78 Beetle no fuel

[BigFoote13]

[list=] greeting some working on a 78 Beetle fuel injection and don't seem to be getting any fuel to run. It runs when I put some fuel in the carburetor but then quits. How do I find out if it's the fuel pump or relay? Don't know much about Volkswagens in this year. Where do I take the fuel line off to see if the fuel pumps working or not? The fuel pump is in the fuel tank right? Thanks, Doug[/list]

[busdaddy]

Welcome!
Is this a sudden new problem?, or has the car been sitting?

Test for double relay and fuel pump operation by depressing the flap in the air flow meter by sticking a chop stick in the rectangular hole under the air filter element in the air filter box. With the key turned on you should hear a click from the RR hatshelf area and a whirring from the RF cowl in front of the passenger footwell, possibly also some faint hissing as fuel circulates.
To check fuel pressure connect a 0-60 PSI gauge to the hose that leads to the cold start valve.
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[David_nc_72std]

[Eric&Barb]

[Eric&Barb]

Have you made sure there is fuel in the tank??
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[BigFoote13]

I figured that question was coming up and I should have put it in there. Yes it was low but I put in 5 gallons. And is there a way that somebody could post a chart that shows where the fuel relays are and the other things mentioned. This is my first time in a long time working on aan older VW. And yes I think you got that it is fuel injected. Is the cold start valve the one that's right below the throttle body that has a fuel line going to it? I did have that disconnected but nothing came out. Also disconnected a line that looks like yours is going to the fuel injectors on the driver's side of the motor. Thanks, Doug

[volksworld]

the dual relay is attached to the computer under the rear window on the passenger side...the bently manual gives the troubleshooting procedure for it...its called the dual relay cause one half works the fuel pump and cold start valve and the other powers up the computer....among other places the wiring for the relay attaches to the battery and starter and can be knocked off by jumper cables or not hooked up by whoever installed either component...the pump is not in the tank, its mounted to the firewall below it....its common for these pumps to seize up if the car has been sitting for a long time....yes cold start valve is in the throttle body, usually light blue plastic

[sawed off]

Is it possible the ecm signal wire fell off the coil and is laying down behind the engine and fire wall? You should have two wires on the negative side of coil.

[BigFoote13]

Thanks for the reply's. I will check those things out when I get back to the car in a day or two.

[Chris333]

Check the little sock inside the tank at the lower nipple:
https://www.jbugs.com/product/111209147A.html

I've read of people finding this clogged up and most leave it off.

Just an idea. I have no idea if a FI beetle has the sock.

[Dwayne1m]

[Randy in Maine]

Have your lovely assistant try to start the car while you are under the front end with your hand on the fuel pump.

You should feel it pumping. The pump hates to have rust from the gas tank reducing the flow of fuel through it as that is what keep the pump cool.

If not, confirm that you have power to it using your 12 volt test light. If you don't it is time to have a good look at the double relay. The DR hates to have water from a leaking 'vert top leaking on it because it shorts it out.

[BigFoote13]

Greetings again, where can I find a better wiring diagram manual for this 78 beetle? Does wiring diagram doesn't tell me much as far as which one's a double relay and which one the fuel pump is. Found a double relays haven't found the fuel pump yet. Thanks, Doug

[Randy in Maine]

The car starts (ie the fuel pump runs) on one side of the double relay when the key is in the "start" position. After the key goes to the "on" position, the other side of the double relay runs the fuel pump using a little micro switch inside the AFM unit.

Break out that volt ohm meter and read up here...

http://www.itinerant-air-cooled.com/viewtopic.php?f=50&t=5459

If you are kind of skinny you should be able to scootch your head about 1 foot under the passengers side of the front bumper and look up to see this...

You can feel it with your hand if it is running. Confirm you are getting 12 volts there. Note which side is + and which is - (I use a sharpie to mark it).

[BigFoote13]

Thanks for that reply, found the fuel pump and got it running the fuel pump that is. now I'm testing the relay To see if it's giving it power when it should. a little off topic but does anyone know where I can get a wiper relay For this vehicle?

[Randy in Maine]

The pump should put out 1L of fuel in 30 seconds.

[Weezle]

Fuel pump ground wire is inside the left trunk where the lights ground. Make sure you’ve got good ground there. That’s what got mine a while back.
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[BigFoote13]

Hello again, so I ordered a double relay since the other one didn't seem to be working. I can command the fuel pump on but I was just wondering when I plug the new relay in if it still doesn't run the fuel pump where do I go from here? Is there like the cold start valve might not be working and how do I test that if anyone knows? Thank you, Doug

[busdaddy]

[BigFoote13]

Hello again, sorry for taking so long to get back to you all. Really appreciate the good information and learning more every time I get back to it. So I put in a double relay that I purchased and it is clicking when I have the key on to operate the fuel pump but fuel pump does not come on. Now I know the wires good because I can jump the positive wire to the fuel pump and get it to run and fuel sue the system. Had to replace crusty broken fuel line underneath to the injectors. Now the problem is even with the fuel pump jumped to get power and running the engine does not start. I can get it to start by pouring some gas down the throttle body but otherwise doesn't seem to be getting fuel through to the injectors. This is when I have 12 volt supply to the fuel pump to get it running not through the relays. With a key on relay connected I can hear it clicking should be sending power to the fuel pump but does not. Any suggestions where I should go from here. I don't think that would have a problem with the resistance to the body negative but maybe so I need to check that next. But like I said with power to the pump manually and getting good fuel pressure, it does not start. Now I just read that 35 PSI is the proper fuel pressure, but it produced a lot more fuel pressure like I think it was 8200 PSI when I had it jumpered bypassing the relay. I might be wrong on that but if the fuel pressure is too high might that cause a problem with the injectors.? I'm thinking possibly clogged injectors? The car has been sitting for a few years so that's where I'm at. Looks like they're not too easy to get to back in there but that's probably what I should go next. Thank you for all your suggestions and time helping. Doug