The Stovebolt Site Forums The Shop Area Engine Shop Fuel drains back from upper filter

My engine wont start without pouring a bit of fuel into the carb...i've noticed that the inline fuel filter (clear type) is empty after sitting a few minutes... it has an electric fuel pump that is gravity fed from the fuel cell.

any thoughts?

fuel pump isnt working

Read my thread rusty. Sounds like my problem I had

Thanks for posting that question Rusty, because I have the same problem. Mine doesn't drain empty after a few minutes. Instead, it is half full (or half empty for you pessimists) after a day or so.

A few months ago, when I wanted to start my truck, I'd pull out the choke cable, give the accelerator pedal two pumps, and the engine would light off without a problem.

Due to some acceleration problems, I rebuilt the carb. While I was at it, I cleaned up the filter bowl and replaced the filter. Now it won't start unless I crank and crank and crank. I believe this is because the fuel bowl drains to about half-filled after the truck is parked.

Once running, it purrs like a kitten. But why is the fuel draining out of the filter???

I read your post, Petmil, but it doesn't sound like my problem. I have a mechanical pump, and it seems to work fine. In fact, I think I've eliminated the pump as the problem since lots of cranking gets the problem resolved. Obviously the pump is pumping fuel up there. My problem is keeping it there between drives.

Suggestions?

Just move the filter so its down by the mechanical fuel pump location and it won't siphon dry. The filter shouldn't sit over the exhaust manifold anyway.

Shouldn't the valves in the fuel pump prevent drainback to the tank? Would the addition of a check valve clear up these problems if the valves in the fuel pump don't prevent drainback?

Doesn't the carburetor bowl have sufficient fuel in it to start and run the rig for at least a minute.

As soon as the engine started, the system would fill and no one would be the wiser, especially with a electric pump...as soon as the key is turned on, the pump starts.

On the clear inline filters (throw-away), I have noticed that the fuel never does completely fill them, even when the engine is running. As Baldy pointed out, whatever type pump you have, it is equipped with check valves of some sort.

I think if the rig won't start, it is a carburetor issue, and has little to do with a system that might be draining.

Stuart

I definitely suspect my carb. I'm on the edge of just replacing the darn thing- the cover doesn't seat flush against the bowl casting. (I've read the thread about doing stress-relieving in my oven, but I'd rather not go that route.) I've noticed gasoline seepage, very slight, down the outside of the throat. I don't think it is air/gasoline-tight. I've suspected this is like losing prime in a pump. For about a hundred bucks, I can have a "new" rebuilt carb and be relieved of this aggravation.

It doesn't seem right that moving the filter to the pump would help. It worked fine before I messed with the carb. As part of the fuel flow schematic, it shouldn't matter where in the line it is positioned, whether at the pump, at the carb, or someplace in between.

Could it be that my problem is evaporating fuel from a carburetor that has poor mating between the castings?

Bill

TxLaTx,

If your truck started OK, you rebuilt the carburetor and now it doesn't start OK, my bet is on the carburetor.

I think the Rochester can leak internally as well as externally.

I have seen the posts lately about the fuel draining back toward the pump/tank. On a scale of 1 to 10, I think the probability of this happening would be about a 30!

If the system was going to do any leaking, it would probably be into the engine. If the fuel bowl held its level, and for some unknown reason the system drained back toward the pump/tank, seconds after start-up it would replenish itself and, as I mentioned above, it would go unnoticed.

It would be interesting to stick a shutoff valve immmediately in front of the carburetor, start the engine, and after a moment turn the valve off. How long would the engine continue to run...I'll bet it would surprise you!

This is all speculation on my part...it just seems like it should work this way. I have been 'out to lunch' before, so it might be close to noon on this idea as well.

Stuart

The problem is you are using a fuel cell instead of a gas tank,I had the same problem,I went back to the old gas tank.LOL (Is your right leg longer now?)

It still could be a faulty pump. I have found that you may have fixed something like your carb and it still won't run and found out later that it was the fuel pump after all or a combination of both. That has happened to me on different situation in my life time. Just a thought. If the pump was alright wouldn't the gas flow to the carb after few cranks not several plus there must be gas in the floats ???