*FIXED* Stumped... Poor Gas Mileage, white smoke.

Discussion in '6th Generation 2002-2013' started by HotPursuit, Feb 10, 2018.

  1. HotPursuit

    HotPursuit New Member

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    I recently bought an '03 VFR800 about a couple weeks ago. It's only got 10K miles on it, and has obviously been parked for most of it's life. The bike looks like it just rolled off the showroom, so I'm going to guess that previous owner kept it garaged. Since I picked it up, I changed/flushed the clutch fluid, changed the oil (it was originally overfilled), changed the thermostat (and consequently, flushed/changed the coolant), switched to 87/89 (whatever is cheapest at the pump), ran a fuel system cleaner additive through a tank, and changed the battery.

    As of right now, it runs ok at idle, it just smells like it's running rich, until it gets up to operating temperature (180 deg F). Once it gets warm, the smoke out the exhaust is very thick, and then the engine idle starts to slow down and eventually dies/stalls. When riding, I don't know if it stops, or if I'm just going too fast to let the smoke plume accumulate, but my gas mileage is horrible. I only made about 70 miles on almost an entire tank. Tire pressure was good.

    When I bought the bike, it had thick white smoke coming out of the exhaust, and there actually appeared to be fuel leaking from the cat.

    After 1 gas up with 87, the smoke had significantly reduced, for a time, but then later resurfaced.

    Tearing the bike down to the thermostat was enough of a headache for me, and I will continue repairs most likely through the local mechanic, but I want to have a good place to direct them towards instead of just throwing parts/money at the bike.

    I don't think it's the spark plugs, the engine sounds like all cylinders are firing.

    The service manual says either a pinched or clogged fuel hose, or a faulty pressure regulator. This doesn't entirely make sense to me, because if fuel flow was restricted, wouldn't that cause the bike to run lean, not rich? There's no smell of gas or sign of fuel leaks from the front of the bike. I feel there's some reason/something that is causing an excess (abundantly excess) amount of fuel to get dumped into the engine. Looking at Honda's breakdown on their computers, even the sensors shouldn't cause this much fuel to get dumped. Does anyone have any experience with this or at least a sound logical explanation on how this might make sense?

    I changed the thermostat on the whole engine running rich to warm up premise. The old thermostat was fine, and the problem persists, even with a new thermostat.

    I don't think it's the O2 sensors, and again, researching seems to show they would fail in a manner which would indicate the bike was running rich, and should get the computer to lean it out.

    I really think there's something mechanical going on... something that is bigger than what the sensors/computer can compensate for, I'm just not sure what. The mileage is so low, and the condition of the bike leads me to believe that most of the components are in good shape/in spec. It just a matter of figuring out which one isn't.

    Any help appreciated, but please provide some sort of explanation for your solution. Again, even if I end up going to a mechanic, I want to be able to pinpoint where they should focus their efforts to minimize the time the bike's in the shop, and how much they lighten my wallet.

    Thanks in advance!

    UPDATE:

    So I'm replacing the Fuel Pressure Regulator next, hopefully the parts get here before next weekend. If the issue persists after that, I'm probably going to just take the bike to the local mechanic and have them check/replace the fuel lines and filters and the vacuum lines, or whatever other further troubleshooting required to sort this thing out. I'm feeling pretty good about the FPR being the culprit, but I felt the same way about the thermostat too... Will update with results.

    UPDATE #2:

    The FPR was the issue. The old one had fuel in the air vacuum line side, and installing a new one immediately resolved all of the listed symptoms. The bike smoked a lot at first, probably clearing out residual fuel in the exhaust system, but after a warm-up and a good test ride, the smoke was gone, and did not return.
     
    Last edited: Feb 16, 2018 at 6:34 PM
  2. Diving Pete

    Diving Pete Insider

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    70miles for a tank - yep something's not right...
    I get 120-130m but ride with enthusiasm.

    I'd ck the compression and the plugs first.
     
  3. Diving Pete

    Diving Pete Insider

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    just reread this: have to stop answering using a phone lol.....

    Its OBVIOUSLY throwing all your fuel out the rear pipe.

    So whats to blame:

    ECU?
    Fuel Pump?
    Injectors?
    Timing?

    Does it have a power commander attached?

    Also HOW does the bike run?

    Does it start ok - cold / Warm ?
     
  4. Lint

    Lint Well-Known Member

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    99% chance your fuel pressure regulator is bad, or missing the vacuum line and it's flooding your bike. You also could have dirty injectors that are basically dripping gas into your engine. Fuel injector cleaner can actually loosen up crud in your tank and fuel likes and dump it into your injectors.
    Get a fuel pressure gauge and check what your pressure is at. Sounds just like it's just dumping tons of gas into it. Check if your oil smells like gas. Chances are very good it's getting past the rings and diluting your oil. I would recommend changing it if it smells like gasoline even a little.
     
  5. Lint

    Lint Well-Known Member

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    To add more about the injectors; fuel needs to get atomized to properly mix with air for a clean burn. Dirty injectors will not vaporize the fuel correctly and can actually squirt the fuel in a stream instead of the normal pattern. Coupled with excessively high fuel pressure and viola!

    Just curious, what does your oil look like? Any water in it? How's your coolant level?
     
  6. Doug7200

    Doug7200 New Member

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    The OP did state the oil level was too high, so check the oil for gas smell first thing.

    White smoke is typically water vapor. Does this clear up after the bike is ridden and warm? Take a look at the recessed area of oil fill plug - Does it have a milky colored residue on it? Sure sign of problems if it does.

    If the bike has sat for long time with the crappy ethanol gas we often are forded to use, expect crap in the fuel system. I would pull the tank and dump the remaining fuel in a clean white bucket to what comes out. I would also remove and flush the fuel lines to what the have inside. If you find crap, I suggest doing a full fuel system service.

