Suzuki ATV Forum banner
21 - 40 of 72 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter · #21 · (Edited)
The petcock you have will flow without vacuum.....You should turn it to off when not in use. ( that's what the vacuum operated one does automatically)

I believe it is supposed to be a vacuum petcock but it will work without it if the vacuum line for it is blocked off

It still has a fuel pump which is vacuum operated....the carb is above the petcock and will not flow by itself unless the tank is pretty full

Suzuki ATV Parts 2000 LT-F250F OIL PUMP - FUEL PUMP Diagram
Thanks for that info. That explains how it does its thing, and I will indeed turn it off, in the meantime, when not running. The reason I ask, is that my petcock valve was broken. The spring washer was rusted away, and it leaked badly. I made a temporary fix by replacing the spring steel washer with a neatly fitting O ring, and in compression that ring seems to be doing well enough, and certainly no leaks. However, since I now have it running nicely, I thought I might make good with a new one, especially as that temporary fix may not last that long.

There's no doubt in my mind that this is original, so there must be a difference between the UK models and those in the US. According to the VIN mine was an official UK import. If this normally has a vacuum switched valve in the US, somehow mine does not. Anyone who could possibly have been in a position to change it, would have had no clue about capping the vacuum on the carb to make it run properly, so this must be original. It also looked and felt original, and as though it had never been removed, when I took it off to clean and fix it.

Moreover, when you look up the part on my model, it shows a valve with only one pipe, and no vacuum to the carb, and it looks just like mine, so when I clicked on the link I was expecting the right item. I nearly ordered it. Instead I went looking for pictures of that part number, and it's clearly a vacuum switched version, which I'm surmising can't work on mine. I don't know why the parts list shows a picture of mine, and links to a vacuum operated one.

I'm totally guessing, but I suppose I could turn a new one to pri, which must allow fuel to flow freely, but then I would lose the option of switching to reserve if necessary, because I suppose reserve would be vacuum operated.

My question then, regardless of what should be on it, is, does anyone know what none vacuum operated petcock valve will fit my tank, because this is what I would like to fit, even if it was changed and it originally had a vacuum one. I seriously doubt that it was changed though, but even if it was, I would still like to know if there is a normal, or old fashioned one that fits, if anyone might happen to know. The type like mine that just has on/off/res.

Thanks very much for any help.
 

·
Registered
Joined
·
2,069 Posts
Any regular petcock that will fit will work......others here have changed over from vacuum operated mainly from the high cost of the vacuum operated ones.
Someone that has changed over may chime in with the one they used......most of the petcocks will interchange.
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #23 ·
Thanks TCIII, that's reassuring to know that they are more or less interchangeable, so something will be available. The issue now is which one specifically will fit, since I don't want to waste money ordering one that does not. Hopefully someone will be able to chime in with something that I can order that has equivalent centres for the screws, and for the reserve and on feed filters.

I'm sorry that I'm such a novice a this, but I've never even owned or worked on a motorbike in the past, let alone an ATV.

Cheers

Sutty
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #24 ·
Hello again guys.

LT-F250FK1 2001

I've just searched the forum, and there is an old thread, which died out without solution, where the issue is exactly like I have now. His was a 1999 version, and probably had a vacuum petcock. Mine is just a plain on/off/res. I've posted here, with my old thread, since it contains the history of my quad, and how I got to where I'm at, with the engine previously having been seized, etc. After having getting it up and running, with all your help, for a few months the quad has served its purpose of getting us all to my remote fishing cabin, along with our fishing gear, water, food, etc, in an ATV trailer, and it has done this very well indeed. Recently, it started running badly, and giving me a lot of trouble, so I brought it home again. I noticed that it had a lot more oil in it than it used to, so I drained it all out and the oil absolutely stunk of petrol. Thinking I had my issue, leaving the petcock valve on when not using it, for many days at a time, because I could no longer put the petcock valve into the off position without it leaking, I thought the issue would be gone with a change of oil and a new petcock valve. I have the valve fitted now, so I can shut it off properly, so as to not recreate that issue, and I have new oil in it, twice now, hoping that this would solve the problem, but it has not.

