Weber 38/38 trouble

[ITzDarcy]

Hey guys man I gotta stop messing up lol..

So I installed my new external fuel pump today and turned the key to check if it worked. It worked alright but in the process i forgot to unplug the return line on the carb :S.
So What happened next was i saw fuel running out of the top of the carb, Actually just below the top of the carb and on top of the choke switch. As I have a turbo hat on at the moment and it also was pitch black outside I thought I'd better take look tommorow instead.
SoI wasn't able to look inside the carby itself.

I unplugged the return and it still trickles out. I was wondering what the cause of this may be.. and what measure I will have to take to fix this.
Thanks

[datzenmike]

It should still work even without a return line. Early L16/18s didn't have a return. Fuel pressure should not exceede 3.5 or so PSI. Perhaps your new electri is higher and forcing it's way past the float and needle valve on the weber. They can be very sensitive to too much fuel pressure.

[banzai510(hainz)]

Fuel pressure should not exceede 3.5 or so PSI. Perhaps your new electri is higher and forcing it's way past the float and needle valve on the weber

 

 

think i just mention this about young guys putting external pumps on.

 

try the manual pump and see how it works

 

 

As I have a turbo hat on at the moment ??????? wht does this mean a turbo car?????????blow thru

[ITzDarcy]

Yea blow through plenum. Lol yea I'm young but will make never make this mistake again.

I have a fuel pressure regulator if I set this 3.5 psi would the overflow stop in theory?

[tr8er]

Could the valve in the weber just be shot?  Basically, wither you are forcing your way in, or the valve is failing to stop the flow.  Either way, not a good symptom.  

[ITzDarcy]

OK I see now that its bad news. Thanks for the help guys much appreciated.

 

So in order to find out the problem would I have to open the carb up and see what's broken?

[tr8er]

Pressure regulator might help. Most of them are real crap though.

 

Mike. Would a sunk float cause this?

 

If you want to check your float, it is easy. Do a google search on the outlaw weber to see an exploded parts diagram. Or look here:

Then open up the float bowl to see if the float is full of air (good), or petrol (not good).

[ITzDarcy]

I got the malpassi fpr

[ITzDarcy]

Thanks for the info mate I'll check the float tommorow got the day off gonna get into it.

[ITzDarcy]

The float bowl was full of air. But I have a picture here and as I'm on my phone I couldn't use paint to make an arrow or something. But you can see a few puddles of fuel bottom side. These little things fill up and overflow with fuel

 

upload image online

[datsunaholic]

That's not a Weber.

 

Anyhow, the symptom you're having is consistent with one of 4 things:

 

1) Sunken float.  And with the extremely poor quality of those EMPI Chinese junk carbs, it's possible the thing is leaking already.  You'll know once you have it out.  Shouldn't be any fuel INSIDE the float. 

 

2) Weak float valve.  See above for the EMPI quality.  It should be able to handle around 4 PSI, but even the real Weber float valves tend to get forced open with anything over 3.5PSI.  I've had plenty that would get forced open even with the stock mechanical pump unless the return line was hooked up properly.  I've tried pressure regulators and they've never worked- either they still overflowed at idle or when "coasting", or they made the engine starve for fuel under heavy load.  Or, in the case of the last time I tried one, it overflowed at idle and starved at load.  I hate those things.

 

3) Too high fuel pressure.  Pretty common issue with electric pumps, as it's hard to find anything below 5PSI, and real webers need less than that (let alone the junk EMPI clones)

 

4) Lastly, and generally uncommon unless it's been messed with, an incorrectly set carb float.  The float closes the valve, so if the float is actually floating and the valve actually works, an incorrectly set float could cause it to overflow.

[tr8er]

^yup.

 

Float bowl is not really relevant. The float itself can get flooded, therefore not float as high, thus not closing the valve. If that was not the case, yes the adjustment could be off, but more likely, it's flooding due to to much pressure. Solution: get a return line (built for such a purpose because there is a restriction in the line to keep the right amount of pressure in the feed line). Or get a pump with the right pressure (stock pump). Sorry you spent money on the am pump.

 

Regarding the fake weber, I bet you can get it running good enough.

[ITzDarcy]

Thanks for the enlightenment guys.

As for it being fake I had no idea, hopefully I should be able to work around that. I tapped the floats and they showed no sign of having petrol in them. I think the pressure is just too high and may have to buy a another stock fuel pump

I have something to go on and can get moving now. I'll post a picture of the inside tommorow.

[banzai510(hainz)]

Theres a guy on the 510realm that has a blowthru(turbo) weber on his L motor and claims 240 HP.

I forget his name as I dont go on there anymore. But Byron510 will know for sure. its a eleborate set up

[datzenmike]

Keith Law. 248 or so RWHP!!! @ 8K

[Charlie69]

Here is a link to the Malpassi fuel filter regulators that I have used for over thirty years for carbureted Datsun engines.

 

http://www.fuelpumpsonline.co.uk/malpassi-filter-king-fuel-pressure-regulator-85mm-clear-or-alloy-36-p.asp

[ITzDarcy]

That's some nice HP jeez.

If I can safely get 170hp I'll be very happy.

 

Thanks for the link charlie69 that regulator is the perfect one for me.

The site didn't ship to Australia so I purchased on off of a eBay store.

Once I get the oil feed sorted out this weekend hopefully .. I'll report back.

[KlassicMotion]

Looks like I'm too late, but the Weber Redline fuel pressure regulator works very well. Part number: 31800.063

 

Also, I've had 3 brand new Webers (the real ones, not the knockoffs) that came with the floats not set to the proper specs out of the box.

[ITzDarcy]

Well I tried buying one but they replied and said they've run out so I will look into the weber redline fpr before trying for another.
I may have to buy another genuine weber i think maybe.

I took a couple of pics

In this pic you cant see much. My silly computer is linux and I don't know how to draw on pictures etc..
So when I start my truck Air and fuel comes squirting out of the nozzle on my palm and it stalls unless i put my finger over it and block it, What is this for? (bottom middle of the picture)

forum image hosting

Looks like I'm too late, but the Weber Redline fuel pressure regulator works very well. Part number: 31800.063

Also, I've had 3 brand new Webers (the real ones, not the knockoffs) that came with the floats not set to the proper specs out of the box.

So this being the second time I took the top off of my carb and the this was how much fuel was in there.

upload images free


Where would be the best place to study up on these carburetors or a book I could purchase online? Thanks.
 

[datsunaholic]

That's not a nozzle.  It's a bowl vent.  Only time fuel comes out there is if the bowl is overflowing or pressurized.

[HRH]

I know from previous experience 38/38s are more prone to having issues with using a return line.  32/36 is fine without, a 38/38 LIKES a return line.

[KlassicMotion]

No return line on my 38dges, with no issues, but I've got the Weber fuel pressure reg.

 

Try this:

http://www.redlineweber.com/html/Tech/Table_of_contents.htm

[datsunaholic]

I have no return line on my 38 (it's in a 74) but I use the L16/L18 type (small) mechanical fuel pump.  I've had numerous 32/36s overflow, both with electric and L20B type mechanical pumps, and all were solved by using the factory Datsun return line.  But only 75+ model years had those, at least in the US.

 

As far as I can tell 38DGAS and 32/36 DGV use the same float valve setup. 

[ITzDarcy]

Fuel only comes out of the bowl vent off revved past 1000 rpm or so then air and fuel gets forces out of the vent.

So I'm thinking nothing is broken just things need adjusting and maybe the return line hooked up?