TheSamba.com :: View topic - No Fuel to Engine

Sat Nov 07, 2009 9:40 am

Greetings all - I am new to the forum and have been the happy owner of a 1977 Super Beetle (Triple White conv.) for a couple of months. I have replaced many components in the vehicle without too much trouble until my recent endeavour of replacing the fuel lines.

Basically, the smell of gasoline is rather strong, so I sought out to replace all of the braided lines, ventilation chamber, tank cap, etc.. I did one segment of line at a time, so as not to confuse myself. Now the engine won't turn over from lack of fuel.

Spark is good, compression is good. The car will turn over on starting fluid only.

I thought that their might be air in my fuel lines, so I pressurized the gas tank and forced fuel through the system while I had someone at the engine hook the fuel lines back up.

I'm thinking that my fuel pump could be bad? Can I bench test it?

Sat Nov 07, 2009 9:50 am

devnull34 wrote: ....I'm thinking that my fuel pump could be bad? Can I bench test it?

Electrical or Mechanical fuel pump?
- If electrical, then connect it up to the battery on the bench.
- If mechanical, then push the lever on the bottom as the rod in the engine case does.

You did not say whether the fuel was making it back to the engine. Pull the fuel line from the tank at the pump and see if it flows out of it by gravity. If not, then your line is plugged somewhere.

if you system is fuel injected, then I'll step aside as I have no experience with F.I. VW's.

Sat Nov 07, 2009 9:53 am

The pump is electrical, and the fuel is making it to the engine when cranking. The system is fuel injected.

Sat Nov 07, 2009 12:30 pm

This may sound stupid, but it happens... did you reverse the hoses accidentally?

Sat Nov 07, 2009 12:46 pm

I don't believe so... When facing the engine with cylinders 3 and 4 on my left, the fuel supply line comes in. The return is on my right where cylinders 1 and 2 are.

Sat Nov 07, 2009 1:50 pm

The fuel pump doesn't seem to be turning off at all. Even with the keys out of the ignition the pump is still pumping away. Is it on some sort of relay that keeps it going until the fuel pressure is just right?
The fuel flow is good - goes into the engine bay and back through the return line. Doesn't seem to be any blockage. Why won't the fuel pump shut off?

Just to be clear, the return line should be on the 1 and 2 cylinder side, right?

Sat Nov 07, 2009 3:09 pm

Find the double relay ( I think that on a beetle it is under the bck seat) and give it a sharp "rap" with a screwdriver handle. It has points in there that may be stuck for some reason.

After you confirm that the wires from the battery to the starter and the chasis ground strap are all nice adn clean and tight, I want you to run a new 12 gauge ground wire to the screws that hold the DR in there. If that doesn't make the fuel pump shut off, I want you to take the top off the AFM unit and make sure that nothing is keeping the silver prong from grounding out against the little copper strip. It sort of looks like this when the fuel pump is grounded out....

Here is a good rap on troubleshooting the DR

http://itinerant-air-cooled.com/viewtopic.php?t=54...highlight=

Tue Nov 10, 2009 5:03 pm

Thank you very much for the help with the top of the AFM unit. I had the cover off of it for about two seconds before I saw that the strip was not making a connection. Flipping the AFM over, I saw a bunch of gunk behind the flap preventing it from closing and a ground being made. So the mystery of the ever flowing fuel pump is solved! Thank you.

Now I just need to get a solenoid on my starter and get the timing all sorted out. Tried starting it from a push but I don't think we got it rolling fast enough...

Thu Nov 19, 2009 6:29 pm

Hrmm... Just got back to working on the beetle again after getting a new starter solenoid installed. Engine cranks but doesn't turn over.

I have spark at every plug. Timing is good...never changed it but checked it anyways.

Fuel pump is working the way it is supposed to now. My double relay and AFM are both good. Fuel pressure good.

Engine WILL start for a few seconds off starting fluid and sounds good when it does. No backfiring, shaking, etc..

So, I am thinking it is still a fuel problem. Ideas?

Thu Nov 19, 2009 8:05 pm

In short this is how it works....

When the engine is being started, the fuel pump runs off 1/2 of the double relay from the starter.

Once the engine starts for a couple of seconds, the little flap or door inside the AFM works a microswitch and runs the fuel pump off the other 1/2 of the double relay. Start by making sure the little door in there is free to swing and is actually running the fuel pump. Use a long thin screwdriver.

If that doesn't work, you need to trouble shoot the DR adn make sure it is well grounded via the screw that holds it in place (even if you have to run a new ground wire to the DR).

http://itinerant-air-cooled.com/viewtopic.php?t=54...highlight=

http://www.type2.com/bartnik/dblrly.htm

By the way, got this?

http://manuals.type4.org/ljet/

Also, the thermotime switch is what tells the ECU that the engine is cold and will allow the cold start valve about 8 seconds to squirt fuel in there to give the engine an extra shot of richness to get it going. Are you sure the injectors are firing? Have someone try to start the car while you feel the injectors with yoru finger to feel if they are clicking. Clicking = firing fuel in there.

Thu Nov 19, 2009 8:12 pm

I'm on the third injector right now... I've been pulling them out and watching them squirt, continuity, etc.. I don't think the injectors are the problem, but I like where you are going with the DR. I'll let you know what I find.