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> Question about plumbing Webers
Porsche Rescue
post Apr 24 2003, 09:26 AM
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I am installing a 2.0 engine with Weber 40's fitted. This is my first experience with a carbed engine. It came to me with the fuel block/pressure regulator pictured below. It was marketed or made by PMO. It has a broken fuel barb and I need to repair or replace it.
My question: Is this a good system? It is "1 in/4 out", 2 out to carbs, 1 out to gauge, 1 out to tank. The return to the tank regulates the pressure with a hose clamp that restricts the outflow to the tank.
Should I fix or replace this or is there a better system. Haven't checked to see what pump I have yet. It has been moved up front. Haven't talked to PMO yet either. Thanks for any advice. Expect more questions in the next week or two as the install proceeds (wiring? breather hoses?). Stay tuned.


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Bleyseng
post Apr 24 2003, 09:44 AM
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Are you still using the stock FI fuel pump with that set up? I would install a proper carb fuel pump instead.
Geoff
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Porsche Rescue
post Apr 24 2003, 09:47 AM
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Like I said, haven't looked at the pump because it has been moved up front and is hidden. Car has been driven for several years with carbs so I assume pump is low pressure. I will check.
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Aaron Cox
post Apr 24 2003, 10:54 AM
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with a carb setup , you dont need return line to fuel tank. I have a noisy lil facet fuel pump up front and a purolator regulator out in the engine compartment. supplies my dual 44's good. facet fuel pumps are noisy!
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brant
post Apr 24 2003, 10:58 AM
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I ran a return line on a carbed car...
Overall.. I recommend running a return line on a carbed car.

The theory being: that you are providing cooler fuel to the motor at all times.

brant
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Brad Roberts
post Apr 24 2003, 11:18 AM
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Hum..


where do I start ..

ok.. I wont.

I'll just say what I use and you can make your own judgement.

I only use a regulator/return line/gauge when I'm running a racing type of fuel pump like a Holley Blue pump or Red pump. Everything you buy from a parts store like the FACET or knock off's of it (even the little rotary pumps) only put out 3.5 psi which is what all carbs (even triple throat) work well with. No need for a regulator or return line on street cars. Porsche didnt have a return line or a regulator on the 9146's and they used a big honkin pump that looks just like our fuel injection pumps (but pumps 3.5 psi) imagine that..LOL

Replace that barb and run with it. Hook up the return line or plug it. You'll be fine (as long as they have a generic pump up front)

Please NEVER try to regulate down a factory injection pump. A well known Rennlister burnt his wifes car to the ground when he put carbs on it and tried to regulate the factory pump to 3.5 psi. He is a ASE certified mechanic. LOL


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MarkV
post Apr 24 2003, 11:37 AM
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I am running one of these w/ DRLA 40's. mounted where the stock pump was w/ no return line & no regulator. Nice and quiet.

rotary
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Lawrence
post Apr 24 2003, 12:27 PM
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QUOTE
Porsche didnt have a return line or a regulator on the 9146's and they used a big honkin pump that looks just like our fuel injection pumps (but pumps 3.5 psi) imagine that..LOL


I beg to disagree. The stock 914/6 fuel pump had a return line running from the pump back to the tank. (SDR setup)

See factory service manual 914/6, Section 2, page 4.2-1/1.

-Rusty
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rhodyguy
post Apr 24 2003, 12:36 PM
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this is the pump i was running on the 72. will be removed and put on the 73'. this location was prob not the best plan, will place on the 73 in a location down stream for the f line outlet at the lower firewall. i can't imagine a clamp to regulate the pressure to be the best way to go,flow restriction not presure reduction. this pump is quiet. the other small cyl is a f.p.r that came with the unit. cb performance. i do intend to install a gauge infront of the carbs just so i know whats going on. lost my f-in job today. lots of time to work on the silver car now, once i calm down.

kevin


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Porsche Rescue
post Apr 24 2003, 04:10 PM
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Burned to the ground you say.......just looked under the steering rack cover. I found a fuel pump that looks very much like a high pressure FI model. It looks the same as the low pressure one on my six, but it has a VW symbol and the number 0580463005 stamped on the motor end. That number does not match the PET part number which begins 311. It is the only number I can find on the pump. Can anyone look at a stock pump and check the number? I have a feeling the device pictured above was attempting to reduce 30 psi to 3.5! According to PMO's installation instructions the pressure is reduced only by restricting flow back to the tank (the clamp you see on the far left fuel line in the picture is the "reducer".)
Apparently it worked for the PO. Now what ?
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rhodyguy
post Apr 24 2003, 04:20 PM
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somebody please explain. how could restricting the flow BACK to the tank, lower the fuel pressure? the 35psi at the pump would be 35 at the incoming side of the gauge. i can't remember what i paid for that rotary from cb, but it was pretty resonable. i'll go to their site and see what they get for them these days. i see, that was the link to the site. $42.95, that and some premium hose is cheap insurance. keeping the filter up stream from the pump is some what important. i'm going to install a petcock upstream of the filter. with where i intend to put my pump, it will be lower than the tank. changing the filter could be a bit gassy.

kevin
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Brad Roberts
post Apr 24 2003, 04:24 PM
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Sorry LB. I should have been more clear.. I think it was early for me..LOL

I meant to point out.. the factory didnt do a return line from the carbs.

