Suzuki LT-R450 Forum :: LTR450HQ.com banner

61 - 80 of 102 Posts

·
Registered
Joined
·
640 Posts
Discussion Starter · #61 ·
Why did you have the cam chain replaced? Any other parts replaced at the same time? Tensioner is not the greatest system on these beasts. What were you doin when this happened? Idle OK? Need more info.
 

·
Registered
Joined
·
27 Posts
While out riding, after approx. one hour, the quad starts cutting out and trying to die. If I let it sit for a few minutes, it runs good again for just a little while then again starts acting like it isn't getting fuel. I can usually do this routine long enough to get me back to the truck. After a couple cycles of it though, it won't run enough to even move a few feet. I can go home, let it sit in garage overnight and it will run great again for first hour or so. Took it to shop and they replaced the swirl filter (also have an inline filter). Drained all the fuel and have fresh in it. Hasn't helped a bit. The shop can't run down the problem and I've already missed a couple races now because of this and don't need to miss anymore. Help!!
 

·
Registered
Joined
·
640 Posts
Discussion Starter · #64 ·
Also, no need for both filters. Pick one or the other. Since the dealer put a new swirl in it, run it and put the in line back. Is it throwing any codes when it's acting up? On the far extrem side of ideas----- my buddy had a issue similar and it was a head gasket that was leaky and wouldn't act up till pretty warm. Only way we caught it was on a whim checking radiator. Water was fine in the bottle.
 

·
Registered
Joined
·
4 Posts
Bogging at pull away !!!!

Hi every one I just want to know,my ltr 450 bogs down at pull away (not much just like a second hesitation ) but when the revs gets up it goes pretty well.It also starts easily and idles without problems.Can it be the timing or wrong shims?:read:
 

·
Registered
Joined
·
103 Posts
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.
 

·
Registered
Joined
·
103 Posts
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.
 

·
Registered
Joined
·
2,788 Posts
That is exactly how I tested my regulators in the past. I have seen regulators test higher than the normal 43 psi. You still need to test your fuel pressure though. The flow test is not good enough in my opinion
 

·
Registered
Joined
·
103 Posts
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)
 

·
Registered
Joined
·
103 Posts
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.
 

·
Registered
Joined
·
1 Posts
bogging probs

ok so i have a 07 ltr 450 with a 20 over bore kit a two brothers racing exhaust and a cherry bomb the problem is it indles strong and revs strong but when i ride it it bogs at a quarter throtle i have no idea wat it is HELP!!!!
 

·
Registered
Joined
·
103 Posts
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.
 

·
Registered
Joined
·
103 Posts
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
 

·
Registered
Joined
·
640 Posts
Discussion Starter · #77 ·
TPS....... Swap out the whole throttle body off the other one and try it. I had something similar on one I worked on. Had an extra throttle body with a tps on it, threw it on and fixed it.
 

·
Registered
Joined
·
2,788 Posts
if you are running a gauge off your fuel pump and bypassing the regulator you should see a minimum of 60 psi. I found this is the single best way to determine if it is a fuel pump dying out or a regulator issue. If your fuel pump only builds 42 psi with no regulator it is only going to get worse when the pump gets hot. If I am reading your post correctly you have not replaced the pump yet?
 

·
Registered
Joined
·
103 Posts
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?
 

·
Registered
Joined
·
103 Posts
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.
 
61 - 80 of 102 Posts
Top