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Discussion Starter · #22 ·
i think i may have figured it out. i only have access to the bike for a couple of hours a week so i can't spend too much time on it. From sitting so long could the air intake control valve just be stuck from varnish build up not allowing it to run properly? would that cause the bike to only run on ether? i soaked a rag in petrol and hung it out of the air cleaner a little bit. i let it run for a good while hoping something might break loose or burn through some bullshit stopping it up. like i said im no mechanic learning as i go. the logic makes sense to me at least
 

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Logic only works if you have background info and experience to understand how the mechanisms work.

No, IACV only makes minor +/- adjustments to idle-speed. It doesn't control ALL air going into engine, just bypasses minor amount of extra air around throttle-plate. Primarily to increase idle-speed on cold-start when throttle is closed. Above 70F, it's not used at all. You can remove it completely and would only have slightly rough-running on cold-starts (might have to hold throttle slightly open), depending upon ambient air-temperatures. But it would still start just fine.

Your issue is you're not getting ANY petrol into engine at all. As confirmed by it running fine when external source of fuel is supplied. You are just 5-minutes away from fixing this.

A lot of old-mechanic's "fixes" come from carburetor days. Doesn't really work for EFI. Engines, intake and fuel-systems are sealed and there's very little evaporation that causes varnish like in carb bikes. Most non-start issues on EFI bikes are purely due to electronics: sensors out of spec or adjustment, broken wiring (mice just love that soy wire-insulation), or some other electrical fault. Luckily those are binary in nature and easy to verify (Is that darn plug connected or not? Is there or isn't there power? Does test-light turn ON or NOT? simple).

It's just like troubleshooting why your kitchen light doesn't turn on. Sure easy impulse is to replace bulb. But what if that didn't work, now what? You've now got spare bulb and injector! Well... is there power in bulb-socket? Then if there's no power, what controls sending power to and removing power from that bulb socket? Simple logic if you understand mechanism behind electricity.

I've had racecars sit for 3-5 years waiting for rebuilds after crashing. This one's had 4 engine replacements (got too greedy with that boost-knob...). Just disconnect wiring, remove fuel-rail with injectors, remove engine, put new one in, re-connect fuel-system & wiring. Once fixed, turn key, push button and VRROOOMM!!!! Of course, 1st couple times, I was too rough with wiring and broke some, leading to hours of testing and head-scratching to find which one I broke. Never had issue with petrol or fuel-system though.



BTW, here's REALLY common problem with injector connectors on older vehicles. There are ways to determine health of wiring without destructive analysis...

 

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Cool 944! Just blew up a Boxster a couple months ago. Porsche makes great cars and easy to work on.
Thanks! heh, heh... yeah so much fun! I wanted to do track-racing and researched for 9-months for best car to get based upon bang-for-buck-performance and Porsche was it! Only car that I could take from showroom straight to track without needing to upgrade suspension, wheels, brakes, etc. They work great if you leave them in stock form....

But... I got too greedy and had to bump up turbo-boost for more POWAR!!!! The adrenaline really kicks in when you're chasing that 'vette up the hill at Laguna Seca... Just a little tiny bit more and I can pass him going into Corkscrew... Just twist that knob a tiny bit for more power... just a little... BOOOMMM!!!!! ;)>

Here's 1st engine I blew up!


Ended up replacing engine in 3-days since I had another race @ Thunderhill the next weekend. :)

 

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Any updates? In summary, you need these components for engine to run:

1. air & compression
2. ignition/spark
3. fuel


You did great job confirming #1 & #2 are OK by verifying bike runs fine with starter-fluid (external fuel source). So now you only need to figure out why internal fuel-source isn't working to provide #3

Alright so now I have rebuilt the fuel pump, it’s working just fine, I have replaced the fuel injector. The thing still won’t fire
What tests did you perform to conclude that fuel-pump is working fine?

Now we just need to devise further tests to confirm following:

  • is petrol flowing from fuel-pump to injector? Yes/no why not?
  • is petrol flowing from fuel-injector into combustion-chamber? yes/no why not?

You're just 5-minutes from fixing this. Just need to figure out why petrol isn't flowing from pump into cylinder. Simplest to split remaining path into individual components to test.
 
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