hard starting after setting for 8+ hours - Chevelle Tech
Troubleshooting Diagnosing problems done here.

 
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post #1 of 3 (permalink) Old Sep 24th, 15, 9:43 PM Thread Starter
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hard starting after setting for 8+ hours

About a month ago I did a headgasket replace on my "69" small block. In the course of this repair I replaced the intake and installed a Edlebrock Performer manifold and put my 1406 Edly on top of it. Everything ran great for awhile,but slowly I started experiencing it starting hard after setting overnight. Have tinkered with the electric choke and it is where it should be at close according to Edlebrock and opens fully on warm up. I have a clear bodied gas filter between the carb and the stock mechanical fuel pump and noticed that after setting overnight the gas filter was half empty. I ran a little experiment this morning and after some grinding on the starter got it to keep running. Ran it this way for a couple of minutes,but engine was still cold and temp. gauge wasn't to the 100 degree mark yet. I then shut it off and waited 8 hours and looked at the fuel filter ( which was full when shut down), it was half empty. I will mention here that when I shut the engine off the fuel pressure gauge stopped at 6.5 psi.( eight hours later it was at 3 psi.). I crawled up into the engine compartment ( not a easy thing for an old fart like me) and moved the throttle to see if any gas from the accelerator pump was flowing into the primary's. Saw a little dribble out of one nozzle and nothing out of the other one! Tells me that there is no fuel in the bowls,but the question is where did it go? Is my fuel pump going south ,do I have a bad fuel filter,or is something in the carb. causing it to leak fuel? I don't really buy into the theory that the carb is getting hot and peculating the fuel. Besides I have a 2 inch Edlebrock spacer between the carb and the manifold and that should take care of any heat issues with the carb. I have the cross-over on the manifold that runs under the carb. fully open and when I ran the experiment it didn't get hot enough to be a factor. Before I buy a new fuel pump would like some assurance that I am headed in the right direction. If anyone has any other suggestions or theories, I am open to all. I had dug up some old posts that hopefully I could find an answer, but kind of went in circles.


Ted

"69" small block Malibu coupe
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post #2 of 3 (permalink) Old Oct 6th, 15, 10:42 PM
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Frank
 
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Re: hard starting after setting for 8+ hours

Your parts are very much like mine, the small block and 1406 carb and Performer intake. My intake crossover is blocked to reduce exhaust heat in the intake.
The Edelbrock 1406 Carburetor guide has a section for troubleshooting on pages 34-35, though it lists ignition timing, fuel filter, and underhood temperatures as causes for hard starting. One indication of trouble is the lack of fuel in the carb bowl for the accelerator pump to prime a cold engine. I would recommend to remove the primary rods and jets and check they are clean and the rods move freely.
I believe it is normal for the fuel level in the external fuel filter to drop a bit as the engine cools. Mine does the same.
Fuel pressure of 6.5 PSI is correct. Residual pressure hours after shutoff means the fuel pump does not leak.
I suggest you retighten the intake manifold bolts to verify the new gaskets are sealed. Torque the bolts in sequence (figure 2 in Edelbrock 2101 instructions, a clockwise spiral from center to the edges) to 25 ftlbs.
Next I would say to connect a vacuum gauge to manifold vacuum to check for a leak in the new intake gaskets. A mild cam should pull about 15 to 18 inches at idle. A lower vacuum reading at idle or a fluctuating needle would indicate an intake manifold leak or leaking intake valves.
Hope this helps you.

-Frank
1970 Chevelle Malibu purchased new in 1970
355 SBC, XE262H cam, Performer RPM heads, MSD HEI, TH200-4R trans, 3.55:1 Posi, digital gauges, QA1 coilovers
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post #3 of 3 (permalink) Old Oct 6th, 15, 10:49 PM
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wagonman
 
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Re: hard starting after setting for 8+ hours

do you have a mechanical fuel pump?

could be bad check valves....
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