Club's Formula Fastback

[Fierofool]

Pat, I looked at the tank when he came over to pick up the 87.  I'm not sure, but I believe the 87 and 88 tanks flare out at the bottom.  That tank has straight sides.  We also looked at the sending unit on it and though the part in the tank appears to be in much better condition, the harness has been cut off.  Another variation we saw when we compared the one from the Fastback was the metal lines.  The Fastback metal lines turn downward and to the passenger side of the car, while the one in the tank that Dave brought over, turned downward to the driver side and were shorter in length on the downturned portions. 

Raydar may have more knowledge of how to differentiate the early and late tanks. 

We may also need to purchase a new sending unit from TFS.  I'm not sure the one from the 88 is any good.  The gauge would fluctuate wildly when the ignition was turned on. 

[GTRS Fiero]

If it helps, this is an '88 tank:

[Fierofool]

That does help.  It looks like the one Dave has in the van.  He said it also had a date sticker for late in the 86 year which would probably have made it an 87 tank.  He also said it was in really good condition inside.  Maybe we've lucked out.

How does that Fiero Store sending unit work?  Any problems or was it plug and play?

[Raydar]

....  He said it also had a date sticker for late in the 86 year which would probably have made it an 87 tank. 

I thought I remembered that, but it's been a while.
In a side-by-side comparison, for the 87 and 88 tank, the seam between the upper and lower half should be much nearer the bottom, than the earlier tank.
That's from memory. I could be wrong.

[Fierofool]

The one Dave has out here has the seam at the very bottom.  There's hardly any bottom pan at all.  Thanks, Steve.

[GTRS Fiero]

How does that Fiero Store sending unit work?  Any problems or was it plug and play?

The arm on the sending unit hit the baffles, and had to be adjusted.  Once the arm moves freely, be sure to test the return values before mounting the tank in the car.

I replaced the seal, lock ring, tank straps, strap bolts, and the filler tube, while I had the car apart.

[TopNotch]

If the barn tank doesn't work out, we still have the parts car with its tank. There's a slight dent in the bottom of the barn tank. It should be OK, though.

[Fierofool]

I picked up some cleaner to wash out the tank and retrieved the tank from my storage unit.  Pat said he's received the new sending unit from The Fiero Store.  Only thing I need to do is to pick up a fuel pump filter.  I think I'll also get a new fuel filter in light of what we found in the old tank. 

[Fierofool]

I think we now have everything we need to put the tank back into the Formula Fastback.  We have a fuel pump, fuel filter, fuel pump filter, a new fuel sending unit, and some extra fuel line. 

From time to time I've read complaints about The Fiero Store sending unit not being accurate.  Some said they had to remove the tank again and bend the float arm.  We don't really want to do that.

That got me to thinking of how we can get the new sending unit properly adjusted prior to installing the tank.  Chime in please and tell me if you think my theory will work.

Assuming the factory unit is properly adjusted and using that as our template, could we take a measurement from the flange where the unit sits down into the top of the tank, down to the float when it's all the way down, then bend the float arm of the new unit as needed to attain the same measurement.  The resistance, when measured with an ohm meter, would need to be equal at comparable heights throughout it's range. 

Even if this works, we still have some issues with the gauges.  When the ignition is first turned on, there is an electric cycling that causes the radio to pop and the sensor gauges to fluctuate in sync with the radio popping, as if a relay or circuit breaker is cutting in and out. 

[Slyp]

I think there is a problem with the float and the shape of the tank.  If the tank was the same height from front to back it would be linear when the gas is used. Since the back of the tank is taller where the float is it would appear that the top of the tank would go down faster than the bottom.  In that case the guage would not be to linear.  Am I not looking at this right or is there something I am missing

[TopNotch]

Ideally, the sending unit should measure 0 ohms empty, and 90 ohms full. If you get close to that with float at the empty and full positions, you should be OK. The empty reading is the most important (since you don't want to run out of gas), and you need to try to figure out where the float will actually be when the tank is empty. It may not be where it is when you just let it fall with the sending unit out of the tank. After you read the ohms with the float down out of the tank, put it in the empty tank and read again and see if you get the same reading.

[Fierofool]

Bob, what you're saying does make sense.  And the upper area of the tank on the 87-88 is the same as the top of the 84-86 tanks, so where did they get the room for the extra 2 gallons in the later years?  In the bottom, of course.  I think that would also affect the operation of the float, since empty in a 10 gallon tank would still leave an extra 2 gallons in the 12 gallon tank.

