Building your own Fuel Pump Relay for 1980 Vanagon

The Background Story

On a drive down from the SF Bay Area to Orange County my Vanagon ran great all 340 miles, until I was about 20 miles from my destination. As I was driving along the 405 freeway, near Bolsa Chica, the engine shut off and I had no power behind my throttle. Cruising at 50 mph, I was able to safely coast to the side of the highway. After 20 minutes of waiting on the side of the highway, the van fires right up again and I am able to drive another 5 minutes before the engine cuts out again. Longer story shortened, eventually I repeat this a half a dozen time to get me home. The next day, the engine starts up and I drive it normally until it randomly decides to quit again. Symptoms of this have been described online by other vanagon owners.

A few trips later, I find myself unable to move another inch with the Van on the side of the 55 freeway. For the first time in the 3 year history of owning this van, I called a tow truck to haul my van back to my house. Luckily I was less than 7 miles from my home to get a free tow by AAA. Upon the delivery of the van back to my driveway, I admit this vanagon has a problem and I need to fix it.

I begin with discussing the cause of the problem with my Vanagon guru, Andre. Andre has a 1989 Vanagon himself and he has been a life saver for keeping both his and my van alive!

Andre and me (Circa June 2014)

My 1980 Orange Slug Ride, as I call it, has had some major issues in the past. When I first bought it, it would start to buck after 20 minutes of driving. Andre and I spent 6 weeks rebuilding the engine with new engine heads [fix to Vanagon bucking problem explained here]. A few thousand miles later I had to replace the transmission when the original stopped shifting properly. Of course I have had dozen of other repairs, push starts and fun trips along the way. So I guess I was not too surprised when this mysterious engine cut out problem appeared. Additionally, I had the van sitting for a good 6 months with minimal to no usage while I was bike touring in Central and South America. However, I was determined to solve this problem with my own two hands!

My Options

Andre and I had a few key suspects for the problem with the van, and my plan was to diagnose the problem in order of cost (lowest to highest). Here is the list:

• Clean contacts (~$6)
• Fuel Pump Relay (~$70 or ~$20 with DIY Solution)
• Fuel Filter (~$25)
• Fuel Pump (~$150)

I was also looking through my VW manual and John Muir's How to keep your Volkswagon Alive book. John is a wonderful mechanic with a very systematic approach to diagnosing your vehicles problem and the quickest surest solution. This book is a very valuable resource to keep in your van and it's worth every penny!

I clean the ground contacts as I read online and double check the electrical connections. John then  recommended to check the fuel pressure, and since I was able to rent a Fuel Pressure Testing kit from Auto zone (just down the street), I figured I would check the pressure in the fuel lines for free. Connecting it up was easy with the spare hose provided in the kit, and I found I had an acceptable amount of pressure hovering right around 30 PSI. John says 29 PSI, but when the engine was running, the pressure needle was a bit jumpy.

With the pressure gauge reading an acceptable reading, I ruled out the fuel pump and fuel filter being clogged. This lead me to my main suspect, an electrical issue. Andre suggested to check the existing fuel pump relay (and combined main relay) for any signs of wear or failure. After all, the part is 35 years old, so yes it looked warn. It uses a coil of wire to build up an electrical magnetic field to flip a switch and close a contact.

Original fuel pump relay and main relay (metal capped removed)

 After a bit of searching online, Andre informed me that the Richard Atwell over at Ratwell posted a solution to build your own fuel pump relay with a few cheap components from the electrical store. Essentially 2 relays a diode and a resistor. I liked this cheaper solution to possibly solve the problem, and really liked that I could learn from a hands on electronic project.

Build your own Fuel Pump Relay Circuit Diagram - Credit: Ratwell.com

Build and Learn

I bought 2 relays ($5.50 each), a diode (~$1), and a 2.7 ohm resistor (25 cents) and the necessary end male/female connectors. I was a bit over the estimated $8 dollars by Richard, but was still way under the cost of the OEM fuel pump relay.

Building Circuit with breadboard and low amp audrino wires

I followed the circuit diagram instructions and built the circuit as shown on the Ratwell website. I was able to test the connections with my voltmeter and a 12 volt power supply to show the relays did close when the voltage was applied to contacts 85 and 86. I installed the circuit in the van, replacing the original one and was not able to get the engine to fire.

Picture sent to Andre for advice on how to get circuit to work

I was worried my connections were not staying connected when I was connecting all the wires. I eventually threw in the towel and sent Andre a picture of the work done thus far.

Debugging

A few hours later, Andre contacted me and informed me my wires looked a bit too thin to carry all the current it needed to the various engine components. This made sense, considering I could hear the relays close when I turned the key from the drivers seat. Andre gave me some wires from a old computer power supply that would carry a higher current. I also went to the electronics store one last time to pick up a few small male connectors to connect to the existing van's connection harness.

I rewired the circuit on the lab bench, and didn't use the breadboard this time to make a more permanent solution. Andre suggested to make sure each connection is secure and apply a little solder on each wire end to ensure the connection stays put. I used the voltmeter in connectivity mode and checked all the connection points, from the relay to the male end to plug into the car. I confident about this newly done circuit!

Success!

I plugged all the connection points in, ensuring each would stay connected no matter what roads I took in the future. I then hopped in the driver seat and turned the key. The engine turned, but to no avail, the engine would not fire up. It felt like my previous circuits I tested. Just as I took a sad moment of disappointment, my neighbor Steve called my name,

"Matt? Do you have an hour to help me move some stuff?"

 "Uh, I have a 1/2 hour, what do you need to do?"

"I have a 4 burner electric stove down stairs and a gas stove upstairs and I want to switch them"

"What's my rate again?"

"I'll pay you 20 bucks if you help me complete the job!"

20 minutes and some heavy lifting up some stairs, I had my new fuel pump relay paid for. There was just one problem, it still didn't work. As I packed up my items and locked my van, I decided to reach over from the passenger side of the van and turn the key one last time. And just like that, all the work to build my own relay paid off. The Van purred  nicer than I have ever heard before. I was ecstatic! I screamed and shouted as the van held it's tempo in the driveway.

The Orange Slug visiting Idle-Wilde (Circa 2011)