Webber Carburator Fuel Pump

[Tonka]

Hello,

Just ordered a 32/36 Carb after reading alot on these forums on how highly regarded they are, especially compared to the overengineered Mikinu. This will be my first time really modding a vehicle, I've only ever just replaced parts with stock, so venturing into this territory is a bit new for myself.

I had an inquiry. I am deleting the mechanical fuel pump and installing an electronic one. I'd like to replace the fuel filter considering the addition of the Webber and new pump. Just I am conflicted if the filter should go before or after the pump. If after, I could use the stock filter and just replace it, if before, I've seen a video use this filter, which I'd just rig before the pump. I've seen some use a filter before and after, but logically that doesn't make sense to me (if its filtered, its filtered, right?).

I also have some questions on EGR/emmissions, and vapor lock and how that works. But currently I'd just like to start with the basics.

Thank you

[85Ram50]

I used an Airtex pump and installed it under the skirt behind the driver side of the cab. I kept the OE fuel filter and have recently rewired it with a relay kit from the interweb. It works better than the oil pressure switch I originally went with. Here are pics of how I installed the pump. I used a piece of sheet metal bent it to fit and bolted it in when I got the mounts on it.

[SubGothius]

Looks like that pump you chose already comes with a screw-in mini filter on the intake side, so you could just stick with that.

For replacement filters, looks like that unit would be a Wix 33046 or Mr. Gasket 1242G (or other equivalents).

[Tonka]

Looks like that pump you chose already comes with a screw-in mini filter on the intake side, so you could just stick with that.

For replacement filters, looks like that unit would be a Wix 33046 or Mr. Gasket 1242G (or other equivalents).

Oh, haha, I feel pretty silly now, canceled the order. That makes me feel a bit better. Is the OEM filter neccessary then (As in, do I need two filters)? I'll be replacing it if I keep it.

[SubGothius]

You won't need to keep the OEM filter, since that was a pre-pump filter for the mechanical fuel pump attached to the engine, and your new electric pump already has a pre-pump filter of its own.

[camoit]

I would keep the oem filter. Bigger and better than the little ones that come on a pump. Doesn’t hurt to have the big one before the pump.

[Tonka]

Hello, thanks everyone for the help.

Does anyone know what the second vaccum port next to the vacuum advance (on the vacuum advance) is? I want to block it off, but I'm not sure what it is. Other than just the vacuum advance, I've blocked everything else off.

[Tonka]

It seems like it's running great, I ended up just blocking that line off. Does anyone know what that 4th line on the mechanical fuel pumps are? Mine is puffing lightly (as the pump goes) and creates a vaccum. It's connected to a short line and just dangling freely.

https://i5.walmartimages.com/seo/Car...5cc48b8a9.jpeg

That little line on the very left. Thanks

Also, what is that mushroom (vacuum diaphram) off of the intake manifold? The one that connects to the ECM via a hose and ground. What is it's function?

Then lastly, when spraying carb cleaner at the throttle linkage/shaft, I sense an idle change as if there is a leak. Truck idles great. Online I see some saying this is normal for even a new 32/36 Weber, can anyone confirm, I'd rather resolve it.

[nskull2010]

I believe that’s the “weep” port, it allows excess pressure to escape

[Tonka]

Hello,

Starting to have some issues now. I've been trying to make the slightest changes to the carb to make it run just right. It loves to diesel, sometimes for over 5 seconds! The pressure in the fuel tank is insanely high, much higher than with the mikinu (large psshhhh, and cap takes alot of pressure to open). And the throttle linkage isn't a fan of returning to the idle screw, it often sits above it. I also have no idea how to activate the high idle apart from at the carb itself.

I'll be honest, I didn't put a fuel regulator on it, it is just running from the mechanical. A guy at Redline said it should be fine, and that he actually did it with his own D50.

Can these issues really all be from wrong fuel pressure? It runs just fine apart from turning it off, slight idle variations/beat skipping, and sometimes false starting.

This is a brand new out the box Weber 32/36 from carburetion.com, I would really appriciate some help.