Pat, since we have the 88 sending unit from the car, what if we found a point that registered, say 10 ohms.  Measure the distance from the base of the sending unit flange to the axle of the float.  Then adjust the new sending unit so that the same distance reads 10 ohms.  Do you think that would work? 

Or, adjust the float to be level with the bottom of the fuel pump at 0 ohms?  That would be the empty point where the pump couldn't pick up any more fuel. 

[Fierofool]

I have assembled the fuel pump into the new sending unit.  The Fiero Store makes note that extra hose will be needed on the 88 because one of the lines is bent at a different angle.  Truth is that the metal lines coming out of the sending unit are located differently than the stock sending unit.  Anyone replacing with a TFS sending unit should carefully compare it with your old unit when connecting it to the vehicle. 

Doing a trial fit before attaching the pump per TFS's suggestion, I found that the unit wouldn't seat all the way down on the tank.  I measured the distance from the flange to the metal base where the pump sits and found the Fiero Store unit to be 1/4 inch longer.  Standing the tank up with the front end upward allows the internal plastic baffle assembly to move to the rear of the tank.  This will give extra clearance at the bottom of the sending unit.

The Bosch pump came with a filter that is a single layer and is small and flat.  I had purchased a Delphi filter, not realizing there was one with the pump.  The Delphi filter is longer, round, and has a second internal sock filter.  Probably to keep the outer sock from collapsing.  I could see this happening with the sock filter supplied with the pump.  Problem is, the Delphi filter creates a little clearance problem.  But you won't have to worry about it ever falling off the bottom of the pump.  Those present at the tech session can decide which filter to use.  For the time being, it isn't installed on the sending unit. 

The Bosch pump also came with a new O-ring seal.  It is too large.  The one that came with the sending unit is slightly smaller in circumference and is a perfect fit. 

[Fierofool]

First thing we did this morning was to run up to NAPA and pick up a piece of J30R10 submersible fuel hose.  We just didn't trust the piece that came with the Bosch pump as being submersible in ethanol, so we made sure we don't have to pull the tank a 3rd time.  This time we had to pull it because the new fuel pump died with only a few hours run time on it. 

New Fiero Store sending unit, new Bosch pump, new Delphi strainer.  The strainer that comes with the Bosch pump is flat and because it sits down against the baffles, we installed a Delphi which has an inner reinforcement to keep it open.

Due to one of the lines being angled differently on the Fiero Store unit, a new piece of hose has to be obtained.  It must be about 16 to 20 inches long.  I suggest you get about 2 feet and then cut it down to it's needed length.  We came up about 1 inch short on the piece we cut.  This is the vapor return line and where it attaches to the hard line is extremely difficult to get to.  It might be a little easier if you don't have a converter on the exhaust system. 

By all means, look at the Fiero Store unit and your old unit.  The metal lines aren't positioned the same on the two units.  Before installing the new unit into the tank. compare and determine where the vapor and the pressure return lines are and mark the ends of them so you get them hooked up correctly.

It was asked that we take lots of pictures, but everyone had their hands full and there none taken of the tech session, itself.  We had Sarge, Deshoe, OldOne, MikeMac, GTXVette and Fierofool all involved in some manner most of the time. 

We had a couple of guests show up and Todd was ready and willing to get in and get dirty.  He was the one that finally got the had to reach line stated onto the body side of the metal hose.  The two guests were Todd of TheFieroFarm fame and his friend Derek (sp?) who rolled in from the Charleston, SC area with a 3800 Fiero in tow that they were taking back to plant in his garden.


 




We broke for lunch about 1PM and met Ron and Susan and Pat and Linda at the diner.  After a brief meeting and a good meal, Todd and Derek headed back to SC, Ron and Susan were headed back to Ron's Mom's and Pat and Linda and Dewey headed home.  Bob, Mike, Dave and I headed back to Northlake Automotive to finish up the tank and pump install. 

SHE'S ALIVE!!!

[GTRS Fiero]

Well, that must be Todd and Derek in the first pic, but who is that looking up at the black Fiero?  Mike?  Please tell me that that isn't AeroDon's old Fiero.

It sounds as if there was a good showing, and obviously the work paid off with a running Fiero.