Sportster 657x NO START

[Sexeado]

Someone please help. I am ready to blow this thing up. It has the 657x When starting engine will crank, putter putter, and die. Since this has happened I have done the following:
-Replaced engine with rebuilt 657x
-Replaced starter
-Rebuilt and analyzed carbs more times than I can count
-Replaced carbs with new set(same symptom
-Replaced stator
-New battery
-New rectifier
-New spark plugs
-New spark plug wires and boots
-no grey lines
-Was told it was MPEM by the dealer. Replaced with a oem 657x pwc MPEM off eBay with same results

After cranking the plugs
come out very oily and wet. Almost as if it is instantly fouling the plugs

 

[etemplet]

I don't see where you replaced the fuel valve. How is your fuel flow to the carb? Is the pulse line damaged or cracked? You could have a bad start stop switch. Hold the switch in when the ski starts, see if it keeps running.

Buy a spark checker from Auto Zone. $5.00 put it on the plug make sure you are getting good fire and it is holding when you let your finger off the switch. Good Luck !!

 

[Sexeado]

thanks for the response. I am getting fuel out of the return line when I pull that off of the back of the carb. The pulse line is good. If I hold the start down, it runs a bit longer but the starter eventually quits trying to start and kind of “spins out” as if it retracted from the fly wheel. The spark is good on both cylinders.

Let me know your thoughts on even though it appears to be getting fuel, is it enough? In the mean time I will replace the fuel valve.

thanks again

 

[etemplet]

Did you buy the spark testor for $5.00 from Auto Zone? I have a story on this forum about my 1996 XP. That thing was an enigma in a couple of ways. My Ski would not start as long as I held the start button in. Once I let go of the button the ski started and ran great. After much checking it was a bad coil. What helped me find this phenomenon was that I was working on the ski at night and it was ourside, so pretty much dark in the engine compartment. The spark checker showed fire but not as bright while cranking as when running. I pulled the black box off another XP I had and viola !! Started up just fine. If you have the spark checker on there test for when you let go of the start button. If you lose spark right away you have an electrical problem. The point being the spark checker can be of good use.

I think it is time you set up a temporary fuel feed system completely separate from the boat. Run directly to the carbs and see what happens.

Did you check voltages at different points with the battery installed and while cranking?

You'll read people against using starting fluid on these skis. I won't argue the point. If you shoot some starting fluid in the carbs and it fires up an runs for a few seconds... you got a fuel problem. It's a simple quick check. Good Luck !!

 

[Sexeado]

Thanks. Sorry I missed that one. I did have a spark issue once upon a time and replaced the coil and I’m pretty sure that was the issue. Do you have any ideas as far as an alternative fuel supply?

 

[etemplet]

You can buy a fuel bottle with a valve on it and a fuel line for about $30 or so, or you can make something. I hated buying the one I have but when I need it.... it's good to have. Look on Amazon or at your favorite store. Motorcycle shops always had them to test the bikes. Good Luck !

 

[Sexeado]

So my return line splits and goes to both the return and vent. Is that correct?

 

[Sexeado]

Also, does the pulse line need to be of a certain quality? I am noticing that the one I have on is a bit more flimsy

 

[etemplet]

I don't know about the vent line on a Sporster. On the Jet skis the vent has its own connection on the fuel baffle. I don;t see how the vent could function properly being hooked into the return line. That probably would not prevent the ski from starting. Are you sure you have the feed and return on the carb set up correctly? Feed line is generally the lower connection point.

Pulse line is definitely an area of concern. Line has to be the correct length and rigidity so it doesn't kink. A few guys here prefer to reuse the old gray lines. Flimsy isn't the description of the hose I would use. When I think I have a fuel pump problem I get a clear fuel line and put it in some gas. connect the other end to the carb inlet and turn the engine over. I watch the fuel get pumped into the carbs. The hose Should fill up pretty quick and should not leak back down when you let off the starter. Hope this helps.

