Idle speed?

[Jeff]

Thanks Dave. Funny how an idle speed question turned into a gas tank removal and cleaning! Luckily, it looks like there is a good place to get this done in SE Portland for $200-275. Not looking forward to removing it and putting it back in though.

 

[Jeff]

Tank removed. That was "fun." It looks awesome. The top is nice and shiny. It looks like brand new steel. There is a tag on top that I think has the part number on it. There is also a single spot of exterior paint on it. I'll pull the sending unit this weekend.

 

[Davea Lux]

Tank removed. That was "fun." It looks awesome. The top is nice and shiny. It looks like brand new steel. There is a tag on top that I think has the part number on it. There is also a single spot of exterior paint on it. I'll pull the sending unit this weekend.View attachment 145932

 

[Davea Lux]

When removing the sending unit, clean the area around the bayonet mount with some brake clean or other solvent and use a brass tool to loosen the lock ring, won't get any sparks that way. With the sending unit removed, you can inspect the inside of the tank for rust etc. If all you mainly have is solidified fuel, a pressure washer will usually clean it out.

Dave

 

[saylor]

keep yer old lock ring, the new ones are junk. get a new ground clip. I used a PVC (maybe a 2" - 4" diameter - I forget) pipe and cut notches in it where the tabs are, so the pvc pipe fit over the lock ring and the tabs go into the notches. drill a hole halfway thru, drive a screwdriver thru that hole, and turn.. like taking off a stuck oil filter - stab a screwdriver thru it and turn.

there is a post/pic somewhere here of the PVC thing I made for this.

try not to die -

- saylor

 

[Jeff]

Hypothetical question: if you were not having fuel issues and you had your tank out of the car for some other reason, would you take the time to remove and check the sending unit and clean the tank?

 

[Davea Lux]

Hypothetical question: if you were not having fuel issues and you had your tank out of the car for some other reason, would you take the time to remove and check the sending unit and clean the tank?

Always. Saves a lot of time and the annoyance of having to do the same pain in the butt job twice. Always at least check the interior condition of the tank for rust, sludge etc. Usually a good idea to at least replace the float on the sending unit. Also if you are putting in a new sending unit, check its function before installing it, some of these replacement (ie made in China) units are defective right out of the box. A simple test can be run by putting a wire with alligator clips into the sensor mount that hooks to the sending unit. Hook the other end to the sensor probe on the sending unit. Now take another wire with alligator clips to the sending unit case and to a good ground. Turn on the ignition and have a helper raise and lower the float arm on the sending unit, the gas gauge should move in concert with the float. If it does not, something is wrong someplace, usually a defective sensor; especially if the gauge worked prior to the installation of a new sending unit. If you use wires for the test that are six feet or so long, you can avoid having to lay under the car.

Dave

 

[Jeff]

Saylor - I found your old thread and will try that PVC pipe idea. I pasted a link below for convenience. Do the notches go on the tabs on the inner ring? See pic below with arrows pointing to tabs. The PVC tool has four notches so it seems like that must be it, but I don't see how that inner ring will come out with that larger outer ring in place.

The inside of the tank looks good viewing from the filler side. I don't see any rust or debris or sludge, just a whitish, powdery coating everywhere.

Thx, Jeff

fuel sending unit R & R

 

[Davea Lux]

The four notches go over the four tabs. You might have to take a brass drift and tap the lock ring to break it loose. The gaps in the center lock ring is where it will be disengaged and can be pulled off. That is some of the ugliest undercoating I have ever seen.

Dave

 

[Jeff]

Got it out. It looks pretty good except for the white powdery coating all over the sock. I think that must have been the problem. The inside of the tank looks pretty good too. I'm not sure I need to anything to it. My neighbor thinks the white coating is lead.

 

[david hill]

The four notches go over the four tabs. You might have to take a brass drift and tap the lock ring to break it loose. The gaps in the center lock ring is where it will be disengaged and can be pulled off. That is some of the ugliest undercoating I have ever seen.

