1987 ford F350 6.9 N/a IDI GP issues..

[8v-of-fury]

Can I even ask questions about Ford's here? :lol:

I have looked for a good forum about ford trucks but have had the worst of luck finding anything. The truck in question is a 1987 F-350 with a 6.9 N/a IDI with 695k on the clock.

It's my gf's moms work truck. They have owned it for 8 years and have done nothing to it. And rightfully so it hasn't needed anything, until now. My gf's dad worked on it and kept it going good, but he recently passed on and now its up to me to keep this beast going because one day I hope for it to be mine They don't run it all winter long because they claim it will never start, now this leads me to believe her father in his mechanical wisdom wasn't much of a diesel guy. I checked the resistance at the gp's and i think I got around 5.5, I thought the number was supposed to be like less than 1 or something? Also, I noticed that some of the gp's wires weren't even connected! Not only that but when you turn the key to activate the gp's the light goes off after 3-5 seconds! No wonder this thing could never start in the winter!!! It must still have decent compression to start the way it does..... ? I measured the voltage at the plugs as well and got a steady 8.4V when i got it going for the first time this winter on Friday i hadn't found out about the gp's yet so i just used a battery charger set to 60A so i could crank the engine up to temperature. When i went to go out this morning to try it again (i was at their place for a few days) I thought to myself.. what about jumping the gp's? so i did that while i had my gf crank her, it fired up in about 10 seconds as opposed to Friday's 45-60 seconds. So it does seem that at least 7 of 8 (due to broken wire) are working.

Question being, where is the GP relay on these things? Also why would it only stay on for 3-5 seconds? It was about 5 degrees Celsius out today i would expect at least 10 seconds of gp's to attempt a start on an engine of such size and age.

I think that if I reconnect the broken GP, use Vince's guide to "pimping" to make sure they are getting as close to 12V at each plug, it will run a lot better. I mean they don't drive it in the winter anyway, but having the gp's actually work in the summer I'm sure will help prolong the life of everything.

The weird thing about this thing is, is that it was used before they got it, to haul a fifth wheel to B.C every year! for like 10 years. I am really surprised with how this truck runs.. Once it gets started it runs like a tank.

WOW this is a long post, I hope you liked reading my blabbering :lol:

What do you guys think? some cheap ways to maintain and keep this old girl going for a few more years?

Thanks a lot guys.

Jeremy

[Turbinepowered]

I think but am not certain that the GP relay is under the hood, rather than in the cab. I've only gone digging around under a 6.9s hood once, and it was really narsty-dirty.  :roll:

[8v-of-fury]

yeah, I joined a Ford Diesel Forum.

They are a different breed over there  :shock:  LOL

Thanks guys.

[ranger station]

THAT IS A GOOD OL' MOTOR. NOT TO POWERFUL BY TODAY'S STANDARDS, BUT ALOT OF WHAT WE HAVE TODAY STARTED WITH THE 6.9.
  I HAVE A '87 F250 4X4 6.9 WITH A FARMERS 4SPD, BUT THE MOTOR IS WORN OUT, USES ALOT OF OIL, ALTHOUGH HE STILL STARTS AT -5 CEL.
  THE GLOW PUG TIMER IS BEHIND THE AIR CLEANER UNDER A PLASTIC CAP. NATCH YOU SHOULD CHECK FUSES FIRST AND USE A TEST LIGHT TO SEE IF GLOW PLUGS ARE GETTING POWER.
  AN EASY WAY TO CHECK THE GLOW PLUGS IF YOU DO NOT HAVE A AMP METER IS TO PULL THE WIRES OF EACH ONE, CLIP YOUR TEST LIGHT TO THE POSITIVE ON THE BATTERY AND TOUCH THE PROBE TO THE CONNECTOR ON THE GLOW PLUG. IF THERE IS CONTINUITY THE TEST LIGHT WILL LIGHT. SOMETIMES THE GLOWPLUG CAN BE DAMAGED AND STILL HAVE CONTINUITY, BUT NOT TO OFTEN.
  ENJOY THAT OL' GIRL
DAVE
www.freewebs.com/rangenstation/

[burn_your_money]

Jeremy what forum did you join? I'm getting a F250 with the 6.9 and need to do some learning.

[8v-of-fury]

These guys are awesome Tyler.. you will learn everything you need to know. lol I did. lol

http://www.oilburners.net/forums/index.php

[bajacalal]

Hi, I have fixed those before, the International 6.9 and 7.3 IDIs. Not a great power to weight ratio with that engine but it's still a good engine, they seem to last well even when abused.

I have noticed that if say 2 of the 8 plugs aren't working, they are very hard to start. That engine seems to depend on working glow plugs to start. Even in here in Southern California, during the daytime, in winter they will not start (in less than 30 seconds) if the glow plug system is not working well. People cook the starters on these trucks with too much cranking when it doesn't start. Let the starter cool down a little if it won't start after a 20 second crank. If the glow plug system is fully functional and the truck has a healthy engine and injection system, they start right up.

These engines can have problems with the glow plug wiring. It sounds like this truck has been driven in a moist environment. The early 7.3s with the bullet style connectors are prone to corrosion and breaking. The 6.9 wiring is a little different but the same problem can occur- bad connections at the glow plugs. Carefully check all the connections on the glow plug wiring harness. If there is corrosion or loose connections you are not getting full voltage and you need to repair the connectors or source a new glow plug wiring harness.

I hear some people upgrade the 6.9 glow plug wiring to the later 7.3 IDI (say a 1991 motor for example) plugs, relay and harness which is a bit more sophisticated. The diesel truck message board would probably be a good place to look for this information.

I'm not sure what the specs on the glow plugs are supposed to be without digging out some papers I have but I think this truck used a "fast heat" glowplug system, something like using a 6 volt plug and hitting it with more voltage to heat it up faster.

Hope that helps.
-AL

[8v-of-fury]

actually 87 is the year they had the later 7.3 style GP system.. so i Get the better one stock! lol

I plugged the two back in with Wire MAretts and it was good to go. Very dependant on GP's these engines.. even after being run it will fire the plugs for a good 5 seconds and will start right up.

[bajacalal]

Hmm, I thought 1987 was the year they switched to the 7.3 liter engine when they switched to the new (uglier I think, sorry) body style with the plastic headlights. Did things wind up differently in Canada? Maybe I'm wrong and my memory is year off.

Anyway check all that wiring for corrosion! I have seen them badly corroded here where hardly anything ever rusts.

I'm glad you got it sorted out.

[maxfax]

1988 was oficially the first year for the 7.3 although in 87 they had all the 7.3 like whatnots like the glow plug system as mentioned..  I think that was also when they routed the injector returns to the fuel fulter housing and the return line.. If that '87 is like that 8v-of-fury, eliminate and plug that sucker off, the one return from teh injectors to the return line is sufficient....   Generally it causes no problems, but if/when the return lines ever develop a leak it also allows air into the feed line to the IP.. ANd we all know how they start with air in the system..