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So, has anyone ever had an issue of a stator getting hot or a CDI cutting out after 30-40 minutes of riding.

I was having bogging, loss of power, popping etc.. tried and found no issues with any fuel componentes, alll filters, hose routing, pump pressure everything was fine but when it was hot and was being ridden hard, like deep sand whoops. it would start popping and losing power, so if it cooled it was better.

we i was told "stator is going bad" and thats a 320 part, one guy says, the valves may be too tight as far as clearance. So i checked them and this is after 3.5 years, never been touched, and they were at .004 intake and .007 exhaust. on the tight side of the spec. so i adjusted them to .007 intake and .011 for the exhaust, rode it this weekend, tried my butt off to make that baby run bad, got it hot in some deep sand, climbed some hills went beserk to the point of scaring myself.

no problems, but it was a cool day, i have my fingers crossed. whaddya think?
 

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So I think I have determined my fuel pump is bad. I checked the regulator, it is working, the fuel flow through my inline filter is great. it runs awhile, then pops, and quits, if I sit for 20 seconds I can get going again, and maybe even ride a mile or more. It is worse when hot.

I have no way to check fuel pressure, can we measure volume instead??, I heard 40cc pumped in a about 5 seconds, is about right.
Of all the things to happen, a fuel pump?? really?? My quad sat for 9 months because I had cancer, now i go riding and this is what I get. My last ride I won my class. this weekend i was getting towed. oh well.
 

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OK, so here is how I did it (checked the FPR) It has three brass tubes, one is the inlet from the pump, one is the outlet to the injector, one is the return line to the tank for unneeded fuel. (I hooked up a leakless hose from my air compressor to the fuel inlet)
On the workbench, blowing through the inlet, allows air to pass through and come out ONLY from the outlet to the injector as long as i keep the psi that i can easily regulate, under 45 psi, once i exceed 45-50 psi, the regulator allows the outlet that goes to the tank (for return fuel) to open and flow.
So to me it seems like hey, I have 45 +/- psi going from pump to injector and if the pressure exceeds 45-50 it gets sent to the tank. just like a stinking car system.

I dont think I need to have actual fluid to test the regulator, just psi and some resistance. TELL me if I am wrong.
 

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ok, well i am installing a new to me fuel pump tonight and going riding tomorrow taking two 450s with me, if mine starts messing up I will swap regulators and see if it helps.
( i pulled the old pump off to clean the inner filter, then i dropped it and broke the plastic end cap. great luck huh)
 

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Update: rode friday thru Sunday. totalling about 4 hours of seat time with 90 minutes of good hot laps and the rest simply play riding, hillclimbs and running some deep sandwashes. No problems whatsoever. The used fuel pump is working fine. I assume my FPR is also fine.
 

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Update on my quad, I still had an on/off stalling issue. I disconnected the fuel line, nothing came out. I shook my inline filter ( I have been using a closed steel filter), and it started flowing fuel. I drained my tank. took apart the lines, found my filter was "rattling" and i shhok it some more and pieces of plastic fell out. trashed it, cleaned out the fuel pump (nothing was in there) and installed a new NAPA glass filter.

oh well, hope this is the end of my trouble.
 

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UPDATE: OK, here is the story, no longer than needed.
Hello folks, I hope you can help me with this issue.

History, My LTR450 Fuel injected atv started running poorly, crapping out, stalling, dying on me (thankfully a mile from the slash X off road bar)

I got it home, figured it was a bad fuel pump, was taking apart the old one and dropped it and broke the plastic cap. so instead of spending 50+ for the new inner pump, i spent 110 on a used pump assembly. just to get the new cap, (not available from Suz as an individual part)

went riding, all seemed well, a couple of times over an entire weekend it seemed to stall out, but It didnt, I figured well its cold, or it flamed out because i was in too high a gear.

OK, that weekend i rode it hard too, put 3-4 hours of trail riding on it and 2 of those hours were hot laps, I am a d37 quad ammie and my best finish ever was 2nd OA at a euro scrambles. I wasn't just putting around.

home again, wash it, dry it, run it down the street 5th gear, i let off and it stalls out and I have to bump start it while it is still rolling. weird but maybe not?

so i research and figure it can't be a bad used pump, what are the odds, it must be a bad fuel pressure regulator. so I buy a used one (OK these are 181 new, and 50 used, i took the risk)

It starts, runs ok, so off we go to the desert and 2 minutes off the trailer it stalls out.

so here are the symptoms if it stalls and dies, if i sit for a minute,it will start again and run ok. BUT at any throttle opening or rpm, whether i am nursing it or gassing it, it may sputter, pop, die and start again if i bump it. i was able to ride around my camp area for an hour nursing it trying to at least get a feel for what was going on.

