I'm NOT getting tanked!

It's tough being a bit of a perfectionist, especially when working on a car that is forty years old.  This project started off fairly innocently: I took the Z for a drive with Honk, Rattle and Roll over the weekend of June 14th.  

It was really hot that day and I had several episodes where the car didn't want to start when the key was turned (an issue that might be solved now and will be described in an upcoming post).  I also noticed that throughout the day the fuel pump began getting louder and louder.  When I had purchased the car, the previous owner had told me that he had the fuel pump replaced as well as the fuel lines cleaned and the fuel tank boiled and sealed.  The external fuel pump was aftermarket and didn't fit very well into the mount; it looked jury-rigged.  I figured the pump was cheap and failing, so I ordered a new unit from ZCarDepot along with an inline fuel filter and a new, modernized ignition relay (for the aforementioned starting issue).  I also obtained some stainless fuel injection clamps from Amazon.com.

When I started to remove the fuel lines from the tank, I noticed that the nipples on the tank were different sizes.  This made me realize that one of those lines was dedicated for pickup and one for return (being a fuel injected car, the fuel is actually circulated through the fuel rail and returned to the tank).  Upon looking in the manual to determine which line was pickup and which was return, I discovered that my lines had been connected backwards when the fuel pump was installed.  A-ha!  This explains why the car momentarily lost power a few months ago when the tank was around 1/4 full and I was rounding a corner.  

At this point my mind immediately began to ponder if this had been done intentionally.  But why?  I pulled the return line and began draining the fuel.  

After the fuel had drained from the return line I pulled the pickup line.  At this point I decided to conduct an experiment: I placed the in-line filter on the end of a long hose and placed the end into a receptacle.  I then poured fuel back into the tank to see if the pickup line would flow freely.

The fuel flowed, but not as freely as I would have expected.  Once the fuel had stopped flowing, I wanted to see if there was any restriction in the lines.  I first blew into the pickup line; this line had some restriction and took more force that I felt appropriate.  Next I blew through the return line; this line was much easier to blow through.  When I pulled my mouth away from the rubber hose I was met with a surprise... fuel in my face!  The short puff into the tank had built enough pressure to force some fuel back into the return line!

I decided to ponder this situation while removing the rest of the fuel delivery system.  I pulled the hose between the pump and dampener and discovered my next surprise: there was no nipple on the pressure side of the pump and the hose was simply clamped over pipe threads!  Wow...  I'm feeling better about my decision to purchase the OEM pump.

  

The fuel pump bracket wasn't hard to remove, although the top bolt wasn't the easiest to reach.  Removing this bracket brought the pump and dampener with it.

I removed everything from the bracket and prepped for painting.  The fuel pump mount is isolated by engine-mount-like rubber blocks to reduce in-cabin noise.  Instead of painting this with Rustoleum like the rest of the brackets, I used Plasti-Dip to cover this piece so that the rubber blocks wouldn't be damaged and the paint simply flake off.  I also added an additional rubber pad behind the mounting block to provide a bit more sound dampening.

The other pieces were stripped and painted.

I reassembled using stainless hex-cap bolts instead of the corroded originals along with the stainless injection hose clamps instead of the worm-gear clamps that had previously been used.  The new pump is now ready for re-installation once I decide what to do with the tank problem.

After pondering my tank situation along with some research, I decided that it was important to use the intended pickup line as it has a baffle around it and thus would prevent that surge situation when the tank approached empty.  It also occurred to me that my rich condition and high-idle issue might be caused by this setup as a restricted return line might cause higher-than-normal line pressure (I hadn't measured fuel line pressure yet).

The tank wasn't too hard to remove.  I used my transmission jack to stabilize the tank while I removed the straps. Once the straps were undone I dropped it a bit and removed the filler neck and vent hoses from the side and top respectively.  I was then able to finagle the tank out.

Based on research the clogged fuel pickup wasn't uncommon.  Many reported that they cut an access hole above the pickup line and cut-out the fuel screen.  This seemed logical but undesirable as sealing that access hole would be difficult.  I used my remote camera to peer into the tank.

