What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

What would cause the fuel to drain back into the tank...

So Im guessing its the 2 on the left but thinking it wouldnt hurt to epoxy all the plugs? When I took it apart it was obvious it had been leaking for a long time.. Thick gooey varnish about 1/8" thick was all around the area circled on the left. Its cleaned up and epoxied now. Everything else was dirty but not too obstructed. I did find 2 dip tubes that had fallen free from the holes and are now back where they belong with a dab of epoxy on each of them?

Untitled-14.jpg
 
Last edited:
What a night! I got the Q-jet back together and slapped it on the truck. Hit the fuel pump and fuel came out every orifice on the carb. Figured the float was stuck so off it came and and opened again. Back on and fuel flowed everywhere again. Tapped on it with a mallet hoping to shake the float loose with no luck. I had an old Holly 600cfm model 4010 laying around for Im guessing 10 years. I opened it up and cleaned it out with carb cleaner and put it back together. Threw an adapter on the manifold and bolted it up. Turned on the pump and no leaks! Turned the key and it fired right off and just purred. Set the idle down a bit and took it for a spin... Problem solved! :whistle:
 
Well Crap, all that I can think of that is left is possible fuel heat issues. Thinking I might have a muffler or exhaust too close to the fuel line somewhere? Now it tends to sputter after it gets warm. let it cool and its good to go for awhile again. Hummm thinking maybe some sheet metal heat shields and insulation? Ideas... Please... We have replaced the tank fuel hoses, fuel pumps, carburetor, HEI Module, Vacuum hoses, Found and eliminated several vacuum leaks, I cant think of anything else that would make a difference? :sign27:
modify_inline.gif
 
Sputter when it gets hot??
That sounds familiar.

I know you have replaced it, but stories abound here about bad distributor modules. Both original and replacements.

Assuming the engine is sound, then its either fuel or spark.
Vapor lock usually shuts one down. If its running fast, the fuel flow will almost always keep the fuel cool enough not to boil.
And it would die when you started to idle.

I'm guessing module. Try to find a genuine GM one, they seem to work better from all the stories around here.
Also heat sink grease is vital. NOT dielectric grease. There is a big difference.

If you have a Radio Shack close by, grab a can of freeze spray. Also some heat sink compound.
When it get good and hot and is skipping, stop it, spray the module with the freeze spray, then crank it and see if it smooths out.
 
Fordum said:
Sputter when it gets hot??
That sounds familiar.

I know you have replaced it, but stories abound here about bad distributor modules. Both original and replacements.

Assuming the engine is sound, then its either fuel or spark.
Vapor lock usually shuts one down. If its running fast, the fuel flow will almost always keep the fuel cool enough not to boil.
And it would die when you started to idle.

I'm guessing module. Try to find a genuine GM one, they seem to work better from all the stories around here.
Also heat sink grease is vital. NOT dielectric grease. There is a big difference.

If you have a Radio Shack close by, grab a can of freeze spray. Also some heat sink compound.
When it get good and hot and is skipping, stop it, spray the module with the freeze spray, then crank it and see if it smooths out.
Click to expand...


Humm, It has a new exhaust system on it and Im thinking it might be close some where? I have a couple complete HEI units maybe just change out the whole thing and see if there is a difference. Little hot today plus football this afternoon. Going to have to wait till tonight. :doah:
 
Fordum said:
Sputter when it gets hot??
That sounds familiar.

I know you have replaced it, but stories abound here about bad distributor modules. Both original and replacements.

Assuming the engine is sound, then its either fuel or spark.
Vapor lock usually shuts one down. If its running fast, the fuel flow will almost always keep the fuel cool enough not to boil.
And it would die when you started to idle.

I'm guessing module. Try to find a genuine GM one, they seem to work better from all the stories around here.
Also heat sink grease is vital. NOT dielectric grease. There is a big difference.

If you have a Radio Shack close by, grab a can of freeze spray. Also some heat sink compound.
When it get good and hot and is skipping, stop it, spray the module with the freeze spray, then crank it and see if it smooths out.
Click to expand...

