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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: swilliams on January 26, 2014, 09:46:06 pm
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Can I put a check valve in my fuel line? When my 86 sits for a little bit you can see that all the fuel has drained out of the inline filter. Then when I try to start it I have to crank it over more than once. All suggestions welcome.
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Fuel drainback from a filter, in itself, is not unusual or alarming, or even meaningful for that matter. There should be a check valve incorporated into the mechanical fuel pump. About how many revolutions of the engine to start it when cold? What carburetor? Is this a new problem that just began? How long does it have to sit before symptoms occur?
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Yes it is a new issue but I just changed the inline filter. I don't know about cold start I just got it back together today but it is not acting like it did before. I still have some tweaking to do. If there is some type of check valve in fuel pump then there shouldn't be drain back should there be. It doesn't take excessive cranking just more than before.
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The fuel pump check valve typically is a fiber disc closed by a light spring against a steel seat that doesn't always seal perfectly. However, carburetors maintain an internal reservoir of fuel called a float bowl. Even if the fuel supply line and filter drain completely, sufficient fuel to start the engine and keep it running until the supply line refills is contained within the float bowl. A notable exception to this is if the float bowl has an internal leak such that it drains directly into the intake manifold. The design of the carburetor has significant impact on the potential for this to occur. Nonetheless, fuel generally will not siphon out of the carburetor back into the tank. So, I don't believe that the fuel filter 'draining' is significant in this case. What carburetor do you have?
Did the symptoms begin with the installation of the MSD ignition components?
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It has happened since I installed the msd and changed the inline filter but I still have to check timing. I believe it should be 12deg before TDC is that correct. the carb is an Edelbrock 1406 I have not had any problems previous so I hope it is just timing or something small.
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Are you still using the 5-pin module?
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yes still using the 5pin
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Since you're stripping it bare anyway, defeat ESC altogether either by (1) altering the four wire pigtail (http://www.73-87.com/7387garage/drivetrain/escrepl.htm) exiting the back of the distributor (the inexpensive approach discussed near he bottom of the link), or (2) replace the distributor with a non-ESC HEI (same link). ...MSD offers some nice billet distributors....
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Are u saying that I should change to a 4 pin instead of 5 pin.
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I won't assure you that it's true, rather, I suspect the engine will perform better w/o ESC, and the symptoms you expressed will likely disappear. There maybe other benefits, as well. At least, that's the common claim from those who have defeated it. You can go about removing ESC by replacing the entire distributor; or you can convert your existing distributor to a 4-pin; or you can modify the four-wire distributor pigtail and continue to use the 5-pin module. The last approach is the most conservative and the least costly of the three. The linked article explains how.
There has been significant discussion on this Forum regarding ESC and the benefits of removal. Perform a search.
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Thanks for that I will definitely check into it. I am not liking the small issues I have been having.