Oh wise and experienced ones,

I've got a 1967 220 with a fairly newly rebuilt engine (I'm guessing - Oil's still honey colored after 600 miles and great mileage) and a weber carb. I know little about the vehicle's history. As part of the process of getting her roadworthy, I replaced the fuel pump, fuel lines from the pump to the carb, and the fuel filter. Rusty at RPR was very helpful and indicated that he was selling me one of the pumps (I forget the brand name, sorry) that don't put out too much pressure, causing flooding. I did (accidentally) neglect to tell him that I had a weber carb.

Now, it is taking about 30 secs. of cranking to get her started after she's been sitting for more than 3 or 4 hours. I've noticed that when she's not been sitting for long I can see fuel in the filter and she starts right up. The fuel filter is empty if she has been sitting. I've got some bogging issues at mid throttle, but other than that, once she starts she seems to run fine.

Did I mislead Rusty by not mentioning the weber carb? Would installing a fuel check valve in the fuel line prevent the fuel from draining back to the tank and make starting easier? Is this just par for the course and I need to get used to it? Any other recommendations or advice?

Thank you all. I never cease to be amazed at the collective knowledge, and equally impressive civility, of this forum.

Thanks for the feedback guys. I'm going to give Rusty a call tomorrow and will let you know what happens.

I appologize for not reponding sooner. I was hoping to have some time this past weekend to examine the carb and see if something is obviously amiss before I called RPR. Alas, nice spring weather, two kids, and a park conspired to eat up most of my time. The little bit that I got to spend on the car, I spent fixing the tailgate latch.

However, I went ahead and called this afternoon. The fuel pump that I purchased was a pierburg. They indicated that there are no check valves in the pump, and that they are not aware of any check valves in the original pump either. Their immediate suggestion was that I check the choke to make sure that it is functioning properly.

My plan at this point is:

1) Examine the carb to make sure that nothing is obviously amiss. I've not worked on carbs much before, so this won't be as effective as I might wish. The primary thing that I want to look at is the float level. RPR indicated that there should be enough fuel in the float bowl to run the car for 30 seconds or so. I'm wondering if, for whatever reason, there is not enough fuel in the float bowl.
2) Per RPR's recommendation, examine the choke. I'm not quite following the logic of how the choke could be causing the problem, and the choke appears to be working in that I need the choke to start the car when it cold, but they know more than I do and it never hurts to check.
3) If all that turns up nothing, I'm going to install a check valve in the fuel line somewhere. Probably, I'll start with it on the tank side of the fuel pump.

Anyone have any guidance to offer? Am I on the right track? I'm more than open to input.

I'll keep you all appraised as I figure things out, but don't hold your breath.; I've never yet set any records for how quickly I resolve problems.

As an aside, I have to admit to absolutely loving driving my 220 to and from work, which is about 15 miles of interstate driving. Even with a somewhat worn suspension, not quite adjusted carb, and no radio or music it's just fun to drive such a cool car.

Thanks!

"They indicated that there are no check valves in the pump, and that they are not aware of any check valves in the original pump either."

They are wrong. That's the way the mechanical pumps work. There are two one-way valves on either side of the diaphragm. The motor pushes the diaphragm down, and a spring pulls it back up (the strength of this spring, and the size of the diaphragm controls the PSI of the output, BTW). When the diaphragm goes down, the one-way valve on the output side prevents it from sucking in anything from that side, so all the gas comes through the one-way valve on the input side. When the spring pulls the diaphragm back up, the one way valve on the input prevents the gas from just going back into the gas tank, so instead it is forced through the one-way valve on the output.

If those vavles are sealing poorly, it's possible for them to work adequately when the engine is running. The diaphragm would just sink back and get pushed up again by the motor more rapidly/often. In typical running, the cam lobe isn't usually actuating the pump lever that much, the lever stays up as the carb slowly accepts gas and the diaphragm is pulled back down by the spring. Worn/leaky valves could allow the gas to go backwards in the system though.

