chugging, stalling and clicking, please help!

[VeeDubDrummer]

Hey, I just recently have this problem where my 90 jetta keeps chugging and stalling. The car was running great yesterday, this just started after work today.

I keep the rpm's up and it will sometimes rev high or will die out completely and stall. I'm constantly hearing a clicking sound in the dash, sounds like a relay of some sort. I've had this happen on occasion before, but after I turn the car off it usually goes away and this time it's 10 times worse. It stalled about 15 times on my 10k drive through the city from work. I think it's a fuel pump problem but i'm not sure, I did put $10 gas in it this morning, could it be a "bad gas" problem? (i doubt it)

any suggestions before I go pay an arm and a leg?

chris,
Vancouver, B.C
Canada

[ohiobenz]

is this an 8v or a 16v?

it sounds like a fuel pump relay - but its hard to tell from your description.

Do you smell raw fuel when this happens??
can you hear either of the fuel pumps run?

[VeeDubDrummer]

Originally Posted by ohiobenz

is this an 8v or a 16v?

it sounds like a fuel pump relay - but its hard to tell from your description.

Do you smell raw fuel when this happens??
can you hear either of the fuel pumps run?

8v
It wasn't the fuel pump relay.
I do smell raw fuel and there's black smoke when I try to keep it running.
It doesn't idle well and when i step on the gas the clicking starts.. it chuggs and stalls.

stumped.
thanks for your time,
--chris

[ohiobenz]

Originally Posted by VeeDubDrummer

8v
It wasn't the fuel pump relay.
I do smell raw fuel and there's black smoke when I try to keep it running.
It doesn't idle well and when i step on the gas the clicking starts.. it chuggs and stalls.

stumped.
thanks for your time,
--chris

Black smoke means that you're way rich - probably flooding to the point of stalling. A 90 8v should be Digifant fuel injection.

A couple items to look for in Digifant:

Vacuum leaks - any vacuum leak directly affects fuel pressure since the the fuel pressure regulator increases the amount of fuel bypassed (lowers fuel system pressure) with more vacuum theres lower fuel pressure.
There is a valve stem looking thing on the fuel rail that allows for you to connect a fuel pressure gauge.

Bad grounds - Digi tends to fry ECU's easily in the fuel control area if there are bad grounds. The injectors are grounded by the ECU to provide the "on" time pulse. If there is a bad ground - the path of least resistance through the ECU usually ends up being a disaster.
When checking/cleaning grounds always make sure the ignition is off and the battery pos is disconnected. A simple spark at the battery terminal can fry the ECU.

Coolant Temp Sensor (CTS) - check for proper resistance per the Bentley manual. This sensor determines cold start and warm-up enrichment.

o2 sensor - voltage signal from the oxygen sensor is used by the ECU to determine the length of injector pulsing. Check signal per Bentley

Throttle switch - Especially the WOT switch. check for continuity with the throttle at idle there should be none. It signals full throttle enrichment to the ECU.

MAF sensor - located above the air filter - check for free movement, spray out with some carb cleaner if any sticky or stiff movement is detected when you move it from the air intake side with your finger.

hope some of this helps

[boschmann]

I'd go for that coolant sensor first, it's very common for it to go bad. It's on the coolant flange where the upper radiator hose enters the cylinder head. Measure resistance across the two pins, should be 2000-3000 Ohms cold & 200-300 Ohms at operating temp.

[VeeDubDrummer]

wow, lots of stuff to try. Thanks for the help. I'll throw down a quick message here when I determine what the problem is, I think i'm going to send it to v.w garage where they have all the gear to test this stuff. I was going to drop the gastank with a buddy and test the fuel pump.. but now I think it's best to go to a mechanic to find out the problem, then figure out if I want to bother trying to do it myself.

thanks again guys!
--chris

[ohiobenz]

Originally Posted by VeeDubDrummer

I was going to drop the gastank with a buddy and test the fuel pump.. thanks again guys!
--chris

there is an access plate to the in-tank pump inside the trunk - no need to drop the tank!!

a multimeter at Radio Shack is less than 1/2 of a VW garage labor charge for 1 hour......

[VeeDubDrummer]

well, It's fixed now.

It was a fried ECU, the garage said they could get one "cheap" at 300 canadian, I found one at a salvage yard for 125, he gave it to me for 100 and threw in a used jack which i needed. The distributor cap was offset so he set that back up and put in the new ECU (30 seconds, ha). The labour was 175 for the diagnosis,.. grand total of 300 bones to get er' back up to speed.

My mechanic buddy has a great multimeter but we just didn't know where to start with this problem and time was a factor this week where taking the bus wasn't an option.

Thanks again OHIOBENZ and boschmann for all your input and suggestions.

cheers,
--chris