Fuel Tank Sending Unit: Two Outlet To One?

[Gregski]

so I have the fuel tank off the truck in order to lower it, so I might as well put in a new sending unit (mine is older than dirt, and may be effecting the fuel gauge reading, got a brand new fuel gauge in already)

So question is, since I deleted the charcoal canister and the hard line that runs along the frame rail to it, do I need the second outlet nipple on the sending unit. Right now I have about an 18 inch long rubber hose on it just venting below the truck.

I do have a second tube/snorkle running along the big filler tube, so maybe also get a vented gas cap and call it good.

What do you all think/suggest?

[enaberif]

Plug off the 2nd line for the charcoal and run a vented cap. Done.

[Gregski]

Originally Posted by enaberif

Plug off the 2nd line for the charcoal and run a vented cap. Done.

I can't believe you would allow me to do that to Rusty, ha ha

[hatzie]

If you're parking it indoors you won't like the smell without the charcoal canister.
The charcoal vent system doesn't affect performance at all and it's darn simple.
There are only three hoses needed to make it work. Ported Vacuum for purge control, Purge Vacuum to suck out the gas fumes, and hose to the fuel tank vent(s) to collect the evaporated fuel.
It purges fumes out to the PCV hose and the purge valve gets control vacuum from the vacuum advance port.
If you don't want the hoses draped over the side of the engine run two steel lines along the inner fender and firewall to the distributor area. Probably 3/8" PCV and 3/16 or 7/32 line for the purge vacuum control line.
Ignore the carburetor bowl vent fume hose in this diagram.

[Gregski]

Originally Posted by hatzie

If you're parking it indoors you won't like the smell without the charcoal canister.

You know I took that under consideration when I deleted the charcoal canister but the truck has been parked inside the garage for the last 5 months since we moved to the new house, and no odor at all, and yes there is fuel in the tank

[hatzie]

The K30 trucks used plastic axle vents in the end of a hose. No need for a vented cap.

[Gregski]

Originally Posted by hatzie

The K30 trucks used plastic axle vents in the end of a hose. No need for a vented cap.

I have the same thought every time I crawl under the differential and see that white plastic thing at the end of the hose, I was thinking would that work for the fuel line as well, I wasn't sure what type of check valve that was if it is a check valve at all.

[hatzie]

Originally Posted by Gregski

I have the same thought every time I crawl under the differential and see that white plastic thing at the end of the hose, I was thinking would that work for the fuel line as well, I wasn't sure what type of check valve that was if it is a check valve at all.

You don't want to put it in the fuel line. The vent connection on the sender usually has a check ball or something similar inside the tank to keep liquid from exiting the tank.

[Gregski]

Originally Posted by hatzie

You don't want to put it in the fuel line. The vent connection on the sender usually has a check ball or something similar inside the tank to keep liquid from exiting the tank.

Oh, I must have confused you, I meant vent line not fuel supply line, I said fuel line as in lines that deal with gasoline instead of lines that deal with diff ventilation. But I got what you are saying.

[tucsonjwt]

Let us know how those Spectra sending units work out. My fuel gauge started bouncing after I installed them on my C20.

[Gregski]

well thanks for the advice fellas but I had to pull the trigger on the new sending unit since no one has the one outlet in stock so it has to be ordered and that will take a couple days, they range in price from $114 bucks at Car Quest to $60 bucks at Rock Auto, I got mine at AutoZone for $90 so I could stack up some AZ reward points

we hope the brand new unit will give us a more accurate fuel gauge reading

Spectra Premium/Fuel Tank Sending Unit

Part Number: FG05P

[enaberif]

This thread reminds me of how I gotta do this all to my tanks :\ Probably in the spring though.

[hatzie]

The gauge repair guys can damp the needle shaft with a silicone gel grease.
The C2 corvette gauges have the same problem.
http://www.lbfun.com/warehouse/tech_...nding_unit.pdf

[hatzie]

GM came up with an electronic damper for the 95-97 T400 CK models. It'd be interesting to look at one to see how they did it.

Bulletin No.: 76-83-05

Date: September, 1997

Subject: Excessive Fuel Gauge Fluctuation
(Install Fuel Level Damper Kit) Models:
1995-97 Chevrolet and GMC C/K 4 Door Utility Models Condition Some owners may comment about excessive fuel gauge needle fluctuation when making turns or braking with less than a half tank of fuel.

Correction

Install fuel level damper module kit P/N 12167652 following the procedure described on the instruction sheets included with the kit.

Parts Information

P/N Description Qty 12167652 Module Kit, Fuel Level Damper 1 Parts are currently available from GMSPO.

[motornut]

I used a Spectra unit,in the 79C, three years now no probs.
I'd heard of some complaints here,but I would suspect the gauge is done.
My 78K bounced like crazy driving,when I swapped idiot lights to Tach/gauges,
I had to change gas gauge,no more bounce.

When I swap a tank I always bend my sender arm up,1 inch or so,
gives me "emergency" gas,below E.
Less chance of a frozen gas line <-- happens up here lol