Fuel filter placement, Front or back Options

[Mcraneiowa]

I have a thought and would like input on placement of fuel filter and a fuel pump. I know there are varying opinions on whether to put it up front or leave it in the back but I’d like to get everybody’s pros and cons on putting the filter upfront and leaving the pump back by the engine in order to clean up the soft fuel lines.
I am in the process of restoring the entire fuel system and just installed stainless lines through the tunnel from tangerine racing. My thought process is since the lines come out the back by the engine bay facing towards the passenger side and the mount for the pump isn’t that far away it doesn’t leave the much room to put a fuel filter in line prior to the pump without running it underneath or behind and looping it back around.
I have on order a Bosch 69133 fuel pump which has the inlet on one side and exit on the other versus my original pump with all three ports on one end.
I can easily place the filter under the tank near that 6 inch opening with enough line that I could pull it out to change it periodically. It just seems like extra work and Would be pretty cramped to try to put the pump and filter up there in order to service it.
For those that have placed both the pump and filter upfront I’d really like to see Some pictures and hear how that has worked out especially when you do occasionally service the filter. I would expect everything to fit under the tank for Aesthetic reasons. I look forward anybody’s comments or suggestions. Thanks, Mike.

[JamesM]

Put them both in the front, for every reason, no question. If you put the pump in either of the places the factory did either by the steering rack or using the 75+ bulk head blister getting to the filter is no harder than it is when placed in the rear. I actually i find it easier especially in the 75+ location using the blister.

Hopefully you used the later (smaller) SS line on the delivery side as that will give the cleanest possible install.

[Mcraneiowa]

Put them both in the front, for every reason, no question. If you put the pump in either of the places the factory did either by the steering rack or using the 75+ bulk head blister getting to the filter is no harder than it is when placed in the rear. I actually i find it easier especially in the 75+ location using the blister.

Hopefully you used the later (smaller) SS line on the delivery side as that will give the cleanest possible install.

James, to date I have not done anything as far as hooking up lines. I really want to get input from 914 owners as to what they felt work best and cleanest. I haven’t measured to see how much room I have under the tank for the pump and filter install if I were to go that route. Pictures are worth 1000 words as I’m not sure what is meant by the blister. If you could elaborate on the blister portion I’d be grateful. Mike

[Mcraneiowa]

Hey guys spoke to Albert at Auto Atlanta who highly recommended putting the fuel filter between the injectors and the fuel pump which makes perfect sense. Due to the fact that you have a sock or a strainer in the tank which is ultimately doing a similar job as the fuel filter would be prior to the pump. I kept thinking I needed the inline fuel filter prior to the fuel pump. This cleared up a lot of confusion for me. Thanks Albert always appreciate an experts advice.

[davep]

Not to mention that hydraulically, it is bad form to create restrictions on the low pressure (inlet) side of the pump. The filter is always on the high pressure side (outlet) of the pump.

[JamesM]

James, to date I have not done anything as far as hooking up lines. I really want to get input from 914 owners as to what they felt work best and cleanest. I haven’t measured to see how much room I have under the tank for the pump and filter install if I were to go that route. Pictures are worth 1000 words as I’m not sure what is meant by the blister. If you could elaborate on the blister portion I’d be grateful. Mike

I have multiple 914s and in fact currently have at least one of each with the various pump mounting locations, so I will try to explain the differences...

First, pump in the rear - This was where the factory put them prior to 1975 however they stopped doing this because it creates problems and then even issued instructions on moving the pump to the front of the car to address these problems. Given there are known issues with having the pump in the rear, and you have everything out of the car already anyways I wouldn't even consider this.

Second - Factory retrofit on early 70-74 cars. To fix the vapor lock issues on cars with the rear mounted pump the factory relocated the pump to the front, passenger underside of the car behind the steering rack cover (right next to the steering rack itself) Pump/filter can be accessed in this location without removing the tank via the underside of the car by removing the steering rack cover. fuel lines extend down from the hole under the gas tank to reach the pump/filter. The pump is very accessible in this location however it is still on the underside of the car.


Third - The factory 75-76 pump location is attached to a removable "blister" panel that attaches to the driver side bulkhead in front of the fuel tank. This is a more difficult retrofit on early cars as it involves having to source the pump cover and cutting a hole in the bulkhead to mount it, but of the three is the easiest to access once installed as it can be done from above the car from the front trunk.



I find either of the factory front mount options both far easier to work on and a cleaner looking install than having the pump in the rear. In addition, having the pump in the rear leaves you open to potential vapor lock issues which i have personally been bitten by several times.

[JamesM]

further out shot of the 75 pump cover

[JamesM]

Another install by the steering rack showing the access hole.

[porschetub]

Theres no real discussion about moving the pump to the front...it makes perfect sense and Porsche worked that out but rather late (IMG:style_emoticons/default/dry.gif) .
Best to mount pump and filter on to the front beam,benefits are positive head to the pump from the tank , these pumps are better off @ pushing fuel than sucking from a distant place like the enginebay .
Make sure you use the best clamps (FI type) and the best hose you can buy ,good luck.

[Mcraneiowa]

I so appreciate the comments, information and pictures. Thanks everyone.

[roundtwo]

Finding this post very helpful as I’m at the same cross roads with my car. Just picked up a 1970 roller and am new to the 914world.

