New float/sending unit probs (Page 2/2) theogre JAN 28, 07:50 PM quote Originally posted by Patrick: IMO, it's a whole lot safer to be using something other than gasoline if bench-testing a fuel pump in an open container (ie large bucket). I've used varsol. Yes likely are "safer" things testing pump but hardly anyone bothers to find/get Chemical X for various reasons. Even w/ "safer" solvents w/ low explosion or even low VOC value, often bad to breath etc & need to test Outside so doesn't contaminate the space or house the whatever space is attach to. Doing Outside w/ minor wind even Gas is "Safe" because fumes blow away before get to Stoic points. Exact opposite of Tank installed where Gas Fumes are Far to Rich even to Burn & why vehicle F-pump etc is not made to meet Explosion Proof construction. MaxxPower1968 JAN 29, 05:49 PM I had a problem with the FS sending unit as well. The car was bucking at 2500 rpm on every gear. I was chasing the problem by changing a bunch of parts since the car had been sitting for 15 yrs. Once I got done with the parts I was going to change anyway, I started from square 1 by checking the fuel delivery system. It turns out that the FS sending unit was 1/4" too long and restricting gas flow to the fuel pump. I found this out because I happen to notice it was tough to put the the locking ring on the tank. The first time I did it, I just thought that the o-ring was a little thicker than the original. Then I test fit it without the o-ring, and sure enough, the unit woulndn't sit flush. I ended up cutting off the excess and rewelding the pump perch higher on the tube. I suggest doing a fit up prior to your final install. Now the car runs like a champ. Should be ready for smog in a week or so. Also, the reason I didn't return it was because I already had it installed for a 1yr while I was working on getting the car back to driving condition. theogre JAN 30, 02:53 PM ⚠️ Warning: All new O-rings to seal the top often will be harder to install the locking ring just because is a NEW O-ring. Do Not alter the seal or can, often will, cause leak problems in the future. Old O-ring there is round cross section to start w/ but age, pressure, fuel, etc, the seal is crush to oval shape even when out now & doesn't have much force left to seal or load the locking ring. You may never fill the tank or worse push the station nozzle after shutoff to "stuff the tank" to leak Liquid but Leaking Fumes is a big problem because also let Air & Water In & Ethanol Love any source of moisture that mix then drops out of solution then F-pump will suck polluted water causing other fuel system problems. More leak problems: Hidden Fuel and Coolant Leaks... https://www.fiero.nl/forum/Forum2/HTML/146198.html As to fit, everyone trying aftermarket Pump/sender assemblies from anyone should have measured the distance from top cover to F-pump bracket. Yes, if the bracket is lower in the tank then Pump & Sock can be crush & limit or stop Fuel Flow. If the Bracket is to high, expect to "run out of gas" sooner, often way sooner, then the OE setup. Quick measuring before to do anything w/ new "kit" would tell you that fast. Measure "taller" = low in the tank. "short" = run out sooner. Remember the OE Gauge setup try to say Empty a bit sooner the F-pump is sucking air on level ground or close to that to prevent dry pump death. Because Fiero has weird shape, driving up/down large hills "empty" & pump sucking air can happen below 1/8 to 1/4 of tank cap. Worse if have aftermarket plumbing w/ high pump location.