FrontEngineDragsters.Org Forum
Technical => Spud Miller's Cave => Topic started by: 421Altered on December 10, 2016, 08:34:58 AM
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I'm a newbie to this site, but, I have checked all posts and can't find anyone having the problem I'm having. Here it is, I've got a 421 sbc injected alky altered. After I shut it down in the staging lanes, then when restarting, it revs up to maybe 3000 rpm, then immediately slows down to about 3-400 rpm, it just barely runs, then, it will come up on the pump and run fine. I think that my idle check valve which is set to 2psi is maybe leaking fuel past it because it's at the very bottom of my tank which is at the bottom of my chassis. Can anyone help me with this?
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Welcome to the site it is almost like already know you. Mine does not start easy and I built a primer system to help it. Turn on primer pump for a few seconds, hit starter and it starts but idles high until it comes on the pump. Then the RPM will drop and I shut off primer pump.
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Bruce good to see you here!!! It's not like that. If i prime it any at all, it just blows white smoke out collector's till it finally fires up like I said above, rev up real high, then drops way low, you think that its gonna shut off, but, then it comes up on the pump. You ought to see the expressions of the people in the staging lanes when it cranks up!! I wonder if I shim the idle check valve to say 4 psi. Would that cause any other problems? It's a Bird on a Edelbrock tunnel ram, with a Enderle cube, #30 flowed nozzles, a 1/2 DSR belt driven pump.
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2 lbs sounds a little light. 4 should be better. I've been as high as 7. You will need to adjust the idle mixture (barrel valve leak down) after raising pressure. It sounds a lot like how mine starts if Im not priming it.
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Thanks to Curley and BK for your replies. That's the info that I'm looking for, I'll try that next spring when I drag it back out.
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I'm going out on a limb here and saying your fuel tank is lower that the pump and fluids will always seek it's own level. Which means the alcohol level is below the pump and must be siphoned back up to the pump. The engine will start with what is in the cylinder and fuel line, but it will run lean. The engine will slow down due to fuel starvation and will run normally once the pump siphons the fuel through the vane and into the injector.
A priming pump is a good idea to alleviate that problem (not to mention less strain on the starter and battery. 7 to 9 lbs. of spring pressure is ideal on the idle bypass.
Keep having fun. :)
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glofria, Thanks for the reply. My fuel pump is as low as I can get it, and still be above the lower chassis tube bottom. So, the fuel pump is actually lower than the fuel level in the tank. Thanks for the info on how much pressure to use in the idle check valve.