Technical Bubbles wont start...again

[usafstud]

So i'm still having trouble with the engine wanting to die after it has been running for a bit. Could the new filter be too big and be decreasing the flow pressure?

 

[JakeF]

I think the o-ring is for the idle mixture screw? I have the same kind of filter with no problems ..hope this helps

 

[Bambino]

Where does the rubber o-ring and brass ring go? Are they spare parts?

As Jake said, the small o-ring seals the idle mixture screw. On the later model IMBs the idle mixture screw is recessed and uses the small o-ring to seal against an air leak. Older IMBs didn't have this feature, nor did they have an o-ring.

I think the brass gasket goes on the carby fuel filter cover.

I've attached a photo.

The main fuel filter should be OK (I also have a similar one) but just check that the it is not one-way (there will be a flow arrow on it if it is).
Also it may be an idea to use a couple of hose clips on the filter. The fuel isn't under much pressure here (gravity only) but if one hose pops off, you may have a fire.

Chris

 

[usafstud]

There was a separate o ring for the fuel filter cover.

I'll put some hose clamps on the fuel filter. The filter is directional and the arrow is pointed to the engine. I may remove the valve cover to check on valve gap tonight.

 

[jjacob]

So i'm still having trouble with the engine wanting to die after it has been running for a bit.

How long is "a bit?"

First, if you have a later IMB carb and you did not install the o-ring on the mixture screw, as Chris indicated, then you may have excessive air bleed which will mess up your fuel ratio, leaning it out. Make sure the o-ring is installed. It goes in the groove, just under the head, of the mixture screw on the left of Chris' picture.

If the o-ring does not solve your problem then proceed to the next step. If the car starts and runs fine, then wants to die once it is warmed up, then I would suspect that the idle mixture is wrong, or the fuel enrichment valve ("choke") is not fully disengaged.

Check to make sure the "choke" is fully off by manually pushing the choke arm fully closed after the engine has run for a couple of minutes. If you find the choke is not fully off, then you need to adjust the control wire so that it turns it off fully when the lever is in the down position.

When the choke is fully closed, then try turning the fuel mixture screw in or out a quarter turn at a time. Do this when the engine is fully warmed up. Turn in until the engine stumbles, then turn out quarter turns until there is no improvement in engine running. Do not turn out too far or the engine will run rich. I usually turn it in until the engine stumbles, and then turn it out 1/2 turn from that point and it is almost always perfect.
John

 

[usafstud]

O-ring replaced and choke fully disengaged. Still having issues. I may check valve gap next.

 

[usafstud]

O-ring replaced and choke fully disengaged. Still having issues. I may check valve gap next.

http://s96.beta.photobucket.com/use...47-2773-0000068F2B727AE6_zps8da7382e.mp4.html

http://s96.beta.photobucket.com/use...BF-2773-0000068F014B19AF_zps3b5aab40.mp4.html

 

[tjmra]

John,

is there much fuel in the bottom of the filter? Is hard to tell from the first video. Does the level change after the car runs and then dies?

Joe R

 

[dunnah01]

Defo not enough fuel in that filter - try taking top off pump to check condition of diaphragm. It may have a small tear which would only allow a small amount of fuel to the carb and show the symptoms you have.
Also try blowing through the pipe to the tank to make sure it's clear and fuel can get through (you should hear the petrol bubble in the tank when you blow) - careful not to suck!! petrol tastes awful, although you may want to prime the filter by attaching some clear tubing to the end of the supply pipe and sucking petrol through until you see it in the tube. Then quickly but carefully re-attach to filter.

 

[Bambino]

From the videos it seems to be running out of fuel. It's as if the fuel pump isn't keeping up with the required delivery rate when the engine accelerates even though it is supplying enough when the engine is idling.

Check the fuel tank breather, the fuel line for kinks and blockage, the fuel filter (seems to be OK - fuel will gravity flow when the car is level), the pump and the filter element in the carby first.

You can check the pump by disconnecting the fuel line from the carby and placing it into a clear glass receptacle (eg: drinking glass). Disconnect the red (+ve 12V) lead from the coil and have someone crank the engine while you see if fuel is pumped or not. The pump itself may be full of gunk and as dunnah has said above, it can be checked by removing the pup cover and inspecting the gauze strainer and diaphragm.

Chris

 

[tjmra]

- careful not to suck!! petrol tastes awful,

If you do make a mistake and suck rather than blow, can you let us know how many mpg you get?

Last time I did that I was running aroung the yard spitting and gagging for about 15 minutes. I think I got about 2 mpg.

Joe R

 

[Bambino]

Be careful if you swallow it too - you'll have flammable diarrhoea the next day. And you thought a vindaloo was bad
Chris

 

[jjacob]

Check the fuel filter on the end of the pick up tube in the gas tank. On my car this was completely blocked with varnish and some rust particles. Undo the nuts holding the sending unit on the tank and remove. Look at the mesh screen on the end of the pick up tube. You can clean it with some lacquer thinner and an old tooth brush.

If you find a lot of rust particles you will need to flush the tank out, and maybe consider replacing it (actually not that expensive).

I did not get any fuel flow to my carb until I cleaned the pick up filter, but my car had sat for 6 years with old fuel in the tank.

The fuel pumps are cheap. If you do not know its age, I would just replace it.
John

 

[usafstud]

After the upper half carb rebuild, the engine still days when i give gas after decel.

The fuel pump filter was clean. I took the fuel pump apart and the inside looked clean with good spring pressure. Here are some pics. I may get a new pump. Advice?

 

[jjacob]

That fuel pump diaphram looks a little tired (wrinkles in the diaphram). Just replace it. They are cheap. I would not worry too much about the brand. Just get the proper one.

Have you checked the fuel pickup filter in the gas tank?

John

 

[usafstud]

That fuel pump diaphram looks a little tired (wrinkles in the diaphram). Just replace it. They are cheap. I would not worry too much about the brand. Just get the proper one.

Have you checked the fuel pickup filter in the gas tank?

John

Fuel pickup filter was clean when i checked.

 

[usafstud]

So I got a new fuel pump. For install, do I need to pack the inside with grease like this picture?

 

[jjacob]

No you do not pack it with grease.

I would go ahead and pour a little oil in there to give it some pre-lube, make sure the oil is still not draining out of it when you install, or the gasket and pump and engine gasket surface will get full of oil (should be dry when installing). The fuel pump is lubricated by the engine oil.

That is not grease in there. That is engine sludge and varnish.

John

 

[usafstud]

No you do not pack it with grease.

I would go ahead and pour a little oil in there to give it some pre-lube, make sure the oil is still not draining out of it when you install, or the gasket and pump and engine gasket surface will get full of oil (should be dry when installing). The fuel pump is lubricated by the engine oil.

That is not grease in there. That is engine sludge and varnish.

John

Thanks John. I'll pre-lube it for the install tonight. Is there anything i got to do besides just putting it back on and bolting it down?

Frank

 

[jjacob]

Nothing special. Don't forget the gasket. Make sure the rod that operates the fuel pump is not bound up. Make sure to tighten the pump down evenly on both sides so it does not get cocked to one side.
John