Dave

The white coating is the remains of the coating inside the tank to prevent corrosion. It breaks down over time. Have the tank professionally clean and install a new sock. Check the fuel sender w/ a DVOM meter that has grafting capability while its out. Saves you time if its bad. Change your fuel filter too if not done already.

 

[66Newyorker]

Personally I don’t use the tank sock. Over the years as a technician I have seen them get clogged with all sorts of stuff. The fuel filter will catch most of the crap coming from the tank. Gas stations today filter the fuel for fuel injected vehicles way better than back when our cars were built. A lot of work for replacing the sock, we used to use compressed air back in the day to blow them off and off went the customer. Just my 2 cents.

 

[66Newyorker]

If your worried about crap getting to the fuel pump and taking it out put another fuel filter before the pump in section of fuel hose from the frame rail and pump. A lot easier to replace a filter then pulling the tank.

 

[Davea Lux]

Personally I don’t use the tank sock. Over the years as a technician I have seen them get clogged with all sorts of stuff. The fuel filter will catch most of the crap coming from the tank. Gas stations today filter the fuel for fuel injected vehicles way better than back when our cars were built. A lot of work for replacing the sock, we used to use compressed air back in the day to blow them off and off went the customer. Just my 2 cents.

Another option is to use a marine fuel filter on the suction side of the fuel pump after you cut off the sending unit sock. The Sea Sense company makes a good one with a clear plastic bowl that has a petcock drain on the bottom to purge water and debris.
At $75, they are a bit pricey, but are a good option on fuel tanks that have a chronic problem with corrosion.

Dave

 

[Jeff]

I like the idea of leaving the sock off and adding another filter before the pump, but how do you get the darn thing off? It seems like it should slide off the tubing but I can't get it to budge. Is it that entire cylinder at the end of the pipe?

I also found another potential culprit today when replacing the rubber portions of the fuel line. The section connecting between the part the runs through the stub frame and the part that runs along the bottom of the car has a pretty sharp bend in it. The back of the bend was cracked and degraded. I couldn't see it because the back of the bend was facing the floor. I think it could have been allowing air into the line.

 

[Davea Lux]

I like the idea of leaving the sock off and adding another filter before the pump, but how do you get the darn thing off? It seems like it should slide off the tubing but I can't get it to budge. Is it that entire cylinder at the end of the pipe?

I also found another potential culprit today when replacing the rubber portions of the fuel line. The section connecting between the part the runs through the stub frame and the part that runs along the bottom of the car has a pretty sharp bend in it. The back of the bend was cracked and degraded. I couldn't see it because the back of the bend was facing the floor. I think it could have been allowing air into the line.

I usually remove the sock with a hacksaw, cut a notch in either side of the sock where it is attached to the pickup tube. Then stick a screwdriver in one of the cuts and it should pop apart. Good time to replace all rubber fuel line parts as well.

Dave

 

[Jeff]

Anyone buy a filler tube grommet from National Moparts? I've only used them once and wasn't thrilled. Van's doesn't have it.

That's the last piece and then I am ready to put the tank back in the car. I tested the sending unit and it read 12-68 ohms. The FSM says the upper number is good. The lower number should be 10 plus/minus 1, but I am going to live with it. I cut off the "sock" and it was full of loose debris. No doubt part of the problem. I put a few gallons in to check for leaks and so far so good. I also connected it to the fuel line and did another pump test and got about one and a third quarts in a minute at the carb inlet, which is much better than before.

Helpful video for checking ohms:

 

[Jeff]

Got the grommet from National Moparts today ($35, inc. shipping ) and have the tank hanging from the j bolts again. Should be able to wrap it up this weekend and see if it will go more than a mile.

 

[Davea Lux]

Good Luck!

Dave

 

[Jeff]

Thanks Dave and everyone else. I got it all put back together and added a second filter. I get 1.5 quarts per minute at the carb so I can cross off fuel delivery as an issue. I also drove it a couple miles and it ran much better. There was no hesitation or sputtering, even going up some hills and giving it a bit of gas. It still seems somewhat sluggish and under-powered, but there are still ignition system tuning issues to work through. Next step is to try again to get it to the exhaust shop to fix the leak at the manifold.