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Trouble Idling When Cold

Not sure the idle is completely fixed though. When I first started it after reassembly it still dropped rpm and chugged for 30 seconds then came back up to where it's supposed to be. I will test it out this weekend and update this thread.
 

one thing to check are the little ground blocks by the throttle position sensor. i had the same problem with a lot of codes. i could wiggle these around and make it run good or bad. to staighten the sled out i cut the wires from the block and spliced them together and the codes went away and it would start right up and idle perfectly. hope this might help. it took me 2 days to find it. sled has run perfect since. started out doing same thing stall when pulling up stop sign, running eratic at sloe speed but ran great on top end
 
musselman said:
Not sure the idle is completely fixed though. When I first started it after reassembly it still dropped rpm and chugged for 30 seconds then came back up to where it's supposed to be. I will test it out this weekend and update this thread.
Click to expand...
Any updates?
 
Still not fixed, I repaired all the ground blocks and fixed the rubbed wire. It doesn't stall now but it still does the low idle. I'm going to try and find some sensors that I can swap in to see if it solves the issues.
 
musselman said:
Still not fixed, I repaired all the ground blocks and fixed the rubbed wire. It doesn't stall now but it still does the low idle. I'm going to try and find some sensors that I can swap in to see if it solves the issues.
Click to expand...
There is a check valve that's by the tank id replace that first and go from there
 
musselman said:
Not sure the idle is completely fixed though. When I first started it after reassembly it still dropped rpm and chugged for 30 seconds then came back up to where it's supposed to be. I will test it out this weekend and update this thread.
Click to expand...
If it was cold out mine always did that... once warm it started fine .. I had to set the Fuel Injection for 10 points from zero to get it to start without stumbling in really cold temps..when starting first time of the day..
I don't know if you have checked the fuel for contamination.. so much today.. fuel goes bad fast.. thought I'd ask..
Also I know WD 40 spray liberlally on all connectors and grounds etc does wonders.. I've seen many miracles happen with it. I keep mine lubed up alot... often.. never an electrical issue on any of my outboards or snowmachines in 30 yrs..
 
Just wanted to give an update, I went through the entire harness and checked and greased all the remaining connection blocks. The only bad ones I found were by the TPS sensor which I soldered together. All the other ones were in perfect condition. I also checked the harness for any areas rubbed through but didn't find any. It still does the funky idle when cold and has a slight bog when warmed up off idle. It runs great on the trail it just doesn't idle well or respond well off idle.

The next step is to test the fuel return check valve, is there an easy way to check the fuel pressure? I see the fuel pressure regulator has a vacuum line connected to it which is supposed to reduce the fuel pressure at idle.
 
I managed to get a bunch of parts to try so I can hopefully eliminate a bunch of things. I received a complete set of throttle bodies with injectors, fuel rail, regulator, IAC valve and TPS as well as a pressure sensor.

So far I have tried the pressure sensor in both locations with no change. I swapped over the IAC valve and that changed the idle slightly but it was still boggy with the idle dropping after blipping the throttle. I also tried the TPS with no change.

The next step is to swap over the complete throttle bodies and see if that makes a difference.

I made a video showing what it is doing, if I stab the throttle too quickly it will backfire out the intake. You can tell when it does rev up that it is boggy and not crisp.

 
Did you try disconnecting the fuel return hose at the tank? If the check valve is not working you could have high fuel pressure.
 
I disconnected the valve and blew through it, there was not much resistance so I figured it was fine. I did not try running with it removed, maybe I should try.

Last night I swapped the throttle bodies which were complete with injectors, TPS, fuel rail with regulator and IAC. After putting them on it seemed to run much the same other than the idle being a bit lower. Once it warmed up completely the idle would drop below 1000 rpm and it still wanted to backfire when stabbing the throttle quickly. I'm going to try a cold start tonight to see if it behaves the same way as before.

Looks like I will need to pull the cam cover and check the valve clearance, anyone ever done this?
 
[QUOTbrick OCK, post: 1361939, member: 7908"]Did you try disconnecting the fuel return hose at the tank? If the check valve is not working you could have high fuel pressure.[/QUOTE]
What jrock said. Try this first I thought mine was fine as well. I'd be looking for a hose that has a kink or a pin hole after that. Did you do a leak down test?
 
I took it outside this morning at let it sit for a few hours at -15C. I tried a cold start and it seemed to run perfect, no chugging idle after it fired up. Also once it warmed up the idle dropped to 1500 and when blipping the throttle it would settle right back there with no hiccups. I will upload some videos shortly.

I can't tell what caused this by looking at my old parts. It must be either a fuel injector, the fuel pressure regulator or maybe the IAC. Wish I found something definitive. Hopefully I will get to try it out on the trails and see how it behaves.
 
Videos below, the first is a cold start, the second is once it has warmed up. Seems fine to me but hopefully will get to test this weekend.


 
I also had a closer look at the intake valves when I had the throttle bodies off and there appears to be some carbon buildup on some of them. All of the center valves are clean but some of the outers have a good amount of carbon built up. Not sure if this is normal or not, would like to clean it but I'm not sure how exactly.
 
That looks perfect now. Did you try playing with the idle adjustment screw on your original set of throttle bodies? Carb sync?
 
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