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Old 07-09-2008, 01:11 PM
C_I_A03 C_I_A03 is offline
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Join Date: Dec 02, 2007
Location: Augusta GA
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lurching while driving

So I'm slowly learning everything I can and am coming a long way, however I now have a problem that I can't seem to fix. While driving, at times, the Wag likes to lurch as though its getting a short burst of gas. It will do this till I either floor it for 10ish seconds, or let the engine die then restart. Neither of these problesm fix it every time, but usually they do the job.

I have other symptoms such as the engine dieing when I come to a stop (or when the RPM drops off.) and not always wanting to start up right after wards. I'm usually able to get things going and I'm getting from A to B, but would like to get it so I get from A to B smoothly and with out having to shift into neutral and feather the gas pedal to keep the RPMs up. I don't think it's dropping too low because when I start up (after the fast idle goes away), the engine runs at a good RPM, least as my ears go.

Help...

Stephen
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Old 07-09-2008, 01:51 PM
Ristow Ristow is offline
 
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you're lean. possibly due to vapor locking.
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Old 07-09-2008, 04:14 PM
eyotajeeper eyotajeeper is offline
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Join Date: Feb 13, 2006
Location: Iron Range, MN
Posts: 156
Check your carb base gaskets. sounds like a slight vaccumn leak.
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Old 07-09-2008, 08:29 PM
C_I_A03 C_I_A03 is offline
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Ok so vapor locking is...? I've done a bit of research and what I've found is that my gas is heating up so much that it becomes gas however isn't there supposed to be a line running back to the tank for that? As the carb base gasket, I'm going to Auto Zone to pick up one of those "flat" gaskets they sell. I took that off when I replaced the carb, but put on a spacer that came with the newer carb. That should ensure that the carb seals well with the manifold.
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Old 07-09-2008, 10:34 PM
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Blue & Gray Blue & Gray is offline
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Join Date: Feb 08, 2007
Location: Knoxville, TN
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Look at your fuel filter, on the output side you have two lines, one is off center and it heads back to the gas tank, it is your return line. The filter needs to be clocked so that this return line outlet is "up" and not laying side by side with the other line, side by side is no good, vapor needs to escape, to rise in the system and therefore the return line must be higher than the carb feed line. Side by side sends vapor into the carb feed as well return line. It is common enough for the filter to get rolled over, with the stock style filter it happens very easy.


I have long since switched to another style filter, with the return line coming out the side of filter cannister. I don't have a part number or picture but I think I got my last one at Wal mart, where I could paw through them and pick it out as that auto parts stores usually hide them behind the counter and I have no clue what car it actually fits. It is the same size hoses (5/16 inlet/outlet, 1/2 return I think) and swaps in easy enough and seems to stay clocked properly.
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Old 07-10-2008, 06:18 AM
C_I_A03 C_I_A03 is offline
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I'll check that on break. Hope the fix is that easy. WOuld this also help on starts?
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Old 07-10-2008, 02:11 PM
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Don S Don S is offline
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Quote:
Originally Posted by C_I_A03
I'll check that on break. Hope the fix is that easy. WOuld this also help on starts?



Vapor Lock Quick Check List update 03.08.06
Is the engine properly tuned and running a near normal temperature?
Is the fuel a winter/high altitude grade with low boiling (vaporization) point?
Is the fuel tank properly vented? Check the fuel cap or carbon canister.
Is the exhaust system heating the fuel tank or fuel lines?
Is the sock type filter in the tank getting stopped up intermittently?
Are the fuel lines and inline filters free flowing?
Have the fuel lines got rotten or rusty and clogged up or leaking air in?
Have the fuel lines been insulated?
Is the fuel pump output the correct volume and pressure?
Is the fuel pump electric so it can pump fuel with the engine not turning?
Is the fuel return line still in operation?
Is the heat riser valve in the exhaust pipe working correctly?
Is the manifold hot air intake working correctly?
Is the fresh/cool air intake hose fastened to the air cleaner?
Is a thick insulator gasket under the carburetor to stop boil over?
Is the carburetor float correctly installed and the level properly set?
Is an air dam installed to increase air pressure at the radiator?
An electric fuel pump does not always eliminate vapor locking!
Vibrations of the fuel lines could contribute to vapor lock problems.
As altitude is gained vapor lock problems increase.
If you think the engine has just died due to Vapor Lock and it is in a safe place do the following while it’s still hot :
Turn off the ignition, put the transmission in park and set the emergency brake. Check under the hood for coolant leaks. Pull off the air cleaner and look for fuel leaks. Check that the position of the choke is fully open. Look down into the front barrels of the carburetor and pull the throttle linkage open four times. If you see a lot of mist or gasoline squirting in the carburetor it would indicate fuel pump and accelerator pump are working and you may have an ignition problem.
If no fuel squirts into the venturi area of the carburetor then there is the possibility of several problems and these are included in the previous list.
What to do? Some times a temporary fix is to cool fuel supply lines and pump and then maybe some shielding might help. Cool water has been an aid to getting back on the road temporarily so carrying a gallon of drinking water is a good idea. In many cases once a vapor lock problem starts it soon gets worse.
Try removing the filter and blowing out with a reverse flow. The flow valves in most fuel pumps will not allow the fuel supply lines to be reverse blown from the carburetor. The fuel supply line to the pump can be reverse blown and, with a helper, the bubbles should be audible in the fuel filler neck.
Heat Soak
Is heat fed back to the engine from the exhaust manifolds when the engine is turned off.
... If the engine does not start because of Heat Soak it is because the fuel in the carburetor bowl has boiled away. It is also possible the fuel in the pump chamber and the lines have vaporized. Automotive mechanical fuel pumps do not pump vaporized gasoline very well. A properly mounted HD electric pump will usually refill the carburetor quickly.
... Cooling the fuel systems will help. But the quick fix that a lot of people use is a very dangerous process. Some people pour small amounts of gasoline (less than an ounce) into the throat of the carburetor then crank the engine. Some people pour the gasoline in while the engine is being cranked. Ether way the problem is the engine will often back-fire through the carburetor blowing the gasoline back out and starting a bad engine fire. A good engine fire is one you can put out quickly and it didn’t burn off your eyelashes!


Have a good one while you can still laugh about it.. Don S..
I am now in the futures market,… hording if you will, buying things I will need in the future because the real American food inflation rate is approaching 20 percent And ‘fixin’ to get worse!
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