Hard to start after two or more days

[uberbeans]

I have a 80 K-5 that I have done complete body off rebuild on. Stats are a 383, sm465, np205, detroit locked 12 bolt, with honestly too many extras to list. My problem is that if the truck sits for more than two days it becomes very difficult to start. I will have to crank it over for at least 35 seconds for it to fire up. This is strange because if I crank it up any other time within that day it fires up as advertised without even cranking a full revolution. I think that the fuel bowl is emptying while it is sitting still. The carb is a 1903 Q-jet(new), holley electric fuel pump(new), -6 braided line from the newly sealed fuel tank all the way to the carb. I installed a "one way" check valve(new) to ensure that gas doesn't leak backwards when shut down. Also I let the pump run through the line to pressurize it before the key is turned to crank the engine. The ignition is a MSD 6-AL. I called Edlebrock's tech line and they said to check the bowl seals under the throttle plate for leaking. I did even though it is new and found no problem (i epoxy'ed them anyway and know that they don't leak). I'm a little stumped about this, because everything is new and runs very strong. It just is difficult to start after a few days of not running. I would love some advice from anyone who has any no matter how strange it sounds. It's kinda embarrasing to have my newly finished project have this problem.

 

[dyeager535]

To figure out if you've got fuel or not after it sits, pop off the air cleaner, make sure you can see down the primaries, and work the throttle linkage. You should see a shot of fuel from the accelerator pump.

If you don't, the float bowl is empty, and obviously fuel is leaking out somewhere.

If you do have fuel (which sounds unlikely in this case) then something else is the cause.

 

[uberbeans]

Thanks for the quick reply. Since I am at work I can't check the carb yet. It isn't an external leak because I checked for that, it could be an internal leak. I checked the fuel bowl seals and they aren't leaking, though I put a coat of epoxy anyway (approved by edlebrock). How else could there be an internal leak? Could the fuel be leaking back through the fuel line? I installed the one-way check valve to prevent this (doesn't mean that it is working the way I want, though), plus the electric fuel line should charge the possibly empty fuel line and fill the bowl, right? The q-jet design is controlled by vacuum. Does that mean that the bowl won't fill unless the engine is producing vacuum? That doesn't sound right. Maybe it is an adjustment on the carb, but I would think that would be a problem for every start. Maybe it is my start procedure. How do you start your truck? When cold, I floor the pedal and release it to set the fast-idle cam and the choke. This is the way that edlebrock says to do it. Maybe this floods the engine. I have a fuel/air ratio meter that says my mixture is right. When warm, I just turn the key and give it a half throttle blip until ignition and let it go. Thanks for your help again.

 

[dyeager535]

With the epoxy, did you seal up the "well plugs"? I would have *thought* with them remaking these that issue would have been solved, but oh well.

As large as the float bowl is, do you wait a few seconds before trying to crank it? Again, test first for an accelerator pump shot after sitting, if no shot, if the pump is wired to run with the key off, turn the pump on and make sure you are getting fuel.

I would speculate that the float bowl is empty, and it just takes a bit for the float bowl to get enough fuel in it.

Float bowl "fill" is governed with the float, so with the engine on or off, it will fill if it's low and fuel pressure is high enough.

Start for me was one pump and crank. If you have no fuel going to the engine though (which you will find out by watching for pump shot) you won't have to worry about flooding. /forums/images/graemlins/smile.gif

 

[Mastiff]

Man, if you figure this out, let me know. I have the same symptoms, except that it only takes about 10 seconds for me, not 35. I also epoxied the plugs, and was certain that would fix it - but no. I don't have a check valve as far as I know, but I have a mechanical fuel pump.

I'm going to test whether it might be a choke problem. My choke was set for winter and never truns on now, so maybe that's messing things up. The thing is, the truck will start right up after sitting for 4-8 hours, wouldn't it be cooled down by then?