You are 100% correct. They used a return line from the pump.

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Porsche Rescue
post Apr 24 2003, 04:27 PM
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Kevin, my thinking exactly.
Brad, how about saying what you were thinking of saying?
The PO drove the car (hopped up race engine which blew up) with the PMO set up. I am installing a new engine in the car. I just found the PMO instructions which came with the fuel block/regulator. The device was (is?) intended to be used when converting a FI 911 to carbs. The claim is that you then do not need to change pumps. Same true of the 914 I guess. The directions are very clear, "pressure is controlled by restricting the flow back to the tank" using the "pressure clamp".
If I install the rotary from CB, should it be installed in the stock location or up front where the pump is now? I assume I must then plug the return line since it looks like the rotary only has "in" and "out".
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Brad Roberts
post Apr 24 2003, 04:32 PM
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Basically they bleed off pressure not used. The stock system builds pressure against the regulator and "dumps off" what it doesnt need.

Jim's setup is doing the same thing.

Jim:

Here is what I would do:

Plug all the lines coming out of the block and turn the pump on for 4-5 seconds. Let the gauge show a reading and release the return line into a gas can. You'll know real quick whether or not you have a high pressure pump. BE CAREFUL. You can use your finger over the return hose to build pressure against. Make sure you have somebody in the car with the key on/off. It will only take a few seconds. Use a long long hose to reach the can if the gauge/return line setup is still in the car.

The guy who burnt his wifes car to the ground.. had a fuel line rupture because the pump built up too much pressure in front of the regulator. It burst a line near the fuel pump under the car while running down the freeway. FLAME ON.

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Brad Roberts
post Apr 24 2003, 04:36 PM
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Sorry Jim.

You replied while I was replying.

On the CB pump:

The rotaries are good pushers but bad suckers. So.. they kind of need to be mounted towards the front of the car near the tank (just like a 911)

The Facet noisy pumps with the diaphram action suck and push very well. They can be mounted just about anywhere as long as they are mounted below the midpoint of the tank.

The stock pumps dont suck very well.. which is why they are mounted as low as possible in comparison to the tank exit lines.

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Aaron Cox
post Apr 24 2003, 04:38 PM
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QUOTE(rhodyguy @ Apr 24 2003, 10:36 AM)
this is the pump i was running on the 72. will be removed and put on the 73'. this location was prob not the best plan, will place on the 73 in a location down stream for the f line outlet at the lower firewall. i can't imagine a clamp to regulate the pressure to be the best way to go,flow restriction not presure reduction. this pump is quiet. the other small cyl is a f.p.r that came with the unit. cb performance. i do intend to install a gauge infront of the carbs just so i know whats going on. lost my f-in job today. lots of time to work on the silver car now, once i calm down.

kevin

wow, you ran yours under the spare tire cover. I ran mine in the cavity below the gas tank and drilled two holes through the pass footwell to mount my facet. does everybody's car have a molded styrofoam piece on the passenger side footrest/firewall?
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rhodyguy
post Apr 24 2003, 04:41 PM
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jim you can simply close off the return line by plugging it at the lower rear fire wall. or do it at the tank bottom and use of new short piece line. what did p use in the early carbed 4 cly engines? a return line? what sort of outlet in the bottom of the tank. to my mind, if the line failed at the reducing clamp, it would be line choking the spray nozzle down on a garden hose that's wide open. fine spray, goes further. i could never trust that setup thats on your ride jim.

kevin
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rhodyguy
post Apr 24 2003, 04:54 PM
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acox, actually it was just above the spare cover. cb expressly warned against doing this (putting the pump in an enclosed space). but i saw a picture of a factory race car with the pump upfront. i wanted the pump loacted where i could see exactly what was going on. brad, if the pump was mounted in the region of the stock filter, i would think thats about the same or lower the tank outlet. as long as the rotary doesn't have to pull the fuel uphill, wouldn't that solve the push/pull issue?

kevin
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Porsche Rescue
post Apr 24 2003, 05:09 PM
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Brad, if I understand correctly, the stock pump is not shooting out 30+ psi fuel but rather the stock FI pressure regulator is "plugging things up" so as to create high psi. If I hear you correctly, I could continue to use the PMO set up, especially if I use high pressure hose and make sure the gauge is reading 3.5 psi (PMO says 4 to 5 and turn up to 6-7 at the track, but maybe that is for a six).
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Brad Roberts
post Apr 24 2003, 05:09 PM
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Yes it does Kevin. I wanted to point out you can't mount them in the engine compartment and expect them to work like they are designed to.

They work fine in the stock location.


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