I have a 1985 F-250 2wd with the 6.9l idi diesel engine. I have been running it for a year off of the front tank and want to begin using the aft tank so I put in some fuel and hit the switch, nothing happened the first couple of times but then one morning I had it in the aft position and the engine sputtered and died, then started right up after switching back to the front tank. Also, when I switch to the aft tank the fuel guage reads empty.

As I trouble shoot this, I want to have a diagram and working knowledge of what is happening in the tanks.

Does anyone have a diagram of the fuel flow?

Are there pumps in the tanks?

Any help greatly appreciated.

1985 F250, dual tank, Lariat XLT, 6.9 liter International Harvester engine, starts first time every time

 

Not sure about the gauges but fuel lines go from each tank to the fuel selector valve (left framerail, 6 ports in total) then to the fuel water seperator then to the lift pump on the right side of the engine then up to the fuel filter and to the IP. From there to the injectors where the return lines start which go back to the selector valve then one return line to each tank.

Long story short no fuel pumps in the tanks, each tank has 2 lines that go to a selector valve then from there 2 lines to the front.

Far as the sputter then dieing sure you wernt just low on fuel? What happens a lot is inside the tank the fuel pickup will have the end break off so at 1/4 tank you cant pick up any more fuel.

 

Good info, thanks a lot!

 

Here you go,

 

Thanks dtgl90vt, all printed up and ready to roll around on the ground lol...and great avatar!!

 

Glad to help, I haven't even had a chance to use the EVTM yet, I just got it the other day. I actually have a similar problem as you with the fuel selector, from what I read they can be a pain, and expensive too.

Good Luck
Devin

PS don't forget to hit up my reputation


EVTM = Electrical & Vacuum Troubleshooting Manual

 

looks like I have a 6 port valve...I am going to have to do some homework here. Thanks again and I will be looking for any additional help. What book are you referencing?
Jonathan

 

1985 EVTM (Electrical & Vacuum Troubleshooting manual)
RockAuto Parts Catalog
Ford>1985>6.9l>Literature>Repair Manual>
BISHKO Part # 7088
1985 FORD BRONCO, F 100-F 350, PICKUP Electrical/Vacuum Troubleshooting Shop Manual

Order one $7.35 plus shipping

Also while your at it

Order your Ford Light Truck Manuals:
Engine
Body Chassis & Electrical
1985 Ford Truck Service Shop Manual Set F 150 F 250 F 350 Bronco Gas Diesel | eBay

Alittle bit more but worth having it when you need it.

And last but not least,

Order a parts catalog
1980-89 Ford 100-500 Series Truck Master Parts Catalog CD - HiPo Parts Garage

Just got mine last night

Enjoy,
Devin

 

Well I thought I had a section in my favorites about fuel selector valves but I guess I don't

But one thing I remember reading is that these valves oem are expensive if you can find them or something that is made to replace them. But I do remember possibly Ctubutis bringing up in a thread I was searching that there is a universal that someone did a write up on and how to make it work with our trucks.

I forget if I did the search here or in the 80-86 forum, but I would imaging the 80-86 forum, cause I think he is a gasser

Enjoy & Goodluck,

Devin

 

This is what I used as the original was not working:

Pollak 6 Port Fuel Valve

Works well fits within the chassis rail (just) and stays where selected when powered down.

You should be able to find a supplier in the US as that's where they are made.

Cheers
Ross

 

Did you have to modify yours Ross?

You reminded me what to search for to find the old thread, it was pollak valve


This has info about installing the valve>>
https://www.ford-trucks.com/forums/1...r-problem.html

https://www.ford-trucks.com/forums/1...-gas-tank.html


https://www.ford-trucks.com/forums/1...ve-wiring.html



Those are all good threads

but I hope you don't mind cause I need to hijack your thread

After reading, there is reference too there being pumps in the individual tanks? I believe the 6.9l is a mechanical pump up under the hood, rather the only thing in the tanks are Fuel Gage Senders which is the float that lets the gage know how much fuel is in the tank, not an actual pump. Correct?

Can someone please confirm this for me?

 

Both the 6.9L and 7.3L IDIs have mechanical fuel pumps on the engine and just senders and fuel pickups in the tanks, all gassers and the newer diesels have in tank pumps though.

 

Not all gassers have in tank pumps.

I can only speak for Australian delivered trucks, but unless it is a fuel injected engine they do not have in tank pumps and are the same as the diesels with a mechanical pump on the engine.

Cheers
Ross

 

No mods to valve.

Just needed to wire up as the other threads show.

I put in new flex hoses from the hardlines to the valve.

The mounting holes are in a different location so you would have to either drill new holes in the chassis or make up mounting bracket.

I made a new bracket which also holds two filters (one for each tank) before the valve.

I'll have a picture of the bracket later this week in my rebuild thread.

Cheers
Ross

 

Would love to see the bracket and the filters

Sounds like a sweet setup

Devin