Last week, @Dion sent me a note asking how my car was doing, to which I responded all is well...no major issues since she returned from in-op to driver status last year.

Today, I went to wash my car and got a bit of a scare while it was idling in my garage...I saw a pool a fuel quickly forming under the car!

Good thing I was out of the car and close by where the leak was quickly noticed. I almost slipped on the quickly forming lake of fuel forming under the car as I was sprinting for the ignition switch!

First thing I noticed after shutting the car off (other than the stench now emanating from my trousers!) was that the fuel pressure at the regulator was zero...OK, so I have a leak in the fuel line between the stainless feed and the regulator.

Didn't take long to find that my 1 year old plastic fuel filter had ruptured!

So I'm not sure if this is a question, or a public service announcement...

Last year, when I re-assembled my car (2.7L six conversion with dual webers), I went with a low pressure Delphi FD0037 fuel pump. Before I disassembled my car for the rebuild, I was running the OEM (hi-pressure fuel injection) fuel pump with dual regulators on the discharge (and maintained the recirc to the tank)...not ideal, but it worked for about 6-7 years with no issues. Just to clarify, I did my 6 conversion several years before I opted for rust repair and a GT body style conversion.

To simplify my fuel feed, I went with a Delphi lo-pressure pump, I did notice what I thought was a high speed "hesitation" and assumed that the pump was undersized...I knew I was only getting about 2-1/2 psi to the regulator ahead of the carbs at idle. (Adjusting the regulator and I could never get anything more than 2-1/2 psi.) That Delphi pump is also rated at 4 GPH which should[i] be sufficient, excluding head pressure loss.

Late last summer, due to what I suspected was a high speed fuel starvation, I upgraded to a higher volume lo-pressure pump...the Walbro GSL395.

When I installed the Walbro pump, I did measure a fuel supply pressure of between 15-18 psi before the reducer (dialed down to 3 psi for the carbs).

I've been running the car since last summer with this set-up until today.

I should mention that I have a WIX 33003 (3/8" feed/discharge) fuel filter on the suction side of the fuel pump (under the steering rack) as well as the same filter installed ahead of the pressure regulator at the engine bay.

Essentially, the filter ahead of the regulator is seeing an inlet pressure of 15-18 psi (measured)...I didn't think, at the time, that this would be a big deal for the plastic filter. (I thought wrong!)

I cannot find a (max) pressure rating for the WIX 33003 fuel filter, although there are a couple of websites (not WIX) that advertise a max pressure diff of 75 psi...color me dubious!

As mentioned previously, I do have a single feed SS hard line from the front of the car into the engine bay.

I use small lengths of Gates 3/8" fuel hose (50 psi rating) for the rest of my fuel feed to the carbs.

Obviously, this failure of the WIX 33003 fuel filter has me a little shook.

I do have a few options.

1) Install a recirc system to reduce "dead-head" pressure at the regulator.
2) Investigate finding a "lower" pressure supply pump.
3) Eliminate the fuel filter ahead of the regulator (since it is secondary to the filter ahead of the pump)
4) Replace the plastic WIX filter with a metal encased fuel filter ahead of the regulator
5) Other suggestions...

The regulator I'm using is the Aeromotive 13222...20 psi max inlet adjustable to a range of 1 - 5.5 psi. In theory, I shouldn't have to run a recirc...this regulator is designed to run without.

My question would be to others running 6 conversions with carbs (or even 4's with carbs)...what are you guys running for a fuel supply system?

I like the plastic fuel filters just for the visual confirmation of fuel system cleanliness. Now I'm not so sure of this convenience.

Has anyone encountered a plastic fuel filter failure like this?

I've seen far too many photos of 914's with torched engine bays...or worse...don't want to be another statistic.

This might be a good time to take another look at engine bay fire suppression systems.

Attached is a copy of the Walbro pump pump pressure curve...as mentioned, I have measured feed pressure between 15-18 psi at the engine bay ahead of the regulator.
Also included is a photo of where/how the fuel filter failed. (I was going to assume "Made in China" but it's stamped "Russian Federation". Go figure!)

Help/ideas would be greatly appreciated!

Thanks in advance!

Rob

I didn’t like the look of that russian made Wix so I went with a metal one


Click to view attachment

That collapsed filter looks terrible. Why are the 2 clamps so close together? Just use the appropriate nipple sized FI filter in front of the pump. They have area than that VW filter.

Rob, so sorry about the filter/fuel troubles. Sorry
I jinxed ya.
I’m using a Carter hi volume lo pressure pump (3.5-4 psi) and a metal casing filter under the steering rack. (2.4L six with Webers) I am running a return line to tank.
Good luck!

