1986 f250 6.9L turns over, no start

[EmjayLion]

Bought the truck a while ago, been trying to fix it before my farming season started, but now it's upon me and I'm in need some fast advice.

The guy who sold it to me said it died with a cloud of grey smoke, loss of power, and then it limped off onto the side of the road,. After, it started up, then he got it to my friend's place, and it hasn't started since. It sat for a year, then I bought it. This was a vehicle run on a mix of biodiesel and chem diesel.

What have I done/replaced/tested?

FUEL
-poured new fuel into tank to top it up in case of pickup tube break
-I thought injectors, got them tested, they were bunk, so I replaced them
-replaced return line kit
-Fuel is getting to the injectors when I crack the lines and crank
-fuel vapors noted in the intake hole when I crank - Ive also removed a few glow plugs and seen fuel vapors to confirm fuel is getting to at least a few cylinders
-bypassed water seperator on firewall because it looked old and leaky as hell
-pulled off the fuel filter and it was full, looked new,a few black specks noticed in the fuel
-FSS works
Q: once I prime the fuel system, no air should theoretically be able to get in, yes?

GPS & electrical
-batteries I've kept on a trickle charge, they're older but still charge fully
-The GP controller was cycling weird so I bypassed it, push button switch style
-GPs are getting 11V (at connectors) through harness when I push the button
-GPs are all checking out at proper ohms
-replaced the three GPs that were dead
-1 negative battery clamp started to melt on me with all the cranking I've been doing, so I replaced the clamp
-can't tell if glow plugs are getting warm with my manual switch, should they be hot to the touch at the nut that connects to the cylinder?
Q: can I pull a glow plug out and push my button and watch it get red hot? How can I measure amps at glow plugs to determine power? Votls is one thing, amps another

I'm not even getting a cough when I turn it over. Im tempted to use my factory heating block and ether to get it started even once, but that won't solve my problem long term or help me troubleshoot.

 

[hoodshauler]

Welcome to the sight to get a quicker responce ask all this in the 6.9 & 7.3 forum. There you will get a lot of help

 

[steelheadguy]

If the block heater works then it will probably be your glow plugs. If your questioning them, I would try it.

If the return line kit isnt perfect, that could be a problem. Replace all plastic tees and orings as well as hoses.

There is way more to check but thats a start until someone else chimes in.

 

[bbjordan]

Are you getting white smoke out the tail pipe when cranking it? No white smoke, no start.

It has to turn over fast enough, or it won't start. As fast as the engine in this video:

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The stock 1986 6.9L had the old round style glow plug controller at the back of the engine on the drivers side, IIRC. These old style controllers are prone to failure, and when they do, they will fry your glow plugs. I see you said you bypassed it with a manual system. That's common. I did that too.

If you are getting white smoke, you may want to save your batteries and use ether instead of glow plugs for the first start.

I've had both good and bad experiences with running biodiesel. Biodiesel or FAME (Fatty Acid Methyl Ester) will polymerize over time when exposed to oxygen and with an iron catalyst, more commonly called the fuel tank. Since that bio-fuel is old, I would drain the tank and inspect the inside for red goop.

It would probably be best to have the lift pump just draw from a jug of fresh diesel. That will eliminate a lot of points of fail. After you get it started, then you can try the old fuel/system again.

 

[icanfixall]

WElcome to this forum. As already posted.. you need a FAST cranking engine to start. Heres why. Our engine is a diesel compression ignition engine. this means we make high compression and this makes the air very hot during the compression stroke. Diesel needs 942 degrees to ignite. This is why we use glow plugs on cold engines. In the vid you see the exhaust smoke telling you several cylinders are not making enough heat to fire off the diesel in them. A SLOW CRANKING ENGINE will never start. So if this forum knew how fast your engine is cranking we could rule out a slow crank. My guess based on your comments of a melted battery cale connection tells me your cranking for too long a time and may have ruined the starter. So please show a vid of the engine cranking before I suggest replacing the starter. Nobody here is going to suggest throwing parts at this till it finally runs. This forum has several members located in BC also.