7.3 if cold wont start
 

i have a 2001 f250 7.3 diesel. it will not start in cold weather. i have had glow plugs tested all of them are good. can some one give me a idea of what it could be. cuzion has the same truck one year older same engine and his starts right up nomatter what the weather is he took it up to ohio and it started right up. i cant even get mine to start where i live in florida

Glow Plug Relay??

someone told me if the wait to start light stays on for a long time it is not the relay switch. can u test that relay

have a 2000 7.3 with about the same problem....in Georgia....if I plug it in at night or for about 30 min after an overnight...it starts fine...but if not plugged in very hard or won't start....have been told I need to replace the fuel pump...that will be done in the next week...

TEST YOUR GLOW PLUG RELAY. MOST LIKELY ITS BAD. SHOULD BE ONLY LIKE .2-.3 VOLTS DIFFERENCE BETWEEN STUDS. ITS ON THE PASSENGER VALVE COVER IN BEHIND THE POWERSTROKE COVER. BE CAREFUL CAUSE THE AIR INTAKE HEATER IS RIGHT THERE ALSO AND THEY LOOK THE SAME. IF MORE THEN THAT THEN ITS BAD.

here's a simple way of doing it.

take a screwdriver and cross the relay terminals, the relay is located on the passenger side of the motor on top under the powerstroke cover. if you cross it for about 10 seconds and crank it over and it starts, your relay is bad.

post what you find, ill garuntee its the relay.

I've had the same problem with my 7.3. Changed the GPR and GP's and it still did it. I've been told it's the nature of a 7.3 to not like it in the cold weather. Single digits to 20's for weeks at a time is what I'm dealing with. Since you're in Fla, I'd guess GPR too.

My resolution.... a shot of starting fluid ( always keep a can with you ). Starts every time no matter what the temp. It does need to stay plugged in though when that cold.

yea if you want holes in your pistons and bad rings...... :argh:

SWITCHING TO SYNTHETIC WILL MAKE A HUGE DIFFERENCE IN THE COLD. MINE HATTED STARTING B4 I SWITCHED. I DONT NEED TO PLUG IN AT ALL HERE IN MAINE. DONT USE THE EITHER THOUGH. YOUR ASKING FOR TROUBLE. HOW ARE YOUR BATTERIES? THESE MOTORS TAKE A LOT OF JUICE TO GET FIRED UP IN THE COLD.

synthetic oil? of course it will because its thinner and it flows better.

lets try testing this relay......

a little shot isn't going to cause that.

no but after a while it ruins rings...

either way its not good.

Never... Never... Never use any kind of starting fluid on a glow plug fired diesel. If the glow plugs are working it can lead to bent pushrods, bent valves, blown head gaskets... any number of bad and expensive things.

Fix the issue, dont make it worse.

Check your glow plug relay, UVC harness and glow plugs. I have never had an issue starting any of the 5 7.3's I have had at temps below -20. Turn key on, wait for about 30 seconds and fire.

I also added a glow plug light to my A pillar, it is on the cold side of the glow plug relay. When the relay is closed, the light is on, when the relay is open the light is off. Cheap, easy way to make sure your GPR is working.

change your relay i have a 99 power stroke and had the same problem your relay is going bad but its not bad yet, change it and youll be happy.

I am aware it's not the best thing to do in a motor with GP's but, in 6 winters I've not had a problem. My 7.3 is in a E350 and I wouldn't think there's much of a difference in a 7.3 in a F-350 besides the turbo and lack of IC. You're correct... try and fix the problem but, when you do that and still have trouble.... it helps to get you going.

Its just very unsafe. I have done it as well, but only on a known dead GPR or by unhooking it myself.

Same thing can happen with a Grid heater on a 5.9, just most times it comes right back at you threw the intake...LOL

HAHAHA my buddy burnt his eyebrows off that way!! lol

Hi...First time post...been lurking around for a few days now, and I'm impressed with all the knowledge put into words on this site. I just read the "chip" post, WOW...all I will say is, I appreciated the good debating going on there from BOTH sides, I learned a lot about tuners. I never knew there were so many other tuners out there that are probably a lot better than my 6yr old Hyper-Tech, I will be asking more questions on that later.
I have a 2000 F350 7.3 with 62 thousand miles on it.....My question is.... I to just started having a problem with it starting in just 30 and 40 degree temps. Never have I ever had a problem with this engine starting in cold temps (much colder than 30 & 40 degrees) I live in the UP of Michigan and on top of all that, I have NEVER plugged it in, and it ALWAYS still started after the "wait" light went off however, just recently it became very hard to start when left to sit to cool down or sit over night. Once you do start it then it starts great after that as long it doesn't sit long enough to get cold. I checked my GPR, and with the key off I have no power to either stud, with the key on and the wait light cycled off, I have power to both studs and they both read 10 volts, if this sounds normal what else should I look for. What do you mean when you say check the UVC harness and how do I go about checking the glow plugs.
Any and all help will be greatly appreciated:tu:

Sounds to me you have a glow plug relay issue. Get a test light, hook one end to a good ground and then with a friend, check each side with the key off (one side should be hot and the other not) and again with the key on. Check each side of the GPR (there are two relays, the one closest to the firewall is the glow plug relay). If you do not get power to the other side with the key on, the relay is dead.

