The Mysterious Fuel Starved Bug

[alwaysuphigh]

Please Help! My 70 won't get gas to the pump.
She defies the laws of physics !

Here is what I have done:

replaced pump, rod, and stand. (Yes rod is correct size and moves up and down)

replaced the gas line from the tank to the pump.

replaced gas tank with new one

When I pull the line no gas comes out unless I bend it down to the floor. Then it only trickles.

20 years of air cooled and I have never seen this.

Any ideas out there?

[mukluk]

Tank vent plugged/obstructed maybe. Does fuel come out of the line better than a trickle if you remove the gas cap?
_________________
1960 Ragtop w/Semaphores "Inga"

[beetlenut]

Venting? Try it with the gas cap off. Does gas flow from the flexible line, in the front, when you take it off of the hard line coming out of the tunnel?

Edit: Dangit Mukluk, you beat me to it!
_________________
scrapyards are for quitters
---------------------------------------

[TDCTDI]

You might also need to "roto rooter" the line from front to back with a piece of cable on a drill.
_________________
Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.


GOFUNDYOURSELF, quit asking everyone to do it for you!


An air cooled VW will make you a hoarder.


Do something, anything, to your project every day, and you will eventually complete it.

[VW_Jimbo]

Pull the fuelline off of the rear hard line at the rear of the car. Does that line flow?
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Cusser]

I wonder if the check valve in your fuel pump is bad.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[cletus_zuber]

Did your 70 get gas flow BEFORE you changed all that stuff?
_________________
1972 1302
HPMX 40's & 019

[hitest]

When you replaced your tank did you get the new sock filter and everything installed? Is it possible your short fuel line from tank to tunnel is kinked?

On TDCTD1's advice- I'd actually blow our roto from back to front- to reverse the direction of the lodging if any. Kind of like giving it a Heimlich maneuver- you want the meatloaf to come back up...
_________________

[alwaysuphigh]

Thanks everyone! I did try everything mentioned.

As it turns out...I needed to prime the carb. Now it flows like a river and runs great.

She is on the road again!

[awreed]

I'm hijacking this thread as I'm facing a similar fuel starvation problem, and the OP has solved his problem.

My '70 has been sitting for a while- long enough for the bowl to dry out. New tank in, carb primed, quick blast of starter fluid, it fired right up. Once the bowl went dry, the engine stalled out. Checked the pump- no problems. Primed carb again and fired up- no gas getting to the engine. Gas cap was removed, so no venting issues.

Hooked up compressor to gas line, 140psi towards the tank from the engine bay:

Pulled the sending unit to see bubbles- nothing. Absolutely nothing. No fuel leaks that I can find or smell, but that compressed air went..... no where, apparently.

Put everything away for tonight. Later I'll pull the short length of flexible fuel line under the tank. It wasn't kinked when reinstalled, but I'll see if anything leaks from the tank there. Gotta be an obstruction somewhere between the tank and the carb. The compressed air should have dislodged something, right?

By the way, that IS a cheap plastic fuel filter in my engine bay- I've run all my VWs like this for the last 21 years with no fires or leaks. Never had a fuel inlet fitting pull out of the carb.

[Cusser]

If you're getting gas TO the carb (check by diverting that hose into a jar while helper cranks, careful: flammable) yet the carb bowl is not filling, check the inlet/float valve that screws into the top cover of the carb.

And wouldn't hurt to measure the fuel pressure too coming from the pump.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[Tim Donahoe]

Unhook the line from the tank to the tunnel up front. Do the compressed air thing again at the back of the car. Use a helper to see, feel, listen for the air to come out the hard line that you just removed the hose up front from.

If no air, you obviously have an obstruction in the hard line that goes through the tunnel.

Check your soft line that fits to th tank up front, as well as from the rear soft line at th back of the tunnel.

Tim
_________________
Let's do the Time Warp again!

Richard O'Brien

[blata]

Hi, I'm working on a similar situation. But I haven't gotten to the compressed air yet. I just wanted to confirm that fuel should flow from the fuel line coming out of the fire wall if removed from the pump inlet?


**update**
NM. I just tried the compressed air and now its free flowing. I guess the next step is cleaning out the tank.
_________________
Ipsa scientia potestas est