OK, so home again, in the garage, going to go from the basics.

pull the fuel line to see if we have flow, yes we have flow, i can fill a pint in a minute or less.
I rig a pressure gauge to the fuel pump outlet, i get 38 psi, now the regulator (which I Bypassed, since i was going for raw fuel pressure) is supposed to activate at 42 psi. ok, so i switch the guts out to my old pump and it is pump at 10psi. yay, i may have at least found something, the initial slash x trip and being stranded there may have been the fuel pump after all.

so then i take the two regulators (FPR) old and newer. and bench test them, i add air pressure from the compressor to the in nozzle and i test the psi of the out nozzle (the one that goes to the injector) and i monitor any flow at all that goes out from the third nozzle, which is a return line to the tank. at about 40 psi, the return nozzle start to let air out back to the tank return line. both FPR work about the same, one opens the return nozzle a little earlier than the other and I feel this is not good.

OK, now the manual says the injector needs 42 psi fuel delivery from the FPR. using the same gauge, my pump was not putting out even 40 psi, so if the pump is weaker than the required psi to the injector, the FPR isnt even regulating anything!!.

With this test, even if my gauge is not 100% accurate, the same gauge shows the fuel press to be less than the required psi to the injector.

YOUR constructive comments on this are welcome, I am stumped and tired of buying parts to chase this ghost AND i want to go riding and not have to keep my tow rope handy.
update 2, I have 2 LTR 450s in my garage, one is not mine, but what the heck I pulled the seat, ran a test hose between the FPR and the injector and let it run for 5-10m minutes and it rane at 42 psi regardless of rpm or temp. so that quad runs good, I will use it for my baseline.

I am now thinking, bad wire connection somewhere?
TOS?
Fuel pump relay?
Thanks Stirling
 

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QR706, you are right, I have not replaced the actual pump with a new one. My first gut feeling was the replace the pump. when taking it apart i dropped it and broke the plastic cap (I know) so I bought a complete used pump, which worked for a weekend it seems. Yesterday I ordered a new inner pump, new. also, HINT, you really cannot get much of a (FLOW test) test from the pump running the pump from the key. once the pump engages and fails to build pressure, it stops. to test your pump for flow, actual fluid output, you have to run the pump from a battery using some jumper wires.
The ECU shuts the pump down if it is just running w/o pressure. and you are right, I was pulling low PSI from the pump to the gauge i installed between the pump and the FPR.

what are the odds of buying a complete used pump that works for a weekend?
 

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brand new pump, runs the same.

OK, so about the FPR. Someone wrote that if you can blow into it, it is messed up. well there are three fuel hose taps, one input from the pump, one output to the injector, one output to the return.

I cannot blow into the output to the return, but I can blow through the input from the pump and it comes out the output to the injector. This seems to me to be how it should be.
 

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OK< well after much time parts testing etc. you guys may want to know what actually happened to my 450 and why it would run great then cut out.
It was not the filter, or the FPR or the pump. ......

It was that I have a desert tank and the vent line from the pump that is supposed to be run up high, i had connected to the swirl line under the tank to clean up the hoses a bit.
Recall, I had to pull the engine to rebuild the trans again. so while it was apart i spent time cleaning the deep grunge and lubing the pivots etc. and one thing I did was replace the lines and the old routing for the swirl return and the vent was to meet up high at a T right behind the steering stem, almost the same level as the gas cap.
I wanted to run just one line up forward of the tank so I Teed the lines off under the tank. Soooo.
When the pumpwas working, sometimes the vent line was full of fuel and was keeping the incoming fuel from flowing into the pump by gravity.
I was screwing around, feeling like I would never get it fixed and realized I could watch the filter run dry (I run a glass filter) HOW??? It was all new everything new new new dammit....!!!, then i would pull the line and it would flow. it was running free. Once I moved the pump vent line to end and terminate up high, it ran great and even when riding it hard. Finally, fixed and now it is 105 out here so no riding until Fall.
At least some of you made some money selling me hard parts I didnt need.
 
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