TheSamba.com :: View topic - 81 Westy with 2.5 Subie no start/no power to fuel pump

Fri May 30, 2025 5:00 pm

https://www.thesamba.com/vw/forum/viewtopic.php?p=10389017#10389017

Having some issues. Searched and found the thread above. But in the end it didn't help me locate my problem.

I have an 81 westy with a 2005 2.5 subbie in it. Had it less than a year, but have taken it on 3 cross country trips already with zero issues. Returned end of March and parked it inside a heated garage. Now it won't start. Turns over fine, no fire.

Upon further investigation, it appears I'm not getting power to fuel pump. The pump runs fine when I apply power at the pump or the back of the fuel pump relay. So I know it works.
I also tested the relay and it appears to function fine.
At the relay I have 1 constant power wire and the other 3 show ground. When you turn on the key, two of those wires show power also. When I try to start it, the 4th wire (this is the one that goes to the pump) does not get power. But again, if I apply 12v power here, the pump works.

I replaced the fuel filter, verified the pump works and pushes fuel (only when I apply external power). The ignition is working because it activates the two other wires at the relay. But for some reason the pump wire is not getting power when the ignition is on/started.

So the pump working when I apply power to the back side of the relay tells me the pump works and the wiring from relay to pump is ok. Leading to a relay problem.
But, when I test the relay it works just fine. If I pull it out of the van and apply power to it I can hear it clicking and verified it closes the circuit. But for some reason when the van applies the power to it, it's not transferring power to the pump wire. And it is getting 12v with the key on.

I also tried starting the van while applying external power to the pump and it still didn't start. The van popped off a little squirting starter fluid in the intake so it should have spark.

Anyone have any ideas?

Fri May 30, 2025 5:31 pm

Camojcory wrote: At the relay I have 1 constant power wire and the other 3 show ground. When you turn on the key, two of those wires show power also. When I try to start it, the 4th wire (this is the one that goes to the pump) does not get power. But again, if I apply 12v power here, the pump works.
Looks like you've answered your own question. The relay isn't getting a ground for its coil - presumably this should come from the ECU. So either a broken wire, or the ECU doesn't want to energise the relay for some reason. When you first switch on, the relay should come on for a couple of seconds, then go off. This pressurises the system ready to start. Then when you crank the engine, the relay should be on constantly - and stay on when the engine starts.

Fri May 30, 2025 6:51 pm

Connect the two green test connectors and turn the key to ON. The relays should be clicking and fuel pump cycling. The ECU will be providing alternating ground. Don't know how you've wired ignition and battery power to the relay and the ECU. Is the ECU getting ignition and battery power? Check fuses for each. Check your engine ground connection to the intake manifold as this is where the ECU gets its ground. Leaving the van parked for a while (several months) and then having a crank/no start is when I had ECUs go bad. I could test crank sensor pulse with my Innova 12v test light so I knew it was getting a crank sensor pulse. Is the ECU getting a start signal while cranking?

Fri May 30, 2025 10:07 pm

Camojcory wrote:

I also tried starting the van while applying external power to the pump and it still didn't start. The van popped off a little squirting starter fluid in the intake so it should have spark.

Wouldn't this indicate that the fuel pump isn't this issue?

.... Now if the ECU is not activating the fuel pump because of a ECU problem or some other logic before I'm initiating start it would explain these symptoms.

Might you have access to a complimentary ECU?

Do you know about the SubaruVanagon.io group? Maybe someone in there close to you has an ECU you can try

https://groups.io/g/SubaruVanagon

Sat May 31, 2025 12:07 am

What donor car?
What codes do you have?
Any signs on vermin chewing on wires?

Sat May 31, 2025 12:43 am

wesitarz wrote: Connect the two green test connectors and turn the key to ON. The relays should be clicking and fuel pump cycling. The ECU will be providing alternating ground. Don't know how you've wired ignition and battery power to the relay and the ECU. Is the ECU getting ignition and battery power? Check fuses for each. Check your engine ground connection to the intake manifold as this is where the ECU gets its ground. Leaving the van parked for a while (several months) and then having a crank/no start is when I had ECUs go bad. I could test crank sensor pulse with my Innova 12v test light so I knew it was getting a crank sensor pulse. Is the ECU getting a start signal while cranking?

Check continuity of the ECU wire from relay to the ECU connector. Use ECU pinout chart for your year here at Busaru.com info/pinouts if you don't have a pinout.
Try another relay.

Sat May 31, 2025 7:59 am

Thanks for all the replies. Donor car was a 2005 subaru forester.

No signs of mice/chewing. I can't read the codes because the scan tool is not being able to connect to the ecu for some reason. It did before just fine.

I've read about these green plugs now a couple times. Are those supposed to be original vanagon wiring?

And I did try and different relay and it still didn't work.

Sat May 31, 2025 8:05 am

Camojcory wrote:

I can't read the codes because the scan tool is not being able to connect to the ecu for some reason. It did before just fine.

well, there's your problem. start diagnosing why you can't communicate. power/ground etc.

if you can't communicate you have something pretty major (and should be obvious) going on

Sat May 31, 2025 11:28 am

The green test connectors are on the Subaru harness usually near the ECU. OBD2 needs power to connect. Check your fused connections for ignition key ON power and battery power maybe in the black electrical box upper left back firewall in engine compartment.

Sun Jun 01, 2025 10:05 am

I do have power to the obd plug, and ecm. But tried 3 different scan tools and they won't communicate with the ecm. I know they used to because I've used one of them to monitor rpms and temp while driving.

