Fuel Filter only about 50% full

[semaj4712]

Quick question. On my wife's 66 c10, she has this inline fuel filter pre pump. It only is ever about 50% full even when running.

I would think it should be more full than this, and obviously, there is an air pocket in it but I cannot seem to get rid of it.

I have done some searching around and cannot find much info on the filter being pre pump like this.

It does not seem to affect the engine idling or giving it gas, we have not driven it yet as this is a rebuilt motor going back in and I still have a laundry list of things to do to get it all finished up.

[Warrens69GMC]

See if you can find non-ethanol gasoline. put that in and see if the air pocket goes away. If it does, thats your problem. The ethanol is breaking down and evaporating causing the air pocket.

[luvbowties]

I'd guess that is normal. Iirc, the post pump filters do the same thing. Install one and see--I'd want a post pump one anyhow--both = better. If it performs correctly, forget the concern.
Sam

[TJ's Chevy]

While running, can you see the fuel agitating in the filter indicating that fuel is being pulled? If it's just sitting and idling the high demand for fuel is not there vs at rpm. If you took it for a drive and accelerated hard a few times it would probably fill up.

[mehoff400]

mine was about 50% full once i replaced the gas cap and tightened a few lines its now full

[andyh1956]

It's not air you see but vacuum. If it was on the other side of the pump it would get full. If you put a metal filter on where you can't see it & problem solved!

[jayoldschool]

Filters go between carb and pump, not between tank and pump (on mechanical systems). The instructions expressly state this for the type of filter you are running.

[andyh1956]

jay is right. But on the other hand my 580K Case backhoe has one of these inline filters right at the tank petcock, then to a primary filter, then the lift pump, then the secondary filter then on to the injection pump. I thought it was a mickey mouse p.o. hack job but there it is in my parts book! Go figure!

[The Rocknrod]

Originally Posted by semaj4712

...
It does not seem to affect the engine idling or giving it gas, ...

Then your golden.

[jtrichard]

Originally Posted by jayoldschool

Filters go between carb and pump, not between tank and pump (on mechanical systems). The instructions expressly state this for the type of filter you are running.

I call BS .......I have run filters pre-pump for years NEVER had a problem (keeps any crap out of the pump and keeps a HARD line to the carb , to many cars/trucks burn to the ground when someone has cut the hard line and installed an in-line filter with hose and few years later the cheap ass hose that is made today starts spraying gas all over the place and POOF )...... IN 72 ( sure there were other years also) chevy (OEM) ran a frame mounted filter JUST UNDER the cab on C60 with 366

[TJ's Chevy]

Originally Posted by jtrichard

I call BS .......I have run filters pre-pump for years NEVER had a problem (keeps any crap out of the pump and keeps a HARD line to the carb to many cars/trucks burn to the ground when someone has cut the hard line and installed an in-line filter with hose and few years later the cheap ass hose that is made today starts spraying gas all over the place and POOF )...... IN 72 chevy (OEM) ran a frame mounted filter JUST UNDER the cab on C60 with 366

I completely agree, but I think the Jay was meaning with that Type of filter it's not a good idea. With the metal screen filters I've never had an issue running one behind the pump and in front. Never have tried with the paper.

[jtrichard]

The frame mounted filter in 72 C60 was a paper filter

THIS is what was used

http://www.2040-parts.com/chevy-gm-o...ebay--i991038/

[ImpalaJim]

if it was plugged up dirty it would be full

[TJ's Chevy]

Originally Posted by jtrichard

The frame mounted filter in 72 C60 was a paper filter

THIS is what was used

http://www.2040-parts.com/chevy-gm-o...ebay--i991038/

Just seen one of those in another truck to.

[61K10]

I thank you answered your own question if it runs ok. Rubber hose? been around for years. use good fi rated hose and keep an eye on it.

[andyh1956]

Back to the ORIGINAL question, the Farther the pump has to PULL the fuel, the more EMPTY SPACE will be in that filter. Don't hurt a thing!

[jtrichard]

IF the OP took the hose off the fuel pump (with full tank of gas) and hold it straight up then re-hook that should get rid of the air pocket

[semaj4712]

Wow lots of good information, there is a filter post pump as well, but its not see through so I have no idea if there is air in it or not.

But generally I think the main thing to take away is that it is fine.

I did try to unhook it turn it upside down but the airpocket didnt go away.

But im just going to leave it for now until we have any problems. Thanks guys
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