The issue is as follows, and is almost word for word the other guy's issue, here. It starts fine when cold, and never needs choke. Idles okay, and picks up nicely, with plenty of power. Can ride around for approximately 10 minutes, and then I can feel that it is not running quite right, and lacks power. If I then let it idle down it will stop. I can sometimes restart it, but very difficult to do whilst warm. If I revisit it an hour later it will start easily and run fine again, for the same few minutes, maybe a little less, because it is somewhat warm.

Changed the oil again to a better quality oil, and it lasts a little longer before developing the same issue. Wasted some money there, but that's life.

If it is part warm, I get a very inconsistent idle, which is extremely difficult to tune. Sometimes after throttling up it will not slow down to idle, and if I back off the throttle stop screw, it will all of a sudden drop into the idle range but then stop because the setting is then too low, unless I keep the throttle open on the handlebar. I think this is more a symptom, as a result of it getting near to its running badly phase, to the point of not being able to run or start it again, as opposed to anything to do with the underlying cause. I have a new throttle cable anyway, since that snapped a little while ago, whilst it was running well, and I have observed that the mechanism isn't sticking, or anything like that. If it was running well, I think I would be able to set the idle run nicely.

I have cleaned the carb twice, but for the second time it was spotless anyway, I was just double checking everything. First time it was filthy, as a matter of interest. With the top off the carb I can see the 'choke' plunger is home, and operates as it should when I move the lever on the handlebar, and goes back seemingly correctly. I have adjusted the float, which was just barely out of spec, at 12.4mm, but is now spot on, at 13mm, as per the manual. I have looked at the jets and cleaned them out with a few squirts of carb cleaner, but they looked fine anyway.

It is too old for it to warrant spending a lot of money on it to have the engine properly serviced, in case it's say piston rings, or valves, or similar, unless it is something you can help me with. Overall it has around 5.5K miles on it, but bear in mind its very chequered history of having been sat in a barn for around 10 years in a seized condition. Having said that, it has done around 90 miles since I did get it going again.

So, has my contaminated oil caused a problem. Is there something else you can think of, that wasn't covered in the other thread.

Spark is good, new plug, pilot screw set to factory setting. Air filter is new. Carb is now clean. Jets look good. Float is set to spec. Jet needle seems to move correctly via the piston in the needle jet. Piston diaphragm seems good.

I worry that it has to be hot before it stops, because this implies to me that it is valves or rings, though I have to say my knowledge is extremely limited, as you will know if you helped me before, or have just read the history here.

Any help or ideas would be greatly appreciated.

Best regards

Sutty
 

·
Registered
Joined
·
2,069 Posts
Check the vacuum line to the fuel pump for gas in it
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #26 ·
Thanks TCIII. Tied up all day tomorrow, so I can't check on that until the following day. If there is fuel in the vacuum line, what might be wrong with the pump, and can they be fixed, or would I need a new one?

When I checked the integrity of all the lines to the carb, and to the pump, I think I remember a little tiny dribble out of the third line, of which I was unclear of its purpose. This is from memory, and I could easily be wrong, mixed up as to which line, but if it does prove to be the case, how does this lead to the issue when warm, and not right from the start when cold? I ask only to help me with my understand of these things.

Thanks

Sutty
 

·
Registered
Joined
·
2,069 Posts
Thanks TCIII. Tied up all day tomorrow, so I can't check on that until the following day. If there is fuel in the vacuum line, what might be wrong with the pump, and can they be fixed, or would I need a new one?

When I checked the integrity of all the lines to the carb, and to the pump, I think I remember a little tiny dribble out of the third line, of which I was unclear of its purpose. This is from memory, and I could easily be wrong, mixed up as to which line, but if it does prove to be the case, how does this lead to the issue when warm, and not right from the start when cold? I ask only to help me with my understand of these things.

Thanks

Sutty
Some of the pumps have rebuild kits....some don't
You can use an aftermarket lawn equipment pump ( use search on that subject )
It may leak more when it gets hot and line pressure gets up

Also check the carb vent line...( the one going up by the tank) to see if it is clear.....if it's stopped up it can cause the carb to flood also
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #29 ·
Thanks Alaskacabinquad, I'm pleased you enjoyed reading it, and thanks for taking the time. I too was excited when I first got it running, going back those few months, now, not quite so, lol.

TCIII, thanks for the info regarding the fuel pump vacuum line. There is some fuel in the line, but the tiniest amount, in that I can smell it and see some dampness in the end of the line when I pull it off at the carb end, but it isn't dripping out. At the pump end, the same, damp with fuel only. The vent line you mentioned was clear.