Things didn't look too bad; surely I could do something without cutting open the tank.  I removed all fuel from the tank then used a 12v brushless fan blowing into the filler neck overnight to dry out the tank.

My conundrum is how to clean out the blocked pickup without damaging the SteelKote lining that had been applied (it looked really good inside the tank).  I first blew some compressed air through the pickup, but this didn't really clear anything up.  I then tried back-flushing water through the pickup using garden hose and water from the spigot.  

After several cycles I still didn't see much improvement.  I was almost relegated to the idea of cutting open the tank, but I had one more idea.  With the tank full of water I connected the air hose to the pickup and blew air into the line using 60 pounds of pressure.

The water inside bubbled violently.  Upon pulling the air hose from the line, a shot of brownish water came out and cleared!  The rapid rush of water combined with the violent bubbling must have knocked something loose.  I repeated this cycle several times until the brown leader wasn't seen.  The flow from the pickup was noticeably improved!  Encouraged by this, I then filled the tank with four gallons of vinegar and let is set overnight.  In the morning, I then blew compressed air into the pickup again.  I drained the tank, filled it with a solution of baking soda and water to neutralize the vinegar, then rinsed several times.  At this point there is hardly any resistance when blowing into the pickup line.  Water flowed seemingly freely from the pickup side.

I drained the tank and began the process of drying it out using the fan in the filler neck again.  While waiting for the tank to dry, I focused my attention on the tank straps.

The straps were stripped and painted.  

I also ordered some strap isolators from ZCarDepot, along with a new sending unit o-ring and locking ring.  

Before returning the sending unit to the tank, I cleaned the gunk and old o-ring from the sealing surfaces with a Dremel and a wire brush attachment.  I also measured the sending unit resistance between full and empty: 11.5 and 86 ohms, close enough to the 10 and 90 ohm spec'ed in the manual.

With the new o-ring and lock ring, I returned the sending unit to it's home.  I did use a thin coating of type 2 gasket sealant (the non-hardening type) on the o-ring before installing, just as a bit of insurance as well as to keep the o-ring in place during installation.

Using my transmission jack, I raised the tank and jostled it into position.  I connected the top-rear hoses to the vapor expansion tank, then raised the tank just a bit more so that the filler hose could be lined-up.  The filler hose probably gave me the most issue as it took a while for me to install the hose far enough into the tank for me to be satisfied. It didn't help that there isn't much room between the rear valence and the tank to work.  I ended up using a heat gun and a lot of muscle, rocking the tube back and forth to wiggle it down towards the tank.  As a measure of protection from leaks, I added another hose clamp below the factory clamp.

The tank was then secured back into place using the freshly painted straps and new isolators.  The pump assembly was next to be returned.

The pump and sending unit wiring was then routed using the clips on the pump bracket, and 3M dielectric silicone paste was used to protect the sending unit and pump connections.

I wanted to add an in-line filter between the tank and the pump which presented a bit of a challenge due to the tight confines.  I ended up using a 1/2" brass elbow from Lowes to make this installation easier.  For fuel hose I used 15/32" fuel hose from Summit racing; while the stock hose is 12mm this would be close enough at 11.9mm.  A Hastings 1/2" inline fuel filter was used to protect the new pump.  Stainless steel fuel injection clamps were used throughout to ensure leak-free connections at the hoses, except for the fuel pickup lines as I could not find injection hose clamps large enough to fit the 11/32 hose.

I filled the tank with about 14 gallons of fuel and checked for leaks.  Finding none, I let the tank sit overnight to ensure the filler and sending unit weren't slowly weeping fuel.  Seeing no leaks after 24 hours, I ran the pump to purge the lines of air.  This new pump is MUCH quieter than the previous aftermarket unit.  I wonder if the old pump was picking up debris from the tank and wearing out.  After hearing no more bubbles in the tank, I started the car and checked for leaks again.

Before calling this project complete, I wanted to replace the fuel filter and fuel hose in the engine compartment.  Again, using stainless injection hose clamps I replace the hoses and filter, then ran the pump to purge the air from the lines.

I plan on performing a fuel system pressure test when I get some time to ensure that things are working as expected.  

Whew!  This was a long one!