[SubGothius]

If it's not coming to rest on the idle screw, the choke fast-idle is still engaged somehow. I covered how to adjust the carb, choke and fast-idle in this thread:

http://www.mightyram50.net/vbulletin...ith-weber-carb

Sounds like your fuel tank may be developing a vacuum, rather than pressure; this would suggest some blockage in your vapor-capture line(s) or maybe the fuel cap (I'm not sure which way the tank is meant to draw air in as fuel is depleted or the fuel contracts as it cools).

Excessive fuel pressure could push fuel past the needle valve in the carb when the float should be holding that closed, overfilling the fuel float bowl and forcing excess fuel into the intake ("flooding"). Most of us with a Weber swap run an electric fuel pump with 2.5-3.5 psi pressure, or some run the stock mech pump with a pressure regulator, tho' that can stress the pump and cause it to fail prematurely. May also be a good idea to check your float levels, which I covered here:

http://www.mightyram50.net/vbulletin...flooding-issue

[camoit]

Sounds like the tank is not venting properly. Get a vented cap. Or hook up the charcoal canister and just let it vent.
as far as engine run on. You should preform a lean idle set on the carb. Use the search bar at the top. I made a full write up on how to do it years ago.
if you don’t already have it. This might help. Weber manual
http://www.mightyram50.net/d-50/Fact...Trans_Only.pdf

[85Ram50]

Here is an info source for Weber https://www.carburetion.com/Weber/weber.htm

[Tonka]

Hello, some updates for you all.

The dieseling and the stop not resting on the idle screw was due to the accelerator cable being a touch too tight (and holding the throttle open). I solved the gas tank issue by removing the rubber seal on the gas cap (not perfect, but eh). I also installed a regulator, but honestly probably didn't need to. When I tested by fuel pressure, I was getting 3-4 psi on the stock pump. Its a return style, and I routed it to the line that was previously used by the charcoal canister. I also swapped to a manual choke.

I installed the linkage reccommended by SubGothius in many other post, find it much better than the trunion, and I can feel the secondaries open when driving much more.

Currently, I have a pretty substancial vacuum leak at the base of the carburetor (choke has little effect). Spraying Gumout will almost kill the thing at idle. Planning to take the plates off, sand them flat, and then reinstall with grease and new gaskets. I'll locktite the studs aswell, as I've read those may separate the plates if rammed too far, and that they may leak if not locktited. Idles fine, but hangs a bit.

[Tonka]

The biggest difference came from mounting the carb the other way around, that helped alot of rich/lean issues that was happening

[Tonka]

Here's some photos, I wasn't able to get them uploaded how I would've liked.

https://imgur.com/a/Qkc7ur1

[SubGothius]

That hose off the back of your valve cover should go to the white plastic barb on the bottom plate of your air filter; just replace that stock hose with a longer piece of fuel hose.

Seems like routing your throttle cable over the top of the brake booster puts a bit of a kink in it at the firewall elbow guide/bracket, maybe try running it in front of the booster, between that and the brake fluid reservoir.

You shouldn't really need a regulator at all if your pump's baseline fuel pressure is 3-4 psi; that's perfect for a Weber as-is.

For that vacuum leak at the base of your carb, maybe try a new gasket and coat both sides with Permatex #85420 PermaShield Fuel Resistant Gasket Dressing & Flange Sealant. The carb mounting bolts only need to be nominally tight, like hand-snug plus another 1/4 turn or so (advise using a cupped or wavy lock washer), as overtightening them can warp the carb base.

[Tonka]

I went ahead and got the hose hooked up finally haha.

I took apart the carb again tried to seal it back down. Spraying the gumout has less effect, but still makes a change if I hold it and really spray.

I'm just going to ignore it for the time being, the truck idles fine and if anything my idle isn't as easy to get high (which, a high idle from my understanding is a negative effect of a vacuum leak). I have to run manifold or run a crazy high initial.

Everything is pretty much perfect now, just I figured out a hard starting issue from I had been having when warm. I kept thinking it was a tuning issue, but it's fuel boil resulting in a flooded engine. The pump jet would dribble a drop of gasoline every 5-10 seconds after turning off. Looking into the slit to the fuel bowl also showed me bubbly gasoline.

I'll go ahead and either wrap my exhaust manifold or put the heat shield back on. I hope that can help. Getting one of those reccomended spacers also might be something I do due to theposibility it may limit my vaccum leak.