Had a few suggestions about checking the ecm ground. Supposed to be two grounds to the manifold. Will look into this later today.

Sun Jun 01, 2025 1:43 pm

For my crank/no starts (2) there were no codes or an intermittent cam sensor code that threw me off. I did have fuel pump cycling, but no injector pulse and no spark. Needed a new ECU both times. New crank/cam sensors became spares in a box.
You have ECU power. Check ground. It should connect with key ON. Check for and cam sensor signals at the ECU connector while cranking
Look on EBay for a replacement ECU with an ID number like yours. eg.22611AJ48C for a 2005 Subaru.

One time I forgot to connect the ground strap to the intake and it was the same crank/no start.

Try disconnecting the battery, reconnect and restart.

Fri Jun 06, 2025 10:11 am

Ok, so I pulled and checked both the camshaft and crankshaft position sensors. They both tested good, along with their wiring, according to videos I found.

So at this point I'm thinking it has to be the ecu. Especially since I can't get any obd2 scanner to connect to it now. I did find one on ebay and ordered it right away in hopes it would arrive before an upcoming trip.

It's my understanding the ecu gets it's ground through the one/both of the ground wires that are on the engine manifold. Both of those grounds appear solid. How would I confirm the ground at the ecu? You mentioned checking it while the key is on, happen to know exactly where/which wire I need to test?

Fri Jun 06, 2025 10:17 am

Forgot to mention, I did try disconnecting the battery and then reconnecting it after reading your post. It worked! The van fired right up. Let it run for a bit and then shut it off and restarted it again. So I thought maybe it was just a fluke and the ecu had reset. Planned to drive it into town the next day and try hooking it up to an scanner again and see if it said anything. Unfortunately, the van didn't start again the next morning and the battery trick didn't work again either. So I checked the cam and crank sensors, and then ultimately ordered a new ecu.

Will I need to do anything (flash, program, tune) the used ecu? Or can I just hook it up and go?

Fri Jun 06, 2025 4:55 pm

It's the ECU. I had the same. I would run once only after re-set.
Get matching number to your OE ECU. It should be plug and play.

Tue Jun 10, 2025 7:30 am

Ok, I need help, completely baffled by this. Tried a different ecu (yes, same exact part numbers) and it still isn't working.
So just to recap here is what it's doing and everything I have tried.

1. The van turns over just fine but does not start.
2. I do not hear the fuel pump kicking on when I crank it over.
3. The van did pop off when I sprayed starter fluid in the intake.
4. I have tested the fuel pump, fuel pump relay, main relay, camshaft position sensor, crankshaft position sensor. All tested fine.
5. There is power to the ecu.
6. The two manifold grounds the ecu gets it's ground from appear tight and not corroded.
7. I have tried 3 different obd2 scan tools and non of them will connect/read the ecu (even the new ecu). There is power to the scan port plug and these scan tools connected before.
8. At one time I disconnected the battery and then hooked it back up. The van immediately started and ran fine. Turned it off and it started again with zero issues. But then let it sit overnight and it would not start in the morning. Disconnecting/reconnecting the battery has not worked since to get it to start. Just the one time.
9. I have kept a battery charger on it this whole time and it's cranking over just fine. Not a weak battery issue.
10. The van also wouldn't start with external power applied to the fuel pump.

So, if it pops off with starter fluid, and started and ran fine twice after the battery trick, that tells me it's not a spark or fuel pump problem. And since it did start and run, it's not a broken wire or blown fuse. It has to be some weird fluke electrical thing. But I've tried everything I know to do, up to and including a different ecu.

What else could cause the ecu to be unreadable and prevent it from triggering the fuel pump on crank?

Tue Jun 10, 2025 12:06 pm

Reading your first post struck me as a lost/intermittent ground to the relay. Will it run with the fuel pump hot wired? I would also verify the readings at the ECM (B135 pin 26) and relay (coil and contacts).

Tue Jun 10, 2025 2:00 pm

Camojcory wrote: Ok, I need help, completely baffled by this. Tried a different ecu (yes, same exact part numbers) and it still isn't working.
So just to recap here is what it's doing and everything I have tried.

Jesus Christ

you've tried everything but diagnose it.

Stop playing parts darts and do some diag. The simple fact that you can't communicate with the ECU is your issue. The ECU isn't getting power

pick up a wire diagram and get to work. I gave you the answer several posts up. the fact it started shows you have a shit connection somewhere and it arched enough for long enough to work

now, get after it....

and hint...just cuz your meter says 12v doesn't mean it can take the load, so I'd load test the wires as well

and another hint, the DLC has 12v all the time. that doesn't mean the ECU has power.

Tue Jun 10, 2025 3:44 pm

Connect the two test(diagnostic ) connectors together and turn the key to ON. Get after it with test light or multimeter. Be systematic.
A spare ECU isn't a bad thing.

Tue Jun 10, 2025 4:54 pm

wesitarz wrote: Connect the two test(diagnostic ) connectors together and turn the key to ON. Get after it with test light or multimeter. Be systematic.
A spare ECU isn't a bad thing.

that won't do much if the ECU is not responding to a scan tool and depending on how it's wired may not do anything at all

once he gets communications restored his problem should be solved

Tue Jun 10, 2025 5:20 pm

13b Bro wrote: Reading your first post struck me as a lost/intermittent ground to the relay. Will it run with the fuel pump hot wired? I would also verify the readings at the ECM (B135 pin 26) and relay (coil and contacts).

No, it will not run with the fuel pump hot wired.