Factory Fuel Filter loop/bypass

Can the factory filter (hangs off trans X-member) be removed and those in out lines be looped/connected?

I believe the factory filter finally clogged and/or I have a sticking fuel injector as my fuel pressure suddenly went low and I have a miss. I want to rule out the fuel filter and if that's it, I'll leave the C5 filter/regulator in the engine bay do the job.

It seems that the stock filter is redundant with the corvette filter/regulator.

Hey XS let me send you my filter, its only a year old, and probably only has 500 miles on it. I have it sitting in the shop, I can box it tonight and ship it tomorrow.

Mark

Much appreciated, but my point is to rule out the fuel filter. I can get one locally for $25. I saw the specs on it as m16 x 1.5 in and out. So was wondering if the lines can just be looped temporarily and then check the fuel pressure on the rail. If I loop it and the pressure is still low, I would then suspect stuck open fuel injector.

What is leading you to believe its something other than the pump? whats your key on engine off pressure? if that is low clamp off your fuel return line and recheck. Offer still stands, and this isnt a $25 filter, it was a new Porsche filter. I would be VERY surprised if a stuck injector was causing your low pressure and the engine only has a miss...

Mark

Why not delete the stock filter and install the Corvette filter/regulator back there in it's place? You can then send the return right back into the tank and you will only have to run one fuel line forward.

If anything, there is a difference between the non-turbo fuel pumps and turbo pumps. The non-turbo ones were apparently pretty weak in comparison. I would be looking at that way before a leaky injector or the likes.

I'll have to trouble shoot it when I get home this afternoon. I've already plumbed the C5 filter/regulator in the engine bay so I don't want to mess with all that. I don't want to run flex hose under the car either. I also am thinking the factory filter as a "pre-filter" to the C5 filter/regulator for it's longevity.
Actually the car is still running, just has a miss and low pressure on the rail.
I"ll post what I find later, Thanks guys.

Are you running an n/a pump, btw?

I have whatever was in the car (85.5) as of now, but have one of these on the shelf. Do you think I should go ahead and install it?....

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xschop wrote:I have whatever was in the car (85.5) as of now, but have one of these on the shelf. Do you think I should go ahead and install it?....

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Most definitely.

I was waiting for it to get warm outside and do that job along with a tank flush. Are our gas tanks plastic or steel?

Should be plastic. The early 924s had steel if I remember right. Should be able to tell by not being lazy and looking under the car.

There is a pre-filter screen in the tank before the fuel pump. I cleaned it out before the swap, but since then I'm running a minute acetone mix and curious what sludge it has released from the walls.

BTW, the tank/tranny/axles and entire undercarriage were so greasy/dirty from the hole in the 4 banger, you couldn't tell what was made out of plastic, steel, or dirt LOL

xschop wrote:There is a pre-filter screen in the tank before the fuel pump. I cleaned it out before the swap, but since then I'm running a minute acetone mix and curious what sludge it has released from the walls.

BTW, the tank/tranny/axles and entire undercarriage were so greasy/dirty from the hole in the 4 banger, you couldn't tell what was made out of plastic, steel, or dirt LOL

Yeah, I was lucky enough to have rust on all the metal parts, so knowing what was plastic was easy.

Don't get me started on the mess in the engine bay.

I would install the pump, but replace the filter if there's any question about it. I replaced my Porsche filter--i figure i'll just let it handle the filtering while the corvette filter does the regulating.

I don't know what pump came in the n/a's, but i would imagine it's not really up to par with the demands of the v8. The 944T pumps are actually a good Bosch pump capable of about 800rwhp in boosted apps, but also really expensive. The pump you have sitting around is what i plan on getting when my Turbo pump goes out.

Oh, BTW--replacing the pump is really easy on my car. Not sure if the 85.5 is the same, but i would bet it is. Jack up the car, pull off the passenger back wheel. There is a removable cover on the front passenger-side of the gas tank. Pull that off, and the rest is easy. Will probably take you about an hour...

Before the pressure drop and engine miss, I was at 53 psi at the rail. Now its like 13! and I'm still driving it. The exhaust has a different note LOL. I'mm looking at the new filter and the end fittings look like they can be looped. I'm gonna try it and see what's crackin'..... Inquiring minds gotta know.

the stock na pump doesnt support much power at all.

also the statement that stock 944T support 800RWHP in boosted application is not correct, but good for a stock ls1.

can you watch the pressuregauge when you drive?

can you verify the pump voltage, and the fact that it gets enough current? a bad ground or similar will do this.

looping around the filter should be quite easy, the filter pricing for oem new is just silly around here, cant get it under 90USD?! so looping around should be good for testing, and.. cheap/free

I seriously doubt that a single injector is even capeable of doing this to your fuel pressure, even with it beeing stuck at 100% duty cycle.

my best tips is clogged filter/lines, bad ground/current to pump, bad pump in that order.

Really depends if you've noticed the problem over a period of time or say overnight. Simplest answer is usually the correct one.

13psi and no lean misfires? Are you sure your gauge is working correctly? All I know is that I highly recommend clearing adaptations when you swap pumps/fix the problem.

A good aftermarket Porsche filter is reasonably cheap...like $30. No reason to buy OEM. I got mine on RockAuto.

a951 wrote:
also the statement that stock 944T support 800RWHP in boosted application is not correct, but good for a stock ls1.

Common opinion from a google search is about 700 rwhp tops. Close enough!

We ran out of fuel with a turbo pump at 375hp at the wheels on Elou's car. It started loosing pressure at 5800rpm.
X, check your gauge, From my experiences the LS won't even fire the injectors at less than 40 pounds. So it definitely would not be running at 13 pounds!

Yeah, my vote is pump also. And if you need one I would go with the GSL walboro inline pump, same specs as the 044 pump for $100! Oh and all your origional fittings thread right into it. MY suggestion is to gut the check valve on the output side as the walboro already has one built in.

Mark

My vote, since its freaking XSCHOP were talking too, is for him to pioneer the 944V8 intank fuel pump conversion.

I know you want to..... I know youve thought about it.......

thats just silly, the placement, stock tank etc for stock is very good.

I hope to assume you are beeing funny as he puts a lot into the mechanical/machine/engineer perspective of things, in that case, haha