Engine reinstalled and won't start...any ideas

[stoutner]

I just finished putting my semi-rebuilt engine in. I made 100% sure that my cams and #1 piston and crank were all lined up top dead center. I even rotated the engine around by hand and double checked again before I put valve cover on. Everything in Cam/crank timing looked dead on the money.

I tried to fire it up after priming the oil pump. The first fifteen tries it tried to fire but ultimately flooded the engine. I pulled the plugs, dried off, cleaned , and checked and all are firing. Reinstalled plugs and tried it. It tried to fire up but just wouldn't "catch". Finally I got it to run "barely" at about 1200 rpm with partial throttle. If I let up the throttle or gave it more throttle it will stall. All idiot lights are off. Engine warmed up, oil pressure good, oil level good. It just won't "catch" and stay running. It seems like it is flooding as I can smell a ton of gas. I don't think it is flooding due to excess gas but due to lack a proper spark and/or spark timing. Maybe a bad ground???

How does the computer figure out where to set the timing? I know it picks it up off the magneto but am not sure if it has to reset itself or what. Is it possible that it is just REALLY FLOODED?

I tried for about 2 hours and am taking a break til Wednesday. Any ideas would be helpful. Last time i did this the engine did the same thing but eventually it just fired up. Now it just won't "catch"

P.S. Sorry to take up space in the Turbo/SC section. My sled is N/A but you guys are just about the only ones who have done engine work etc.

 

[TurboJamie]

Did anyone mess with the IAC screw the black one ontop of the fuel rail?

Did you install fresh spark plugs? Thinking out loud thats all really, if you got oil on one maybe during the rebuild or coolant. Carb boots are all good sealed no leaks etc?

 

[mbarryracing]

Maybe your cam timing is off at the crank. That will make it run like cockapoopoo...

 

[srxguy]

I would def check timing again

 

[Ted Jannetty]

Your engine uses a Cam Sensor in the Valve cover, this raises a few concerns this tells the computer where #1 is, you can still have the Cam timing off, or not plugged in.

Also Air temp sensor must be plugged in or the computer thinks it is 50 below Zero and it will flood the engine.

This is all I can think of right now.

Ted.

 

[stoutner]

I'll double check all of these things. As far as cam/crank timing, the crank dot and arrow are lined up up the clutch side, the mark/arrow are lined up on the mag side, and the dots on the cams are lined up. I am going to recheck if I can't figure out the problem though.

Any Idea how to bypass the airbox sensor? I've heard that you can install a 2K ohm resistor in the plug?

I installed fresh plugs. No one messed with the IAC screw. The wires from the magneto are all plugged in. It will run at about 1200 rpm long enough (15 - 20 seconds) to where the headlight will come on.

I am going to double check that cam sensor.

 

[stoutner]

Well, double checked everything. Found one hose off the #4 cylinder throttle body. Installed it. Also pulled plugs and they were soaked with gas. Installed new. Tried to start still just fires intermitantly.

Pulled mag cap and lined up hash mark for TDC. Pulled cam timing sensor and spun around til tdc and notch in exhaust cam line up....It doesn't line up exactly. The notch in the exhast cam is about 15-20 degrees off. Is that notch lined up with the dot on the cam??? Anyone have an exhaust cam out that could check it? I'm at the point of pulling valve cover off and checking but was curious.

P.S. I ohmed out airbox sensor and got 3.5 K ohm's at about 60 degrees. I put some snow on it and it rose to about 5.5K ohms. I think it is fine.


.......

 

[gsxr]

Fuel in the tank ?

 

[stoutner]

Fuel tank is half full with fresh gas. In fact, I filled my truck up and then filled a brand new gas can with the same gas at the same time. Truck runs fine.

Pulled everything apart checked cam/crank timing. Everything is dead nuts on. All dots lined up with arrows etc. Now, I'm not stumped anymore...i'm just getting pissed.

Supid question...everyone always talk about error codes. Do they show up un the display or do you have to check for them somehow. If so, how. I have never seen my sled have an error code and don't have any now as far as I know.

 

[wantboost]

wayne just gonna throw this out there.when i rebuilt my 03 engine i by mistake hooked my fuel feed line for my nitrous solenoid directly to my carb boots,bypassed the solenoid by mistake.anyway the fuel pump was just blowing raw fuel into the boots.would hardly run,tons of black smoke out of exhaust.i know you have a system,maybe something to look at.

 

[mbarryracing]

Wayne, by chance did you disconnect your speed pickup sensor on the drive shaft? Is that plugged in?

Make sure the tube to the IAC is not pinched or restricted, you didn't leave a rag or paper towel stuffed in it or something.

The day of the Trail Shootout on 4th lake in Old Forge a few weeks ago, BigMooseTurbo had HUGE issues with his IAC valve closing off (not flowing any air) and the engine did the exact same thing your describing !!!
Huffed black (rich) exhaust and wouldn't idle or or rev up, wet plugs, the whole bit.
We spent HOURS that day at Big Moose Yamaha trouble shooting all the sensors and fuel pressures, etc. to finally concluded that it was the IAC valve.

 

[adirondac blue]

If you had the carbs of for a while, the floats stick open. When you turn the key on the fuel pump runs and floods motor. Make sure fuel pump only runs for a second when you turn the key on. Check your oil to see if it smells like fuel or level is too high.

 

[kinger]

Its a apex so no carbs.

Back to basics, fuel air spark = run.

Do you for sure have spark on ALL cylinders, fuel - yes, so air IAC. The IAC's can do wierd things on cars not sure on the sled.

The only other thing I can think of that actually happened to me on a car was a fuel injector stuck wide open and it caused the same symptoms, be a easy check to measure the ohms of each injector.

 

[mbarryracing]

It's an Apex with fuel injection. No carbs.
But brings up a good point, make sure the return fuel line isn't pinched or restricted too. That will dead head the fuel rail and flood the engine.

It's flooding ALL the cylinders so it's not just one injector...

focus on the IAC circuit... it is basically just like a coolant thermostat with bees wax inside. The temperature of the coolant moves the air pintle, controls the amount of air flowing around the closed throttle bodies.
If it's not flowing any air, or not enough, it still injects the programmed fuel.

 

[stoutner]

I think fuel is flowing back to the tank because I can hear it when cycling the key. I have full bright blue spark on all four plugs (After I take them out and blow the gas out of them.) I also pulled the return line off, hooked a hose to it and watched the fuel flowing. It is flowing very well.

I'm seriously beginning to believe that it is a computer/electronics issue. It is sparking great and getting plenty of fuel on all four cylinders. I think it is just sparking at the wrong time...like the cam sensor or ECU is not working right.

I'm so frustrated...I am seriously considering parting it out and buying a 2 stroke....probably Polaris.