help 85 6.9 van i may buy - Diesel Forum

BlackSmoke96 · 11-17-2009, 03:29 PM

Hi all !!! I am interested in a old van for sale for cheap but it does not run the guy knows nothing about the van or what may be wrong with it not even sure its a 6.9 or 7.3 ?? strange, all he told me is that he has been running veg oil in it for about 2 months but the guy said that he had used a tank of oil mixed with water and then the van stopped running,he cleaned the tank and put a new "fuel pump" on it and still no fire I have not seen the van yet but i will assume that it may be a 6.9 and any info for me to look for like were to check for fuel press would be great thanks Jim

Scoobywagon · 11-17-2009, 03:53 PM

1985 is certainly going to be a 6.9 unless someone has done a swap. If that's the case, then all bets are off until you go look at it.

You're likely to have to check fuel pressure from inside the cabin. Pull the dog house and, again I'm guessing here, you're probably going to have to fish around for the fuel filter. But there's a schrader valve there to check fuel pressure. That'll be low side pressure, of course. You should see about 4-5 lbs there when cranking. Fuel pressure guage also makes for a really easy way to purge any air from the fuel line.

Also, make sure to drain the fuel/water separator. Unless its been removed or relocated, it should be under the van on the left hand frame rail. If this person was dumb enough to run oil and water through it, he probably couldn't figure out the drain, either.

BlackSmoke96 · 11-18-2009, 10:05 AM

Hey thanks, I dont know much about Fords with IDI engines in them, I do know that the IDI's run injection pumps for the injectors but is there a lift pump to fuel the injection pump? is there a in tank pump as well? Just wondering what would have burned up from the water in fuel this guy ran.I cant see the injectors in this eng going bad from a little water and anyways there are cheap to replace it seems,the injection pump is a little expensive I think and if there's a way to see if thats what needs replacing/rebuilding im not sure I can afford to buy and then repair this van so I dont know, i am kinda in the air about this one.

Scoobywagon · 11-18-2009, 11:33 AM

The injection pump is sufficiently expensive that I'd probably look at everything around it first. I don't really see a particularly good way for the injection pump to get eaten with a little water in the fuel. Unless, of course, there is also air in there in which case I could see the innards of the injection pump corroding. That would be bad.

Yes, there is a lift pump. Its just a crank-driven mechanical fuel pump on the block. To check its operation, all you need is a fuel pressure guage. Attach that on the scharder valve at the fuel filter and crank the engine. You should get about 5lbs of fuel pressure while cranking. So far as I can tell, there is no fuel pump in the tanks. I could be wrong on that one, though.

How much does this guy want for the van? If its cheap (like $500 or so), I'd go ahead and buy it. Drop both tanks to drain and clean them. Purge the fuel lines with petro diesel. Drain the fuel/water separator. replace the fuel filter. Replace the fuel return lines, injector caps, etc. Purge air from the system. Then I'll bet you it fires right up.

BlackSmoke96 · 11-18-2009, 05:54 PM

For sure, the guys moveing and cant bring it with him but dude wants $800 for it, I would like to wave 4 or 5 in his face and see if he takes it,if he's smart I will have me a diesel ford van !!

So i can check FP at fuel fillter,then its like a 7.3 PSD my truck had a bad pump and would fill the bowl with fuel but would not build sufficent fuel press, man was that a pain in the rear...that freaking bolt !!
Thanks for the help.

Scoobywagon · 11-18-2009, 08:07 PM

Absolutely. Let us know what happens. I know I'll be interested in the outcome.