However, that leads us to the design of the carbs. All the carbs I've ever messed with (which does not include the DGV, but regardless) have 'float bowls'. Wherein a modest amount of gas sits, with a float and a valve to regulate the level. The various jets and metering gizmos all pull gas from this pool under influence of vaccum produced by venturi effects inside the carb throat. The float bowls are not pressurized, they typically have vents to the atmosphere. Any pressure in them could cause the gas to be forced into the carb throat, and flood the motor.

In any case, invariably the fuel inlets and float valves are in the top of the float bowls. This means that it is impossible for the gas to siphon back out of the carb due to any sort of spurious suction on the fuel linies after the motor is shut off. The float bowls (at least in any carb I've ever seen) are never 'full', and have a certain air gap at the top (maintained by the float valve). Simply impossble for gas to jump up off the bottom of the float bowl and back into the fuel inlet and down the fuel lines. The amount of gas in the bowls is more than enough to start a car up and run it for a while, until the fuel pump replenishes it. At idle, a car with a pair of SU's can run for about a minute or so on the gas in the bowls.

What may be happening, however, is that the fuel may be boiling out when th car is shut off hot? If there is inadequate heat shielding between that hot chunk of cast iron exhaust amnifold and the carbs then heat soak after shut off could be evaporating all the gas out of the bowl. Thus requiring a lot of cranking to get the pump going and refill them.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

Thanks, JohnMc. As I indicated at the start of this ordeal, I don't have a lot of experience with carbs. My '83 245 was injected, I don't do much work on my wife subaru, and my '83 toyota pickup has never had a problem.

How quickly would the fuel boil from the float bowls? It seems like after 30-45 minutes, things would have cooled down enough that the fuel wouldn't be boiling any more. I'm assuming I would smell gas while it was happening? Is there a normal amount of evaporation of the fuel that happens normally? Could I be boiling out just enough fuel that ig I start the car within a couple hours, it starts right up, but that the normal evaporation process finishes off the remainder of the fuel after that?

I'm sorry for the stupid questions and very appreciative of your help.

Not sure, a cold start issue isn't probably really a fuil boiling issue, I was jsut trying to imagine other scenarios that might empty the float bowl out after sitting for a while.

Maybe some sort of slow leak at the base of the fuel bowl? I looked at a schematic of a DGV ( http://www.mgexperience.net/article/images/weber-3236.jpg ) and it looks like it's posible to have something like the accelerator pump slowly drain the fuel in the float bowl into the intake tract.

--
'63 PV544 rat rod, '93 Classic 245 + turbo

Thanks, again!

At this point, I'm more or less giving up on the carb as it stands now. Either a rebuild or replacement is in my near future. In addition to the cold start issues, I've got a huge hole in performance where it bogs at mid throttle. Light on the throttle, good response. Foot down, OK. Anywhere inbetween, and it's a dog.

I've got some research tpo do on whether to rebuild or revert back to the original SU's.

Thanks again for your help!

I'll add my opinion to the anti-DGV band wagon. They seem to be adequate replacements for stock motors and are probably superior to a worn out set of ill-adjusted SU's. But inferior to a well adjusted set of SU's with good throttle shaft pllay. A decent set of SU's shouldn't cost you too much.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

Yet another update...

I looked at the carb a little this weekend. It looks like it was poorly rebuilt at some point in the past. There was some sort of sealant/form-in-place-gasket material that had oozed from all the seals. Ugly. It was enough that I'm going to start reading up on rebuilding carbs. It seems entirely possible that some of that gunk is blocking a valve, or even possibly leaking and allowing air in where it doesn't belong.

I will probably look at putting in a check valve in the next couple weeks as a bandaid solution. I'll let you know how that goes.

Here I go making my life more complicated - what would be involved in swapping back to the original carbs? Carbs and manifold, for sure. I'm guessing the linkage is different as well? Would it be worth it? Weber's don't seem to be highly regarded on this list, and it would be nice to return the car to a more original state. Is there a consensus on the mikuni system yet?

