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 write up - R&R fuel pump.

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Location : Finger Lakes of New York State
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write up - R&R fuel pump.  Empty
PostSubject: write up - R&R fuel pump.    write up - R&R fuel pump.  EmptySat Nov 21, 2020 9:12 pm

I got a junkyard fuel pump assembly to replace the one in my Riv.    The one in the car was OK but the fuel sender wasn't working properly.  It would start reading full when about 1/3 full, and would increase until about empty at which point the low fuel warning light would turn on and the needle would peg at either the full or empty end.  

So... I went to a pick and pull, and pulled a pump from a '99.  The pump looked to be in good condition (looks are deceiving), the car had 130,000 miles on it overall. I had fun pulling it and cleaning it up (ha ha).  I got the pump and the o-ring.  I visited the yard twice.  First attempt to remove the pump failed, the o-ring was too rusted and I started too late (this time of year the yard closes at 3, sundown is about 4-4:30 PM).  One of the yard techs had tried to pull the pump for me with WD-40 and a drift; that didn't end well.  I returned with a factory tool J-39765 and a breaker bar and the lock ring unlocked quickly.  Using a screwdriver as a drift I spun it the rest of the way (about 1/2 inch) without any drama. The pump assembly I got is a factory-style unit, with the original factory plugs and a Delphi pressure sender.  By all appearances the car was well maintained and ran when parked according to the yard decal, the general statement of condition printed on a decal on each car.  This one was motor/transmission good/good with 139000 miles.  The car however appeared to have rusted enough to fail inspection.  I couldn't tell more, as the registration stickers were gone and no hints were in the glovebox. The pump would have been made after the May 1999 spinoff of Delco into Delphi.  Remembering all the posts about fuel pumps on here I figure the original one may have been replaced at some point by a GM dealer, as the original should have had a Delco Electronics sticker and the tank pressure senders rarely, rarely fail.  

I bought a replacement fuel strainer sock for the junkyard part, as NOS off eBay for $9 shipped (they are on rockauto.com for $4 but then add shipping). It was tricky to figure out which one to get. HINT - take measurements then match up a strainer using pictures. Dimensions are not needed if you calculate ratios as measurements in the pictures and compare those to your strainer.  I also cleaned the electrical contacts for the fuel level sender and treated the contacts with CRC 2-26 after cleaning them with a pencil eraser and then dry gas on a qtip.  What you do is leave the float all the way down then scrub over the reachable part of the contact patch arc with the eraser.  Blow the crumbs off then raise the float all the way up and clean the other side of the contact patch arc the same way, blowing the crumbs off again.  You will need several qtips for this next step: wet a qtip with dry gas (alcohol) and clean off the entire contact patch arc. Use a dry qtip to wipe it dry.  Then repeat alternating wet/dry cleanings until the qtip does not turn gray during the dry cleaning (it may take 3-5 rounds).   Then wet another dry qtip with CRC 2-26 (or radio shack tv tuner cleaner) and wipe over the contact patch, then using another qtip wipe it dry again.  This conditions the surface of the sender, much like reconditioning a volume control or fader in a guitar amp.  

The junkyard part came with its o-ring.  I cleaned the o-ring with dry gas and soaked it in silicone oil (dimethlypolysiloxane, alba-chem #1749, albachem.com) until it quit stinking like gasoline (took about a week). You don't need much of the oil - basically you just wash the o-ring in dish liquid, dry it, then rub silicone onto it well, and put it into a baggie to soak. Do not bother  putting extra silicone oil in the bag.   When the silicone oil is soaked up (takes several days) and the ring does not smell strongly of gas anymore you are done.

The factory service manual is interesting.  It was actually helpful.  It tells you for instance when you can get away with removing the pump assembly (when the car is down to  3/4 tank of gas or less is best), and reminds you to relieve fuel pressure and to use a shop towel to catch fuel when removing the assembly, too. It also has instructions for replacing the fuel level sender, the strainer, the pump, and other parts of a factory fuel sender assembly. Nice to see that GM at least intended for these things to be repairable.

My locking ring and trunk tabs were not in bad shape at all.  I soaked the lock ring in a homemade rust converter (oxalic acid and acetic acid in hard water that's softened with potassium chloride - converts the rust to a black coating) - found out, to my surprise, that the ring is galvanized with black paint.  So the rust converted alright but there wasn't much of it.  

