the power port and cigar lighter on the dash too, for whatever reason.

Since you're well short a full volt I'd wager a couple/few of your GPs are not working. Word is use genuine Ford ZD11s and do all 8 of them, not just the one that burned out like I did.

 

"Voltage at batteries sits at 12.6 -12.7 in the cab I see 12.3 - 12.4"

Is this with the engine off or running? Running voltage at the batteries should be ~ 14 volts.

 

Don't forget that until the GPR times out you won't see more than about 12.5 volts with the engine running.

 

 

 

That's sitting ... engine off. Engine running I register anywhere from 14.1 to 14.3 volts with the plug-in voltmeter. I've been convalescing the past week and have read a ton about GPRs, GPs, how to remove and replace the old GPs etc. I've concluded based on my symptoms, I do have some bad glow plugs. I have all the classic symptoms; 1) < a full volt drop when GPR is activated; 2) good cranking - hard starting (I have two new batteries); 3) lots of white smoke when it finally does catch (usually at the begining of the 3rd GPR warm up cycle) and exhaust stays white until it warms up properly ... then everything is normal and; 4) warm(er) weather/warm engine starting unaffected.

Of course this condition only presented itself as the ambient temperature dropped over the past few weeks. So, I'll order 8 new Motorcraft ZD11 glowplugs to replace my current GPs. I also have a new GPR I ordered last year when I thought maybe it was the problem. (the old one tested out fine). I've never removed the valve covers so this will be a first for me. Besides checking the wiring connections, torque on the injectors etc., is there anything else I should do while the VCs are off? I know my "oil breather" o-rings are leaking so I'll also be replacing those too.

Sure appreciate all the input guys!

 

Starting at 10-degF is near the bottom of the starting range for a clean start. You may have a few GPs out but not too many.

I know my GPs are working and get that full volt drop, it still smokes like mad but not as long as you state your does.

 

The only thing I can compare with is how it used to start previously. Two winters ago, I had no issues if I plugged it in (block heater) a few hours ahead of time.
Last winter I noticed it was tougher to start i.e. took several cycles of the GPR activation for it to "catch" strongly. This past September (warm temps), I noticed it cranked slower. I tested and replaced the batteries after this.

Now, it struggles compared to how it used to start in the cold weather. It always used to produce some white smoke until it warmed up. However, now the white smoke seems "thicker" and smells like diesel fuel ... if that makes sense. Before, it was just wispy white smoke for a bit with little noticeable fuel smell. Perhaps I should test the GPs one by one but everything I've read says if one or two are gone, the rest are not far behind. I'd rather just replace them all and know I have good GPs. Does this make sense?

 

Just did 6 of 8 gp's because 2 were stuck(oem), and my drop is from a resting 12.6 to 11.6/8...

 

You are exactly right, that is the symptom of a few GPs not working. If they were all out (or the relay not working) then it wouldn't start at
all at that temp. Using a few hours of plug-in would really help at 10-deg even when they are all working.

My truck the GP controller (it is a CA truck so has one, no GP relay) had died and it wouldn't start at 30-deg. Had to plug it in for a few hours to even have it start and
smoke the place out for awhile.

 

I just replaced all 8 of my GP's after 3 tested bad from the outside connection on the UVCH. I was in there doing the SXE install anyway, so thought I would check them and glad I did. I ended up replacing the gaskets and UVCH's for each side as well because the passenger side was original equipment and the driver side was Dorman replacement.

With the new GP's, my truck started with less than a second of cranking it at ~38 degrees the other morning. I let the GP's fire for ~25 seconds when I did that start.

Not a bad job, just takes a lot of bending, twisting and swearing.