Engine stalls randomly for 30 seconds

[King Stone Dragon]

I've been viewing Samba posts for years and have found much information and help but never signed up until now. I need help fellow VW'ers. I hope I'm posting correctly...

I bought one of the last VW Mexico crate engine years ago and installed it in my 74 Thing and it has ran like a top for a couple years as my daily driver. I live in Montana so it runs in 40 below weather in the winter and up to 90 in the summer. It has always ran a little lean and hesitated slightly at times (esp in winter) but other than that it ran great.

Recently it began stalling, mostly at stop lights, and won't start again for about 30 seconds or so. At first I thought it may have been a problem with my gas cap being sealed too well as I would hear air suck in when I loosened the cap (can you believe it sealed?) but I tore a small piece of the seal out to vent it and the problem persists.

I have an electric ignition, gas tank is clean and coated, gas tank filter is new and clean, new fuel filter, blew carb jets out, fresh oil, battery tests in good shape, new distributor cap and rotor, coil has good spark, new power band and flux capacitor still my problem persists...I plan on changing spark plugs and wires, checking fuel pump for debris (doubtful) and doing a complete carb rebuild with valve adjustment (last one done a couple months ago and not far off)...

I hope I've given enough info, if not let me know...thanks for any help/info/guesses!

[citroen]

check the flange under the fuel pump sometimes they shrink and the fuel pump rod sticks and won't move when the engine cools off the rod moves again try replacing the flange and rod first a cheap fix. if that does not work replace the distributor with one with points the units sometime over heats.

[Riffster]

I am certainly not the expert, but I think I can guess at some of the questions they'll ask:

When you say "it won't start for 30 seconds":
-Is it turning over?
-is it 30 seconds of turning over?
-does it matter if you let it sit for 30 sec. and then try to start?

Am I correct in thinking it only stalls when the car is at a complete stop for a period of time and idling? Does this only happen when the engine is warm, or when it is cold as well?

Have you checked the RPMs at cold/hot idle?

-Larry

Edit: Aaaand Citroen gets in while I'm typing!

[carsdlt]

Yeah, the VW gurus need more detail. When you say it stalls "mostly at stop signs" when else does it stall? Cruising-hard accel.-cold-hot...? Have you checked your fuel pump pressure? When it dies, do you have to hold the accel. Pedal down to re-start?...
_________________
Thanx, DLT
'73 181 stock 1600 - "Dr. Bombay"

"If it works, don't fix it....let it break on its own."

[King Stone Dragon]

Awesome response time and comments guys!

@carsdlt:
Yes, mostly at stop signs but a couple times it has cut out and then died a few seconds after going forward like the bowl emptied of gas but the float isn't stuck or bad and the needle and seat seems fine although I will be replacing it when my next parts order arrives.

Once or twice I've had this dying feeling with the pedal to the metal but it was short and quick to recover...all this I believe happens when engine is warm.

@Riffster:
Yes it does turn over fine when stalled but wont start whether I feather or hold it wide open or don't touch the pedal at all (I should add that the pedal part is as far as I can remember while in a panic state in traffic trying to get moving)

Basically I try to turn it over again for about 3-4 seconds and then wait 10 seconds and try again. I haven't been patient to wait longer than that. Today for instance it stalled on the way to work after driving for about 8 minutes when I pulled up to an intersection, took more than a minute to get going as I had the opportunity to get out and look at engine and open gas cap (fuel filter had gas in it and gas cap is "vented" so had no vacuum issue)

@citroen:
I will check out your suggestion tomorrow and let you know what I come up with on the fuel pump. I do have some points/condenser distributors that I can try too.

Thanks much!

[CraigInPA]

If the car is running fine and then dies out at idle or off throttle, that sounds like a fuel delivery problem. i.e., the problem is in the carb, fuel pump, lines, or tank.

You might want to check the fuel pressure going to the carb. Insert the gauge between the pump and the carb. Too much pressure and the pump floods the carb, resulting in a stall. Too little pressure and the carb bowl runs dry, resulting in a stall. Too much or too little pressure is overcome when the car is above idle. Too much is burned off due to the increased need for fuel. Too little is overcome by the carb vacuum pulling more fuel through the pump than is actually being pumped. The cause of too much or too little is the length of the fuel pump rod.

How do you know if you have too much or too little pressure, if you don't have a gauge? If the engine compartment has the overpowering smell of gas when the car is at idle, it's too much. There's no easy external test for too little unless you have a clear fuel filter between the pump and the carb. In that case, you'll see the fuel filter emptying. But, it's no big task to confirm the length of the rod. Two bolts to remove the fuel pump and you'll have the rod in your hand. The length of the rod is different for the two types of fuel pump. You'll find more info on fuel pump pressure and rod lengths at http://1800vw.bizhosting.com/fuelpumps.htm

There's still a possibility that you have:
1. a bad fuel pump, possibly a clogged internal filter screen or a ripped diaphragm.
2. a bad float in the carb
3. a sticking jet in the carb
4. a sticking fast idle solenoid

Let us know how things progress.

[Wildthings]

Not sure what is up, but add some FI/carb cleaner to your fuel tank and see if that makes any difference. Are your running the stock single centermounted carb? If so how hot is your intake manifold?

Your tank should vent through the carcoal canister, so if the tank is drawing a vacuum something is clogged in the tank ventilation system.

[King Stone Dragon]

SO a quick update...After doing a complete tune-up I wound up with the following results:

Valves we're fairly loose on 1&2 and a tiny bit on 3 but right on for 4...adjusted all correctly

Spark plugs were pretty white and gap was way to far...replaced with new NGK BP5ES

Replaced distributor, cap, rotor and plug wires

Accelerator pump rod had some gunk on it that I cleaned off and replaced gaskets but there was no debris in pump

Cleaned carb, jets and rebuilt with a kit...diaphragms were stretched but not torn

Interesting thing happened while I was timing the beast (and had my strobe light on)...after a few minutes and it had a chance to warm up, guess what?, it cut out! Best part was I was facing the engine and noticed the strobe light died instantly so I was able to deduce that it was electrical and not fuel. So I swapped coil with another one and it ran great until it died again.

I put it all back together by about midnight and quickly ordered another electronic ignition which I think now is the culprit...

[GI Joe]

[King Stone Dragon]

Yeah that is next on my list while i wait for my electronic ignition. The only reason why I am concerned is that when I had the points/condesor distributor in before it would get hot and melt the little plastic piece that rides up and down on the square shaft...so there's probably something wrong there too...did I mention this was a vw mexico crate engine that came with a distributor that hooked to a C.D.I.?

[doublecanister]

[King Stone Dragon]

Sorry it took so long to respond to your question T...

I had a magfire electronic ignition I got from CIP1.com (ACC-C10-5844) they seem pretty cheap (like 35 bucks) and I had to file a bit of the casing metal as there was some left over from the mold that would have rubbed on the distributor shaft.

I had the Thing running with the new electronic ignition until about a few days later it started sputtering again like it was missing on a cylinder. It didn't die like last time but the distributor was hot to the touch.

About ready to take it to a *gasp mechanic...