Thanks again!

Find a good set of SU carbs with manifold and linkage. Sell the weber setup on ebay to recoup some of your costs.

Or if you have the cash, the mikuni setup seems to be proving itself. If it weren't for my ever so nice set of Z-therapy HS-6's I would be getting a set.
--
Lee 75 244 (80k original miles) 79 242 65 220 project

Howdy!!!

Thanks again for the update!!!

I am considering driving my 220 to work day in and day out now
as my daughter may be returning home(LOL) and I will need a car
for her to drive. I have found a very nice(mechanically) 240 that
I may purchase so I don't have to drive the 220 but I need to see
it first.

I have the same problem with my Weber. It is fine if I run
it all day but the next morning(for me) I have to crank it
a little more than I would expect I have to. Once going she is
fine!

I may experiment with a check valve as well!

My problem is I have been so consumed with getting my
son's 66 sedan on the road that the 220 has fallen to
a lesser status on the list of priorities.

Thanks again for the update and I too will share
my experiences if I get things sorted out.

Cheers,

karl

--
66' 4-door 122s, 66' 2-door 122s (RIP), 67' 220, 78' 244, 87' 245, 88' 245 (RIP), 91' 245...and always looking for more!

I don't know anything about Webbers, but could there possibly be a fuel bowl vent that is blocked at the carb / carbs causing a siphon effect back to the tank?

--
Tom - '60 544, '68 220S, '70 145S, '86 745T, '06 Mazda MPV

Also, depending on the heat shielding situation, sometimes the fuel can boil out of the carb when it is shut off with the motor hot. It's a drawback to having the carbs right above the hot chunk of cast iron exhaust manifold.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

Been suffering from the same thing - although for me it's more like fifteen secs after two or more days. No obvious leaks. I don't recall seeing fuel at the filter when this happens, either. Not sure about that, though, 'cause I don't take her out during the winter.

So if you find a cure, I'd be very interested in hearing what it is.
--
the Finn with the Swede

hmmmm.....I seem to have the same problem with my wagon
when it sits and I am running a weber as well. I have just
always pumped and pumped until it started. Just like you, once
starts and runs for a short while it is fine.
I didn't know much about these cars at all when i got it
and now it has just become "normal" lol.

Please post what you need to do to correct this if
you would; as I guess I need to do the same.

Cheers,

karl

--
66' 4-door 122s, 66' 2-door 122s (RIP), 67' 220, 78' 244, 87' 245, 88' 245 (RIP), 91' 245...and always looking for more!

Rusty is a GREAT guy. If I were you I would call him and discuss the problem.
--
George Downs Bartlesville, Heart of the USA!

I agree, Rusty is a great guy and I didn't intend to indicate that he is in any way at fault. I've since placed a second order with him and look forward to sending him more money in the future. :)

I just wanted to make sure that I wasn't missing anything obvious (like a check valve somewhere else) and that this wasn't the expected behavior.

Thanks again!

The fuel pump has two valves in it that should be preventing the gas from going backwards in the system.
--
'63 PV544 rat rod, '93 Classic 245 + turbo

John;

You are absolutely right, but I have seen where one of those valves was completely shot, but the car (Toyota) ran and started without too much strangeness (it was a carburatet car and - from memory - it was I believe the output valve which crumbled apart)...the way I reconciled this is that the valves are essentially two check-valves in series, with a diaphram variable volume in between, allowing flow in ONLY one direction...to the carb!...so if the output valve goes away, and the diaphram decreases the volume, I figured the pump flows toward the carb, when the diaphram then changes direction and increases the volume, it was somehow easier for fuel to flow from the (vented?) tank through the input valve than it was for fuel to get sucked back from the (sealed?) bowl.

Point is that....wouldn't both valves have to be open to flow to allow drainage back to the tank?

Interested in the answer too!