Fuel pump running key off
Hello everyone, I recently installed the 600hp fitech system with inline fuel pump on my 1999 Boss Hoss motorcycle with a 350 zz4 motor. All went well, upon 1st actual ride the bike would shut off ( I think my fuel pump was to close to the engine causing vapor lock) after a few minutes she would fire and run fine. Once I got it home, I keyed off and the fuel pump would not shut off. Ran for atleast an hour before I heard it and pulled the fuse. I have since relocated the pump and double checked all of the wiring. Ground is solid to the frame, power is directly to the battery. I rode it for 15 minutes and all functioned fine. Then rode 20 minutes to town keyed off and pump continued to run. I unplugged all the connections and reconnected and it was off. Ate lunch and came back out to pump running. I can't seen to find any woring issues or bad wiring. Any ideas on what could be the culprit? I don't know enough about how the ECU controls the pump to know if a bad ecu could cause it. I am going to try swapping my ignition switch next weekend but I disconnected the white wire and the pump still ran so I'm not optimistic that the switch is the cause. I can upload better pics if needed.
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I have to ask why would you put a V8 on a motorcycle? Crazy... You need to disconnect the fuel pump wire to the fuel pump and attach a multimeter to the line to see if there power with the key off. If there is, it may be a ECU issue with a sticky fuel pump relay on the ECU. It's a common problem with fuel pumps that draw too much current. The max the Fitech can supply is 15 amps and I wouldn't push it to that spec. Walbro branded pumps have units that only draw about 8 amps. Does your Fitech unit have a external fuse/relay box? Also based on your picture, it looks like the Fitech is being deprived of air flow, which will kill the ECU. The ECU doesn't like heat and heat kills them.
Well it's a manufactured bike so there are thousands of them. I doubt the air flow is an issue since it's wide open under the tank and has a nice tunnel to allow air flow. I can't see anymore heat than would be in an engine bay since the engine is open air. The fuel pump is the fitech pump included in the master kit. The only relays I know of are in the small fuse box included inline with the harness. It does act like a relay as it stopped once then started back up without touching the ignition. Without a doubt I have power to the orange wire with the key off since the pump is running even after I disconnect the white trigger wire. The only way to shut it off is the pull the 20 amp fuse or disconnect the harness connector. I'll have to test the relay in the fuse box bit it would seem I may have to run my own relay and just let the pump run at 100% instead of letting the ecm control it.
There are PWM "compatible" solid state relays that you could use so you don't lose the speed control capability.
Quote from BossHoss on October 4, 2022, 10:35 pmWell it's a manufactured bike so there are thousands of them. I doubt the air flow is an issue since it's wide open under the tank and has a nice tunnel to allow air flow. I can't see anymore heat than would be in an engine bay since the engine is open air. The fuel pump is the fitech pump included in the master kit. The only relays I know of are in the small fuse box included inline with the harness. It does act like a relay as it stopped once then started back up without touching the ignition. Without a doubt I have power to the orange wire with the key off since the pump is running even after I disconnect the white trigger wire. The only way to shut it off is the pull the 20 amp fuse or disconnect the harness connector. I'll have to test the relay in the fuse box bit it would seem I may have to run my own relay and just let the pump run at 100% instead of letting the ecm control it.
Yes it is a manufactured bike that I assumed came with a carb and not Fuel Injection and engineered to work with a carb. Fitech engineers designed the Throttle body units for cars and not bikes. As I said heat kills ECU's as they are part of the TBU. The Fitech Fuel pumps are total Chinese junk and especially the inline ones. I would get a Walbro pump instead as they are made in the USA ( unless that has changed ). Does your Fitech have a black plastic box that opens and has replaceable fuses and relays? The fuel pump relay may be bad. It is replacable. You can remove the relay and use a multimeter to see if there is power going to the coil part of the relay that triggers the relay on. Usually pins # 85 and 86. I would also use a carb spacer to isolate the Fitech TB from the heat of the intake manifold. I still say judging by your pictures the Fitech is restrictive of air compared to a car engine bay. Does the rad on the bike have a electric fan to help cool the engine? I cant see it in the picture. Good Luck with the project.
Quote from tony-muscle on October 5, 2022, 8:53 amThere are PWM "compatible" solid state relays that you could use so you don't lose the speed control capability.
If he has the Rev 2 version of the ECU, PWM was removed for the Fuel Pump as told to me by a Fitech Rep. According to the rep they were having too many support calls due to the PWM for the Fuel Pump as alot of pumps are not PWM compatible.
It was purchased a month ago so I am assuming I have revision 2 system.
It would seem that everyone is leaning towards the relay in one way or another.
I'll be trouble shooting the relay and at worst I'll be bypassing the entire fitech power system for the pump.
As I stated before the airflow and temps are fine since the tank site above the TB, I have perfect AFRs at idle to WOT and the heat isn't a problem since its open air and yes there is an electric fan, the motor runs at 180 to 190 degrees continuously.
I'm going to to proceed as of the relay may have went bad and trouble shoot it and go from there.
Spoke to fitech today with some trouble shooting steps and they said with confidence that there is a short in the ecu causing the pump to activate full time. Getting rma to return and replace.
Quote from BossHoss on October 5, 2022, 7:11 pmSpoke to fitech today with some trouble shooting steps and they said with confidence that there is a short in the ecu causing the pump to activate full time. Getting rma to return and replace.
Yes you have Rev 2 of the ECU which is a good thing. The ECU may have gone bad due to the cheap Fitech Inline pump drawing to much current killing ether the Relay, which I highly suspect, or the ECU. I highly recommend you get a Walbro branded pump from Summit or Jegs. When you do get the replacement TBU, put a carb spacer under the the FiTech TBU to prevent heat soak. Especially after you shut down the engine. Thats what I have done. I also have my electric fan running a few minutes after I shut off the car to cool down the engine and the Fitech. I have had no issues for 5+ years. Keep us posted if all gets resolved. It must be scary riding that bike with all that power!!!!!!!
They didn't seem to think any heat was the issue they said it was a short that has been seen before. The relays were fine and the fuses didn't pop. It would seem the short has to do with the trigger wire (white wire) being shorted inside the ecu since even with that wire not connected the pump still runs. I guess we'll see once I get it warrantied and returned. We shall see.