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I just installed a weber carb on my '79 D50 2.0, 4 speed. I have two fuel lines that run into my old mikuni carb and one return line running out. The new weber only has one fuel inlet. Should I just cap the return line and second inlet line to the carb? I read a couple posts about the conversion but nobody really touched on this.
I am not sure about you fuel line setup - on Geronimo, a 1980 D-50, there was a can that had 3 lines on it - 1 from the gas tank, 2nd line to the return line for vapor and excess fuel, and a third to the mechanical fuel pump that now goes to the carb. There was also a vent line from the evap canister to the carb for vapors from the tank. I retained the 3 line can as it was originally plumbed, used the fitting on the air cleaner to use for the evap line, and that should take care of all of the lines. But, if you have a california emissions vehicle, there could be more lines, such as a carb bowl vent line going back to the evap canister. I am also running an electric pump mounted back at the tank, so the lines to the mechanical pump are gone. I do know that some of these trucks have 3 lines on the fuel pump instead of the 3 line can, but the function is the same. If you don't have the 3 line can, the return line would be plugged unless you are trying to use the mechanical fuel pump, which I don't recommend as it is too high of pressure for a weber and will force fuel through the carb uncontrolled.
I found the performance and reliability better with changing to an electric pump w/ the weber. Used an AC EP-42S as recommended by Top End Performance. Mounted right by the tank,on my 87. lasted 20 years. They cost about $45 thru Amazon.
Yea I put an electric fuel pump on it. Thanks Pennyman, I'm starting to think I hooked my fuel lines up all wrong. Do you know which line should go where. The top one on the canister I have capped, the middle one runs to the fuel tank and the bottom one runs to the carb. Should my electric fuel pump be on the line that comes out of the bottom of the tank?
If it matters, you can get pressure regulators with a return line (the ones that do ain't cheap). The Weber doesn't have on normally and it ain't a bad idea. You should be able to trace those fuel lines back, one will be return, one will be feed, and the last should go to an evap (charcoal) canister. You can ditch the evap line or continue to run it to the can. If you keep the can, you'll probably have a line that used to go to the carb like Pennyman said, and I think he alluded to being able to run it into the air cleaner. Suppose it depends on if you have to take it through emissions and how picky they are.
This is the regulator I got, it uses AN fittings, but you can just us an AN plug in one hole, and put barbs on the other 3 for fuel flow:
http://www.summitracing.com/parts/maa-4309/overview/
One trick about that regulator, though. The return hard line (and rubber line) need to be equal in size or larger than the feed line. Means you might have to plumb a larger piece of hard line (cheap, but a bit of work).
I haven't changed to the electric pump yet with my webber, so I installed one of these adjustable kind regulators with an inline min-pressure gauge. I run around 3-5 psi with the setting.Quote:
Originally Posted by yamahlr
Attachment 4702
I have the 3 hose mechanical pump and soon to be replaced w/elec. because they do flood if your not careful.
I will post the connections on here after I look at Geronimo later today. That can becomes an issue if not hooked up right - the weber install manual tells you to remove it completely, but it is better to leave it in. I have had it in place for 30 years with the weber without problems.
Had one of those regulators, diaphragm blew in about 2 months. Reason I got the Mallory.
Perhaps I just had bad luck, but worth mentioning.
Edit: Running a Carter P4070 pump, not a real high-pressure pump. The mechanical is higher line pressure, less volume, as I recall.
They are not well made I admit and expect a failure sooner then later. It was a quick install for the Weber at the time because of engine flooding and will be replaced during my short block replacement.:) I'm sure your diaphram was not bad luck, but poor design instead.
Just another FYI, the best type of regulator to use is a return type. I had problems on my build truck. It was building the pressure up with a regulator. I have a Holly set up. The one that came in the box was a non return. It would go from 5 Psi to 6, 7, 8, 9, 10, ~ then finally 14 Psi. It took about 2 minutes but it did it. So out it came and in went the return type. But you guys probably don't have the flow mine does. It runs 110 GPH.
Wow, that is 1.833333 GPM, what are you filling a swimming pool? lol
Geronimo's pump is pushing 70 gph - webers like flow more than pressure.
Well at that flow you should have a return type system. I know a top fuel engine pumps a minimum of 100 GPM and runs a pressure of about 200 PSI depending on what size injectors it's using. But the "injectors" look something like a flat washer with adjustable flow. After the fuel shoots out the hole it strikes a plate at about a 30 degree angle. Then the fuel bounces off that. Thats it. They continuously spray tell out of fuel.
I run a Holley Blue(110GPH) with the Holley regulator and so far have had no problems,But then again I am feeding a 600cfm carb into a 10.78:1 compression V-8 :P
Heck, even the "mild" P4070 is 75GPH @4-6PSI.
