DonB

Fuel Injected, 2015 AC XR550XT ATV (renamed the Alterra from 2016 on). 1300 miles. I had written an earlier post concerning part of the problem, but a new one has arisen... 2 PROBLEMS: Engine sputters & fails when throttle applied (even from idle and while in Neutral), and, now... Fuel pressure reads @ "0" despite clear line and operational fuel pump. Unit originally suffered fire in muffler - presumably due to engine driveability problem & resulting unburnt fuel... fuel pump ultimately died when starting repairs. Installed a new fuel pump as dealer advised it was the problem. Have now been chasing a proper fix for several months, as, while it generally starts fine, the engine will not take any sort of throttle - even from idle. Instead, it immediately starts to miss, backfire & die. From the beginning, the dealer claimed that a new genuine AC fuel pump was all that was needed. However, the replacement, non-AC fuel pump runs at 42 psi & works fine). NEW ISSUE: Unexpectedly, the first replacement pump stopped registering any fuel pressure (per in-line pressure gauge). This despite confirming both: (a) pump clearly pumping & (b) fuel line - all the way to the fuel injector - clear & delivering fuel. Tried a 2nd replacement pump which, initially, registered pressure (engine performance issues remained). But, when I tried to start it today, no fuel pressure again (and, therefore, apparently no fuel to injector). Again confirmed pump working and fuel line to injector clear & delivering fuel. Engine continues to start easily with starter fluid but, of course, stalls once fluid has burned off. While cleaning/replacing the fuel injector seems the next logical step, it strikes me that, were the injector plugged, I should still be seeing a psi reading on the installed, in-line gauge I've been using (not zero)! Any ideas before I surrender this to the dealer and a B-I-G bill? thanx, db

Thanx, Mech. I'll take a look.

Had fire start in muffler due to failing fuel pump &/or fuel pressure regulator. Must I spend the $750+ for a new assembly from Arctic Cat?!? Here's what I've tried so far. Replaced fuel pump & regulator - both from Quantum. PSI is 60 rather than the 42 the dealer advises it should be, so problem persists. I've now twice replaced the Quantum regulator & discussed w/ Quantum. They advise that they don't have an alternative regulator that would bring PSI down to 42. I've tried several in-line, adjustable pressure regulators but they either didn't work or I couldn't get a constant pressure from them. FYI, I've only tried the adjustable regulators for Fuel Injected engines however, it seems that they require vacuum to function properly. When I can temporarily get the PSI right, everything works great. Anyone else ever dealt with this problem, and, if so how did you fix it? Perhaps I should adapt the fuel system to include a gas tank return line? Any insights are greatly appreciated, Don