    Fuel injection can survive longer with crappy gas than a carb system, since it is sealed which limit evaporation. But the old fuel still breaks down and leaves deposits.

    Hope this helps and you find a simple fix.
     
  7. Diving Pete

    Diving Pete Insider

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    Oil level being too high is probably fuel in the oil..

    I'm with Lint - but CK the VACUMMN PIPES - If the Bike runs FINE & starts fine hot / cold then its unlikely the ECU.

    Heres an interesting link for the OP...
     
  8. HotPursuit

    HotPursuit New Member

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    No power commander. The bike is entirely stock save for the windshield, heli bars (edit), and a tail tidy. I tried running with and without the PAIR/flapper mods (currently connected) and it didn't make a difference. Took the snorkel out, and left it out as it was cracked. No pieces appeared to be missing from it, but I don't want to wait until it decides to start coming apart further.

    (Added after edit)
    It seems to idle ok, smells just a little rich, but when the engine gets up to operating temp, the smoke gets thick, and then the engine idle will gradually decrease until it stalls without any throttle input. Cold, it starts right up. After I let it warm up, and it stalls, it doesn't start as easily when cold, and originally made me think the battery needed to be replaced. Again, changed the battery, and problem persists.

    Rolling down the road, it seems fine, other than the crummy gas mileage. I do get this kind of flat spot/lack of power feeling at around 5krpm until the VTEC kicks in. It's bad enough where if I'm climbing a steep grade, I need to downshift to get into the VTEC range. My Magna had a similar feel in the same rpm range until I had it rejetted, so I'm not sure if this is something normal for Honda V4's, or a symptom of a fueling issue.

    Sent from my SM-G920V using Tapatalk
     
    Last edited: Feb 11, 2018
  9. sarge383

    sarge383 Insider

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    my 03 was doing the same thing as you describe after checking everything i could think of it ended up being the fuel pressure regulator.
    now runs like a champ no smoke and great mileage.
     
  10. 34468 Randy

    34468 Randy Well-Known Member

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    Just food for thought to those who are trying to help out. It would appear that heat has something to do with this. HotPeruit here mentions that it seems to start and run fine when it is cold but as the engine heats up, the roughness appears. So. With that, I suggest adding higher heat to the equation tells me that it could be something to di with shifting of parts due to heat changing the operation of something. or by heating up the fluids, something is happening.

    Hot persuit and I talked this over in Chat last night but I can't help out. Following my advice is likely to sustain the problem and drain the wallet needlessly.
     
  11. HotPursuit

    HotPursuit New Member

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    I'm suspecting this as well... looking into how much a new one costs, and how difficult it is to replace. The service manual isn't very clear other than it's under the airbox. And maybe I'm using the manual incorrectly, but I'm not seeing a part # for it either...
     
  12. Lint

    Lint Well-Known Member

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  13. HotPursuit

    HotPursuit New Member

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  14. HotPursuit

    HotPursuit New Member

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    Just changed the oil last week, so far looks fine, as does the level. The old oil looked more or less like old oil. Nothing crazy going on, just a high level, I think the previous owner just overfilled it.

    Just changed the coolant yesterday. The old stuff looked pretty clean, and flushed the system with 50/50 distilled water and distilled vinegar, which, when drained, came out perfectly clear. The level on the old coolant did not appear low. Refilled the coolant, ran it to operating temp last night, and will top off today, as it should be done burping.
     
  15. RllwJoe

    RllwJoe Active Member

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    You may want to watch the wax unit controlling the choke. If it does not move as the engine warms up, it would run rich. There may be air trapped in the wax unit keeping it from warming up and changing the amount of fuel being added to the mix.
     
  16. 34468 Randy

    34468 Randy Well-Known Member

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    Do not adjust this wax sending unit. If it is not working proper, you need a new one. They are not made to be adjusted at all.
     
  17. GreginDenver

    GreginDenver Active Member

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    Every time you describe thia problem it sounds like an overfueling issue, especially the fact that it cold starts well then gets over-rich when warm. It really does sound like a failed fuel regulator.

    The fact that you don't have an FI light + the overfueling situation is actually a very good indicator. The bike's fuel pump is designed to produce pressure well in excess of the system's needs and the fuel pressure regulator takes care of the necessary reduction. This means there's "overhead" available in the system for when the fuel pump gets older and weaker as its factory tolerances slowly get exceeded by long term wear.

    If the regulator fails and allows the full pressure provided by the fuel pump to reach the fuel rail and the injectors the fuel pulse-width commanded by the (otherwise completely healthy) FI system will deliver too much fuel.
     
    Last edited: Feb 12, 2018
    34468 Randy and Lint like this.
  18. HotPursuit

    HotPursuit New Member

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    FIXED! It was the fuel pressure regulator. When I disconnected the old one, there was fuel leaking out of the air vacuum line side. Put the new one on, and fired the girl up and she started perfectly, warmed right up to about 205 deg F, and then idle just fine. There was a LOT of smoke at first, mostly burning/clearing out all the excess fuel/residue left from when the bike was running poorly, and then once all that stuff was all cleared out she ran BEAUTIFULLY! I won't be able to take a long enough test ride to verify the fuel economy, this weekend, but it definitely seemed better from about a 30 minute test ride. No issues idling or starting when hot, and NO MORE SMOKE! And now that I've been able to ride her with proper fueling, the throttle was definitely very sluggish before by comparison. Thanks to everyone for all your help, you saved me a very costly trip to the mechanic.
     
    Lint and Diving Pete like this.
  19. Lint

    Lint Well-Known Member

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    So happy to hear!!! Well done on fixing it!
     
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