 

[Sexeado]

Thanks for the help. I will give that a try. After further research I think the return is setup correctly. The sportsters have a separate line off of the tank that leads to a one way check valve out the side of the boat for ventilation. I also still have the gray hose for the pulse so I will put that back on and give it a try.
Hypothetically, if all fuel concerns check out, would this be a symptom of an MPEM failure? Are there any tests to bypass the MPEM to see if it will run?

thanks

 

[rusty nail]

i am not a fan of starter fluid, but in this case i would shoot some in and give it a crank. In your first post you said the plugs are coming out "oily and wet" which means you could be flooding it out some how. pull the plugs and let the cylinder dry out for a few hours, wipe off the plugs, turn off the fuel selector and send in some starter fluid for 1-2 seconds and see if she fires. If so, you definitely have a fuel related issue and nothing is wrong with your mpem.

 

[rusty nail]

there is a 5amp fuse on the mpem that controls spark. make sure it is ok.

 

[Sexeado]

I am hitting with the starter fluid and the same thing is happening. Not even running long enough to take another spray to try and keep it going. Attached is where I am at on the MPEM. Kind of a hot mess with subing the ski MPEM. I am thinking that I should start over here. Would the recommendation be to by a used stock MPEM or used aftermarket?

thanks for all the help.

 

[etemplet]

Can't quite see how it could be the MPEM. You might have the small red wire on the wrong side of the solenoid. When you let off the start switch power shuts down to the MPEM.

 

[Sexeado]

What is the best way to do a make shift gas tank. I attempted this tonight but it wasn’t pulling any fuel.

 

[etemplet]

That might well be your problem that it is not pulling any fuel. Is the fuel pump on the carbs assembled correctly? Then again, it didn't run when you gave it a shot of starting fluid. So....

Best course would be to get the fuel pump pumping. It should easily pull the fuel to the carb. Remove the spark plugs if you like, ground the wires, the engine will spin over more easliy and you'll verify the fuel pump's operation. The fuel should be drawn up the line and should not flow back when you stop cranking the engine. Good Luck.

Note: I can put a piece of hose in my mouth, and suck and blow into the hose connected to the fuel pump pulse line. I don't have any special talents with that but even that archaic method draws fuel to the carb in a short amount of time.

 

[Sexeado]

Hi there,

quick update:
I did confirm that the fuel pump is working and drawing fuel.

I replaced the fuel selector valve.

Engine continues to fire, putter putter and die continuously.

many additional insight would be appreciated.

 

[etemplet]

Did you paint the carbs? I once tapped over the vent holes for the diaphragm. That baby ain't runnin if that happens. If you are confident you are getting consistent fire, it has to be fuel.

 

[mikidymac]

Engine fires sputters and dies?
Is your idle possibility set too low?

 

[etemplet]

Is the timing set correctly on the mag? When you reinstalled the magneto there were marks that needed to be aligned.

 

[Sexeado]

I attempted to raise the idle but similar if not worse results occurred.

I am aware of the holes in the diaphragm. I did make sure to not paint those by sticker a small screw in there.

The Stator timing was a bit of a guess for me on alignment but I thought that I had got it. Might be worth pulling again and taking a look. Does anyone have any clear instruction on this alignment?

The only other thing I can think of is the rotary valve timing which came with the rebuilt engine along with a new cover. Also, this boat did run at one point with the rotary valve timing in its current position.

I am hearing pull the stator and ensure correctness?

anyway to bypass MPEM to see if it will continue to run?

 

[Sexeado]

Also, any thoughts on pop off pressure for a 657? I have these set at about 23psi currently.

 

[etemplet]

Sure wish I had all my pictures. LOL Hopefully they might be able to get it off my hard drive. I have pictures of the alignment. That said, there are two small marks. One on the stator One on the housing. I think 4 very small screws hold it in position. Line it up exactly. Be gentle with tightening the screws.

If you used starting fluid and it didn't run you have more than a fuel problem. I don't know how much experience you have with rebuliding carbs on these skis but they can be a bear for some people. It is very difficult to help when we don't have the ski in front of us. It can be frustrating. Hang in there and good luck !!

 

[Sexeado]

Hey guys,

I threw in the towel and sent it to the dealer. They are suspicious of the carbs. I will be sure to let you all know.

 

[rusty nail]

is this the same dealer that thought it was the mpem in your first post?