electrical gremlin

summ8rmk

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My tank on my Alpha will have pressure a week after i shut it off.
Not so sure about my proclimb? Ill have to check...

Legends ZX2 SR
 

kidwoo

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My tank on my Alpha will have pressure a week after i shut it off.
Not so sure about my proclimb? Ill have to check...
Tank or fuel line?

You have a pressure gauge on the line?
 

sno*jet

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how's the compression on this motor? have you replaced the fuel line in question?
 

kidwoo

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how's the compression on this motor? have you replaced the fuel line in question?
According to my shoulder compression is just as annoying as every other cat zuke H.O. motor I've owned.

I do have a replacement line that just showed up. Haven't installed it yet. Again though, no gas or vapors anywhere when I pop inside.
 

89sandman

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I can do 0 pull ups:behindsofa:

But seriously I would still try the noid light when it won't start. There has to be something that tells the ecm when to ground the fuel injectors. In cars it is usually the crank or cam sensor and in the older obd1 system the ignition control module which gets its signal from the distributor. Not sure what tells a snowmobile when to fire the injectors without a wiring diagram, but your ecm can be good but if the sensor that tells it when to fire the injectors isn't working they still won't fire. Same with an intermittent short in the wiring harness. Thus testing with the noid light will rule out that entire part of the system without guessing.
 

sno*jet

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these are with back of your hand facing you right, not the cheater reach-around.

LOL
I would slap that new line on though, cut the old one open and see if it was breaking down at all.
 
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You could take you injectors out and see if they leak after there is pressure in the rail. You could also get a fuel pressure gauge and hook it up to the line and see how fast your fuel pressure drops off.
 
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matt159

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I appreciate all the followups you posted on this thread Kidwoo. It stopped me from buying parts right away.

Following video is only applicable for about 45 seconds after it starts. And not directly relevant since it is a mechanical fuel pump in a hot location, but could be illustrating what is happening inside our fuel lines when under hood temps are high.


I am going to try wrapping my fuel line. Did this end up helping your issue Kid or did you run out of snow last spring before working it out?
I wonder if lack of shielding on aftermarket pipes plays a role in this issue?

It would take quite a while to build enough "vapor" in that decending 24 inch section of line that runs from the our fuel pump down to the injectors to displace all the fuel since the vapor stays at the top and any liquid fuel runs to the bottom. Maybe when I shut my sled off once the line is mostly full of vapor, the 45 psi of pressure bleeds backwards through the pump & actually vapor locks the pump? or maybe the rest of the fuel in the line vaporizes down by the y-pipe & its simply vaporlocked line?

I have never taken off my fuel line, but by the time I change the plugs everything has cooled off enough (or some vapor escaped the fuel pump) and it starts again... but plugs looked fine when I take them out last time & only had 100 miles on them. Mine normally takes at least a few hours of riding before it acts up. It will normally restart easily if I don't leave it off for more than a minute or two.

Anyone have thoughts on this theory? :unsure::unsure::unsure:
 
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kidwoo

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Just saw this post. I just sent you a lengthy message. I'll just copy it here for everyone else. But short answer is yes, think it's heatsoaking and getting vapor lock.

Hey man! I'm not completely convinced I've fixed it but I think I know what's up. Last spring at the end of April I had it out and it did it again, same scenario: run it hard, then let it sit for 10+ minutes then it burbles once and won't start. I pulled some gas, dropped it in a cylinder and then it worked.

I had it out on a cold day last year and ran it really really hard in deep snow. Lots of extended stops and never missed a beat. The only difference was that I had the pipe and y-pipe heat wrapped. It started falling apart so I took it off...then it started doing it again.

So I think what's happening is that it's heat soaking the fuel line, causing back pressure that induces vapor lock. So when it's time to pull the rope, the fuel pump isn't getting enough voltage to overcome the vapor lock. The fact that yours is getting worse (and mine did too over time) tells me that it might be because the insulation around the pipe is breaking down, causing more heat soak under the hood. If you look at a c-tech or polaris, the fuel line is nowhere near the exhaust. On the zuke motors, the rail is right under the y-pipe. It's dumb.

I got the pipe and y-pipe ceramic coated this summer, and I put some fuel line wrap around the hose and the rail. Hopefully that does it. At this point the only thing I haven't changed is the injectors. I've already replaced the stator, harness, plugs, plug wires and fuel pump. But I've got some little 2ml containers I'm going to fill with gas and keep with me until I'm convinced it's fixed.

In the meantime, try wrapping your pipe. When mine was wrapped it wouldn't do it. So I think that's it, and maybe a solution. We're still not riding here yet so I can't try it out.
 
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kidwoo

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Just an update, first ride out of the year, just road riding. Worked fine out in the woods but in the time I loaded at the end of the ride and got home (25 minutes?) it did it again on the back of my truck trying to unload it. Got some fuel in a cylinder and flooded it. Then just let it dry out and started.

So much for ceramic coating the pipe and heat wrapping the fuel line. I might replace the injectors next. That's really about the only thing that's left.
 
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The times i had simular problem was when the crank sensors was not set correctly (snow had gotten in an pushed them out). Made the sled realy hard to start but once i got it running it would work. But after the sled had cooled down after an hour or two of riding, it was dead.
Second time it happend, it was snow/ice/water in the ECU plugs
 

kidwoo

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I put dialectric grease on the ecu plugs long ago.

Shouldn't be the crank sensor since I changed it with the stator.

I did reroute the fuel line under the pipe last night simliar to how it was placed on the old m series. If it still does it now, I'll know a little bit more.
 
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sno*jet

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Did you ever do anything with the air temp sensor?
You always running non-ethanol premium or have you mixed it up?
I hope you figure it out so I can keep a copy of this handy incase mine ever starts this BS up.
 

kidwoo

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Did you ever do anything with the air temp sensor?
You always running non-ethanol premium or have you mixed it up?
I hope you figure it out so I can keep a copy of this handy incase mine ever starts this BS up.
I've got non-ethanol 87 in it now. But I also live at 6300ft and usually only ride above 7k so don't use 91 unless I've got some tuning going on. I've had everything through there, 91, 91 corn free, and 84ish corn and no corn. It makes no difference.

I've never messed with the air sensor. If it were a problem it wouldn't run correctly. And it does run correctly. It just doesn't start.
 
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summ8rmk

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What is the voltage sent to the injectors while pulling over vs running?
Also fuel pump voltages?

Are they the same when it doesn't start vs starting?

Sent it
 

sno*jet

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I've got non-ethanol 84 in it now. But I also live at 6300ft and usually only ride above 7k so don't use 91 unless I've got some tuning going on. I've had everything through there, 91, 91 corn free, and 84ish corn and no corn. It makes no difference.

I've never messed with the air sensor. If it were a problem it wouldn't run correctly. And it does run correctly. It just doesn't start.
well I think I would have tried the air intake sensor relocate by now just because they say it improves starting. not saying thats it for you but just something I know I would try in your shoes. Also I think you've pissed this sled off big time running that fuel. EFI should compensate for elevation and lean the fuel spray. 84 is way too low imo. The one time I ran corn premium I noticed lazier starting and more backfires that ride and a couple rides afterwards too. It takes a couple tanks to flush that crap out of there completely. No bueno.
Also you said you ran a hillclimb tune on this thing with that fuel? broooo... Id seriously check your top end out.
 
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