I can imagine, seems logical, but don't know for sure, that the vacuum side of the diaphragm should be completely free of fuel, and it isn't, so this needs resolving regardless. Doesn't look like it can be disassembled. The manual shows bolts on the front plate, but this is a plastic Mikuni one, and seems, at first glance, to be sealed shut, with no bolts or screws to remove the cover.

I'll take a look for the lawn mower type.

Regards

Sutty
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #30 · (Edited)
Further things now tried. I didn't know if I could do this, but tried anyway. I clamped off the vacuum line, filled the tank some more, and put it on reserve, so it would be a slightly lower tank exit, and it did run, even without pump, just as well in fact. I'd thought it might, being as sometimes when you leave the valve open you can get fuel to leak out of the tank and into your sump, as had happened to me, so I figured it must flow fairly readily. The problem is it didn't make a scrap of difference to the running issue. Same deal. Runs fine when cold, and then starts to lack power, and then stops from idle, and will not restart. Whilst still accepting there is an issue here, in having fuel get into this line, do you agree that this test rules it out as the underlying cause of my problem?

Can I also ask what experience people have with the setting of the pilot screw? Do I go for the default, which I'm at, or is there no real way to know without trying? Unfortunately, I can't adjust that without taking the carb off, as I suppose you'll know, but if there is a more 'normal' setting that works for people, I'll try that too.

I've now adjusted the valve clearance, through those little removeable caps. Not easy, but I bent my feeler gauges at the tip, maybe about 30 degrees, and did manage. I couldn't really 'feel' the precision fit, but I turned them in until they gripped the gauge a little, and then backed them off until it was just a slight resistance to remove them. I went for a mid range value, I think .002" on the intake, and .004" on the exhaust, if I remember the numbers correctly, because I didn't really know what to do. Subsequent reading, that I found on this forum, suggested that this should be fine, but if anything, err on the side of loose, thicker gauge, if you're going to do anything other than mid range, but mid range should be okay, which is where they're at.

Since adjusting the valves, I would say it starts worse from cold, still starts, but the tapping noise seems to have gone, or lessened a lot. Sadly, the exact same running issue persists. 10 minutes, and that's your lot.

I wish I knew more, and could diagnose by listening, but I just don't have the experience. Open to any ideas you gentlemen may have.

Cheers

Sutty
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #32 ·
Thanks Jamie. Good luck with your project.

TCIII, you mentioned an aftermarket fuel pump, and I think I have found one. I'm changing it regardless of if it is the cause of my underlying issue, because as I described above, it's definitely weeping, and they seem cheap. Does this seem like the right sort of thing. Only a few pounds, and includes postage, so not much lost if it isn't, but I thought I'd ask.

Pump

Thanks in advance.

Regards

Sutty
 

·
Registered
Joined
·
2,069 Posts
It should work fine......let us know
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #35 · (Edited)
Hi Guys

Got the new fuel pump fitted, and it didn't solve things. Came with a clear fuel filter, which I've also fitted, just because I though it might be nice to see the fuel, and for the extra security of filtered fuel, especially since there's no original filter. Of course this won't help if I can't sort it out, lol. During my test today it ran for longer than I've managed recently, and it never completely failed on me. I managed 3.5 miles, but that I suspect was because it was a cold day, so it took a little longer for things to warm up sufficiently. Once it did though, I got some of the same symptoms, although as I said it would just about keep working, and I could restart it, if with a little difficulty.

I've been trying to read up on running issues of this sort, and one thing that seems to match nicely is a leaking inlet manifold, but in my case it would need to be warm before it starts to leak. The aspect that has made me focus in on this is the way I get a strange over fast idle, that won't initially back off when I close the throttle. I sometimes have to blip the engine run switch on and off to get it to back off enough to drop back in to idle. If I adjust the throttle stop, backing it off until it drops into idle, then it cuts out as soon as it idles, because by then the throttle stop is too far out.

I've taken the intake manifold off today, and I note that there is an O-ring. This ring, in my case, is almost totally flat, and is not rebounding to any sort of round. Is this meant to be flat, or a normal round O-ring, and if so, which part number do I need, oem or aftermarket? Alternatively, could I try some silicon sealant, and see if that has any positive impact. Incidentally, there was all sorts of dirty streaks across the gasket, and lumps of collected dirt around it, in certain spots, which makes me think it could have been sucking in air and dirtying it. After I gently cleaned the manifold contact surfaces, and the gasket, all were nicely clean and smooth again.

