1993 GL1500 Asp No Power to Fuel Pump

[gmulleriv@gmail.com]

I have a 93 GL1500 that I can't seem to get power to the fuel pump.
This model's ECM is the relay to the fuel pump. With that said, I have tested all the other relays and they are all fine. The bike has spark and the starter spins the motor when you press the starter button. If I jump the fuel pump to the battery it pumps fine.
Here's what I have tried:
Tested all fused and relays. All fine.
Tested the bank angle sensor (BAS.) It tested fine. I have also tried a different BAS I know to be good.
Jumped the fuel pump to the battery. Pumps fine.
Tested kill switch. Tested fine. Bike has spark so I know it isn't that switch.
Tested ground to fuel pump. Ground is fine.

I have a factory service manual and Electrical Troubleshooting manual for a '95 but it's slightly different than the '93.
I tried downloading the correct manual for the '93 but the Helm site doesn't seem to be working.
I'd love any help any of you might offer!

[Rambozo]

Have you got the bike running by jumping the fuel pump? Then check for voltage at the pump wire with the engine running.
There is no fuel pump relay, it is switched by a transistor in the ECU. Bad or dirty fuel pumps have been known to take out that transistor. However, it can be replaced.

[landisr]

Have you had the battery LOAD TESTED? These beasts demand a LOT from the battery at startup.

Ron in AZ

[gmulleriv@gmail.com]

Rambozo, I haven’t tied starting it with the jumper wire. It has a new fuel pump and I’ve tried different ECUs.

I do need to load test the battery.

[Rambozo]

A little history of the bike would help. It sounds like you just got this bike and it has never run for you. If so, any idea how long it has been sitting?
I expect the carbs will need to be overhauled.
On a working bike the fuel pump isn't required to start it. It will run for a bit just on the fuel in the carbs.
You can also try to prime it with a little fuel or starting fluid to confirm that everything else is working.
If you have spark while cranking the odds are your battery is doing enough. You can also check battery voltage at rest and while cranking to see how much it's pulled down by the starter. The 1500 does require a tip top battery to have a good spark while cranking.

[gmulleriv@gmail.com]

Rambozo,
I am working on this bike for someone else. I think he was having the same problem and replaced the fuel pump thinking it was the cause.
At this point, I'm not concerned about the bike running or not. I'm confident you're correct in the carb issues but that's not the issue I'm trying to resolve. once the fuel pump is operating properly I'll address any carb issues. Until then, I'm trying to solve one problem at a time.
Thank you for your reply!

[Rambozo]

The fuel pump will run when the engine is running and stops when it stops. It should be pumping when you are cranking, but only if the ignition is delivering a clean spark and the battery voltage is high enough. The 1500 has some issues in getting enough voltage while cranking, so a test of the pump might give a false result. That's why I would try to get the engine running before condemning the ECU.

[ct1500]

If CB equipped it will have the 4 wire noise filter as part of pump wiring. Check for pump voltage on harness side the blk/blue wire with 4 wire white connector disconnected while cranking. A defective filter can cause the voltage loss.