1985 F250 Deisel fuel problems

I bought a 85 ford 250 4x4 diesel, automatic, last week. I drove it home, and was feeling pretty good about it, because it ran well, shifted well, and handled good. The next morning it wouldn't start, but cranked over ok. Now here comes the confession! I have never owned or worked on anything Diesel, and don't know diddly squat, about them. It seems to be getting air in the filter when it sits, and has no fuel getting thru. I put a pump on, thinking that it was bad, but it still gets air in the filter, and won't start unless, I give it a shot of starter fluid. then it runs well except some surging . Shut it off, and next time it wont start. I think it is the 6.9 engine, but am not even sure about that! Without the owners manual, how do you tell? Any one feel like helping out the ignorant?

A few tips from a guy that's worked with these beasts since they were new...

ANY tiny pinholes rusted into the steel fuel lines from that tank(s) will let air in at shutdown

There's a water separator ahead of the firewall in the fender area on the driver's side that commonly fails an lets air in at the water dump port.

Also, the plastic return fittings at each injector can crack, or the "O" rings that seal them can get hard and brittle, also letting air into the system after shutdown.

(Plus quite a number of other things.)

Had an 84 with a kind of the same problem,first when you shut it off,have it parked (nose) downhill.Fuel drain out of the injector pump.Next check the water seperator,maybe leaking or sucking air.tank selector may be faulty.I put an inline electric pump on mine,worked good untill the ijection pump went at 420,000.How many miles on the pump that's in it now?
jim

wow surprised it still runs , i haven't seen a old 6.9 for years.

rattle rattle rattle

You have an air intrusion problem which is very common on these trucks.
Here"s a web site that will answer any question you have about it.

www.ford-trucks.com

Then scroll down to the 6.9 & 7.3L IDI Pre-Powerstroke forum.

Ford diesels in 85 were known for getting air-leaks in the little Schrader valve by the filters (looks like a tire air valve). Causes the system to get air-bound when parked for awhile.

GM 6.2s had a similar problem caused by a leaking check-valve in the retrurn line.

A leak in the rubber fuel return hoses on a 6.9 can do the same. Allows fuel to flow backwards.

I just hsd the same happen to my 85 F250 with a 6.9 but mine had all new hoses on it. The new hoses were absoolute junk and went bad in less then a year. I ordered some Viton hoses and now it's fine.

May also want to get a voltmeter out and check each glowplug's resistance. Bet a few of those are out also.

Agree with the rest, you got a air leak somewhere in the supply.

6.9 is a very solid engine.

Another good diesel site is www.dieselstop.com

John

I don't know if the 6.9 filter is the same as the 88 to 92 7.3,but Wix filters are bad bad and bad again about leaking down while setting.Put a Motorcraft or Fleet filter in and try that first and if that doesn't help then look into what else has been said.

Leonard, I have a 86 Ford..

Drove it for 2 years with the 6.9, now it's repowered with a newer 7.3.

The 6.9 shouldn't use the same fuel filter as the 7.3, at least mine didn't.

I never had a leakdown issue such as yours, but, when I bought the truck it had a leak on the return lines, and on the lines on the injection pump. I believe your feed line from fuel filter to inj. pump have rubber "seals" on them.. that was another of my leaks.. And I had one loose injector line.

The return line kit was something like $50 from NAPA.. and I opted to spend quite a bit of money for the socket that you can use to tighten the lines on the injector pump while it's still on the engine (as opposed to removing the assembly)

Another thing I did was I installed a "spin on" filter base and a water separator filter, as someone had removed the factory water trap and replaced it with a sediment bulb from a tractor!!

I need to get down to the shop, but when I'm there I'll try to remember to look, I think I have some of the 6.9 fuel filters still on the shelf, and I don't see me using them anymore, so if you'd like em, I could toss em in a box and send em to you.. I know they're NAPA filters.

Brad

Since i can't edit my post I guess I need to learn to read.. I meant Ralph, not Leonard..

Losing my mind, and WAY TOO YOUNG for that!!!!

Sorry
Brad

I've still got my 85 6.9 F250. Use it all the time for a daily driver,haul the livestock trailer to the stockyard,etc.

Thanks Guys! It looks like I have got a lot of search and destroy, ahead of me! I waited till noon today, to allow as many posts as possible, to happen, now I need to use the knowledge you guys supplied. Thanks again, and here goes nothing! Ralph

I still have my 88 7.3
Folks are right with the schrader valve going bad and the return lines leaking air, but the sympton for air intrusion is it will start right up when cold then "run out of fuel"

Are you having a hard start when cold? Mine starts like the day it was new. To make that happen you need a few things to be right.
1) Batteries strong and fresh
2) Battery cables not all corroded
3) ALL the glow plugs working
4) A good starter!

I've spent a lot of time on mine, figuring out the starter was bad was the hardest since it would still seem to crank over just fine, just I did not know it was not cranking fast enough. Put a new starter in and wow!

Wayne