Anyway, your thoughts, as always, would be appreciated, especially with regard to sourcing the correct O-ring, since even if it should be flat, a new one certainly couldn't hurt.

Cheers

Sutty
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #37 ·
Silicone gasket sealer applied, and allowed to cure for a while. 5 miles completed with no change in running, or ability to re-start. I assume when warm it leaked and it screwed with the air mixture for idle and start, whilst also having a lesser effect on the high running mixture, which is why I could hear it, and perceive some loss of power, and then when backing off to idle it would either over idle, or stop, depending on where I was with regard to the degree of leak, or maybe its mood, lol.

Anyway, I consider the gunk to be a temporary fix, so have ordered the O-ring, and will perform much more extensive testing once fitted and report back. Maybe I should reapply a thin film of sealant to the gasket too then anyway, to be doubly sure? It says it's designed to be used in conjunction with gaskets.

Seems positive so far, but will be back with confirmation after much more running in a week or so.

Thanks all.

Regards

Sutty
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #38 ·
Sadly not good news. I got the new O-ring, and the running issue is the same, but I have noticed a new symptom. I'm sure this would have been there before, but I just didn't notice it, due to wind, seat being in place, etc, basically just circumstances. Today I ran it at idle for 20 minutes, whilst I had some lunch, I then went out and rode it around for about 5 miles, so that it was good and hot, and it was still working. Then I put it in the garage and left it running, thinking all was now well, leaving it for another 20 minutes. When I returned to it, it was still running, but I could see smoke coming from it. Difficult to say where it was coming from, and as I continued to peer at it, trying to spot the location, it just stopped. I could then still restart it, with difficulty, but could not easily keep it running, and it was lumpy when trying to rev it up, basically the same issue.

Could this be a cylinder head gasket issue? Does it ever happen that they leak when hot and not when cold, and could it result in such symptoms? Also, if it is a possibility, how difficult a job is it to replace it. Something someone inexperienced could attempt, or should I just consign this 2001 quad to the scrap heap? I can't imagine it would be worth having it repaired by a suitably qualified engineer, since the value of the quad will be so low. It's a pity, because realistically, it would only be required to do 3/4 mile there, and 3/4 mile back, once a week during the fishing season. Sometimes, maybe a couple of trips on any given day, and it runs enough for that, but I can't really risk it being unreliable, and I'm sure whatever the issue, it will likely get worse.

Your thoughts would be very much appreciated.

Cheers

Sutty
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #39 ·
Took the rocker cover off yesterday, and checked the cylinder head nuts. One was loose, actually loose. Two were not tight enough, and one was okay. Tightened them all to the same degree, pretty tight, to what I thought was right, since I have no way to check properly. Replaced the rocker cover with sealant. I'd followed a trick I read on here somewhere to keep the bolts matched up, by poking them through a piece of card, which worked nicely. Wasn't sure of the correct torque order, so I very carefully and progressively tightened them always leading with the inside ones that clamp the rocker, I suppose you'd call it, since that made most sense to me, to ensure that lined itself up nicely. Just a guess though, but it seems to be okay.

Today, before running it, I re-did the valves, because I wondered if the sealant may have repositioned the cover slightly, and changed the gaping. Having done them before, I was now much more practiced at the procedure, and it went very smoothly. There wasn't much change to be noticed, or applied, but nice to have checked them.

Ran it for ten miles this afternoon. No strange running, no smoke, no dodgy idle, no stalling, apart from after five miles when it just stopped, and I thought, oh here we go again, no difference, still faulty, but I'd actually run out of petrol, lol. Put in another gallon, and it started after a few turns, needed to get the fuel through, and then off I went again for another 5 miles. Still running perfectly as I parked it in the garage at the end.

Could not be happier.

Thanks to all who contributed to help me, and thanks to the site in general for all the tips and tricks picked up.

Cheers

Sutty
 

·
Administrator
Joined
·
9,546 Posts
Glad to hear she’s running ok now.


Sent from my iPhone using Tapatalk
 
21 - 40 of 72 Posts
Top