Sprint '99 St Poor Running

Discussion in 'Sprint & Trophy' started by Brian Pinn, Dec 7, 2020.

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  1. Brian Pinn

    Brian Pinn New Member

    Dec 7, 2020
    North Devon
    Newbie here and I'd like to finish off a thread with a result, rather than all the others I've read that just stop.

    Apologies if it's a bit long but the more info given helps a lot..

    Owned my '99 Sprint ST for coming up 2 years, never had an issue. Did a short 10 minute ride, started the bike again and there was a pop like a balloon popping followed by a whistle/squeak. but running fine. Rode back home just with the noise, engine running smooth but lacking a little power. Removed tank/air box and found number 1 vac hose broken (replaced with Triumph ones about 18 months ago) replaced all 3 with silicone hose, everything back on and missing on number 1 cylinder. All through this there has been no engine warning light on. thinking maybe coil/plug (plugs replaced with Iridium ones about 12 months ago) but tuneecu doesn't show any faults. I then went down the valve route, seeing pressure had returned up through the vac hose, compressions at 200 give or take 5 either way over the three cylinders. I've now replaced with standard plugs. I know it's not running on number 1 as that down pipe is a lot cooler than the others. injectors have been removed and cleaned/checked and number 1 ignition coil replaced. I have also noticed the fuel lines are opposite to the triumph manual 'suggestion' as in supply and return but doesn't even start if I connect them that way. Anyone able to shed some light? I've been trying to sort this for 3 weeks now and possibly read every forum thread on running issues.
  2. Hubaxe

    Hubaxe Good moaning!

    Mar 25, 2020
    Aix Les bains - French Alps
    Sorry I can't help. Have you considered using a ODB reader like Tuneecu to have a better view on what's going on?
  3. Brian Pinn

    Brian Pinn New Member

    Dec 7, 2020
    North Devon
    Have Tuneecu and shows no fault codes
  4. Peter B

    Peter B Active Member

    May 24, 2020
    West Yorkshire
    Have you taken the no. 1 plug out and checked you are getting a spark?
  5. Aidan

    Aidan Well-Known Member

    Dec 31, 2018
    Don't want to teach anyone to suck eggs, but non running either means no fuel or no spark. Two simple tests - 1) check spark (as Peter says above) but use a spark tester - cheap on ebay and easier than trying to hold a plug to earth and cranking it over. 2) if you have a spark, then check fuel. Do this by squirting some Easy-start in the TB inlet. If it runs (then dies), you have a fuelling problem. As I said, I don't want to state the bleeding obvious, but sometimes the basic simple checks are a better start. Hope this helps.
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