Electric pumps just move a lot of fuel, period.
Makes me wonder what the stock mechanical is exactly. As I said earlier, I know the line pressure is higher and GPH lower, but no idea of the actual numbers.
Pumps don't create pressure, they create flow. Only a restriction creates pressure. Depending on how they are made depends on how much flow they create witch is directly proportionate to the pressure they can make. AKA a pump curve.
I thought I would throw this on for someone needing the hose line information for the stock fuel pumps of this design and year.
A question that just comes to mind after viewing this image, Wouldn't the stock pump work just fine for a weber as long as it was pressure/flow regulated only? By this I mean instead of an electric pump mod, plus regulator and gauge? Since the stock pump has a return flow connection, wouldn't this guarantee that the pump would not continue to overload the carb or regulator with line pressure? or is return line used for something else?
Attachment 4719
I have never used a regulator w/ the fuel pump I indicated in an earlier post. I placed the electric pump after the fuel filter, there is a place where it fits well and is protected if you do any off roading. I might be able to post a pic if someone needs one by the weekend, let me know as I'll be out on biz next week.
HelloQuote:
Originally Posted by BradMph
I am about to do a weber install as well. I have a 1987 2.6L automatic 4x4. When I talked to the salesman at carbs.us he said these weber carbs will work with the standard pump.
I've never replaced a carb on a truck before. I have "fixed" carbs on motorcycles before. Mostly remove, clean, and clean out the jets to fix carbs which had been gunked up. I've done this on two motorcycles and even lawnmowers. Simple stuff really.
What appeals to me about the weber install on my vehicle is that mine is a california emissions model. It appears that due to missing lines, o2 sensor etc that my vehicle is a partial california setup already. I've read/heard that the weber is simple and does not use all these vacuum lines. This appeals to me. I'm curious though, is there anything I should read before I attempt this job?
Also how many vacuum lines will I lose? Ive heard that I can do away with the computer inside the engine compartment. Should I label all vacuum lines or just the ones which attach to the carb?
John
The only one that's left when you're done is vacuum advance from the distributor to the carb. Might be a good idea to label everything if you're in a state that requires any kind of emissions, if you're not, trash it.Quote:
Originally Posted by netskink
Not sure about getting rid of the computer but I wouldn't be surprised if you don't need it. It's a very simple truck without the stock carb. Now I want to find a wiring diagram and check...
I think Noahwins means remove it, don't trash it. You never know when you'll need things that were needed for smog laws since they change so regular. I know a few people that end up re-buying everything because they recycled all the OE.
Trash it.
I have done the Weber retrofit to Ol' Reliable, an '88 MM 2.6. The only vacuum hose left remaining after the Weber was installed is vacuum advance to the distributor. My state is tailpipe exempt due to age but emissions control equipment must be in place and "working". AHEM...LOL. In reality the truck can pass any emissions tailpipe sniffer test. If the state will pay to have the tailpipe sniffed somewhere and pay for it, they are welcome to do that. ;) That thing will pass with flying colors no bullshit. (Despite the fact that there are no vacuum lines whatsoever hooked up.) LOLQuote:
Originally Posted by netskink
I just removed the original vacuum harness within the last two months. It had been laying in the engine compartment disconnected for five years at least.;)
The factory carb is warmed with coolant in your case, as was mine. A coolant fitting will have to be plugged on the intake, but that's not a big deal. Drill, tap and plug. The "computer" is pre-OBD II the old socket box tested system. You had to count how many times the green light flashed to get the fault code.:lmao:
PA had the same rules, but now any vehicle older than 86 are exempt, with the date rolling to pre 96 shortly - they found that the cars needing tailpipe tests didn't fail, and they were losing money on every test, so they canned it. Not all the state had it either, just the major metro areas.
You will need the vacuum lines for the other things in the engine compartment though, right? I believe some connect to the carb and the other lines connect to other devices. So I think when people say you will not need any vaccuum lines. They actually mean that you will need the vacuum advance line which connects to the carb and all the other vacuum lines which connect to the various devices.
Vac advance off the dizzy to the carb. Only other lines that should remain are two for the PCV system (breather and valve lines off the valve cover) and one to the brake booster. Block off or plug everything else. Correct me if I'm wrong.Quote:
Originally Posted by netskink
You can throw away EVAP charcoal canister and the hardlines running back to the fuel tank and to the air cleaner.
So long as in you're in a smog test free area, you're OK to get rid of all this stuff.
Again, this carb eliminates a LOT. By installing a Weber, you're axing almost all of the smog control system. Deletes a good bit of engine harness wiring, too. You'll be amazed how de-cluttered the bay becomes.
I left my canister in and plumbed the line to the fitting on the bottom of the air filter, with a vac line to make it work. Geronimo has the old style canister that had an external valve to open and close the vapor line to the carb