I replaced the glow plugs about this time last year well only having put about 9 k on it this year shouldn't have been to many miles for the glow plugs so I'm thinking its something else if it's about 40 deg it starts no problem any colder it better be plugged in or it's gonna take 30 + minutes to get it started well now that it dropped below 20 deg it seamed like the block heater had no affect last high and wouldn't start being plugged in and after trying for a while the battery's also new only 6 weeks old started to get low I had to either it so getting new glow plugs again but need to fix the problem any ideas

 

Before you start disassembling things to change glow plugs, have you checked the glow plug relay? If it didn't start at 20F with the block heater plugged in, you should also check the block heater. At 20F, I don't even need to wait for the WTS light to start mine if it's been plugged in.

 

Have you checked your glow plug relay? It is simple to check with a test light or multimeter. Strong warm weather starts and okay cold weather starts when plugged in generally indicate a relay issue. The large post closest to the passenger side (one thick wire) should always have power. The small post nearest the firewall should have power only when the ignition is in the ON position. The other large post (should have two wires, maybe tied together) should have around 12v when the ignition is in the ON position. This indicates the relay is sending power to the glow plugs. I can't remember for sure but I believe the relay only sends power to the glow plugs for a set amount of time then shuts off so turn the key and then immediately check your meter. Check Youtube for videos for more details....
When you replaced the glow plugs did you replace the wiring inside the valve cover? If not do a search on how to test those with a multimeter to make sure power is getting to the GP's from the relay. If I remember right, the two outside pin on the plug that goes into the valve covers are the GP wires...good luck!

 

Haven't checked relay yet going to go check it in a sec and the fuse for the block heater is that under the hood or dash

 

It doesn't mater hot or cold it won't start without waiting for the glw plugs and some time it can just be a chilly day and I might have to let it cycle and turn over a couple times going to get a test light now will keep you posted

 

Just replaced the glow plug relay but with the engine already a little warm I'm not sure if it fixed it and the parts place didn't have a test light so until tomorrow I think I got what I got but I want to get to the bottom of this

 

Hopefully that took care of it....keep us posted!

 

The glow plug solenoid seams to have done it didn't plug it in last night started first time today I do want to check into the block heater more though because yesterday morning and it didn't do anything so I think the fuse I just am not sure where that fuse is in line under the dash or hood and thanks so much for the help so far you guys are life savers

 

There is no fuse in the truck for the block heater. Make sure you have a known good extension cord. You can also ohm across the the spades on the plug with a multimeter. According to Ohm's Law it should be in the neighborhood of 15 ohms. If it's infinite or nearly infinite resistance, the element is toast.

 

I had some troubles with my 99 7.3 cranking and my glow's were good and I had the starter rebuilt and still cranked horrible. Put a gear reduction starter from DB electrical on it and wow what a difference! Best upgrade to that truck yet!

 

Definitely got a good cord it's a 12 ga with a light in the plug to show power or not but it didn't heat how bad is replacing the block heater the starter turns it over and it starts but I kinda wish it would spin the crank a little faster it just doesn't seem like it's turning very fast but it starts would like the block heater to work never played with them much unless plugging them in counts

 

Check the cord all the way from the front to the heater element in the block too. The cord is replaceable on its own if it's damaged. I haven't had to replace an element yet. I know it involves draining the coolant, unscrewing the old one and screwing the new one back in, so it should be pretty straightforward. Its located at the back end of the oil cooler, above the filter.

 

You probably don't want to hear this but I was having the same problem. Hard starting when it's cold, even with the block heater. Make sure the oil is clean and full before doing anything. I know your glow plugs will last longer than a year. If I spray starting fluid in mine it would start after a couple of tries have you tried that? And after mine started it would be slow going with no power at first then after it warmed up all the way would be fine. How is yours? I ended up buying rebuilt injectors, and new glow plugs while I am in there. Now the truck startes like new, with plenty of power, I have 190,000 miles on it. 1999 7.3
-Sean

 

Found the problem with the block heater cord is split and it arced out and melted the wire a few inches from the plug got a new one on order all issues already discussed seam resulted otherwise and yes same with it having not much power until completely warm but once warmed up good runs like a champ

New problem started it headed to town (15) mi got to the edge of town truck shut off didn't sputter or act weird just just died all at once when it shut off I tried to restart turns over and spins fine just won't start sputter anything I almost wanna thing the fuel pump or injectors just stopped all at once when I turn the key all the dummy lights except the glow plugs comes on just won't start any ideas please

 

Check maxi fuse #30. If it's blown, unplug the connector from the fuel heater on the fuel bowl, replace the fuse and see if it starts. You can leave it disconnected without hurting anything but it will disable the water-in-fuel sensor also.