1976 Eldorado w/FI Fuel Tank Inspection-RENU?

[toukow]

We pulled this tank with the intent of sending to RENU for coating, replace all fuel hoses and both pumps. I have to admit I’ve never looked inside a 43 year old gas tank, but was amazed at how good this one looks. If someone told me this was a ‘new old stock’ tank I would have believed them. There is no rust or corrosion whatsoever- none! Conjecture on my part, but the previous owner had very convenient access to pure gasoline (no ethanol), so I’m wondering if he only used such fuel as we do.

Photos are obviously a challenge, but I’ve included a photo showing the fuel tank tray that is unique to the fuel injected cars as I understand it and keeps the fuel pump bathed in fuel.

Lesson Learned: We have always kept this tank full to minimize condensation, so have never tested the fuel gage low level.  The fuel gage was saying 3/16ths  and I was going to drive a bit more to empty it further-glad I didn’t. Manual says when the gage is on Empty, you have 1.5 gallons left. When I dumped the tank there was just about 1.5 gallons. I measured the ohmic value of the sender and its minimum was 13.5 ohms, and I’ve read that GM uses a 0-90 ohm range. I sprayed it with contact cleaner and got it lower but still erratic, so from now on we’ll use ¼ tank level as being empty.

Siphoning: I had a hard time trying to get a hose into the tank to drain it, and it was obviously already empty. That said, given the relationship between the filler tube and the baffle holes, I see it being a challenge to accomplish draining with a siphon hose. The tube needs to be stiff enough to force into the tank and through the baffle, and flexible enough to bend down to the bottom of the tank if pushed in far enough. At the tube elevation shown you’d still have well over half a tank.

I’m debating whether to proceed with sending to RENU or not, as I have other items I’d rather spend the $400 on if not needed. I have a lift, so pulling the tank isn't too bad.   

Hope this helps, Dean

[bcroe]

Going through the fuel system is good maintenance.  I will again post
this pic of my tank pump completely disconnected from the pipe.   This
on whatever I could get at the pump. 

Typically I find the gauge circuit is starting to develop extra resistance
at any junction in the circuit.  Mine need a bit of work to eliminate
these, so that it would be accurate again.  Ignoring them may allow
them to increase and make the gauge read higher and higher.  An
ohm meter tracking along the path can find them, fixing has the
challenge of survival while swimming in gas. 

Do not throw away the old pumps, might be useful. 

good luck, Bruce Roe

[toukow]

Save the pumps, eh? OK, they are both in working order. I had seen your post on the pump hose issue, and this one's hoses are in very good shape for the age. The in-tank return hose I'm going to reuse given its condition, and if it fails I'm not seeing a significant consequence. 

It would appear someone has been into the system before, given the zip ties and different hose clamps on the tank. The frame pump has a manufacture date of 1974, so unless the previous owner found a NOS, it's original.

I considered the conversion to the single, high pressure pump as you have done, but was unsure of the complexity. Submersible wire required (PTFE insulation?) and lugs, etc. plus anything else to be addressed. So I wimped and went stock.

I ordered a Delphi pump FD0011 for the frame high pressure unit, and will respond as to noise level once back in service. I had seen questions about the brands available, but little feedback other than Airtex. The noise is a concern to me. Time will tell...... I ordered a Spectra SP1138 in-tank low pressure pump, mainly because I could get the strainer in short order. I'd rather they raised the pump price $3 and throw in the strainer if they're going to say it voids the warranty to not use one.


Dean

[bcroe]

For inside tanks I use Gates Fuel Line Hose - Submersible 27093 5/16" X 12"
Submersible 27097 3/8" X 12"
and other sizes.  Do not want another failure soon.  Bruce Roe

[dennisspeaks]

I know this is a old post but you were exactly where i am, about to drop the tank and replace the fuel pump/sending unit and take a look inside and see what I am working with. 

How did things work out for you?

[bcroe]

The old units usually can be repaired, I would replace the hose,
even if it is a NOS (45 year old) never used.  Check out the
gauge circuit that should run about 0 to 90 ohms over range,
look for loose connections if too high.  Change the pickup sock
on a used one. 

Unless the tank is in premium condition, I run them thru RENU. 

Bruce Roe