You can get a good replacement at Napa, part number GPR109... DO NOT ask for a glow plug relay for a powerstroke, the price will go from 30 bucks to over 90...

OK....Thanks CSIPSD....Well, I now know I checked the wrong relay, I checked the one closest to the radiator. I am going out there in a little bit to re-check the GPR again. Should I have power on any of the studs of the GPR with the key off aside from the main power lead, and then what should the volt reading be on the studs should they read the same as the main power lead (12v) or a little less .
I will let you know what I find.

With the key off the only stud that has power should be the big one closest to the passanger side.

You should have the same or close to the same voltage across the GPR when its on. Little tough to throw a number at it, as every truck will have differant voltage in the batterys.


BTW, Welcome to the site!!!

Just went out and re-checked the GPR and this is what I found....with the key off, I have no power on the two smaller studs....with the key on, I have power on ONLY ONE of the smaller studs (the stud closest to the other relay) and the stud closest to the fire wall has no power. That tells me power is not going across the relay correct? or could there be anything else that would cause the relay not to work. I don't know much about diesels so I have to ask.:c::w2:

Just check the big studs... But you should have power with key on to both smaller studs.

Thanks for that diagnoses, It was spot on, and yes I have power to both big studs and only one small stud "with the key on". I will be going out to get that GPR you suggested.:tu:

With the key on and power to both big studs then you are fine, the GPR is working. Time to dig a little deeper...

Well then is it normal to not have power to both small studs with the key on

I dont know, I would have to go test mine.

But if you have power to the drivers side of the GPR (big stud) then your GPR is working.

The small studs are controls,

OK.. That makes seance. I did test the voltage on the drivers side stud and I get 10 volts, I have both my batteries on charge now to see if it makes any diff when I try to start it later.
Is it possible that I am loosing fuel pressure wile the truck sits for a wile??

No, you have an electric fuel pump, when you turn the key on the pump starts and pressurizes the rails. All PSD's will show 0-10psi fuel pressure in the rails no more then 30 seconds after shut down.

You could have a HPO res issue, but I doubt it. Next time you cold start it, before you crank remove one of the small caps on the HPO res and see if there is oil in there. Should be within 3/4" of the top.

Ware do I find the HPO and what does that stand for

HPO is High Pressure Oil... and then HPOR is the High Pressure Oil Reservoir...

Need to work on a post with all the acronyms in it...

Can you describe the best you can on ware to look for this HPOR and what it looks like.

http://inlinethumb28.webshots.com/43...600x600Q85.jpg

Red arrow is pointing to my old autometer oil pressure sender. There is normaly a plug in that port. Remove it and check the oil level of the res...

My personal experience with trucks not startin in the cold, that have good glow plug systems, is worn injectors.

I hate to say it, but especially in the case of the guy from FL, your poppets probably ain't sealing anymore.

I appreciated your advice along with CSIPSD advice that he has been giving me.

What I have done so far, is check the GPR and it checks good, check the HPOR and oil is close to the top, I charged both batteries and they still check good with a load test.

When I try to start this engine (when it's cold) it does start BUT, it cranks and cranks before it fires. After it starts, then it starts just fine for the rest of the day or UNTIL it sits long enough to cool down again. This 2000 truck has less than 6500.00 mi on it, do you still think it's possible to have worn injectors? I have not checked the glow plugs them selves to see if they are ALL working. If you guys can tell me how to go about it checking them I will, if you guys think that they could be the problem. My wait to start light is coming on and going off normally. I am the original owner of this truck , so I know there has NEVER been ANY kind of repair work done to this motor. I did get a recall to have "I think the crank sensor" replaced, and that has not been done yet

6500 miles on a 2000!!! Holly hell!:tu:

I really cant do much more for you without putting hands on it. Pull the valve covers and check the harnesses.

run a few tests with a scanner hooked up. Hard to fix over a forum.:argh:

Yea....I understand, I'm going to try to find someone with a scanner before I go any farther, but, can I test the glow plugs with them still in the engine or do they have to be on my bench to test.

You can test them in the truck... I will have to do some digging to find the test procedure...


http://www.forddoctorsdts.com/public...tInjection.pdf

Down load this link and look at page 72... That whole page walks you thru what a ford tech will do on a hard start complaint.

Thanks for the info on that Ford site VERY GOOD site.

Have you, or anybody else ever heard of using the wrong "grade or weight" of oil in the crank case causing a hard start (when cold) problem, because I did change oil, and for the first time I used a different brand than I usually do. I always used Mobil 1, and this time I changed to Valvoline which claims to be comparable to Mobil 1. After I changed the oil I drove the truck on a 300 mi non stop trip then it was parked for about a week and a half, and now I have the problem of hard start when cold. I can't believe that would make a difference, but I got to ask just to make sure.

Is it Diesel Rated??? Thats the most important thing... I stick with Rotella or Dello for mine... 15-40 dino...