LOL...no worries...what happened was going to happen...just thankful I was able to catch it before catastrophe!

Thanks for the photos of your set-up. I was looking at the Carter, but, didn't think I could shoe horn it under the steering rack (self imposed limitation, I know!).

I ran the old fuel pump/filter inside the trunk for 6-7 years...wanted to remove it underneath in the event of any potential leaks (and to keep potential gas fumes out of the frunk in the event of a fuel line leak/failure).

I need to make a plan moving forward, and was hoping to get some ideas here.

Today, I just went the simple root and replaced the WIX with a metal filter so I can continue to enjoy driving. Do I really need to run two filters? Obvious answer is No.

The longer term question is am I comfortable with 15 psi fuel pressure (with my existing pump) up to the engine bay regulator?

Seeing what other people are running with their carb set-ups is helpful.

Hope you're enjoying your car...she looks fantastic!

Have a great weekend!

I also prefer a metal filter.

#3. I vacuum fuel through plastic hose clamp fuel filters versus pressuring through them. Those plastic filters are not designed for significant pressure, they are suction filters...plus putting the filter ahead of the pump protects the pump too.

Not that it's relevant, but my carb'd race car (GM TBI pump in the fuel cell with a sock) feeds a FRAM filter in the front trunk and the fuel pressure is regulated up front, all through AN-6 lines. A preference on my part to only feed 3 psi through the car back to the engine compartment.

On the other hand, the D-Jet/Microsquirt street car runs whatever the Bosch pump puts out through Tangerine stainless lines back to a 3-bar Bosch regulator in the engine compartment, using 5/16" hose and fuel injection hose clamps...but I still suction fuel through one of those white plastic fuel filters ahead of the Bosch pump.

I certainly won't consider another plastic filter in a pressure application...I still like the visibility factor on the suction side.



I'm leaning in this direction now. Just need to start investigating options for other inline, low pressure, high volume pumps...and hopefully one I can squeeze under the frunk...otherwise it's back to a frunk install location.

Only use a metal fuel filter. I only filter fuel between the pump and the tank, on the scavenge side of the system.This protects the pump and allows for continuous fuel lines to be ran from the pump/ regulator to the carbs.

I select a fuel pump as close to the targeted regulated pressure as possible. If you have a pump that makes 15-18 PSI you are depending on the regulator to drop the fuel pressure all the way to 2.5-3 PSI and this puts a ton of "dead head" load on the fuel system between the pump and the regulator. If you are trying to reduce the pressure this much, then the regulator definitely needs a return type bypass back to the tank.

To me I'd shoot for a fuel pump that would make 5-6 PSI at max, regulate that to 2.5 PSI dynamic, use a metal fuel filter on the scavenge side, couple that to Gate Barricade fuel hose, and roll with confidence.

Thanks for the feedback Jake...much appreciated!

Having just set this up I went with the cb performance rotary FP. It comes with a metal pre-filter. The pump is mounted up front with SS fuel lines. I set it up to mimic OptimusGlens setup. It is supplying fuel to a pair of Zeniths. I have a return line run, but it is currently not in use.

Thank you for the feedback!

Do you recall the barb sizes? I'm assuming you went with the 3193?

Yes I went with the 3193. I believe the barbs are 5/16(edited)? I am using stainless braided lines as I was using AN-5 (5/16) when I had EFI and made them work with this new FP/filter setup.

Glad you discovered that without a tragedy! I'm personally a fan of the recirc system regardless of fuel delivery system or pump used. That way no part of the fuel system is under any more pressure than is needed and the reserve fuel scavenger bowl stays full as the factory designed it.

Thank you...I found a thread online quoting 7.9 mm (5/16").



I'm considering myself very lucky this time! (But I don't want to play those odds again!) It looks like I'll be revisiting my entire fuel supply/delivery system...that includes recommissioning the recirc. Thank you!

Update:

I did find another (Napa In-Stock) solenoid fuel pump that was rated for max 6 psi and 28 GPH fuel flow.

Earlier this week, I installed that in place of the previous 12 psi pump and did see some improvement (but with other issues!). With the new, lower pressure solenoid pump, the fuel pressure would fluctuate after the regulator by about 1/2-1 psi. The bigger issue was that after about 5 minutes run time, the engine would just quit (fuel starvation - as the pump would stop, unexpectedly). Wait a few minutes, turn the ignition back on and the pump would restart and build pressure to (regulated) 3 psi. Restart the car and it would run about another 5 minutes with the fuel pump cutting off again.

OK...so maybe a defective pump (or perhaps an internal, faulty thermal switch). Rather than try to find another 3/8" low pressure solenoid pump, I elected to upgrade to a rotary vane pump.

