The GMC CCKW

Am wondering about putting a 2nd clear plastic fuel filter in and wondering where to put it ( I have bypassed the old filter).
The current clear plastic filter is sited a foot or more in front of the fuel pump - can I put another in series here - or will that restrict fuel flow too much - or should I cut the steel fuel line near the fuel tank and put in some rubber fuel line and another plastic fuel filter here. BTW cutting the steel lines is there anything I should watch out for regarding bits of metal falling into the line ( I was just going to cut with a hack saw)

My thoughts would be to re-commission the original filter and not bother with the in line plastic filters at all. Particularly downstream of the pump where it is subjected to pressure and heat. Maybe I'm being a bit skittish but I just don't like the idea. Why do you think you need a second in line filter anyway? If you're worried about fuel contamination, always use a strainer when not filling at a station and you shouldn't have a problem.
If you feel you must have an in line plastic filter put it between the tank and the pump and get yourself a tubing cutter to make a decent cut with the edge rolled in and no residue.

David

Hi David
The current plastic filter is upstream of the pump ( by about 30-40cm or so - ie on the fuel tank side of the pump)- but rapidly collects a lot of "gunk". A few on this site have suggested running at least 2 fuel filters - a few have 2 plastic filters as well as the original filter. My original filter was a complete write off and was bypassed(then removed) shortly before I got the vehicle. You may also notice in some other recent posts of mine about getting my fuel tank cleaned (which should be done around now) .... and yes have also given consideration to getting the tank plastic lined - but the problem seems to be "crud" rather than rust. The tank itself came from the phillipines so who knows what it had in it over there .....

The major consideration with filters located before the pump is the added restriction. Most paper filters are down in the 10 - 20 micron range and can add a significant amount of restriction making the fuel pump work that much harder in order to pull the fuel through the filter.

The production frame mounted filter/water separator is on the fuel pump inlet. I don't know what the rating is for the filter "element" in there, but it seems pretty porous. I'm thinking that the designers were relying more on the depth of the filter housing to catch dirt and sediment (and water, too) than the actual filter. There are paper elements that will fit the production filter housing. Not sure how restrictive they are since they have the low rating of most paper filters - however they are pretty large, so at least they offer a lot of surface area.

My truck has an aftermarket electric fuel pump. The fuel pump manufacturer recommends a filter before the pump, but it has to be one that is not too restrictive. I was looking at this filter to insert before the pump.

http://www.summitracing.com/parts/hly-162-553/overview/

It is a little pricey, but its 100 micron rating means that it should be good for a pump inlet. Also, the stainless steel element can be cleaned and reused.

I agree with Motto, in that I am very uncomfortable using those inline plastic filters anywhere in the engine compartment. If you do decide to put a filter in that location, there are a number of all metal inline filters that would probably work. Something like this, perhaps:

http://www.summitracing.com/parts/wix-33032/overview/

Not sure where the best place would be to install one. I'm sure others on this site have faced this issue before, perhaps they can share some insight.

BTW, if you do install one anywhere on the pressure side of the pump, make sure that it is connected properly. I would either try to borrow a tool that can put the small "bead" or "barb" on the end of the fuel line tubing, or have new lines fabricated with it in place. Companies like this can fabricate new lines quickly and inexpensively:

http://www.inlinetube.com/

I know that the CCKW fuel pump does not put out a lot of pressure, but the last thing you want is to have a fuel hose pop off and spray fuel onto a hot engine.

Best Regards,

Bob

p.s. Getting metal chips into the fuel line while cutting it is a real concern. As Motto mentioned, use a tubing cutter. There are a number of compact ones that will work in tight spaces such as this one: https://www.ridgid.com/us/en/close-quar ... ng-cutters These are very handy to have in your toolbox.

RE the original filter: The WW2 Jeep has it up on the firewall considerably higher than the pump.

You can slightly double flare the tubing to add another filter. That will give you the bulge for the hose/clamp to seal better.

On my cargo CCKW, the pump is mounted on the frame where he filter would be. When I get past about 125 miles, the pump starts to have a problem getting the fuel and it is an electric pump with a plastic inline filter just before it.

This year I am going to replace the torque rods and will take the cargo body off to make it easier. At that point, I will move the electric pump to just inside the frame from the tank.

So Dr D - where is your fuel filter - and do you use the original or a modern plastic one?

Sorry Dr D - you have answered my question in your last post - just didnt notice

But interestingly your problem sounds a little like mine - and I dont have an electric fuel pump - but I do have an inline plastic filter ( which yes guys I am about to remove and replace with an original filter assembly). Typically I have fuel supply problems after about an hours driving - or say 60km ( 40 miles) less than you Dr D but still after driving for a period - I was thinking that this this was purely "crud related" blockage of fuel filter - but your description makes me think that these modern filters may well be the issue - though why it would only be a problem after an hour ( or several hours) driving is beyond me - perhaps the rubber in the fuel pump softens when warm and no longer pumps as effectively ...? just a guess ....anyone any thoughts ... and has anyone else had the same issue ...?