Hi Ford Trucks forum.

This is the first post I have done on this forum but I have been reading posts for some time now. I bought a 1999 Ford F-350 with the 7.3 L powerstroke with about 300k on the clock about a year ago. It has the zf6 and is basically stock. The guy I bought it from sold it to me pretty cheap($2400) so i suspected that their are a few things wrong with it. I have been driving it to work tho so its not in too bad of shape.

Here are my questions. It will start now that it has warmed up but would not start without starter fluid in the winter(like anything below 40F). The glow plugs do not come on one their own so i have ran a manual switch. Having the manual switch in the winter helped but sometimes it still needed the starter fluid. I know that it's bad to use starter fluid but I figured that as long as I didn't run the glow plugs my chances are good to not hurt the motor. i did it everyday for almost 6 months and didn't notice anything. Anywho, the truck seems to run well once the EOT comes up to about 150 F or so. I have forscan running on a windows 10 tablet so i can read most of the basic sensors. From what i gather the EOT seems to be fine. It gets a little hot( maybe 210F) but seems to stabilize so I don't think there is any issues there. I am leaning towards needing a set of injectors. As per advice from my brother in law who has some experience working on these trucks he said I should start with a LPOP. I put in a melling LPOP and that helped but did not solve the cold start rough while cold issue.

Before I decide to toss injectors at this truck or rebuild them I wanted to make sure I wasn't missing something. I get erroneous numbers on the engine coolant temperature sensors that I read off of my forscan. I have looked into this and my truck since it is a manual it should have 2 ECT sensors. The one on the dash is now working but i have looked at all of the spots that the second sensor it supposed to be and can not find it. Today I went out and pulled the main harness to check pin number 18 and there is not terminal there on either side of the connector. I snapped a pic and will post it as soon as i figure out how. This leads me to believe that this at some point this truck has had a new motor put in and that new motor was an auto. The people that put the new motor in must have just switched over the main harness/PCM. I will go out next chance I get and pull the info off the PCM to see if that is for an auto as well. The question I have is, could having some sort of Frankenstein set up in this truck cause is to run rough while cold and run fine while hot? I have also looked on this forum and read about HPOP parameters as well as IPR parameters and the high pressures and duty cycle percentages while driving the truck seem to be fine. Even while running rough as far as I remember. Sorry for the long post but I am very interested in hearing what your thoughts are on this truck. Thanks. I am working on a budget so I plan to do a rebuild injector kit follow the info that is posted on this forum and take my chances instead of purchasing a new set. Also, I was a mechanic some years ago and so I have some basic tools including a power probe III/DVOM to test sensors etc.

-Paul

 

Before doing anything else swap/upgrade GP relay and change new Motorcraft/Beru GPs.
Batteries and starter needs to be in shape.
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7.3 is dependant on GPs in COLD weather.
If all is good,it will start from -30celsius with one 120s GP cycle..

I have also manual GPs and indicator LED.
My PCM decided to not provide ground to GPs..

 

Guys from Finland know about starting cold, I'd go with his advice.

And no more starter fluid once the GP system is working.

Don't do anything about injectors yet, lots of diagnostic ground to cover first. Quite possibly a working GP system will solve the issue.

 

Avoiding the use of ether cannot be stressed enough. These engines are tough but they have their limits. Mine felt fine until I blew a hole in piston #3.

As for the missing ECT sensor, it is possible that your truck was an auto that had a ZF6 swapped into it. What is the code on your PCM?

Please spray out both sides of that 42-pin connector with contact cleaner. That looks nasty grimy and that female contact at the lower right corner looks corroded.

There are too many possibilities at this point to answer your question directly. Let's get her back to nominal then we can start troubleshooting.

 

Not all 6spds have (2) ECT sensors. Your truck would not run good with an auto PCM - that is not the case. The scan tools typically do not monitor ECT. This PID is not monitored by PCM and the sensor reports directly to the ‘gauge’ on dash. The PCM does not use ECT, so this is not your problem.

