Losing Power...maybe just at high altitude?

[clicknathan]

I've got a series of problems trolling me lately.

1978 VW Bus, 2.0L fuel injected.

Two months ago I did a tune up, and then took it into a well renowned mechanic by the name of Geraldo in La Paz, Baja California Sur, MX. Everything checked out. I did this because I was traveling to Mexico's mainland, particularly to cross the mountains in the middle of the country.

So I go from elevation 0 to around 10,000 ft over the course of three weeks. There's a lot of going up and down in these mountains. Things seem fine, until a series of strange events occurs...I'll try to keep it entertaining but please note I'm in Mexico, my Spanish is (ahem) next to just below decent, and I'm up against a race against time as my temporary visitor's permit is going to expire in a few weeks.

Part one of our good mystery is I show up at a Pemex (the government / only gas stations here in MX) and get a tank full of regular. That's ~89 octane.

"Your gas tank is leaking," says the guy filling it up, en espanol. The word for "leaking" and "creating a massive waterfall" must be the same in Spanish, because it was just POURING out. It was coming from the center of the tank, near where the line comes out / overflow lines go back in to the tank.

That sucked. I pushed the Bus out of the way and a mecanico showed up. I followed him (the Bus no longer leaking after going down to about 80% full) to his garage down the road. This "garage" was little more than a slab of concrete in front of his house where he'd painted the words "Electronico" and "Mecanico" in red paint. But, such things do fly in MX where they never would in the US...

He crawled underneath and came out with my fuel filter, which had a small crack in it. A chip, really, it didn't even necessarily look like it was a hole, just a little chip in the outside.

He insisted this was the problem, and so I let him swap it out, then I headed down the road.

I figured he just didn't want to remove the tank / repair it (his "garage" wasn't quite equipped for any such work) and this was his way of getting me out of his driveway.

Now, and this hadn't happened before, the Bus started losing power. Luckily, I was going downhill and it would get power every few seconds.

Power.

Nothing.

Power.

Nothing.

Floor it? Nothing.

Let off and hit the gas again? Power.

So I drift into a dirt lot, and swap out my air flow sensor (I happen to have a spare), thinking this might be the problem. Doesn't fix it.

Another guy walks out of his house, right next to where I've landed, and he's also painted the words "mecanico" in red out front of his place. Okay, what can it hurt?

At this point, I know I have gas pumping through the filter. I know I have gas pumping into the engine (remove gas line there, hit the gas, gas comes out, clean up gas). He swears it's the pump. So he puts a new pump in. Now the Bus will start and doesn't lose power as I test drive it down the road with his son, but upon returning to pick up the rest of my family, it starts cutting out and dies. Then it won't start again.

We rip open the distributor. Replace the points and the condensor, check the timing. Bam, everything seems good to go. And so we do.

That's at around 6000 feet. We drive up and down the mountains again until we get to a volcano that's this beautiful national forest type setup and we're just dying for some of that tall tree beauty after so much time at the beach and in the deserts.

The Bus feels a little sluggish, but it's been a 3 hour day, and those are often hard on her, so I don't think a whole lot about it. We're literally 30 feet from the campground and the hill gets considerably steeper, but nothing we haven't done before.

I slow down to look / read the National Park entrance sign...probably my biggest mistake since I started smoking when I was a teenager. The oil light starts flashing. If I press on the gas, it stops.

If I let off the gas, it flashes. We're not low on oil. The wire that runs into the sensor / whatever just behind the distributor is in place correctly. I figure we'll just get to the campground and let her cool down and take a look later when it's all cool.

But we now can't make it up this hill. Again, it's steep, but nothing we haven't done before. Reverse has absolutely no power at all. 1st has barely any power.

I give the Bus an hour to cool down while I try and find a place on the side of this cliff we're on to call home for the night, but there's nowhere within an hour's walk. So, an hour later, my wife says, "What are we going to do?"

I tell her I'm going to start up the Bus and drive it up this hill to the campground. And I do. And it makes it.

So WTF?

It's still clearly way under power at this point.

And remember, we're at 10,000 feet or so.

In the morning, 15 hours or so later and a really chilly night (aka, it's definitely cool as a cucumber's mojito by now), the Bus fires up just fine, but we still don't have much power. I can push the pedal to the floor and it doesn't rev. Maybe 5 minutes later, and it will now rev up.

So I rev it up and we head down the mountain.

Three hours / 96 miles down the mountain later (and I swear it was almost ALL down hill, praise whoever it is you praise!), and with no problems on the way down, we're now stuck in a hotel in Veracruz, MX.

But that's an irrelevant story.

What I can't figure out is?

#1. Is this a fuel problem? Lines all check out. New filter, new pump, new Air Flow Sensor, where could the problem be?

#2. Is there a chance that the leak in the gas tank could be screwing up the air / gas / pressure ratio?

#3. Could my loss of power be primarily caused by elevation?

I'm going to have a garage pull the tank and fix or replace it and all of the lines (they're the originals, so why not I suppose) before moving on, but I'm hoping there's some creative genii out there who can help me put more than duct tape on this series of unfortunate events.

Gracias!

[timvw7476]

this story sounds like water in the tank/gas, any way to get a sample
in a clear container, let it settle a few moments & look for H20 at the bottom?
If you find it, just drain sample after sample till you see no more water, it
collects right there at the low point, ready to feed the pump.
PS: don't waste time /$ dropping the tank, it drains fine in place, if it comes
to that.

