WTH Fueling issue?

Ok, the short of this hic up, if that's thing. it's 99 vfr, #4 cylinder is not getting fuel after 2800 rpms, runs really good when above that, below that is a whole other story
Here's what I' have gone through with no avail.

Replaced coil leads and boots with new spark plugs first off thought was ignition. Nope
Now onto fuel.
Replaced the injector, all 4 while there
tried another ecu
replaced FPR.
checked all TB mounting boots and tubes for vacuum leak.
check and tested fuel pump replace filter though with 26k didn't think that was it. pressure is good. went and found a FI tester that sense pulses, it seem to tell me that it is working though with the no room for much and trying to do this running was a trick to do, I feel confident it's not a bad injector. So now I'm stumped. There is a thing I'm pondering, could it be a bad injector harness where there's a weak wire that only above 2800 it makes it work, yet the injector test tells me the injector is doing it's thing.
l also did a double check making sure it is a fuel issue by squirting fuel down into the #4 TB and used a temp gun to see if that made a difference and it does. so it is a fueling issue below 2800 rpm
I read over the Fi section in the shop manual yet doesn't cover this issue though Honda really should rewrite all this as they say use a injector tester Ha-Ha but don't tell you how to get it all apart and run to do so, what a joke. Though it did mention something if I understand this, that there is a pulse sensor? is that a thing? if so where? Any who there ya have it. thanks for spending the time here, any thoughts would be great. I'm pretty sure I've covered all there is but obviously not since its still doing it thing.

 

Wish I had something truly solid to offer, but my next step would be checking resistance and comparing across anything responsible for individual injector operation.

Kinda seems like something has some corrosion from sitting if the owner didn't remember this as the reason it got parked.

 

Yes my thoughts as well. Looking over the wire loom has me going WT.....%$#@! just read about Noid lights that attach to Injectors that make it seeing the pulse, LOL, only thing is Holy Sh%$ I'm not sure they'd get in there., no room down there. Now to make an airbox mod to get it running while fooling around down there.

 

Good to know that you are still with us RVFR!

Sorry that you are having issues with what is otherwise a pristine 5th gen.
I'm afraid that I don't have direction toward a solution, but your thought of an electrical issue is a logical next step.

I will be following this thread just in case I run into the same in the future.
Please keep us updated.

 

Up date Ta-da, in short it was found to be a cantankerous TPS. I found this through talking to a injector tech where I had all injectors tested, plus I saw how they work. He was pretty sure there was a partial signal loss some where. In looking for the trigger sensor I stumbled upon in the circuit diagram where the TPS talks to the ECU. Doh! Thing was in my case it was only the #4 injector not all 4, it was only getting a partial signal up to 2800. Once I located a TPS, whew, those bugger are getting like rocking horse poo, yet thanks to Darryl I was able to get my hands on one and Wa-la .. LOL after I got it dialed it in. So now I'm able to offer this pristine 5th gen for sale. If interested to know more go here https://www.facebook.com/marketplace/item/642239281834680/

 

carbs are alot less complicated

 

Gotta keep that dream alive.

 

Funny you say that as I have a 86 vf1000r that needs a carb going over, so we will see

 

I'm glad you have it sorted Jay. But now the sale of your long time friend is sad news. I hope you check in now and then.