Engines only runs for 40 seconds?

1600 starts and runs fine but for only 40 seconds. I am getting fuel out of the fuel pump. Thought maybe the alternator was overcharging but I took the alternator out of the loop and ran only on battery, but still the same thing 40 seconds. Strange..Any ideas?

Thanks
Bruce

Bruce: Need a little more info. Single or dual carbs? Can you rev the motor up during those 40 sec.? It initially sounds to me like it's a fuel problem in the carb. Bad float maybe? Just a guess.

BD

I think Bill is onto it ... sounds like the motor might be runing only on the gas in the car bowl(s)

something in fuel line or bad fuel filter?

Mentioning fuel filters, I've seen the cylindrical mesh type get sucked shut, restricting fuel flow.

BD

If it is a single carb? Check the idle control solenoid on the side of the carb ,it could be lose or the wire could be off.

Thanks for the info. Single carb. Seems to be getting fuel but will only run for the 40 seconds.

Bruce: go back up and re-read the above posts to make sure you didn't miss something.

After it dies, how soon before you can start it again?

What happens if, when you start it, you rev it up and hold it at, say, 3K - 3.5K rpm?

Also, when it starts, can you blip the throttle up a few times to get the rpm's up over 3,500 or does it cough and sputter?

Also, HOW does it cut out? Does it cough and sputter a few times and then die, or just be running OK one second and completely dies the next?

I'm not yet convinced that it's a fuel problem, rather than electrical, so a little more info would be cool. Like, when it dies, is there still 12V at the coil + terminal? You could also check the gap on your points (or do you have electronic ignition?)

With a single carb (and a single float bowl) you have about 40 seconds of fuel in there at idle before it runs out (if nothing more is getting in at the correct flow rate) - less time if you rev it a few times.

Therefore, if you're coughing and cutting out after 40 seconds, then it's usually something clogging the fuel line somewhere along the way (filter, in-tank strainer, or even a weak diaphram in your fuel pump (I assume you're also running a stock VW mechanical pump). If it just plain dies instantaneously, then it might be electrical.

Let us know what you find out.......Gordon

If all the above fails, check the fuel tank for gremlins.
ed

Make sure you only have 40 second errands to do. :) A little humour on an otherwise rainy day. I suspect that this is fuel starvation. Can you get the car to run longer if you pump the gas pedal.....?

Another possibility is a coil shorting out to the case. Usually it takes longer then 40 seconds to heat up and expand the coils inside, but I would check for spark next time it dies out.

Most coils have a primary and secondary windings.
The primary is for start up and then it "switches" over to the secondary winding to run on.
I had one that would fire right up and then barely "spit along" at 5 mph the secondary windings were toast. In the cover of darkness I climbed a closed and out of business gas station fence and "borrowed" a 12v coil from a junk Chebby and away we went.

Alan

It'd be frozen fuel lines if you were up here. Throw some gas line antifreeze in the tank.

Brian: At least you haven't hit the "Mud" season yet..........

Actually we have two seasons...winter and construction. Both of which are not that great for driving our cars.

Drove the IM to work yesterday...this morning woke to half a foot of snow. It'll be while before its out again.

Ok still have not solved the case BUT I did notice that the wire from the alternator to the starter is getting VERY hot to touch. Does that sound like ashort somewhere? I eliminated the alternator and it stll ran for only 40 seconds? I do have an electric fuel pump, could this be problem?

You still haven't ansewered the questions I posted above, so the info to help with is a little thin.

What do you mean by "eliminated the Alternator"? Just pull off the drive belt, or did you disconnect the big wire going from the alternator to the starter? (Be careful if you pull the big lead off the alternator - it's UNFUSED and connected directly to the battery!!! Carefully remove it and put the connector end into something non-conductive, like a leather glove or wrap it up with electrical tape so it won't short out to something (and maybe start a fire - see Simon Habley's earlier posts!!)

It may be trying to charge the battery heavily, but I don't think the big lead from the alternator should be getting hot to the touch. Yes, it might be the fuel pump, but, again, we need to know exactly HOW it dies - cough, sputter and die, or instantaneous shut-down? Makes a BIG difference in where we tell you to look next!

Carefully answer those questions in the post 10 up from here and we'll try to get you going for this weekend!

gn

I just remembered my first beetle,
It had a stopped up tank filter that would allow gas to trickle in but would stall when you ran the engine. The filter would colape under a fuel draw .
I remeber I had blew out the lines, replace the pump and it still did it after.
Then I pulled the tank. Ah Ha I found a very crusty stalk filter.

Im not saying that's your problem, but it sure seems familiar.

I would at least pull the tank sender and give it a look see with a flash light. You shoud be able to tell from that.

Another way you could check it would be to drop a 3 ft hose in a fuel can and hook the other end to the fuel pump. If she runs you have your answer. If she dont. then replace the condencer on the distributer.

I she still won't run pop the top off the carb and check the needle and seat and if you see trash in the bowel ,remove the the 13mm drain on the lower side of the carb and flush it out.

well?

Found out the problem.. power from the battery during start powers the fuel pump. After the alternater takes over the power goes to the oil pressure switch and then to the fuel pump. If the oil pressure switch fails or does not sense oil pressure the alternator will not power the fuel pump. A cheap saftey valve so you do not run the engine without oil. Who would of thunk it???

The oil pressure switch was shorting out hence the hot alt. wire

I Like it!!

It's like a belt and supenders.

I would have never guessed !! but now that you know its their, It;s time to take notes and add them to your shop manual.

Would never have guessed?

surprise, surprise.

Nope......never would have guessed that one in ten years!