Itinerant Air-Cooled

Update. I had the problem again duing the Maupin trip, always going up extended grades, in any gear from second to fourth. When it happened, I would take the load off the engine, shift to a lower gear, and slip the clutch a little to keep the revs high. That kept me going.

Unrelated to that problem, I also had an "electrical issue" when an always-hot wire to the ignition switch shorted out and burned, melting a few adjacent wires. I'm currently trying to get up the courage to start mucking with the wiring myself, but I may end up just taking it to the beamish boys at Kombi Haus and letting them deal with it.

JLT wrote: ↑

Thu Jun 21, 2018 1:28 pm

Update. I had the problem again duing the Maupin trip, always going up extended grades, in any gear from second to fourth. When it happened, I would take the load off the engine, shift to a lower gear, and slip the clutch a little to keep the revs high. That kept me going.

So you have a non-stock carb (Brosol) fed by a non-stock fuel pump (ie. the hunched-over kind which you would have had to install when you installed the alternator to clear the larger diameter of the alternator). I don't mean to be pedantic, just outlining the operating parameters.

Did you replace the fuel pump pushrod with the one that is 4 mm shorter when you replaced the pump? I recall that when I installed a new pump on my '72 Super Beetle waaay back when, the pump that the VW dealer partsguy sold me was the alternator version, and then, almost as an afterthought, said "oh, yes, you will also need this shorter pushrod, but it has Porsche part number, so it will cost you $4.75 instead of the $1.50 it would have cost if it were a VW part."

Sigh. I miss the '70s.

SlowLane wrote: ↑

Fri Jun 22, 2018 12:44 pm

So you have a non-stock carb (Brosol) fed by a non-stock fuel pump (ie. the hunched-over kind which you would have had to install when you installed the alternator to clear the larger diameter of the alternator). I don't mean to be pedantic, just outlining the operating parameters.

That about sums it up. I think that if I had to replace the carb with the Solex 34 PICT 3, I'd have to replace a bunch of other stuff that came with it but which I no longer have (if indeed I ever did, because the bus may not have had the right carb when I bought it ... the distributor was definitely not the right one). OTOH, the Brosol had been running well for the past seven years, until this stumbling thing started happening.

Did you replace the fuel pump pushrod with the one that is 4 mm shorter when you replaced the pump?

Yup.

sgkent has been in touch with me about several other things that might be wrong with the fuel system, and I'm eliminating them one by one but still haven't nailed down the problem. I will definitely let y'all know what happens down the road.

JLT wrote: ↑

Fri Jun 22, 2018 2:38 pm

SlowLane wrote: ↑

Fri Jun 22, 2018 12:44 pm

So you have a non-stock carb (Brosol) fed by a non-stock fuel pump (ie. the hunched-over kind which you would have had to install when you installed the alternator to clear the larger diameter of the alternator). I don't mean to be pedantic, just outlining the operating parameters.

That about sums it up. I think that if I had to replace the carb with the Solex 34 PICT 3, I'd have to replace a bunch of other stuff that came with it but which I no longer have (if indeed I ever did, because the bus may not have had the right carb when I bought it ... the distributor was definitely not the right one). OTOH, the Brosol had been running well for the past seven years, until this stumbling thing started happening.

Did you replace the fuel pump pushrod with the one that is 4 mm shorter when you replaced the pump?

Yup.

sgkent has been in touch with me about several other things that might be wrong with the fuel system, and I'm eliminating them one by one but still haven't nailed down the problem. I will definitely let y'all know what happens down the road.

Okay, i'm just going to throw in a possibility here, and that is that your alternator-friendly fuel pump may not have the requisite capacity to keep your float bowl full when the engine is at full load and sucking fuel for all it's worth.

That fuel pump was fitted to alternator-equipped Beetles from 1974 onwards, but the bus (in the US and Canada anyways) never had that combination, because it had been upgraded to the Type IV powerplant in 1972. So the hunched-over pump may have only been spec'd to be adequate for powering the lighter, more fuel-efficient Beetle, Ghia and Thing.

Just a thought.

I'd wonder how much the fuel pump push rod is sticking up above the fuel pump stand at it's highest point? It should be 13mm. A lot of these cheap, third world fuel pumps are notorious for putting out 5+ PSI. As a result, some folks shove too many gaskets under the fuel pump. They do this to move the fuel pump up and away from the push rod to reduce the stroke. This in turn reduces the fuel pressure. It also can reduce the volume of fuel to where an engine can suffer fuel starvation under a load.

I think more likely is the fuel pump is getting weak and is not producing enough volume under load. I ran a very thirsty 2277 engine in my bug. It had a cheap, alternator style pump. It had no problem keeping up with the fuel demands of the dual Weber 44's. Not that I ever drove that engine hard :)

Stick a fuel pressure gauge between the fuel pump and carb and see what that pumps pressure is.

I had a chance to look at it at Maupin! I wudda, cudda, shudda.
Colin
(enjoying your book regardless . . . I am just where you all shut down the touristy hang-gliding school and you got a job with a hang glider manufacturer and you rebuilt your engine because you wanted to, this time)

SlowLane wrote: ↑

Fri Jun 22, 2018 4:33 pm

Okay, i'm just going to throw in a possibility here, and that is that your alternator-friendly fuel pump may not have the requisite capacity to keep your float bowl full when the engine is at full load and sucking fuel for all it's worth.