Bad GP relay or GP’s are most likely cause of poor cold start. If those parts are good - you’ll need injectors. Shimming/DIY reseal is a bandaid for injector wear and can buy some time for some people. Rebuilt injectors are $1300 for stock or (upgraded) Stage 1 single shots.

LPOP does not produce those symptoms...

Starting fluid is Russian Roulette and it has little to do with GP’s. Your chances of destroying your otherwise good engine are HIGH. Broken pistons, broken rings, etc are COMMON with ether engines. Your luck is STRONG, I recommend you buy lottery tickets....

The reason is in a Diesel engine - the timing is controlled by the fuel injection event. When you put a flammable vapor in the air intake, you have no control of the ignition event(s). This can allow very eary combustion while a piston is being driven UP (by other pistons that that have fired). This is akin to smacking the top of the piston with a sledge hammer. People get away with this, but a lot of people have destroyed perfectly good engines that needed <$100 worth of parts (GP’s and relay).

 

I have plans to work to figure out why the GP's are not coming on automatically but the relay works well. My manual switch is just tapped into the PCM wire that's supposed to ground the relay and that has been working well so far. I ran a quick continuity test on the GP's and all but one work. I do plan to replace those as soon as possible as well as track down why the PCM does not ground my GP relay. The GP relay looks semi-new so it doesn't seem like replacing it with another one will help here. At least while I diagnose it. It looks like a cheap one so I will keep that in mind. Id rather pay a little more for things that work properly. At least for the most part until my wallet runs dry.

The issue I want to attack first is the rough driving issue. I will let the truck idle for 5 minutes before I take off for work and I will get 10 minutes down the road on mostly 55 mph roads before it fully warms up and smooths out. I feel that feeling that has been mentioned on here before I think where you can kinda feel each injector 'come on' as it warms up so to speak. I wouldn't think the GP's or GP relay has anything to do with this issue so I am hoping to fix that issue and then see how its starts and go from there on the cold start problem. And that's if the cold start issue doesn't go away after the rough driving issue is fixed.

So my truck is an early '99. I am not sure if that changes anything but thought id mention it. Does the second ECT sensor do anything for the PCM at all? If I look at the second ECT sensor data, it is all over the place. My main concern here is: could that second ECT sensor effect driveability at all or is that simply another way to display coolant temperature. And if not then I do not see how this driveability issue could be anything but worn injectors since everything else seems to be fine once the truck is at operating temp but I am quite new to these trucks so maybe I am missing something. If the PCM doesn't even use the data for the second ECT sensor then it seems like I shouldn't worry about it since I have EOT and the sensor on the dash to monitor temps. Right? I do not plan to do a ton of towing with this truck. At least for now. This is mostly a toy for hauling around small trailers and some overlanding and will also double as my daily unless I can convince the misses to let me keep my 6 cyl Mustang as a back up daily. Thanks again for all of your feedback. I appreciate your quick responses.

-Paul

 

Hard start and rough running when cold are common symptoms of tired injectors. Some have had success fixing this by resealing and shimming the injectors - aka DIY rebuild. But, the long term solution is full rebuild (machine work, etc) or new Alliant injectors.

If (7) GP’s are good and GP relay is working, you would likely not notice a difference in cold weather starting.

 

Also upgrading GP relay is a good thing to do.
Stock relay is undersized for the GPs drawing current.

Heres few examples:



^^^^I personally use this Trombetta style relay..^^^^

 

Another option is synthetic oil. If you are running dino and the injectors work better on synthetic it tells you they need shimming/rebuild.

 

No. You have a 1999. Ford didn't put in the ECT that you are looking for until 2001, for the 2002 model year, when the manual ZF 6 speed equipped HP rating was bumped up to 275 HP.

Doubtful.

Bingo.

It does, insofar as Early 99, Mid 99, Late 99, 99.5, 2000, and most 2001 models did not have the ECT that you are looking for. It was added to manual transmission trucks in 2001, and one way to tell is to look at the emissions label on the valve cover. If it says 275 HP, then it has the ECT that you are looking for. If it says 235 HP or 250 HP, then it does not.

 

Keeping ECT in the loop and information accessible through various paths, I have added the link below.

https://www.ford-trucks.com/forums/1...l#post19102855