Working on a 1989 Ford F-150, 300 six, five speed. Wow! bad gas.

[Henry W]

An elder couple gave me an 1989 Ford F-150. It's a long bed, two wheel drive with the 300 six and 5 speed. The truck had 68,000 original miles. The engine and all the fluids were kept up when they used it. The front tank was only used and I was told the rear tank has not been used in years. Well I decided to remove the filler cap and the odor took over the whole area. You could smell it over a 100 feet away. I took a scope and I never gas so bad. It looked like brown stain with chocolate chips in it. The smell was so bad that I had to wear a carbon filtered mask while removing the complete fuel system from the selector valve back. Did anyone else run into a situation like this?

[sailawayrb]

I had that model beast for many years.  I would cycle pulling from each tank every time I fueled up.  Never had the issue you described, but suspect something happened that prevented the bad tank from getting used (switch or valve)and things deteriorated badly from there.  It was a great truck in the day.

[playdiesel]

Yes, been there several times.  As I remember when the switch or valve goes bad in Fords of that era it defaults to the front tank. There is a solvent that works pretty good to clean out the old fuel varnish but it has been too long,, I think MEK??, maybe Naptha??

[Henry W]

I had that model beast for many years.  I would cycle pulling from each tank every time I fueled up.  Never had the issue you described, but suspect something happened that prevented the bad tank from getting used (switch or valve)and things deteriorated badly from there.  It was a great truck in the day.

They were a great truck in the day.
I think the issue started by the rear fuel pump going out. The switching valve on the fuel reservoir is operated by in the tank fuel pumps. What ever tank is selected by the switch in the cab the pump in the selected tank pressurizes the diaphragm in the selector valve and routes the fuel to the high pressure pump. When the rear pump gave out the couple drove it for years with the unused fuel in the tank. I just pick up a new tank, tank vent valve, complete pump and fuel sending unit assembly and single tank fuel reservoir. I decided to delete one tank. The mid tank started to show signs of rusting inside so I decided to get rid of it. I do like the room around the driveshaft If I need to install new u-joints it will be much simpler. But, what I am thinking is installing a plastic mid tank for diesel to run the RV generator. I think the rear tank is 17 gallons and that's fine for my needs. The fuel switching valve assembly was priced at almost $400.00. The single tank reservoir is only $56.00 delivered. Cost of all parts to get the truck running was under $300.00. The price to replace everything would of been approx $900.00.

[Henry W]

Yes, been there several times.  As I remember when the switch or valve goes bad in Fords of that era it defaults to the front tank. There is a solvent that works pretty good to clean out the old fuel varnish but it has been too long,, I think MEK??, maybe Naptha??

Yes the dual tank setup is known to have problems if tanks are not switched regularly. The tanks and pumps were to far gone to save. The best thing is complete replacement.

[LowGear]

I'm curious about just not gluing the cap on the bad tank?

[Henry W]

Hi LowGear, just finished taking off that was bad and than replace the rear tank with a new one. If everything work out good with the truck I am thinking of buying a mid mount plastic tank for the diesel RV genset. The truck should be ready to test run tomorrow. Hoping for the best.

Henry W

[Henry W]

The tank and pump assembly is in! Waiting for the new fuel reservoir to arrive tomorrow.

Henry

[LowGear]

I can almost feel your excitement. 

But my question was to the general population as the bad tank syndrome doesn't seem to be yours alone.  Why not just close the bad tank off and watch the gas gauge a bit more respectively?.

[sailawayrb]

Having those usable two tanks allowed for greatly extended driving range which was highly desirable when doing cross country trips, etc.  Plus, it was always cool to see your fuel gauge approaching Empty, just flip the tank selector switch and watch the fuel gauge then go to Full...

[Henry W]

Got it running. It ran very rough for about 5 minutes and than it smoothed out and ran like it should. I do have an issue and hoping I could get some heap to figure out what's wrong. The engine starts up and runs fine when it's cold. When it's at operating temperature and it's turned off than you try to start it up the engine just cranks over and will not fire. When it sits for about 30 minutes it starts up fine. Any ideas, what could be wrong?

Henry W

[LowGear]

Coil or condenser?

Air / vapor lock in the fuel line?

[sailawayrb]

Dirty fuel injection system?  Check/clean plugs?

[Henry W]

LowGear and sailawayrb, thanks for the input. I appreciate the time that both of you spent with diagnostics. Did some tests and found that the voltage was fluctuating badly. It turns out it was a loose ground on the frame.
Just dropped the oil and filter. Where the filter screws on to the block the casting has no discoloration or sludge. This engine was taken care of. Soon as the rain stops the oil change will be completed.

Henry W

[LowGear]

Do you use the copper infused grease on larger electrical connections to slow corrosion?