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EFI Backfire into intake - twin cam 88B

rvgriff

Member
Been reading on here for a few days and decided to join in. Fantastic site and look forward to sharing a few tip/tricks/stories with you all. In order for me to do so I need to get my 02 Deuce up and running first...

Here is my issue and what I have done so far:

Important note is that this is a Deuce made from 2 parts bikes and a custom frame. The 88B and Baker 6-speed are brand spankin new. The wiring harness/ECU/TSSM and all sensors are from the same running bike.
As the title states once it starts up it immediatly begins to run very rough and backfire through the intake. Will do this at any RPM so long as the throttle position is not changed. When I pained the tank I replaced all of the internals, pump, regulator, filter before sealing it up. I have since replaced the seals from the throttle body to the jugs as it appears that I have an intake leak according to some searching on here and elsewhere. No change... Tried spraying carb clean around intake area but I am not getting an RPM change anywhere. New plugs/wires..no change. Cleared the codes and let her run for about 10 min by slightly twisting the throttle to keep it running. No DTC codes being thrown at all now. 88B is stock with a set of V&H pipes and screaming Eagle intake w/ K&N filter.

Here is a pic of her before I cleaned up the wiring and such. Please help me get her on the road where she belongs! Thanks in advance for any ideas/advice you may have:rider
 

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I would start with a compression test to see if both cylinders are up to the task being it's popping back from the intake.
 
Also I have verified that voltage stays between 13 - 15V when running so I'm pretty sure it is fuel related not voltage.
 
You could drain the tank and clean it out and start over again with fresh fuel if you feel it's fuel related.
 
You could drain the tank and clean it out and start over again with fresh fuel if you feel it's fuel related.

did this as well with premium fuel as well as injector cleaner...no change

Thanks for helping me out!

Doesn't sound like you held the throttle open for that compression test, kind of low readings.

manual states that anythign > 90psi is "normal"

This may be part of the issue if ~100psi is not acceptable.
 
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