On my AMC 304, if I let it set over night, it seems as though the fuel drains back from the filter etc, past the fuel pump. It takes some cranking to get it fired back up again. I thought the pump had a check valve in it?
Beat it to fit, paint it to match!
I had the same problem. Have you got the fuel filter turned so the return to the tank is positioned at 12 o'clock? Mine was down at 6 o'clock so the fuel was draining back to my tank I think. I adjusted the filter and set my choke. That was about 2 weeks ago, its started every time since then. Before that a few days sitting and it wouldn't hardly start without a splash of gas or a shot of fluid. Seems to have worked so far, fingers crossed
In that case you may be on the right track looking at the fuel pump check valve. It could be just weak enough to drain but not bad enough to cause low pressure and driving problems yet. I was thinking with this new ethanol gas it also evaporates quicker.
I guess if you could pinch the line or add a cutoff valve between the carb and pump. Then you would know if it was evaporation or it was leaking back past fuel pump.
Mine is the same way... If it sits longer than a day it takes quite a while to get fuel to the carb. I haven't spent a ton of time looking into it, just dealing with it at this point. One thought I had was that my gas tank leaks a little around the fuel inlet and maybe that causes it to flow backwards. Don't know if its a lack of pressure thing or not...?
[SIZE="4"][B][COLOR="DarkOrange"][I]The world would be a better place if being stupid hurt...[/I][/COLOR][/B][/SIZE]
The original system had a mechanical pump, a 3 way filter and a U bend before the carb. Fuel was stored in the filter, the U bend and the float bowl. Standing overnight they should start first time, you just pump the throttle twice to get it on the fast idle cam and inject a little fuel and she is good to start.
I had this trouble for years. Then I popped the top off the BBD one morning and realised it had fuel in the bowl and on the second revolution on the starter more flooded in. It was not fuel starved at all, it was a mixture problem.
So I replaced all the vacuum hoses. Some were loose, some perished.
Both CJs now start first time every time. It is uncanny how they just fire up and sit there purring.
An electric fuel pump would only help if you had an issue with fuel draining from the pump to the tank. As the tank connection is at or above the pump this seems unlikely but you could get a syphon effect. The hoses also split at the tank, letting in air etc.
These things were properl built so if you have a problem it is fixable. An electric pump is a sticking plaster over the issue which may be leaking hoses at the tank, a fuel filter wrongly installed or a vacuum leak.
This carb (Q-Jet) never had a return on it when it was in a Chevy truck.
The fuel pump is brand new. I will never run an electric fuel pump other than with fuel injection, so that is out of the question.
The mixture is tuned the best I can get with out an o2 sensor driven meter. It constantly holds 19hg at idle.
The whole fuel system is brand new. New pickup in the tank, new soft line from the pickup to the new hardline on the frame, new line from hardline to pump, new pump, new line to filter, new filter, new line into carb.
I just had a thought (I know, it happens sometimes). What if I put a 12v solenoid valve in the line just as the fuel line comes out of the tank and hook it to 12v switched? That way, I can run it though a switch and also act as a theft deterrent device.
Beat it to fit, paint it to match!