[wonkipop]

have just been through this with mine.
its a very original car (1.8 1974, stored for last 16 years).
the original 3 port pump could not be brought back to life. internal leaks.
have replaced with the newer 2 port.
we kept the original location of the filter before the pump, with the pump in original location for 1974, up under the engine off the side of r h chassis rail.
the plumbing gets a little more convoluted but its all still stockish.
we introduced a second filter after the pump as is modern practice (and was something porsche did on later cars). reason, if your fuel pump ever lets go internally, it does not end up in the fuel system and injectors. having just searched the world to find 4 bosch injectors sealed in their bags and boxes (getting scarce) i don't want to lose them. its a small chance a new fuel pump could grenade itself, but its just good practice. and if the 914 had been still in production 10 years later, they would have done it factory.

originality guys might have a beef introducing a second fuel filter into engine bay.
we mounted off side of battery tray support.

only thing i did to the engine bay thats non stock non original.

peace of mind.

i've kept all the parts, on the faint chance the original fuel pump can be rebuilt.
but i've got my doubts it ever could be and not sure i really want the fuel pump to start leaking lots of fuel just adjacent to the exhaust system. and in any case even if it could be i would still have the second fuel filter.

Auto Atlanta are right on the money saying there should be a filter between the pump and the injectors.
its not original but its good advice.

[mlindner]

I installed a 356 tank up front instead of a fuel cell. Pump and filter is below with access. Best, Mark

[JFJ914]

Auto Atlanta are right on the money saying there should be a filter between the pump and the injectors.
its not original but its good advice.

Just make sure you don't use a stock PLASTIC filter! Find a metal filter if you're going to pressurize it.

[Frankvw]

"Just make sure you don't use a stock PLASTIC filter! Find a metal filter if you're going to pressurize it."
But that depends on WHAT plastic filter oyu use....
Because...the one in the picture below is suitable to handle the pressure, is specifically for that ......and is plastic (IMG:style_emoticons/default/smile.gif)

[JFJ914]

"Just make sure you don't use a stock PLASTIC filter! Find a metal filter if you're going to pressurize it."
But that depends on WHAT plastic filter oyu use....
Because...the one in the picture below is suitable to handle the pressure, is specifically for that ......and is plastic (IMG:style_emoticons/default/smile.gif)

Are you sure? That looks like the stock Bug/914 fuel filter, and it's 8mm in/12mm out to 12 mm fuel pump in which is only gravity feed.

[wonkipop]

@ FrankVW and JFJ914.

correct.

metal cylinder high pressure filter after the pump.

og plastic filter would not be a good idea on pressure side.
it is a beetle part and is for gravity flow or low pressure side.
(but in aust we never had EFI beetles, all were carb, but my understanding of the plastic cube filters is they are for low pressure fuel lines or carb. car fuel delivery - so ok on a carb car after the pump).

pretty sure the orig plastic cube filter was on mine (1974)just before the pump but could be wrong.
(probably have a photo somewhere prior to taking all the lines out).
suitable to the feed line from the tank.

in the end i removed all the plastic elements in the fuel lines (right through from the tank to the injectors). is a hot little area where the earlier 914s mount the pump.

don't know how the later front pump cars work with filter placement.

i've got a few of those old plastic cube filters stashed that i bought 30 years ago - might be suitable for the tank feed lines but i would not use them now. plastic de-plastizes with time and ultimately ends up brittle. even if sitting in a box in the dark.

[wonkipop]

^
the factory manual schematics make it clear the stock (plastic) filter is before the pump.
its a tight tangle on the earlier cars before the pump was changed to up front.
i think its even tighter on the 72 - 74 cars where the pump was slightly moved in location. originally it was on the rear firewall below the engine? never seen one of those so wouldn't know for sure.

on the 74 the feed line swings around below the pump into the filter (plastic cube) and then back into the pump. the filter is mounted towards the rear of the car, pump to towards the front in the tight little area off the side of the longitudinal. not a lot of room.

the later cars might have a different philosophy = have heard there is a difference between pushing the fuel all that way from the front, versus dragging the fuel in.
but i don't know enough about that stuff.

[Frankvw]

@wonkipop @JFJ914
yes, you are right, I have mounted that square filter before the pump. JFJ914 was talking about a metal filter behind the pump.
We also did not have the EFI beetles in Holland, some made their way here from mexico in 1990-1995, so that square plastic bosch fuel filter is not a beetle part over here, but a part for a VW T2b Type4 engine with fuelinjection.

[wonkipop]

thats right frankvw.

do the metal type high flow, high pressure after the pump. outlet side.

not necessary before the pump. you could use a plastic cube style before the pump.
its really only gravity feed or very low pressure suction on the inlet side of pump from tank. the pump pressurizes the fuel circuit to the injectors.

i think that is the reason for the three port system the older pumps had.
its about maintaining pressure in the injector loop, almost like its own closed circuit.
and on the inlet side and tank return side its much lower pressure.

somehow the modern two port pumps achieve the same thing but its done internally within the pump without the need for an extra return port.

the only reason for a filter after the pump is to save your injectors from the pump.
i have heard the modern two ports can let go.
hence its just a prudent bit of protection to have that extra filter, up to spec with the pressurized circuit, for peace of mind.

i have never heard of the old three ports failing internally (in a destructive way), but someone might have.
so they probably did not ever require a safeguard filter on the pressure outlet side.

you can use a metal filter before the pump if you are circumspect about a plastic filter near the hot parts of the engine (which is stock location in variations from 70-74).
i have.
and i will test this when things get hotter down here in aus.
maybe there could be a problem due to radiant heat, heating up the metal filter, and i might get vaporization.
i will wait to see.
if i do, i will exchange it for a plastic filter.

my post pump pre injector metal filter is mounted up in the engine bay.
there was no room to do it anywhere else in the 72-74 set up.