1977 Westy - Bad Double Relay? Something Else?

[yondermtn]

1977 2.0 FI

I have the following symptoms and suspect the relay might be bad.
Engine dies/misses under load and at idle. This feels like it is running out of gas. I was able to limp home and when I got home I shut off the engine and the fuel pump was still pumping with the key out of ignition. I looked in the AFM and the contacts were open, so I ruled that out. The following morning I connected the battery (pump still running) and started the engine. Engine sounded fine. Moved bus to the street and turned off engine. Pump now turned off. Later that day I test drove the bus and it ran fine for about a block then got the same symptoms of the engine die/miss.(fuel pump off when I removed key)

My theory is that the double relay is turning the fuel pump on and off on its own regardless of the ignition position.
The only other variable is the heat. It is the first time I've driven the bus in weather over about 82 degrees. It's been around 90.

[Westy78]

You say the contacts were open in the AFM. Do you mean that the potentiometer wasn't making contact with the piece of spring metal at the right side? If so that is why the pump was running. Those have to make contact to signal the pump to shut off. Is the pump running even without the key in the ignition?

[yondermtn]

Okay, so it sounds like I have it backwards?

Those contacts were not touching and the pump was running. I moved the contacts and the pump did not turn off when they did make contact.

I'll have another look when I go home for lunch.

[yondermtn]

Right now the pump seems to be working normally.

With the key in the ignition and in the "on" position the pump is off. The AFM has the wiper all the way to the right so the contacts are open. When I move the wiper counter-clockwise the contacts touch and the pump turns on.

The other day the pump was running even when the wiper was to the right and the contacts were separated.(no key in ignition) So, I still think the AFM is working properly.

[Westy78]

Sounds like it's working properly. I wonder if the double relay is sticking when things get hot? Next time it happens take a screw driver handle and lightly tap the relay to see if it switches.

[dtrumbo]

I wonder if the double relay is sticking when things get hot? Next time it happens take a screw driver handle and lightly tap the relay to see if it switches.

X2. I had the same thing happen on my FI Beetle. A light whack with the handle of a screwdriver allowed the stuck contacts inside the relay to unstick. Don't worry, they'll stick again so you can either replace the relay, disassemble the one you have and clean the contacts or both so you'll have a spare.

[yondermtn]

Alright, so this backs up half of my theory. That the double relay is malfunctioning and telling the fuel pump to be "on" when it should be "off".

But, is my double relay telling my fuel pump to turn "off" when it should be "on" causing my bus to miss and run poorly/die? Or by coincidence do I have two separate issues going on?

[Gypsie]

Alright, so this backs up half of my theory. That the double relay is malfunctioning and telling the fuel pump to be "on" when it should be "off".

But, is my double relay telling my fuel pump to turn "off" when it should be "on" causing my bus to miss and run poorly/die? Or by coincidence do I have two separate issues going on?

Methinks that whatever is causing the relay to 'seize up' may contribute to funky FP flow, though I am not sure how as yet. Perhaps the symptoms you are experiencing now are the result of something else that has gone unnoticed til now. Whatever has caused the double relay to seize may be at play here. First gremlin that pops up for me is a short somewhere.

Though, here is my thinking:

The AFM contacts close and complete the circuit for the fuel pump when the engine starts. If this connection point is giving a solid signal the pump should be flowing steady, if all the innards are o.k. Can't necessarily see how the double relay power would inhibit the AFM power source.


Flow test (X amount of flow, post FPR, over Y amount of time).

Pump operation testing (steady pump action with manual activation).

I wonder if the issue with the double relay may be tapping power (i.e. shorting) to the point the FI is acting up. Do you have a voltmeter? How is electric power? Perhaps the DR fault has put the screws to the alternator.

You could test by starting up, and beginning to turn on electrical items (headlights, wiper, etc.) to see if it starts to act up the more power you demand for things other than FI.

Then of course there is that ol' bad flow from tank issue (cut open your most recent filter to see if there's any gunk/chunks).


2 cents.

[yondermtn]

Finally got around to tinkering with it tonight and she's running great.

I started it up and let it idle for a while. I turned on and off lights, tapped the DR a few times, bumped various wires to see if they didn't like movement and it idled fine. Then I drove around the neighborhood a few times and no problems.

Would it be a good idea to buy a new double relay and have it onboard as a spare? They're not cheap, but it seems like they do go bad. I have an all metal one, does this say something about it's age? I see the new ones are plastic.

I'll do another test tomorrow and report.

Thanks for all the input.

Chris

[Amskeptic]

Finally got around to tinkering with it tonight and she's running great.

I started it up and let it idle for a while. I turned on and off lights, tapped the DR a few times, bumped various wires to see if they didn't like movement and it idled fine. Then I drove around the neighborhood a few times and no problems.

Would it be a good idea to buy a new double relay and have it onboard as a spare? They're not cheap, but it seems like they do go bad. I have an all metal one, does this say something about it's age? I see the new ones are plastic.

I'll do another test tomorrow and report.

Thanks for all the input.

Chris

Sorry I'm late . . . . the ground for the double relay must be secure before you indict the double relay itself. Brown wire that is trapped under the mounting screw. You have evidenced good diagnostic thinking here by the way.
Colin

[Manfred]

I was having strange FI problems and it turned out to be double relay problems.

[bretski]

In my very humble opinion, more FI problems can be traced to bad ground connections than any other problem. It's the very first thing I check when Klaus gives me any type of miss, idle, ignition, etc.-type problem.

Just throwing this out there...most of us have wiring harnesses that are 30+ years old...

[yondermtn]

**Update**

So, I took the bus for several test drives and poked around a bunch each night this week and it seemed to be running fine. We decided to go for a longer drive and pick some strawberries. About 10mi from home the symptoms returned. I pulled into a Thornton's gas station and assessed the situation. We were right next to a Carquest and an Autozone, so I tried to see if either had a double relay. Neither did. Carquest wanted $75 and another place wanted $115 for them when they're in stock!

Pulled out the Bentley and read over the Fuel Injection section one more time, slowly. That led me to check the wires at the starter solenoid. BINGO! Wire was off. Reconnected the wire and all was good. Went on to pick a load of strawberries.

[dtrumbo]

Glad you found it! When you're home, crawl under there and make sure that connection is good, clean and tight. If it pulls off easy, gently squeeze that quick-disconnect connector with some pliers so that it fits more snugly and won't fall off again.

[midatlanticys]

. . . check the wires at the starter solenoid. BINGO! Wire was off.

Yonder, well done!!! Sorry for the dumb question, but did the solenoid wire just come off on the 'berry pickin' run or was it off all along and explain the earlier sticky double relay theory?

. . . and another numbnuts question, which wire goes to the solenoid? Power for the relays w/ignition key on? Still trying to get both my neurons @ f/i.

Thanks!