Just a thought.

My thought as well. The alternator and fuel pump were installed by Ronnie Feitelson's garage in Lake Havasu City, and I would have assumed that he would be savvy enough to know if there were any adaptation problems. But maybe not.

I will have that checked out sometime soon.

Amskeptic wrote: ↑

Fri Jun 22, 2018 8:18 pm

I had a chance to look at it at Maupin! I wudda, cudda, shudda.

Well, I didn't feel that had a right to your time, since there were people there who were paying you good money for that. And I figured that you had a right not to be hit up for free advice every time you show up at a gathering. Was I wrong about that?

(enjoying your book regardless . . . I am just where you all shut down the touristy hang-gliding school and you got a job with a hang glider manufacturer and you rebuilt your engine because you wanted to, this time)

Well, to be honest, the last time I did something to an engine when I didn't absolutely have to was a few years ago when I took out George's engine for the first time. (That comes later in the book.) Before that, my buses were daily drivers and I had to get them back on the road immediately.

JLT wrote: ↑

Sat Jun 23, 2018 1:17 pm

Amskeptic wrote: ↑

Fri Jun 22, 2018 8:18 pm

I had a chance to look at it at Maupin! I wudda, cudda, shudda.

Well, I didn't feel that had a right to your time, since there were people there who were paying you good money for that.

There were? They did?
Colin

SlowLane wrote: ↑

Fri Jun 22, 2018 4:33 pm

Okay, i'm just going to throw in a possibility here, and that is that your alternator-friendly fuel pump may not have the requisite capacity to keep your float bowl full when the engine is at full load and sucking fuel for all it's worth.

I think I might have tracked down the problem, and you were closer than everybody else.

While I had the bus at Kombi Haus for them to sort out an electrical disaster from my last trip (details on request), I had Daniel take a look at the fuel pump pressure and volume, and check out the carburetor for various things.

It turns out the fuel pressure was about 3.5 psi at 1500 rpm, and the book says that it should be around 2.8 psi at 3500, so he took the pump off and added four base gaskets to adjust the fuel pressure. Now I've got between 2.8 and 3 psi.

What's more, he noticed that the carburetor float was sitting low in the float bow. He took it out and weighed it. It weighed 18 grams. He installed a new float, which weighs 9 grams.

Daniel is much smarter than I am.

We'll see if these things clear up the problem.

Good to see some details being tended to!

John, do you keep track of fuel economy? High fuel pressure and a sunken float could manifest as a rich running condition.

Robbie

(I enjoyed the first few chapters of your book here just two days ago.)

asiab3 wrote: ↑

Sat Aug 25, 2018 1:32 pm

Good to see some details being tended to!

Well, Colin's whole goal with the web site was people not only posting problems, but posting solutions (or possible solutions) to the problem, thus expanding the knowledge base.

And BTW, it was good to meet you at Maupin and put a face to the name.

John, do you keep track of fuel economy? High fuel pressure and a sunken float could manifest as a rich running condition.

I do, and we'll see how this influences my mileage. Historically, it's been about 18 mpg (igive or take a gallon or two) on long trips, and around 16 in the city, but we'll see what it looks like from here on out. It hasn't changed in the nine years since I swapped out the old carb (which was a 34 PICT-3) and distributor (which was god knows what, but certainly wasn't one for a bus) for the Brosol and an Aircooled.net SVDA dizzy.

(I enjoyed the first few chapters of your book here just two days ago.)

Glad you like it! Those who might be curious about it are hereby steered to this page, which is the introduction to the book:

http://dragonwing.biz/on%20the%20bus%20intro.htm

And the chapter on the Idiot Book was an expansion of a review I wrote for Amazon.com about eight years ago. That review is buried among the other hundreds of reviews, but when I was looking for the URL just now, I found that they're selling a used copy of an earlier (mid-70s?) edition for an astonishing $738.11. Complete with authentic grease stains.

JLT wrote: ↑

Sat Aug 25, 2018 3:42 pm

Idiot Book used copy of an earlier (mid-70s?) edition for an astonishing $738.11. Complete with authentic grease stains.

I got one of those . . . 1976 Edition greasy as hell missing pages detached cover.
$737.10
Colin

More update:

I've put about 300 miles on the bus since I got it back from Kombi Haus, and the stumble has not re-appeared. It's been mostly flatland cruising, though. I'll have to take it into the mountains next month to see whether the problem is really gone.

Well, it's been about a year since Daniel worked his magic, and I hadn't had a lick of trouble, until a week ago. When I was accelerating up a hill, it has just a trace of a stumble (like fuel starvation) and then it went away.

Three days ago, it happened again. So I pulled over to the side of the freeway and checked all the electrical connections I could easily reach ... distributor, spark plugs, coil, fuel cut-off valve, etc. The lead to the #3 spark plug was a hair loose ... a little click when I pushed it in all the way. Got back in the car and drove 300 miles. No problem. So I'm hoping that was it.

The boys at Kombi Haus remarked on something else, too. They asked me how old my battery was (coming on six years now). They said that the Pertronix ignition, which I got with my Aircooled.net SVDA distributor, likes to have a fully charged battery, and that low-battery situations can sometimes mimic a fuel-starvation situation. Anybody else hear of that?

At any rate, I think I'll get a new battery before I go to Maupin, just to be safe.