Ordered the Carter P4070.

Today, I installed the Carter Rotary Vane Fuel Pump. Unfortunately, it was not going to fit under the steering rack. Mounted it low in the frunk (definitely below the tank level).

At the same time, I rewired the electrical feed (all new wiring with a dedicated fuel pump relay). I did this to rule out any potential electrical issue as I experienced with the Napa pump earlier this week.

First trial, and I thought the pump wasn't priming...no fuel pressure recorded at the regulator. Backed the regulator all the way out. Initially, I maybe had about 1 psi showing on the gauge before I started the car.

Car runs fine, but, the pressure is very very low. Prolonged idle, pressure will bump up to about 2 psi (max.). Revving the motor will immediately drop the outlet pressure (almost pegged at zero). Car will not stall/starve out of fuel after running (a combination of idle/high speed) for about 20 minutes.

I did not take the car for a road test...didn't feel like getting stranded with a known low fuel pressure issue.

A refresher from an earlier post, the Aeromotive regulator I'm using is rated for a max 20 psi inlet regulated to between 1-5.5 psi. There is no recirc on this regulator. I don't think the regulator/gauge is the issue. I had no issues with the regulator with the original Delphi (low flow) pump I installed last year, nor the higher 12 psi pump I was running for about the last 8-9 months, up until the fuel filter issue last weekend.

I have doubled checked fuel supply lines for obstructions (thinking I may have crimped a line installing the new Carter pump). I pulled the tank again and replaced the in tank "sock" as well as the suction feedline (just to be sure it is not collapsing, although, I couldn't see the suction line collapsing when the car was idling).

I am at my wits end. Did I receive another defective pump??? This is the first time I've gone with a Carter RV FP.

I am running a 40 micron 3/8" fuel filter (brand new) on the suction side of the pump. I removed the fuel filter ahead of the regulator.

The last time I drained the fuel from the tank, I disconnected the line between the filter and the suction side of the pump. It gravity drained about 4 gallons in less than a minute. I really don't think I have a suction side issue to the pump.

My entire fuel supply is either 3/8" tube or 10mm SS hardline.

Attached is a short video after replacing the suction line and fuel tank sock (although there was no difference from before) with the new Carter pump.

https://www.youtube.com/watch?v=97lfeG11JO4

I'm leaning toward this Carter pump being defective (a weak spring). The other thing I noticed, when the car is shut off, the fuel pressure drops off to zero right away...never had this with the solenoid pumps...it would take hours before the fuel pressure fell off.

If I do have to replace the P4070 pump, I'm wondering if I should install the Carter Marine pump (P4389)? It is a slightly higher pressure at 6 psi. (I'm guessing the exact same pump as the P4070 with a slightly higher pressure internal spring.)

Would appreciate feedback from others running this set-up and thoughts on other things that may be causing the fuel pressure issues I'm seeing with this new set-up I'm trying.

P4070 Installation Instructions:

https://static.summitracing.com/global/imag...s/crt-p4070.pdf

Thanks in advance,
Rob

Rob , I’ve got nothing Your running the same system as
Me now. No issues currently. Only thing I see different is the regulator. Could that be messing about?
More knowledgeable peeps will chime in.

Thanks Dion!

I've thought the same thing as compared to your car. I haven't tried to disable/bypass the regulator yet...need to see what I have for available fittings for a tee + pressure gauge port.

I have run three different pumps with this regulator, my original Delphi FD0037, the Walbro GLS395 as well as the Napa pump I tried earlier this week. It worked for all three of those pumps.

The P4070 is supposed to be internally regulated to 4 psi...I wouldn't expect to see a high line loss to only read 2 psi at the rear...and variable to boot!

What leads me to suspect a faulty pump is the way the pressure immediately drops off after the pump shuts off...although I'm not familiar with these rotary vane pumps.

This is just one of those times to walk away and re-think a strategy...

Update 2:

Turns out the pressure regulator is the issue now (where I didn't have any issues with the previous pumps).

Set-up a temp metering block (without a regulator) and the pressure is fairly constant between 4-1/2-5 psi from the Carter P4070.

https://www.youtube.com/shorts/UdxPQAPEoQ0

Ordered a rebuild kit for my regulator. The delivered pressure is a little too high for my liking for the Webers.

Rob, Sure am glad you caught it when you did and averted a real catastrophe.

Thanks Kevin!

Could've been a very bad day! Posted this thread more as a PSA to warn others of my dumb mistake! Still waiting on my back-ordered regulator rebuild kit...can't wait to get back on the road!

Enjpy seeing the updates on your build! Keep up the great work!