Pumpin' Fuel

Pumpin' Fuel

Niedhogg

Old Time Jeeper
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Location
Thor, Iowa
Vehicle(s)
'79 Jeep CJ7 Renegade with 304ci V8, TH400 auto, Quadratrac T-case, Stock 20 and 30 rears with no mods yet, not sure of the gear ratio.. 4" Softride Superlift, w/widetrac shock towers and 35x12.50x15 BFG Mud-Terrains

'76 CJ5, 232 ci, T-150 3-speed, D20 T-case, Corp. 20 rear w/full float axles and lockout hubs and Detroit auto locker, D30 front w/lockout hubs, gear ratio is unknown..
Installed a new pump on the CJ5, but it won't suck anything from the tank.. It has been sitting for some time, hence the new pump, and the fuel lines look to be original as they have the crimped clamps on the hoses.. and the hoses are a bit dry rotted but don't seem to be damaged, in fact, I am able to blow air back through them into the tank, and placing my finger over the end of the pump I do have suction. I've put about 7 gallons of fresh gas into the tank so it should be at the pick-up, in fact, my wife could hear the bubbles from the air I was blowing in.. gas into the carb and she fires right up, but it's not drawing from the tank..:confused:

I guess I'll replace the rubber lines from the tank to the pump and see what happens?
 
Replacing the rubber lines is a wise plan. You might try to siphon gas thru the line up to the pump to remove the air out of the system.
 
I guess I'll replace the rubber lines from the tank to the pump

Replacing the rubber lines is a wise plan.

Yes it's very possible that you have a leak. You would still be able to blow bubbles into the tank. A agree with both of you, replace the fuel line.

Also I assume you are using an OEM style mechanical pump. If you installed an electric pump you need to prime it.
 
Yes it's very possible that you have a leak. You would still be able to blow bubbles into the tank. A agree with both of you, replace the fuel line.

Also I assume you are using an OEM style mechanical pump. If you installed an electric pump you need to prime it.

Ya I seem to recall yeeears ago, a certain '71 Chevelle that had given me similar problems, I could blow air back to the tank and hear the bubbles, and after I had replaced the pump and rebuilt the Holley right where it had broken down, I finally pressurized the tank and found the bad rubber line...

And yes, I installed an OEM style pump, so I guess that's my project for the day then.. Thanks guys..
 
are we sure we are on the right track? Could it be the carb?
If you remove the fuel line at the carb and hold it over a coffee can or some other container have someone crank the engine. Does fuel come out?
 
are we sure we are on the right track? Could it be the carb?
If you remove the fuel line at the carb and hold it over a coffee can or some other container have someone crank the engine. Does fuel come out?

Nope, I tried that and she's bone dry and the filter is clear as well...

Seems weird that it won't draw any fuel at all though..
 
The pump is made to push gas to the carb you should have gas at the pump. Gas coming from the tank to the pump is more like a siphon.
 
The pump is made to push gas to the carb you should have gas at the pump. Gas coming from the tank to the pump is more like a siphon.

That may be so, but it's dry there too... there is suction, it'll hold my finger on the tube..
 
Yes it does siphon as Mtnwhlr stated and that siphoning effect can have a problem if there is no ventalation at the gas tank. This can affect both manual and externally mounted electric fuel pumps.
 
Yes it does siphon as Mtnwhlr stated and that siphoning effect can have a problem if there is no ventalation at the gas tank. This can affect both manual and externally mounted electric fuel pumps.

Everything is stock, all the lines are hooked up, even the canister in the rear wheel well, and I had the gas cap off... can't get much more ventilated than that.. we'll see what happens tomorrow when I replace the rubber lines.. I found my supply of gas line is gone so it didn't happen today.
 
I have had to take a air hose and a rag to the fill tube and pressure rise it untill I have gas at the fuel pump. Then prime the motor and you should be good. :)
 
I have had to take a air hose and a rag to the fill tube and pressure rise it untill I have gas at the fuel pump. Then prime the motor and you should be good. :)

I had thought about doing this, in fact, it's how I found the bad line on that Chevelle.. I might just give it a try today before I go to town for fuel line.. thanks mtnwhlr..
 

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