cyclopticgaze

bmw 2002

Fuel System Refresh (the Right Way this Time)

Sep 21, 2014


Longtime readers might remember this ancient post in which I drained the gas tank, pulled it out, cleaned and painted a newly-sourced tank, then dropped that one into the car. That small project was an attempt to get rid of a bad tank full of bad gas. My hope back then was that just replacing the bad gas and swapping in a random new tank and new fuel sender would be good enough to fix my fuel issues and I wouldn't have to actually refresh the whole fuel system.


Well, thing is, the car's never really run right. It ran and idled OK for a while. Then later it barely ran; it wouldn't idle at all and I'd have to ride the gas pedal all the time to keep the engine going. And anytime I got a whiff of fuel, it smelled like lacquer.


I suppose it's no surprise. The car's original tank was so far gone, here's what the fuel sender looked like when I pulled it out (on the right, obviously):

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To think that just throwing in some random new tank and sender when the rest of the fuel system looked like that horror show was the height of magical thinking. The system had been left to dry many times. Who knows what ancient evils lurked in all the nooks and crannies.


That was six years ago that I replaced the tank and sender, six years in which gas has been sloshing around inside the whole system, dissolving the layers upon layers of varnish coating the interior. To wit, here's what the inside of my "new" tank looked like when I recently pulled it back out and drained it:

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Looking down through the fuel sender's hole, that's a nice thick coat of tank sealant down in the deep end. Someone's rehabbed this tank before. But the sealant is flaking off, leaving tons of nooks and crannies for dried gas and other debris to settle into. Perhaps what's worse, if there was varnish down there in the past, it's gone now; the sealant's gleaming white and clean. Any demons lurking in this tank have had plenty of time to get resurrected.


When I pulled this "new" tank and emptied it, the substance that came out could not be called gasoline by any reasonable person.


Moving forward, I felt I had two options: 1) take this tank to a shop and have them do what they could to truly clean and maybe re-seal the inside, or 2) source a third tank for the car. In the end, I chose both options. I found yet another "new" tank that looked clean on the inside and had never been sealed, and then I took it to a radiator shop and had it cleaned and sealed anyway. (I took my flaky tank to the shop, too. Their professional opinion: they were happy I brought a different tank.)


$120 later I had basically a brand new gas tank. They even painted the outside and installed a drain plug in the bottom so I'd never again have to do this terrible siphon routine to empty the tank without pulling it out.


My problem now was fitting my fancy pants "new new" tank into the car. The new new tank came from a late model 02 just like the old new tank it replaced. That means that the tank's filler spout is long, requiring a short rubber filler connector to join it to the right rear fender. I had hacksawed the old new tank's spout to make it short. This time, I just sourced a short rubber filler connector from a late model 02.


The late model (short) style filler connector fits pretty well on my early model car, but not perfectly. I used a large hose clamp to attach it to the fender. It's supposed to be secured by a large metal ring, but that part doesn't fit on my car's fender. Still, I think this is secure.

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Above, in the trunk, I have the fuel return line plugged into the filler, but truth is I don't use the return line. I still have it plumbed through the car in case I ever want it, though. Below, in the engine bay, I have the other end of the return line (blue) blocked off to prevent vapors travelling up it. The black line is a new plastic fuel delivery line that I purchased from Blunt, loyal friend of the FAQ. It's an OEM replacement for the stock plastic line, designed to melt closed during a fire. The rubber fuel hose connects it to an in-line paper fuel filter, then the fuel pump, then the carburetor.

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Back in the trunk, the new black fuel line connects to the fuel sender by a length of hose, too. The tank has a built-in connector for the fuel return line (that I could have used instead of connecting to the filler), and I've blocked it off with a cap so fuel and vapors don't escape the tank. I put a hose clamp on the plug to strongly secure it.

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In the finished trunk, the wires to the fuel sender (which inform the fuel gauge on the dash) are a tad short. They should route through the depression on the top of the tank so they don't get compressed by the trunk's floorboards. That is a vanishingly minor concern for me at this point, though.

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All that's left now is to bolt the tank down to the trunk floor, take off the fuel pump and wash it out with carb cleaner, then pull the carb and do the same to it. The latter may actually be the most annoying part of this fuel system refresh. This really wasn't a difficult project; pulling new fuel lines and replacing hoses is cheap and easy — sourcing a decent fuel tank is by far the hardest thing here.


I'm in the middle of a few other projects, so I haven't tried to fire up the engine yet, but here's hoping I rehabbed the fuel system properly this time and can get it (and keep it) humming from here on out.