2L surging during accel

[Mark]

Hi,

Strange things a'happening this morning. My 76 Bus (2L manual) seems to be a steady surging or lunging forward under accelleration. If I back off on the gas a bit it seems to disappear. At a stoplight, I gave it some gas in neutral and nothing strange, so it only seems to be when under load. I changed the engine bay foam seal last night & figured I might have knocked something loose?!? Does anyone have any suggestions where to start looking? It's my daily driver & would like to find & fix the problem asap. Thanks in advance.

[keifernet]

Okay, I'll throw out a few things, withoout being there this could be tough.
Any wires you messed with to get the seal in... head temp sensor, group of white wires that go to ground on center of case under the manifold center section.
wires that run over to the "resistor unit". and or any wires that go to the injectors themselves...
Surging could be an injector sticking, or maybe one 'coming in and out'? and your feeling loss of power coming and going not surging like more power that you'd expect for the amount of throttle your giving it?
( hope that makes sense)
Or how about vacume connections/ hoses and big rubber snake boot to the air flow meter/ intake. did you mess with any of that to facilitate the install of the seal?
Lots of questions, sorry I do not have a definitive asnwer for you... investigate, about all you can do...

[Mark]

Thanks Keifer,
I changed the fuel filter as I've been meaning to anyway, & changed the line from the tank to the filter, a PO had cut it too short (sharp bend in line) and the old hose fell apart in my hand when I took it off the old filter! Scary stuff, but a HAZMAT fuel spill was narrowly averted. This alone was worthwhile, but didn't solve the problem. At that point I checked over the engine bay to see if I knocked anything loose with the foam seal replacement. I found several hose problems. The line coming from the driver side firewall by the fuel rail to the intake body has a hole in the hose connecting the two lines, (temporarily fixed now). The line leaving the decel vv to the vac advance was dry/cracked so I replaced that section, and the hose from the charcoal canister, (long ago rendered useless I'm sure) to the air filter housing was disconnected. To me, it seems that a vacuum leak would explain why the bucking/surging occurred only under load, (improper timing/advance). When I cleaned out some of the leaves & crap from the engine bay when replacing the seal the other night, I noticed a short wooden dowel plug in there. In retrospect, I think that was used to 'plug' the hole in the vacuum line by the fuel rail! Funny thing is the owner previous to the last was a vw mechanic, HA! Happy ending to the story though, as it's running fine now.

[keifernet]

Great Mark, glad you got that stuff taken care of. sounds like you averted impending disaster.
that's usually the case with the FI models , lots of old cracked toasted hoses and connections to be found. The FI system is suceptable to poor running from even the most minor of leaks. I would ( I'm sure you will) get around to replacing everything I
could all at once. good luck with it...

PS if you haven't yet get the Bentley Factory Manual... a must for keeping the FI system alive...

[Mark]

I hear that! The Bentley was the first thing I bought after the bus & has already paid for itself. New hoses on the shopping list for sure. Disaster was NARROWLY averted, remember the little Dutch boy with his finger in the dyke? (Not THAT kind of dyke, ha) That's how I felt, holding the fuel line pinched with my fingers until my fiance could get a container for the gas. She's a keeper.