Fuel pick up in tank?

T

Tracy72RN

Member
A few weeks ago our '74 became hard to start and it seemed as though we inadverntantly ran it out of gas. It has an aftermarket fuel gauge that up until then seemed fairly accurate and it still read half a tank.

Any way I put 5 gallons in and it fired right up. Since then...and after filling it up it fires up real easy but after a few minutes at idle it starts to stutter and dies. It will fire right back up...and you can drive it down the road but if you let it sit and idle it will die after just a couple minutes. It is not running rough while idling (short as it May be).

Gauge is reading at about half a tank and if I shake the rear of the rig I can hear fuel sloshing around.

The po put in a new aluminum tank about a year or so before we bought it.

I checked fuel pressure 2 different times and got ~5.5 psi both times.

I have 2 fuel filters one right after the other...and the first one after the pump is clear then it goes into the 'regular' filter. The clear filter shows no dirt/debris or anything else. But it does not ever fill up...even under full throttle. Fuel just seems to trickle in even at 5.5 psi I would think it would stay full or close to it. I've run it with the inlet of the filter pointing down and also pointing up... And it doesn't change anything.

Looking like I am going to have to drop the tank to check the pickup but I wanted some opinions on what...if anything else it May be...?

74 Scout II, 345, 4 spd, 2 bbl Holley 2300 series.
 
Visible filters normally display roughly one half to 2/3rds fuel level while the engine is running and after being shutdown. Perhaps the first filter in the series is plugged and not allowing the second filter to fill. What about running it with the non-viewable filter removed to see if that makes any difference? Another thing to verify is the carb fuel bowl float level. This is done with the engine idling while parked on a level surface. Have a rag positioned under the fuel bowl to catch any spill. Remove the brass site plug. Fuel level should be just at the bottom of the hole allowing just the slightest amount of seepage to escape. It should not be a gusher, but the threads of the hole should not stay bone dry either. Make the necessary adjustment to the float needle depending on what condition is present.
 
The clear filter is the first one in the series and it isn't filling up much more than about 10% even under full throttle.

I will try to run with it by itself and I have been wanting to mess with the carb float...I've been wondering if that's been an issue with the off idle hesitation as well.
 
Thinking about this, I May need to clarify my remark. Fuel filters on the carb side of the pump will show a half to two-thirds full level. I don't know if the same would hold true for a filter on the tank side which is upstream from the pump. The pump is only going to draw and delivery as much fuel as it is calibrated to draw. The pump diaphragm is supposed to keep the fuel between it and the carb pressurized, but I don't believe the fuel in the line between the tank and the pump is under any pressure. In the case of more modern vehicles with tank-mounted pumps, the entire length of the fuel line is under pressure.
 
My guess would be a small leak in the pickup tube or line from the tank. Try hooking the inlet to the pump to a small gas can on the ground under the engine and see if it fixes the idle issue.
 
Yeah I definitely need to check for leaks. I found a couple the day we brought it home so I am sure there May be more lurking.

Scoutboy74 I did understand what you meant in your original reply...you were very clear :icon_cool:

my fuel system runs in this order:

(1)tank
(2) line to pump
(3) pump
(4) line to clear filter
(5) clear filter
(6) line to 2nd filter
(7) 2nd filter
(8)line to carb
(9) carb.

As I mentioned the clear filter never seems to fill up more than about 10%...and as you said I would expect it to be 50% or more full of fuel at any given time.

I May just replace everything but the tank, carb, and pump and see what I find. Along with adjusting the float. I am wondering now if there's a leak somewhere in one of the short lines between the pump, filter(s) and carb.

Pesky work schedule keeps getting in the way!! :shocked:
 
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