BigLou 0 Posted November 10, 2022 I'm getting spark. It'll run with a shot of starter fluid. I replaced the fuel filter and injector. I get fuel to the injector cap. All I can think of is maybe the ECM? Any thought on how to further diagnose? Share this post Link to post Share on other sites
shadetree 5,543 Posted November 10, 2022 37 minutes ago, BigLou said: I'm getting spark. It'll run with a shot of starter fluid. I replaced the fuel filter and injector. I get fuel to the injector cap. All I can think of is maybe the ECM? Any thought on how to further diagnose? have you checked the timing ?, checked the compression ?. tried a new spark plug ?. if it will fire off on starting fluid ?, this tells me its not getting enough fuel ?, or the fuel pump does not have enough fuel pressure ?. Share this post Link to post Share on other sites
BigLou 0 Posted November 10, 2022 Like I said. It'll run with a shot of starter fluid. The fuel pump pressure is fine. Timing is fine. Spark plug and injector are new. Share this post Link to post Share on other sites
jeepwm69 7,212 Posted November 10, 2022 Try running a jumper wire from battery positive to the red black coil wire (just pull the connecter back a bit so that it's still on the terminal, and touch the jumper wire to the bit of exposed terminal). It it starts and runs then, I'd check your fuel injection relay (unplug, knock on the rear rack a couple of times, clean connections, plug back in) and the rollover/ tilt sensor, which is on the left side of the frame under the seat. That jumper wire will bypass those two components. If it doesn't start with the jumper wire in place, your fuel pump is probably toast. Share this post Link to post Share on other sites
BigLou 0 Posted November 10, 2022 Thanks! I'll try that. The fuel pump is definitely working, so I'm betting on one of these. Might not get to it until next week. I'll report back. Share this post Link to post Share on other sites
toodeep 1,732 Posted November 10, 2022 I know you said it's getting spark but have you tried a different spark plug? You would be surprised on how many of them, that's all it takes this time of year. Share this post Link to post Share on other sites
shadetree 5,543 Posted November 10, 2022 14 hours ago, BigLou said: Like I said. It'll run with a shot of starter fluid. The fuel pump pressure is fine. Timing is fine. Spark plug and injector are new. and like i said...if it will hit with starting fluid, but not fuel from tank ?, this tells me the fuel pump is not working to give enough fuel pressure. you say its firing plug..ok..this rules out spark. you say timing is ok..did you check it ?. 30 yrs of working on honda atvs, not much gets by me when it comes to not starting and running on its own. some of the trx420's came with defective fuel pumps from the factory. Share this post Link to post Share on other sites