Gas Tank Leak

[maxtwms]

I'm starting another thread since issues lead you down several avenues. I was complaining about lacking power and was advised to check fuel flow rate and exhaust blockage. While requesting new exhaust I was informed my tank was covered in gas. Sure enough it was sloshing out of the top somewhere.

My plan is to remove the bed by the 8 bolts holding it to the frame, and possibly dropping the tank a bit. I found the 3 hard lines running above a crossmember from the driver tank to the passenger rubber lines can be disconnected from the tank by another set of rubber lines. From the pic below, you can see what I mean. The sender gasket looks pretty awful too so there may be more going on here. The picture is looking between the cab and bed from the driver side just above the tank. Feel free to give me pointers or just watch me frustrated myself through it all. Enjoy!

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[PrairieDrifter]

Looks like you found the issue, if not the whole issue I’m sure that’s most of it!. I’d go through the fuel system and replace all the rubber lines you can find and put a fresh fuel filter inline.

 

[maxtwms]

After thinking about all the trouble of taking this thing out, ill be replacing the sending unit as well. No reason to let $50 be a reason I have to do this again. I do have a question though. I still have the charcoal canister plugged up to the vent line. Do I just cap all the other fittings coming off of that canister and run one to a ported vacuum in the carb? How is that maintained? Seems like Id lose pressure in the tank if I didn't try to complete a circuit so to speak.

 

[smoothandlow84]

I would also check the fuel tank where the mounting straps come in contact with it for hairline splits. My 78 squarebody developed a crack in the tank and I could smell gas fumes ever so often when the truck was parked.

 

[maxtwms]

I would also check the fuel tank where the mounting straps come in contact with it for hairline splits. My 78 squarebody developed a crack in the tank and I could smell gas fumes ever so often when the truck was parked.

Will do. I'm ditching the bed removal after all the struggle to get them off and twisting one up to where the bolt and nut just spin within the bed hole. Not sure how I'll fix that one. I'm going to try and salvage the metal tubing crossing the truck but if not, I should be able to replace with some tubing. I have metal lines running from the bed all the way to the pump so I guess I'll try to blow that out?

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[smoothandlow84]

A longtime friend of mine has his own fabricating and car shop. He once showed me a picture that he took of a truck that came into his shop in need of work. Someone actually sealed the top of their fuel tank with glue/epoxy instead of replacing the gasket for the fuel sending unit for the metal tank. I can honestly say after that....I have seen it all...lmao.


The best part was....the truck wasn't in his shop for a leaky fuel tank, but to have the rear suspension swapped out for air ride.

 

[1987 GMC Jimmy]

After thinking about all the trouble of taking this thing out, ill be replacing the sending unit as well. No reason to let $50 be a reason I have to do this again. I do have a question though. I still have the charcoal canister plugged up to the vent line. Do I just cap all the other fittings coming off of that canister and run one to a ported vacuum in the carb? How is that maintained? Seems like Id lose pressure in the tank if I didn't try to complete a circuit so to speak.

You could cap the sending unit’s vapor port, install a vented cap, and get rid of the whole thing or keep the vapor line and put an inline filter on the line going into the canister or keep the canister going to its ported source, and it should be fine.

 

[maxtwms]

You could cap the sending unit’s vapor port, install a vented cap, and get rid of the whole thing or keep the vapor line and put an inline filter on the line going into the canister or keep the canister going to its ported source, and it should be fine.

Man.... I'm thinking this vented cap sounds so much easier..

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[maxtwms]

A longtime friend of mine has his own fabricating and car shop. He once showed me a picture that he took of a truck that came into his shop in need of work. Someone actually sealed the top of their fuel tank with glue/epoxy instead of replacing the gasket for the fuel sending unit for the metal tank. I can honestly say after that....I have seen it all...lmao.


The best part was....the truck wasn't in his shop for a leaky fuel tank, but to have the rear suspension swapped out for air ride.

I don't understand why ppl do things like this. If you had the room to put glue on it you could've spent at least 4 bucks on a gasket. Blows my mind

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[1987 GMC Jimmy]

Man.... I'm thinking this vented cap sounds so much easier..

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That’s how they did it back in the day. You’ll just have a smell of gas fumes hovering around your truck sometimes. The canister holds all that in. If it was me, I’d keep it.

 

[smoothandlow84]

Once all of my emissions crap was removed, I opted to keep the charcoal canister connected. It made things easier.

 

[maxtwms]

Ok I may do that too then. I like things to be used as intended. I have the hoses so I might as well. Any gain from replacing the filter or is the redirection of fumes to the carb sufficient?

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[1987 GMC Jimmy]

The canister filter? I did with the assumption that it could breathe better and be more effective. I think I got it from NAPA for like three dollars.

 

[maxtwms]

Why does this exist? Is this a dent?

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[crpntr78]

Going back to your bed bolts, try heating the nut on the bolt with a torch. Worked great for me.