[Tom Powell]

Carbureted engines run richer at elevation and lose power for two reasons; mixture and less oxygen. FI engines keep their mixture correct and lose power because of the thinner air. As you climb to altitude it becomes noticeable, but it is a gradual loss of power, not dramatic as you have experienced. For the cause of your problems I would expect overheating, bad gas, clogged filter or poor fuel delivery, points that wore quickly, overheated coil, or bad timing. For carbureted engines you advance the timing a few degrees as you go to altitude. For FI ?

Aloha
tp

[Tom Powell]

[busdaddy]

What kind of filter did mechanico #1 replace yours with?, if it's not meant for FI it'll cause issues.
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[SGKent]

I thought about this thread before answering it.

First - while it might serve your artistic abilities well, flow of consciousness writing won't work well for the people around here who fix buses. They may have an artistic side, but they use analytical skills to troubleshoot so keep it to the facts if you are asking for help.

It takes 3 things for an engine to run right. They are fuel and air mixed in the right amount, spark at the right time, and compression. A problem in any of those areas and your bus will run like it is running.

You are guessing that it is a fuel problem, and that is a good guess but it could also be something else. I am not listing them because it is a long list.

How mechanically inclined are you and what kind of spare parts are you carrying?
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[clicknathan]

@SGKent Noted. I guess I find that when I approach mechanics they ask very few questions and I end up going through the same steps (ie, check the timing / distributor / replace this filter or that) and I end up being too bashful (or poor at Spanish as is the case down here) to tell them that isn't the problem or that's been tried already. But definitely, noted.

I am not incredibly mechanically inclined. I have basic tools and the basic spare parts, ie air filter, fuel filter, spark plugs, some clamps and hoses, sandpaper and the John Muir book. I am also, however, in a very large city now (Veracruz, MX) and there are countless VW shops and places to get parts, and even though they can vary a bit, they've been making Type IIs down here until just a few years ago so I should be able to find whatever I need.

I just don't want to walk into a shop completely stupified and have them do something that works for 30 miles, only to find myself in this situation again but with a thinner wallet.

@busdaddy I don't know the exact brand name but it looks identical to the one I had in there before and the spare I have now.

It's round (as opposed to a more boxy shape that was in there 2 filters ago, ie the one that was in it when I bought it 5 years ago). If that helps.

@tompowell & @timvw7476 Thanks for the suggestion. I will do this and see what I find.

And thank you all for your input!

[aeromech]

Remove the gas cap and go for a ride
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[Wildthings]

[clicknathan]

Lots of troubleshooting on this as I'm having more symptoms, namely now a flickering oil light at idle. So I dropped the oil pressure relief valve. Mine is grooved at the top, and hollow inside from the bottom.

It just fell right out so I wasn't able to see how it went. Does the grooved part go to the top and the hollow part against the spring at the bottom?

[timvw7476]

The flat surface faces oil pressure side, should be facing up.
Oil light flickering at idle is acceptable, at least it is per most VW
operator's manuals.

[Tcash]

Spring goes in hollow or hole.

[Wildthings]

The VW oiling system will let the oil get very hot at high speeds especially if you are running a thick oil. As you slow down quickly from a highway run the oil will still be hot and thin so you may initially have the oil light flickering at or near idle until the oil cools.

[clicknathan]

Thanks @timvw7476 & @tcash, much appreciated. I took a guess at it based on the Idiots guide diagram and a video I watched, but was ready to remove it should it be necessary if someone posted otherwise.


@timvw7476 & @wildthings - mine has never done that before, but then again I am running a thicker than usual oil (10w 40) and it's a lot hotter down here than I've ever really been in before I guess. Just wanted to cover all of the bases.

@sgkent and everyone else who'd asked. The new fuel pump I've got looks like this: http://www.busdepot.com/gfp301
But it's black, and I'm assuming Made in Mexico, likely specifically for their Type II models.

Bus Depot says I should have this one, though, since it's fuel injected: http://www.busdepot.com/251906091

Still, the new one looks much like the old one that was in there, and neither look to be the same as what Bus Depot is calling for.

I was mistaken before when I said they had continued to make these here in MX up until a few years ago. It seems that sometime in the mid-90s was the end of production here in MX, but in Brazil they kept going until 2013.

Aside from checking the pressure relief valves, I did a compression check, and that came out to be:

#1 130
#2, #3 & #4 140

Way higher than what the Idiot book talks about, but I've seen other threads here that have similar results.

The oil isn't that old (1000 miles), but I'm going to change it and the filter tomorrow (asked a guy in La Paz to do some other stuff and he changed the oil too for some reason, though that oil was only 1000 miles old too) and the filter, just to be nice to the old girl, and then try and do the timing check...though I've yet to do this before so we'll see how it goes.

Let's assume that comes up all good, that would seem to send me back to the "fuel / air" issue...as I'd mentioned, I've got a new air flow sensor in it, new pump & filter.

So, still welcoming any thoughts.

[Wildthings]

FWIW, when I tried a bunch of oils to see how hot each got in similar conditions, straight 30wt ran the coolest of all. I really can't say why as I had expected the 5w20 (or it might have been a 0w20) to run the coolest.