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Sat Jul 09, 2005 6:51 pm

Okay, it turns over fine, lightning-fast in fact, thanks to my new plugs and wires. Sometimes it doesn't quite catch though. It will will rumble at very low rpms then stall, or the revs will jump up to normal idle within a few seconds. This has only been happening once in a while, usually after the van has been sitting for a few days, but I've noticed it more lately. This was happening occasionally before I had it tunes as I mentioned in my AirCare rant. The engine is an inline 1.8L with CIS fuel injection. Any thoughts? Thanks!

Sat Jul 09, 2005 7:34 pm

Does it have a fuel pressure check valve on the pump?

Sat Jul 09, 2005 10:04 pm

A1 cars had the fuel press check valve back at the fuel press accumulator. I'm guessing that this bus is a converted one. It may not have a press accumulator. Also, is the stock Bosch digijet pump strong enough for CIS?

Sat Jul 09, 2005 10:23 pm

Thanks for the info. Sometimes you guys are so logical, it's scary.
I have a new filter so I'll start by looking at the pump. That's a good question about whether it's the stock Vanagon pump. Hmmm...must find out!

Sat Jul 09, 2005 10:41 pm

I don't recall seeing a pressure accumulator on a Vanagon. Plus, I too would think a stock Vanagon pump is not up to CIS pressures or flows. I'd do the basic CIS tests to see about fuel flows and pressures. Otherwise you are only guessing. Do the basic tests first.

Or are you using Digifant A2 or pseudo Motronic A2 injection? I just sort of assumed you were using CIS. In any case you have to do the basic checks otherwise, as stated, you are only guessing.

Sat Jul 09, 2005 10:47 pm

buspor63 wrote: A1 cars had the fuel press check valve back at the fuel press accumulator. I'm guessing that this bus is a converted one. It may not have a press accumulator. Also, is the stock Bosch digijet pump strong enough for CIS?

This is why I asked the question. Almost EVERY CIS or CIS-E car I can think of offhand has a check valve, and when they go out, they cause symptoms similar to what the OP is describing, or worse. A lot of these cars had TWO fuel pumps- one in- tank, and a main one under the car in or around the accumulator.
It could be that the OE Vanagon pump doesn't have enough poop, which would become MORE evident as it wears. Either that or the pump has been converted, and the check valve ist kaput. Or, the filter is plugged, or the pressure regulator is getting tired. Oy vay! :roll:

Sun Jul 10, 2005 1:34 am

MY 16v 2l engine code 9a cise motronic does this. It has two pumps and a check valve in the accumulator somewhere. I am convinced the check valve is bad as it always starts after I reset the key and kick the fuel pump on again. You might try that to narrow it down.

Sun Jul 10, 2005 6:11 am

digifant and digijet pumps are ok for cis(air NOT OK) look at the check valve, accumulator,filter and warm up regulator. Good chance it's one of them. Mine sometimes does it too,bit of a pain!

Sun Jul 10, 2005 6:18 am

The accumulator on CIS cars keeps a reserve of pressurized fuel for start up. A bad check valve would allow it to leak down. I think?
This conversion may not have those parts installed. Since the vanagon fuel tank is more of a gravity system, not all that important. A trip to the scrap yard to pick up pump/accumulator system may help solve the problem in the end. I remember that on A2 cars they are packaged together on a neat little tray, just ahead of the rear axle.