Newbie Here - 79 Beetle Convertible

Besides the old fuel, it's just possible that there is an electrical problem. The electric fuel pump runs all the time the starter motor is cranking the engine during starting. That builds up pressure in the fuel ring. When the key is released, the pump *should* continue to run on its own, as controlled by a switch contact inside the air flow meter.

But, if the pump does not run with key released, the engine will run a while, then stall.

No guarantee that's your problem, just so you know...

There is an FI electric section on my web site.

Speedy Jim

Thanks for the prompt reply. I actually was able to keep it running by working the throttle, but never to the point where it would idle comfortably for more than a 20 or 25 seconds. I've ordered some troubleshooting guides, and have been checking out helpful websites such as yours. We'll see what I can dig up. My guess is that it's initially just in need of a major tune up, and possibly may some fuel pump / FI issues, as you said. I'll keep plugging away.

Thanks,

Tim

Check the whole intake system for cracks in the rubber parts/hoses.

...MIC

Hi Tim. Well, the first thing you should do is change the oil! Get that 7-year-old crap out of there. Don't run the engine any more until you get fresh oil in it. Also, your fuel lines sound clogged. Drain the old fuel and replace with fresh new fuel, replace the fuel filter in the fuel line (if there is one...check under the car by the transmission, check in the engine compartment, and if it's not in those places, it must be under the fuel tank in the front...or you don't have one).

A clogged line could cause your problem. The line will fill up with enough fuel to run shortly, and then after the engine uses up that fuel, it won't be able to pull more past the clog fast enough. After you shut off the engine, the line will slowly fill with fuel again, allowing you to start it again for a short period.

Eather that..........or your fuel injection (is it? Should be, it's a

79) electrical system, injectors, fuel rails, vacuum system, etc. is screwed up somewhere. For this, I will be of NO help, becuase I don't have fuel injection.

Oh yeah. Get the Muir book! Get the Bentley Manual!

Good luck!

~Anthony

To avoid confusing him, the FI has the pump AND the filter located up front, under the tank. No filters in the back. There are 2 fuel lines: pressure and return.

Speedy Jim

This whole fuel injection thing! I just can't get it.... :)

Sorry, forgot to mention that FI systems loop the unused fuel back into the tank after passing it by the injectors. I supposed if eather one is clogged, it could cause the problem.

But I'll cease to reply anymore, becuase I'm not sure I know what I'm talking about!

~Anthony

No. No! All replies have some meaning. That's why a forum like this is so valuable. No *one* of us has all the answers...

Speedy Jim

This is all incredibly helpful! This notion of unused fuel looping back to the tank is wierd, but it may make sense, and you may have saved me from discharging my fire extinguisher prematurely (I read the TULZ chapter and bought one immediately.) There is a "circuit" of tubing, with a plastic harness in the luggage trunk that has a broken connector. I smelled it (before and after running engine) and did not smell gas, so I figured it was brake, washer or some other fluid that would become important once I had it running. After that last post, I traced it, and at one end, it connects to the fuel filler hose! Must be the unused fuel recirc. Thanks. I'll beware and be sure to not fart around until it's fixed.

BTW, I have several books on order, including Muir and also Bentley.

Thanks. I think I've stumbled into a pretty cool project/group of people.

Tim

Now if only I can figure out a way to keep the old style Colorado plates and "SUNBUG" tag here in the northeast.

...thats what they all think at first.... 8-)

..Gareth

The 2-pipe system is quite common on positive displacement pumps. There is a pressure regulator located on the engine which sends excess pressure (fuel) back to the tank. The regulator is vacuum- controlled.

The return pipe (and the suction line) is located on the bottom of the tank, not up top.

Speedy Jim

Whoops! The tube you found is the fuel tank venting line, not the recirc. line. Your tube is the one that keeps the tank from colapsing under atmospheric pressure as fuel is drawn from it. It vents fuel tank fumes into a charcoal canister that has air blown through it by the engine fan. That air is then blown into the air cleaner. (pretty sure, but FI could be different) The fuel lines that take fuel to and from the engine are on the bottom of the tank. To see them, you'll have to take off one of your front wheels and look under then tank. For FI the pump should also be under there on the bottom of the tank. However, your vacuum actuated fuel pressure regulator could be to blame. It might think there is too much pressure, thus sending too much fuel back to the tank, and not enough past the injectors. As the regulator is vacuum actuated, it might be stuck too high or something.

Any comments Speedy?

Oh yeah, this group is THE best place for VW info on the web!

~Anthony

............To clarify: In an L-Jetronic system, the fuel pressure regulator is a spring loaded diaphram style regulator that only responds to changes in vacuum from the throttle body. When it fails, it's usually because it doesn't respond to increased vacuum which is supposed to result in lower fuel pressure. In other words, a bad one usually causes too much (unregulated) fuel pressure which results in a richer mixture mostly when there's reduced throttle/increased vacuum.

There you go....

The Muir book has a great section on FI. It should prove very helpful when you get it. I should probably re-read it becuase I only skimmed it the first time because I don't have fuel injection.

~Anthony