I'm grasping at straws at this point... I got some dielectric grease for the Module today. I also made a couple 18 ga. sheet metal heat shield to separate the muffler from fuel lines in the frame. I'm thinking the gas cap might be bad so I'm going to run without that for a day or so and see if that changes anything. :dunno: if the grease doesn't make a difference I will change out the whole HEI.
 
Metal Twister said:
I'm grasping at straws at this point... I got some dielectric grease for the Module today. I also made a couple 18 ga. sheet metal heat shield to separate the muffler from fuel lines in the frame. I'm thinking the gas cap might be bad so I'm going to run without that for a day or so and see if that changes anything. :dunno: if the grease doesn't make a difference I will change out the whole HEI.
Click to expand...

Uh uh uh. Dielectric grease is an insulator. Bad.

You want thermal grease, which is a nice conductor of heat. The idea is to draw heat off the ignition module and onto the body of the distributor. Worst case you can use silicone heat sink goo from a computer place -- the nerds use it for heat sinking computer chips.

-- A
 
dremu said:
Uh uh uh. Dielectric grease is an insulator. Bad.

You want thermal grease, which is a nice conductor of heat. The idea is to draw heat off the ignition module and onto the body of the distributor. Worst case you can use silicone heat sink goo from a computer place -- the nerds use it for heat sinking computer chips.

-- A
Click to expand...

Which is funny, when you go to buy a new module, that's what they come with now.. :doah:

Radio Shack also sells the thermal grease stuff.
 
4xcrazy said:
Which is funny, when you go to buy a new module, that's what they come with now.. :doah:
Click to expand...

Well, they are in the business of selling modules.......:whistle:

I use a lot of the heatsink stuff since I'm in electronics. Some of the regular greases are pretty good at heat transfer.

But, I always use the best stuff I can get, since its cheap insurance.
I think Arctic Silver is one of the top line one right now.

The most important thing to remember is to apply it very very thin. No matter how good the compound is at conducting heat, it is poor compared to metal.

So, you want the metal parts to touch nice and solid with nothing between. The compound fills in the microscopic pits and valleys where the surfaces don't touch.
If they are not filled, they will have air in them, and air is a great insulator.
 
Drove it quite a bit yesterday without incident... Fingers are crossed but I will be able to give it a better test this next weekend. :waytogo:
 
Well I thought I found an additional vacuum leak so I pulled off the carb and made a new gasket for the base. Tightened things up and it appeared to have fixed it. as soon as it got hot it fell on its face again. I checked it again and it has a vacuum leak at the intake manifold? I'm at the point now that I am going to put on a Edlebrock street master intake this evening. At that time I will drop in a different HEI that I have. After this I just dont know what else I can change out, Shield, or modify to make it work? Plugs are good but I havent replaced plug wires.... but if one was bad it would be all the time right? Can heat affect plug wires somehow?
 
Ok, I have the edelbrock manifold on, a different HEI distributor, The Holley now sits where the q jet did last week. have it all tuned up and it sounds great. I will try to give it a good test tomorrow? Hope this works this time! :doah::confused::zombie3:
 
Maybe I missed it in the thread somewhere. What evidence is there the fuel is going back to the tank?
 
Blue85 said:
Maybe I missed it in the thread somewhere. What evidence is there the fuel is going back to the tank?
Click to expand...

It was draining back out through a couple of see through filters below and before the carb. The carb bowl was leaking into the manifold as well over night. Not enough fuel to fire it off in the morning and none in the line so it would almost crank through the battery charge. Major PITA!
 
Final update I hope...

:D Just took the beast out for a 20 mile drive. Got it good and hot without issue, not a single stumble. It did diesel a little when I turned it off so I think I will recheck the timing and call it good. I wanted to thank all you guys for your input on this. It was a giant help to get good feed back from others that have had similar issues. Thanks again
 
You must log in or register to reply here.

Latest Posts

Top Bottom