Since the rear fuel tank was leaking, I decided to drive on that tank until it was almost out of fuel. I drove on the rear tank for a day and a half then the truck died, because it got air in the fuel system. I figured that the pickup tube must have had a hole in it, so I flipped the fuel tank selector switch to the front tank again and bled the system. I got about five miles and the truck died again! That’s the second time that I ever broke down and had to get towed home in over 30 years of driving! When I got a good look at it, I noticed that the fuel tank repair was not the reason for my fuel leak. The o-rings in the fuel line quick-disconnect at the fuel sender were worn out. I figured that it must have been sucking air from there. I tried to get replacement o-rings, but ended up installing a different line from my parts truck instead. With that replaced, I tried to bleed the fuel system. It wouldn’t bleed! It’s a good thing I was using an electric fuel pump to prime it! I checked the fuel tank selector valve and it wasn’t clicking! It checked out good when it was installed back in April. I turned on the electric fuel pump again and heard sucking noises in the front tank no matter which position the switch was in. The selector valve had failed and I ran the front tank empty after 408 miles. After putting some fuel in the front tank, I was finally able to bleed the fuel system. I left the fuel tank selector switch in the “Front” position and drove to the fuel stop and back without problem (21 miles). The next morning on the way to work the fuel return line popped off after about 10 miles of driving. The return port must have been restricted in the fuel tank selector valve! It was 5:30am on a 25-degree day! I walked to a Wal-Mart down the street and bought two fuel filters. One was for a Windstar (5/16" Fram G8018) and one was for a Chevy (3/8” Fram G7333). Using the Ford quick-disconnect clips and those filters, I bypassed the selector valve. What a mess on the hotel parking lot and me! I still had the priming pump in the truck and was able to get going on the fuel that was in the rear tank. It is going to become a single tank system!
After looking over the front suspension, it appears that the left radius arm bushings are allowing the radius arm to sag. I believe that this is the reason for the 3 extra degrees of caster. Time will tell.
The fuel tank selector valve and the front fuel tank were removed. Manual 6-port selector valves cost too much, so it’s one tank for me from now on. The plan is to replace the rear tank with a 38-gallon unit. Before all this happened, I had been concerned about the rear suspension of the truck because the left side was always ½” to 1” lower than the right side. The rear of the truck is now level. The weight of the fuel was tweaking the suspension to the left. I got some 5/16” & 3/8” nylon fuel line unions (they are made of steel) at NAPA. I hope to make the permanent repair to the fuel lines soon. I’ll be incorporating a section of rubber hose for a future electric fuel pump installation. There was a harmonic drone/vibration from the engine between 60 and 65 mph (the speed I usually drive). After removing the fuel tank selector valve, the drone went away and the truck has more power. I’ve been trying some of that power and it shows with the latest fuel economy figure. I don’t like what I’ve been reading about the K&N-type filters. The air cleaner was exchanged for a Taurus SHO air box. I now use a paper element, but I also have a K&N filter for the air box. It’ll probably be used for horsepower testing in the future. A coworker picked up a Taurus 130-amp 3G alternator for me. It is the same size and shape as the standard-size 60-amp alternator I’m running now. The plan is too install that soon also.
The truck was weighed at a local rock quarry. With about 9 gallons of fuel, about 50 pounds of tools & parts, and no driver, the truck weighed 4995 pounds. I still have to add the air conditioning compressor and the 38-gallon fuel tank (plus fuel), plus some other things. I’m expecting to have a completed weight of about 5300 lbs.
Driving impressions so far. The 105hp 4BT is barely adequate for accelerating into heavy 60-mph traffic from a side street with a 1/8-mile opening. In the first two gears, the truck slowly revs more than it pulls. Once into third gear the truck pulls pretty well. The transmission spacing is just about perfect. I believe it needs a sixth gear (about 20% reduction) for cruising at speeds higher than 60 mph on terrain that is level and up to about 2% grade. The engine has enough torque as long as there isn’t a heavy headwind. That is why a double-overdrive system would probably work best. The gearing would be about 14.0:1 in first gear and about 0.60:1 in sixth gear with 3.54:1 rear end gears.
The fuel lines that came with the truck (6.9L diesel-powered) were 3/8-inch OD nylon for the supply line and 5/16-inch OD nylon for the return line. The unions to join the lines (where the fuel transfer valve was) have an ID of 1/4-inch for the supply line. This is the same as a 5/16-inch OD steel fuel line. I’m wondering if I should upgrade the supply line to 1/2-inch nylon.
The “temporary” 35-micron Fram G7333 filter started plugging up after 2,500 miles. I had it in the supply line where the old fuel tank selector valve was and I was hoping to repair the fuel line (and install a 38-gallon fuel tank) when the weather warmed up. When the fuel was cold (about 25 degrees) the partially plugged fuel filter would not allow the lift pump to supply enough fuel. The engine was hard starting and after driving less than a mile it would shut down as if it had run out of fuel. After priming the fuel system, it would start right up. Even though it was still cold outside, it was time to remedy this problem. I decided to use the stock Ford nylon fuel line wherever possible. The rear fuel line was cut back to the raised humps closest to the quick-disconnect. Because the front fuel line had two sections of steel line, it was replaced with a nylon fuel line from a 351W-powered F350. The front fuel line was then cut back on both ends to the raised humps. Fuel injection rubber hose now joins the two sections of nylon fuel line. Up front more fuel injection rubber hose joins the front nylon fuel line to the lift pump. The engine has run great since repairing the fuel supply line, however a fuel drip has developed near the rotary head of the injection pump. The fuel mileage is around 27.5 mpg even with the leak. Contrary to what I believed at first, accelerating fast or slow doesn't seem to affect fuel mileage much.
I'm glad you asked. I cut the old filter apart to check it out today. It had a red silt in it. There is a lot of red clay around here, so maybe one of my fuel stops had a dirty storage tank. The truck's fuel tank was cleaned out at the beginning of the swap.
I've swapped to a 1993/1994 F150 front clip and front doors. The doors have the smaller mirrors. I installed the front bumper today. The last two fill-ups were with the new clip and doors, but without the front bumper. The truck got over 29 mpg on both tankfuls! I don't know if it is because a change in fuel quality (from the same fuel stop) or because of a change in aerodynamics. This great fuel economy is happening in spite of the injection pump having a leak (drips between the pump body and the rotary head).
haha! When I had the newer doors (and smaller mirrors) on the truck with the old 1985 front clip, I contemplated stopping right there. It looked good! Obviously, I went ahead with the swap anyhow. With that kind of mpg increase, I guess it was worth it. I wonder if there will be another increase with the front bumper & 4" chin spoiler on?
Thank you. Our financial situation and the direction that our economy is going gives me the incentive to press on. There would have been easier ways of doing this, but the sacrifice would have come from our children instead of me.
I've been gone on vacation, had medical issues to deal with and I've been too busy to spend quality time on the forum or on the truck. I'm now in the process of working out some braking issues. The truck was put on the road as cheaply as was feasible. That proved to me (after 8k miles) whether it was worth pursuing the project to completion. It will be back on the road shortly, but it is in need of a little more TLC until then.
I am going to do almost the exact same swap, except with a zf 5 speed(hopefully) and an extended cab, not crew cab. Are there any other probloms you faced with the installation(not the truck), that you didnt mention? Any other clearance or fabrication probloms?