Should fuel filter be full?

[eightbanger]

Now my truck is runing real bad, it starts fine and idles fine, but when I take it out and give it Gas it starts bogging and miss fireing. I cleaned the plugs but they weren't that dirty, i'm starting to think it's a fuel problem I took a pic of the fuel filter when the truck was runnning, and it has only a small bit of fuel at the bottom should the glass filter be filled to the top? has anyone got any ideas?. Thanks.

[69long"n"low]

mines not always full but id make sure the timing is dead on i was having the same problem and it ended up being timing

[eightbanger]

Had'nt thought of that! Thanks Josh.

[ChevLoRay]

I situated my filter, same kind as yours, horizontally and lashed it down so it couldn't bounce and break the glass. The filter didn't always have very much fuel in it when I was doing a cold start (overnight), but it pumped up quickly. When it was running, it would fill up, but not be "packed".

There are those who will tell you these filters are dangerous because they are made of glass and etc. Just be sure that it is assembled tightly so it doesn't leak. The nice thing about them is the ability to take them apart and clean the rust out of them....you don't have a NEW petrol tank, do you?

[MrBeast]

Well, here is what I see, the fuel level is uber low for a running engine, usually these sight glass style filters will be full of fuel and have a small air bubble at the top.

I would highly sugjest running a pressure test on your fuel pump, as well you need to consider the condition of your gas tank and lines. a crimped or clogged line will cause not enough fuel to make it to the carb. This will still allow the truck to run, but it wont give it enough gas.

It is like trying to drink through a kinked straw, you might be able to pull some fluid through, but not a large volume.

If you have a spare fuel pump laying around, id try it, or I would actually consider picking one up to have as a spare and installing it.

(I always always always keep a spare on hand)

If that doesnt cure your woes, I would inspect your fuel lines and tank. Also do you ever smell gas in the cab?

this is a problem I have encountered before, where over the years the line running through the floor board from the behind the seat tank had developed a small crack in the radius, this caused the vehicle to dump fuel as it traveled down the road. not a shiny happy thing for sure.

[Sinister]

Originally Posted by MrBeast

Well, here is what I see, the fuel level is uber low for a running engine, usually these sight glass style filters will be full of fuel and have a small air bubble at the top.

[LockDoc]

As another idea I would check the size of the fuel line. Was it originally a big block truck? I think all of the big block trucks had a bigger diameter fuel line. If yours has the smaller fuel line it could be staving for fuel. At least I think that is the problem with my White '67. Maybe someone more knowledgeable on fuel systems knows for sure if that could be a problem with a big block.

Just had another thought. There is a strainer or "sock" on the end of the fuel pickup tube, inside the tank, that could be plugged up. This would also cause fuel starvation....

And yet another.... Although this doesn't sound like your problem I will include it here too. The 69 BB truck I purchased a while back had a non-vented gas cap on it, and after it was driven for a while it would start running crappy. After realizing what was going on I replaced the cap with a vented one and no more problem...

Just some things to think about.

LockDoc

[eightbanger]

Bummer what happened to multi quote? Chevloray I hear what your saying on the saftey issue but it's all secure.

MrBeast, a spare fuel pump is on the list for sure, there is a small psi gauge in the fuel line and it reads 7 psi, and yes I always smell Gas in the cab but I thought they all smelled as the tank was behind the seat, and i'll check the fuel lines for sure.

LocDoc, bought this truck from the US with zero history, just that it had a 454 crate and the mods in my sig, the sock on the sender is a good idea I renewed that recently but ran the tank down a couple of times so it could have sucked up some crap. Not sure about my Gas cap but it's the same one that has been on it since I bought it I just added an extra rubber washer to the back to make it sit tighter when it's on...I wonder? but my truck is a 71 and has that internal vent thingy.

Thanks a hole lot guys.

[MrBeast]

Originally Posted by eightbanger

MrBeast, a spare fuel pump is on the list for sure, there is a small psi gauge in the fuel line and it reads 7 psi, and yes I always smell Gas in the cab but I thought they all smelled as the tank was behind the seat, and i'll check the fuel lines for sure.

My memory is a bit foggy on this so dont quote me verbatum, but I do also know there is a rubber gromet around the fuel level sender than can leak, as well the lines coming out of the tank from the top can.

I dont know if I would trust that gage to be right though, I have seen gages stick in place. It should read between 6&8 psi.

[Nelson]

I agree with the timing issue. Myself, After reinstall the distrubutar, I had it off by one tooth. The truck starting and idle fine, but the filter was almost empty, and the engin backfired often.
Fix the timing problem, and no more issues.
Goodluck.

[d10s69c10]

i got a glass filter also(laid flat on the frame rail) and sometimes it is full and some times it is emptier than yours looks and i have no issues i think its just evaporation from the heat before the pump. its not really air and just takes time to work its way out.

what type of carb are you using? Q-jets got that little filter in the carb that is notorious for all your above symptoms.

you may have air in your lines from running it low pump may not be priming.

has this motor ran fine before and just started this or did you do some tinkering?

[eightbanger]

Originally Posted by d10s69c10

i got a glass filter also(laid flat on the frame rail) and sometimes it is full and some times it is emptier than yours looks and i have no issues i think its just evaporation from the heat before the pump. its not really air and just takes time to work its way out.

what type of carb are you using? Q-jets got that little filter in the carb that is notorious for all your above symptoms.

you may have air in your lines from running it low pump may not be priming.

has this motor ran fine before and just started this or did you do some tinkering?

Carburetors are a mystery to me all I can say is it's a Holley Performance carb...and yes this prob started out of the blue, actually the truck was parked for 2 weeks while we went on vacation and when I got back and took it out for a run it was doing this.