Found gas leak on my 1st Gen - fuel sender

[k7mdl]

Periodically I fill the tank on the way home, and the next morning the garage smells of gas. Ride 30-50 miles (about a gallon used) to work and the next several days and nothing smells anymore. It sat full for the last few days and gave me a chance to track it down. It was a slow leak so just have to find the wet spots. Sounds easy enough.

 

Originally thought I had a oil leak in the rear shock area, the lower shock links were crusted in black dirt, and the puddle under it represented oil, rather than gas. The gas washed the old oil and dirt down to the floor and evaporated off. Once I cleaned things it was clear gas alright.

 

Finally started pulling hoses, cleaning under the tank, shining a flashlight everywhere, entire bottom of tank area was wet and dirty, no one place. petcock area was dry. Finger on the rear plastic fender next to the shock was wet with gas. Had to be from up top. Feared a rust hole or broken seam at the top of the tank somewhere.

 

Looking through parts drawing for the tank, I saw the fuel sender under the seat. Forgot all about that. Doh! Pulled the seat and it looked dusty and dry. Nto wet like the area further down the fender/rear of tank. I filled the tank to the top and then looked and sure enough, s small weeping spring appeared on the fuel sender. The center nylon insulator sealant is falling off and gas is welling up around it.

 

Plan to drain the tank some and pull the sender out and drill out the riveted asembly, reseal, and re-rivet if possible. Pulling the seat first would have saved much time.

 

- Mike

[GigaWhiskey]

Interesting! Wonder how many people have a fuel leak that they cant find and it is in the same location as yours.

[k7mdl]

Drained tank, pulled unit. 2 wires go to the fuel sender unit. One is a spade lug to ground. The other goes to a lug that is riveted to a brass rivet/washer/solder post )all one piece), sandwiching a nylon insulator on top, and a rubber washer on bottom. The rubber washer had shrunk some over 20 years and gas was leaking by it and out under the upper nylon insulator. There appeared to be remains of sealant under the nylon insulator, but it had mostly vanished.

 

Opening the tank the sender was totally encrusted in rust and a thin layer of sludge. I used a screw drivers to easily scrape off the layer. It all turned to powder and easily fell off. I adjusted the tension a bit tighter on the wiper arm while I was there.

 

I unsoldered the wire to the wiper from the brass post. I drilled out the brass rivet/post all the way thorugh to reuse the washer portion since it nicely clamps the rubber washer - plus I did niot have the right size brass washer on hand.

 

I put a 3/4" long #6 brass bolt through the spade lug, nylon insulator, sender plate, rubber washer and the drilled out brass washer. Put a brass nut on loosely, doused all surfaces of the plate and bolt and washers/insulator with Perma-tex adhesive/sealant I had on hand. Let is set up a bit then tightened it up compressing the rubber washer a bit.

 

Took a long piece of brass strip and bent a right angle about 1 in long at teh end. This created a scoop. With a flashlight and the scoop I scraped out the bottom of the tank and removed about 2/3 cup metal rust flakes.

 

The rust sediment settled to the rear bottom portions of hte tank. The petcock riser for normal is well above it, but the reserve intake hole is flush with the bottom or a bit below, and the screen sticks up about 1 inch, maybe 1/4 inch diameter. Further I saw my screen around the reserve intake was damaged and sediment was free to flow into it. Sediment was piled high beside it but was settled in place and not free moving. I shoved the flap of screen back into place, and plan to use normal position most of the time now. Was using reserve most of the time. Now I can see why my fuel filter looked so bad last year when I got the bike and went through it.

 

Reassembled, refilled the tank to the top and so far so good.

 

Probably took about 3-4 hours to gravity drain and do the whole repair. Not difficult at all. If I used the fuel pump it might have sped things up a lot.

 

Alternative is a used or $50 replacement part.

 

- Mike

[Squidley]

Good post, glad that you got it figured out and I'm sure this will help someone down the line

[k7mdl]

Despite the work and teh promising initial good results, after 12 hours, this morning it is leaking through the insulator again, this time through the bolt threads itself. Likely did not get enough sealant into the bolt threads. If you can find a non-leaking unit, I suspect it will be much easier than fixing a leaking one. Thought I would try it.

[mark reed]

My 83 developed pin holes in the bottom of the tank.The paint was still appeared almost new on the outside of the tank and bike is kept in a tight shop.Removed tank and did the KREEM treatment.A big job but its fixed now.

[k7mdl]

I was waiting for a replacement unit. While in the hardware store looking for something else I came across 3/16" tube rivets in various lengths. At $0.12 a piece I grabbed several sizes. I removed the leaking sender and replaced the brass bolt with the tube rivet and also cut and drilled pieces of a large rubber washer to fit top and bottom tightly. Soldered the wire to the brass washer I had drilled out before and reassembled the stack again. Took a metal rod and hammer to flare out the rivet and pounded it tight. Since I had already dione this once and the parts are all clean this round, it only took about an hour. Refilled and 2 days later still no leak. Usig teh bolt it was hard to seal up the threads, the rivet is nice and smooth. The old original reused rubber washer was somewhat hardened, but not a tight fit around the bolt.

 

- Mike