Fuel supply issues

[evesdropper]

1984 Scrambler, 2.5l here. Starting to put this together and ran into a problem.

backstory: bought the jeep with a tank full of nasty old gas. I assumed that was the reason it ran like garbage and wouldn't start without ether. The fuel lines were rusted up pretty bad and crumbled when I tapped it. Plugged fuel filter also obviously.

Now: Fuel line running into a gas can, new filter and rebuilt stock carb (bypassed all the sensors. nutter bypass ICM). Jeep will start if I pour a little gas in the carb but dies right as soon as that is burned up.

Troubleshooting I have done:

1. unplugged the carb side fuel line and put it in a bottle. cranked the engine for about 20 sec. No fuel.
2. Took off the filter and ran the line into the bottle. cranked for 20 sec. no fuel.
3. Tried to pour gas down the fuel line to see if I could prime it. Cranked for 20 sec. even the fuel I poured in was not pumped out.

At this point I am thinking I have a bad fuel pump diaphragm in addition to the other problems this had when I got it. Before I drop the cash on a pump and gasket, is there any other thing I could check?

Thanks.

 

[jammer1]

Connect a hose to the in side of the pump and have the hose in the gas can. Take the fuel line where it connects to the carb and run the hose to a plastic jar or another fuel can. Crank the engine to see if you can pump fuel the the second fuel can. If you can, let it crank (around 10 sec then stop for a few sec than crank again) to get rid of any old fuel then connect to the carb. You probably will have to crank out any old fuel in the fuel bowl before you would have a chance at starting. If you get no fuel to the 2nd fuel can in the beginning the diaphragm in the fuel pump might be bad and you'll need a new pump.

 

[Lumpy Grits]

Take the cap off the gas tank and see what that does.
IF-no change, I would go with a new fuel pump. Don't go the cheap here!
Go to NAPA and get their best.
LG

 

[evesdropper]

Connect a hose to the in side of the pump and have the hose in the gas can. Take the fuel line where it connects to the carb and run the hose to a plastic jar or another fuel can. Crank the engine to see if you can pump fuel the the second fuel can. If you can, let it crank (around 10 sec then stop for a few sec than crank again) to get rid of any old fuel then connect to the carb. You probably will have to crank out any old fuel in the fuel bowl before you would have a chance at starting. If you get no fuel to the 2nd fuel can in the beginning the diaphragm in the fuel pump might be bad and you'll need a new pump.

Tried all that. The bowl was empty when I started. I can't get any gas out of the output hose of the pump.

 

[evesdropper]

Take the cap off the gas tank and see what that does.
IF-no change, I would go with a new fuel pump. Don't go the cheap here!
Go to NAPA and get their best.
LG

No one stocks the pump around here. I will head To Napa and order one. Thanks.

 

[evesdropper]

Checking back in.

New pump installed and I definitely have pressure now. Spurts out of the main carb feed and a bunch out the top return feed also.

The only pump Napa has is the Airtex model.

Jeep still won't start but that is for another thread.

 

[Lumpy Grits]

Checking back in.

New pump installed and I definitely have pressure now. Spurts out of the main carb feed and a bunch out the top return feed also.

The only pump Napa has is the Airtex model.

Jeep still won't start but that is for another thread.

How long ago was that carb rebuilt?
Will it still start when you pour gas into the carb?
If it does-Sounds like the carb needs rebuilding/cleaning again.
Good luck,
LG

 

[evesdropper]

I rebuilt the carb probably 2 years ago. I had thought it was dry then but maybe not. I will pull it off. I have to order a carb kit. Would I be better off in the long run to just replace it with a weber k552 kit like this one?
http://www.amazon.com/GENUINE-WEBER-ELECTRIC-CHOKE-CARBURETOR-WK552/dp/B000JLKZYQ

It will start if I pour gas in the carb or use starter fluid. It won't stay running though.

 

[Lumpy Grits]

Rebuild what you have-
Wonder if ANY fuel is get'n into the carb's bowl?
When you work the throttle-Can you see any fuel squirt'n into the carb??
LG

 

[evesdropper]

Rebuild what you have-
Wonder if ANY fuel is get'n into the carb's bowl?
When you work the throttle-Can you see any fuel squirt'n into the carb??
LG

no squirt of fuel in the carb when I work the throttle. I took it off and will tear it down.

 

[evesdropper]

well, it wasn't as dry when I stored it as I thought. Carb is all nasty inside. I will rebuild and report.

 

[evesdropper]

Rebuild what you have-
Wonder if ANY fuel is get'n into the carb's bowl?
When you work the throttle-Can you see any fuel squirt'n into the carb??
LG

I notice there is not a check valve or flapper covering the bowl vent in this carb. there is definitely a place for a metal disc and valve. I am betting a PO discarded it. Is that important or can I block off that port? I am concerned that this would just a allow the pump to overflow the bowl all over the engine if the needle valve should fail.

 

[Lumpy Grits]

Any updates?
LG

 

[evesdropper]

The carb kit came and I soda blasted the upper and lower halves. I started to put it back together and noticed that all the soda residue was not cleaned off. I need to finish that tonight and put it back together. Then we will see how she runs if at all.

The vent flapper or disc missing is bothering me. is that something I should be concerned about? Seems to me that if the bowl overflows, all that gas would end up in the charcoal canister without a check valve of some kind.

 

[evesdropper]

Carb parts are soaking in a diluted vinegar bath now to ensure all soda residue is gone. They will get a compressed air blast and a rinse with brake cleaner. Then it's on to assembly.

 

[Torxhead]

I am sure you are correct with your concern about the bowl vent, as I remember on my bbd carb on the AMC 258 i6 / 4.2l . I once tipped the thing on its side without any fuel leakage. Anyway the carb float bowl does require a vent of some sort, If you could extend it up a bit that would help, the flapper valve would be best though. I do remember how nice it was to clean out carbs with parts dip which is no longer available.

 

[evesdropper]

I am sure you are correct with your concern about the bowl vent, as I remember on my bbd carb on the AMC 258 i6 / 4.2l . I once tipped the thing on its side without any fuel leakage. Anyway the carb float bowl does require a vent of some sort, If you could extend it up a bit that would help, the flapper valve would be best though. I do remember how nice it was to clean out carbs with parts dip which is no longer available.

Any suggestions on what I could use for the check valve? This model appears to have had a metal disc holding in a rubber flap or something. It has been gone a long time.

 

[Torxhead]

I am not familiar with that particular carb, you are going to have to get creative on that one. Maybe starting with a trip to the local carb shop,hardware store or industrial supply outfit. Good luck with that.

 

[evesdropper]

just an update...

I was delayed by having to order a new vacuum choke pull-off. The old one had a bad diaphragm. It arrived today and I should have a report this weekend.

No idea what to do with the bowl vent yet.

 

[evesdropper]

Update:

Carb is rebuilt and reinstalled on the motor. gas is definitely getting to the motor now. The motor fires up immediately but dies as soon as the starter is disengaged.

I read in another thread that AMC used two ignition circuits: one for starting and one for running. I still have the stock distributor in it (HEI in the wings) but bypassed the ignition module some time ago. It did run (on nasty stale gas) before I neglected the carb and started this thread.

I am certain the float is set correctly and I followed all the adjustments listed in the service manual I could do without running the engine. I do not know how many turns out the idle mixture screw should be. It is out 2.25 now.

I was thinking I should start with the timing but I am open for any suggestions.

Thanks.