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Weber fuel pump?(new questions on setup)


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14 replies to this topic

#1 Snowman

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Posted 15 March 2004 - 11:24 PM

Has anybody used the weber fuel pump that you can buy from www.carbsunlimited.com that is apparently suited to weber carbs? It puts out 3-4 psi, which is what I've been told the weber likes, so I would assume that no regulator is needed. Does anybody know the rating of the stock ea82 carbed fuel pump for pressure and volume? As I mentioned in another thread, I think my stock fuel pump is getting tired after 166,000 miles, or maybe it was never designed to produce enough pressure for the weber carb in the first place.

Your thoughts please.

#2 Flow

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Posted 15 March 2004 - 11:43 PM

For the carb'd '86 the FSM lists:
Pressure 2.6-3.3 psi
Volume 10 gallons per hour.

I'm running a stock pump with my weber and it seems to do great with just a couple exceptions. Pull a lefthanded U-turn and it will die and sometimes it will diesel on shutdown. I don't think the dieseling is a result of too little fuel tho. Too much if anything. What symtoms is your old pump giving you?

#3 Snowman

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Posted 16 March 2004 - 12:41 AM

I haven't pinned it to the fuel pump yet, but it seems like the most likely candidate. The car accelerates great (for a soob) and will cruise just fine at nearly any speed. The problem comes in any situation where a large quantity of fuel is required, which leads me to the pump since I changed the filter last fall. For example, if I try to accelerate for a long period of time, it runs out of steam after a while, presumably when the float bowl is devoid of fuel. I can tell that there is a difference in power between short bursts of acceleration and longer-duration acceleration, so I don't think it is something that results in a constant power loss.

I also noticed when I had the top of the carb off to replace the power valve that I destroyed that there wasn't a lot of fuel in the bowl. This means that either the float level is off (unlikely since I bought the carb new last fall, but I can check it if that sounds likely), or the fuel pressure is inadequate. Since you say the stock pressure on a new pump(thanks for the info, by the way) peaks at 3.3, which is on the bare minimum end of what the weber apparently wants, I would think that this could be a likely culprit.

#4 GeneralDisorder

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Posted 16 March 2004 - 12:45 AM

incidentally - the fuel pump pressure for the EA81's is 1.6 - 2.03 psi or something like that....

GD

#5 Flow

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Posted 16 March 2004 - 01:40 AM

It does sound like your webber wants more juice. I had a fram fuel filter come apart on my old ford truck that partially blocked the line. It idled fine but would cough and sputter as soon as you touched the pedal. Have you ever pulled your fuel line and eyeballed what kind of volume your getting? Are you running a return hose? Sorry I'm not much help. It's weird how some webbers do fine with a stock pump and others don't.

#6 Snowman

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Posted 16 March 2004 - 02:05 AM

Don't worry, any help is great!

I am running the stock fuel return line, as I've been told that our stock pumps don't like to be "dead-headed", or run without a return line. When I've got some time next week, I'm going to pull the line and run it into a jar to see what kind of volume I'm getting, as well as pulling the top off the carb to check the float travel just to be sure. I might just break down and buy a fuel pressure gauge too.

Yeah, I don't get it why some webers are fine with the stock fuel supply and others aren't. I would suspect mine wants more fuel at high throttle settings because of the hi-po cams it now has, although this problem seemed to exist beforehand as well.

#7 GeneralDisorder

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Posted 16 March 2004 - 05:01 AM

I would say that some of the pumps out there are starting to fail, and drop in pressure or capacity. They are all nearly 15 to 20 years old after all, and some have a lot of mileage on them. I think I'll be going with a carter pump that's around 6 psi....

GD

#8 Snowman

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Posted 28 March 2004 - 06:14 PM

So here's another question, just what fuel pressure does the weber carburetor want? I've heard 2psi, 2.5-3 psi, 3-4 psi, and 4 psi. I'm going to buy a fuel pump asap, so I need to know what pressure to get, or if I need to get a regulator as well.

Yet another question. The hitachi carb and stock fuel pump utilizes a return line. With the weber carb and aftermarket pump, does the return line need to be used, or should it just run straight into the carb? My weber came with a fuel line fitting that just goes straight in.

Any help would be greatly appreciated.

#9 Flow

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Posted 28 March 2004 - 08:59 PM

Hey Snowman,

Posted Image

I prefer to run the return line. Makes sense to me to give the fuel somewhere to go. I've seen alot of muscle cars that run no return. If this is because of the huge amounts of fuel they use or the mechanics of the particular pump they have, I can't tell you. Anybody know?

#10 Snowman

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Posted 29 March 2004 - 01:35 PM

bump

Anybody know if the return line is needed?

#11 Mike W

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Posted 29 March 2004 - 02:12 PM

Everyone I know uses a return line and seem happy with it.

There is another common brand of pump other than Carter that doesn't cost so much but I forget the name. Ask at a shop that caters to the aircooled VW crowd and they'll hook you up.

#12 Qman

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Posted 29 March 2004 - 02:34 PM

Every one I set up has had the return line. I also ran a regulator on most. My latest install I went with a 5-7 psi pump and a regulator. Make sure the vent line from the canister is unplugged if you removed the emissions. I've just left it open after removing the hard metal lines. If you plug it it will cause a vapor lock of sorts.

You should check the float level. Some have been set kind of low. It sounds like the bowl may be emptying itself. My '86 Brat (lifted) is running the stock pump with a regulator(probably not neccessary) and has no issues.

#13 Snowman

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Posted 29 March 2004 - 09:33 PM

Thanks guys.

Yeah, emptying of the bowl is exactly what it feels like. It goes like a bat outa h*** for a while then falls on its face (3rd gear up hills SUCKS).

I bought a 2.5-4.5psi pump from NAPA and an adjustable regulator from Schucks today. I should be able to install them tomorrow morning before class, and if it gives me any more trouble I'll mount a fuel pressure gauge so I can verify the actual pressure. The float travel will also be checked just to make sure.

I figured that the return line was necessary, I just wanted to make sure since the Weber is a new world for me and I didn't want to make a boneheaded mistake.

Ahhh yes, an engine that runs like it should is a lot closer to reality.

#14 subusolo2nut

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Posted 30 March 2004 - 02:09 AM

One good reason for a return line is that you get a constant flow of cool fuel--no pun intended--this decreases the possibility of vapor lock in hot weather as well as increasing the HP output--colder fuel is denser & will provide more power..you can change the amount of return fuel by putting a restrictor orifice in the return line--fancy words for a small piece of metal with a specific-sized hole in it--to change the fuel availible to the carb you can make a restrictor--just start with a very small hole & keep checking the fuel level--when you can make a long run without too much or too little fuel, the hole is sized right---still won't fix a pump that is failing:)

#15 Snowman

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Posted 30 March 2004 - 02:47 AM

Thanks for that bit of return-line theory. That bit had always made me wonder, and it gives me another thing to tinker with. I should think that the stock fitting would be about the right size, since the rated pressure isn't too far off.




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