'83 VW Vanagon fuel pressure mystery...

[seann]

"83 Westfalia, 1.9 litre watercooled, Digifant injection...idles perfectly and when accelerator is depressed, runs perfectly. If VERY moderate pressure is applied to accelerator the engine surges on & off, on & off, repeatedly. Prior to this, while cruising, fuel would just shut off for 2 or 3 seconds, then come back on. Injector spray pattern looks good. Traced bad wire to pump and replaced, shortly after, this started.
Have been told this problem is common on these vehicles, known as "Vanagon Syndrome". Any suggestions?
Thanks

[Dave at Pelican Parts]

Digifant... Is that manifold-pressure based? If so, then I would check the throttle position sensor. I recall that Digifant is based on some of the older Bosch EFI, and if the one it is based on is the D-jetronic system (as used in most 914s and some early VWs and other cars) the throttle position switch is a fairly common cause of that symptom. Unplugging the sensor will take the D-jet TPS out of the system so it doesn't affect anything. Acceleration will really really suck, but if the problem goes away then the TPS is the culprit.

--DD

[taberbob]

"Vanagon Syndrome"

Make sure your fuel pump is functioning properly UNDER LOAD. ALso check the Fuel Filter.

What happens at idle, in the garage is not the same as what happens under load on the road.

Hope this helps

Bob