I'm in TN, so I might try 100% gas. Would rather not have to spend extra, but considering how much gas I waste after shut-off, I'd really want to limit this boiling.

[Tonka]

Hello, I disconnected the charcoal canister and used the return line for a fuel pressure regulator.

This causes vacuum to build in the tank for large wooshes when removing the cap. I remedy this by taking the seal of the gas cap so it isn't airtight. The downside is that I feel this allows gas to evaporate out if my tank.

Does anyone know a good way to let my tank vent? I cant find any vented caps.

[SubGothius]

The tank is meant to vent positive pressure/fuel vapor to the charcoal canister and draw negative pressure (vacuum) from the ambient air. There should be a two-way valve in the vapor line between the tank and the canister that controls this; tank vacuum should draw air thru this two-way valve. Compare the photos in post #2 above to the manual scans I'm attaching here. Sounds like that two-way valve might be malfunctioning if your tank is developing a vacuum, or maybe a hose between the tank and that valve has collapsed internally, causing a blockage?

Why did you disconnect the charcoal canister? And I'm not clear what you meant by, "used the return line for a fuel pressure regulator" -- was that line connected to the canister, or unrelated?

[Tonka]

But even with that connection, and thus freeing up the vapor line. Doesn't the canister need to purge itself somehow? The weber deletes that "To Carb" line. My understanding is that line basically fed the fumes into the engine like the PCV does.

[Tonka]

I flat out used that vapor return line as a fuel return line for my fuel pressure regulator. It has three points, in, out, and return to tank. The return to tank is hooked where the charcoal canister used to hook up.

I disconnected the charcoal canister for three reasons, atleast, in my mind the Weber doesn't support easy use of it right? Wouldn't the canister just fill up and be useless if it cannot expel back to the weber like it did for the mikinu? Also, I was hoping to empty out the engine bay. Then finally, I wouldn't have a point to connect the third end of the fuel pressure regulator to if the vapor line was hooked to the canister.

So far it seems like it successfully sends the fuel back. I've had no signs of leaks or decreased MPG's, they actually went up a bit from 18 to 20. Still way less than it should be, but I attribute that to my timing being off. I dont have a means to really put it accurately currently, so I just guess and check with whatever allows me to start the car the easiest when hot.

I see what you're saying with the two-way valve. It does vent whenever I hook it up, but then I can't use the regulator (which seems to get me slightly better gas mileage). What im was hoping for was another way to vent the tank. Currently I took the rubber O-ring off of the gas cap which basically lets the tank leak out the fill cap, just this also lets vapors escape.

Bear with me, as it seems I am really undeducated with alot of this, most things that are said here go over my head. Is there such a thing as a venting gas cap that can help me vent the tank without the canister?

I've also thought about adding a connection to make the mechanical fuel pump and regulator flow back down the same line, but unsure if that is too much.

[FMS88]

Since you’re using the stock fuel pump which has three ports (in, out to carb float bowl and out to the accelerator pump), and assuming the regulator is in the pump-to-float-bowl line, what did you do with the pump-to-accelerator pump line? Also, the Mikuni had three fuels lines: fuel pump to float bowl, fuel pump to accelerator pump, and accelerator pump to fuel tank. What did you do with the accelerator pump line to tank line?

Rather than the canister’s “Tank” line, try connecting the regulator’s return line to the Mikuni's accelerator-pump-to-tank line. Then reconnect the vapor return line to the canister so the fuel tank has a vent out. The vapor return line is one way (tank to canister) and not intended to transport fuel back to the tank which the check valve and overfill limiter will block. The fuel cap should vent allowing air in only to replace consumed fuel. If tank vacuum build-up is a problem, you may need a new cap as others above suggest. With the Weber and all vacuum lines removed, the canister won't purge into the engine. Any vapors entering will vent to the outside. Not a worry since it’s probably the original canister and after all these years its ability to retain fuel vapors ceased long ago.

[Tonka]

Thats a great question, I have no idea what I did with that extra return to tank line. I must've capped it off. Where is this line? Following the other fuel lines and brake lines, I dont quite see it.

[Tonka]

Ill try and add some photos, currently I see thicker line that is the fuel into mech pump, another fuel line that is hooked to back to tank of the mech pump between two brake lines, and then that vapor line in the back, closest to the firewall.