I put the new fuel strainer sock onto the pump (I used Delco TS-63, it's the same as TS-100 but the oring is different, square profile not round - either buy one or rehab/reuse the old one, don't use the square one,  you'll never get the ^$&%&& lock ring back on because the square-shoulder ring won't compress right. Ask me how I know (roll eyes rolleyes ).  

Taking out the old assembly, I took off the hoses (used needlenose pliers to pinch the quickconnects) and electrical connectors, then brushed the loose rust with small wire brush (kinda like a toothbrush) then used a vacuum cleaner (hose attachment) to vac up the dust.  Then I used the lock ring tool to loosen the lock ring.  The tool will not remove the ring, it quickly gets it loose past the locking bumps and then you turn it by hand to finish removing it. Lift the assembly out being careful not to spill gasoline, not to drop any dirt or dust whatsoever into the tank, and not to bend the float arm.  I then dumped the extra gas into the can for the lawnmower, then took the lock ring and cleaned it up (coarse 0 gauge steel wool in water with dish soap) and then set it to soak in the rust converter. (tablespoon of oxalic acid powder in 1 cup water, with 1/4 cup vinegar added -- use in ventilated area only, plastic or glass container with flat bottom - a thrift store or discount store glass pie plate for instance, or plastic storage container from dollar store). It does not have to soak all that long, just long enough to turn the rust spots dark gray or black, but it can be left to soak for a while because any reaction in a spot stops when the rust there is converted, and the solution will not attack plated (the ring is galvanized) or painted surfaces.  

I then wiped the rim of the opening clean with the rag I used to catch the dribble of gas when I removed the quickconnects, again being careful not to get any bits of dirt or grit or whatever into the tank...

Next, I  installed the JY assembly in the reverse of the removal of the current one. I quenched the lock ring in a solution of baking soda in water (a tablespoon of it in a cup of water) then wiped it dry, took the oring out of the baggie and set it around the tank opening, inserted the fuel pump assembly into the tank, reinstalled the lock ring, reinstalled the fuel hoses and electrical connectors.  I reconnected the battery, turned on the key and waited, listening for the pump.  It whirred quietly, and then stopped.  I then turned the key to start the car, car started, fuel gauge read correctly (about 1/4 tank) and then I turned the car off and put the cover plate back on the trunk pass-thru to the fuel tank.

Next day I set about seeing if I could get the old sender to work properly.  The sender resistance is supposed to sweep from  50 ohms to 250 as the arm is moved from empty to full.  On my replacement it swept from 39 ohms to 248-point-something after I reconditioned it.  Before reconditioning, it jumped around - after about half a tank it would show full intermittently as the tank contents were used, so I couldn't really let my spouse drive the car, as she'd rely on the gauge... smh...  Testing the level sender, the resistance from empty to full jumped about as I moved the float arm slowly from empty to full. I tried cleaning the sender and managed to bend one of the contacts... I was a bit sleepy... so I found and ordered a NOS sender off eBay, along with strainers.  It was hard to fit an internal strainer because on line, the critical dimensions (size, filter screen mesh, etc.) are not usually listed.  The only exception I found was the RockAuto parts "info" pages where they do list that info for *some* screens.  

When the NOS level sender arrived, I could see that my "victory" with overhauling a pump will be short-lived.  The new level sender brushes look different from the ones on the sender that's in the tank now - that is, the ones in the tank now are obviously worn in comparison but still working fine.  That also explains why the sender on the pump I removed from my car broke when I tried to clean it ha ha.

Anyway... I'll finish fixing this unit and re-install it when the one in there finally fails.  Might be a year or three...

Fun and games...


UPDATE: The following week, I swapped the original pump, with new sender, back into the car. On the original pump, I replaced both strainers - one with another eBay NOS part, the other with a part from NAPA that the tech matched up for me from stock. It's in and working fine. I am thinking about getting a replacement electric pump cartridge to install on it only because it's so old anyway. but want to be sure to get the SC spec pump (not the standard pressure) and not so sure I want to spring for a Walbro. More funandgames...

Last edited by albertj on Wed Feb 24, 2021 5:43 pm; edited 1 time in total (Reason for editing : Updates)

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