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2014 Foreman 500 has spark, fuel and compression but wont start

32197 Views 29 Replies 8 Participants Last post by  carlzsdropz
I just purchased a 2014 Foreman with less than 500 miles on it that the previous owner sunk over the handle bars and let sit for a year. When I purchased the bike it would not start but I knew that going to buy it. First thing I did was dump all the old fuel out of the bike and clean the tank. Fuel pump works but seems very loud compared to any other fuel pump I've heard on my previous Rincon 680 and Rancher 420. I cleaned the fuel pump but did not take it apart and clean the filter because at the time I was not aware there is one. I removed the injector and made sure it would spray. So at this time my diagnoses was bad compression because I had spark and fuel (the plug was wet with fuel). I checked the compression and it was about 120 psi by turning over with the starter. So I'm not sure what RPM that is for the compression check. I then decided to install new rings, gaskets, and honed the cylinder. Rechecked the compression after the new rings were installed and I got the same reading within 2 psi. So overall I think I have good compression, fuel, spark, and no error codes but this thing will not start. I've also tried bypassing the angle sensor and switching the relays around. Bike will run briefly on starting fluid though.

Could this still be fuel pump related?
Could the ECM be bad and not throw a code?
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Id check the timing that's the only other piece of the puzzle if your 100% sure its getting spark and fuel.
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That was my only other thought too. I don't think it has anything to do with the mechanical timing though, I just cant imagine a new machine skipping the timing chain or something of that sort. But the timing for fuel has to be driven by the ECM correct? And the loud fuel pump is still throwing me off.
If its a fuel issue the bike should run for a few secs spraying quick start in through the throttle body.
Run a jumper wire from battery + to the red and black wire on the coil, and see if it will run like that.

The EFI machines have all kinds of electronic crap on them that will keep them from running. That bypasses a lot of them.
It will run briefly on ether.

The jumper wire trick didn't seem to change anything.

I am getting spark but it seem spastic to me, the plug is a new NGK.
If it fires on ether I'm guessing your fuel pump is shot.

On the 420's, the fuel pumps will go bad if you let them sit for long. Just a weak pump.

The newer Foreman's are basically big 420's so I'd take the pump out, clean it out good, and either replace it or clean the crap out of it and see if you get fuel pumping.
Agreed, your getting some fuel but probably not enough. I'd do a fuel pressure test to see if the pump is bad or the injector. Injectors don't like water, if it was sunk someone may have tried to run it on fuel with water in it. Noisy fuel pump is definitely a symptom, I'd replace that just for good measure.
The tank did seem like it had water mixed with the fuel when I dumped it originally.

I removed the pump again, disassembled it, and cleaned it. I tested the pump and it seems to flow plenty of fuel. Also installed another new NGK plug then measured voltage at the plug it jumps a lot from 10v-17v.

While doing all this I have it hooked up to a jump started box to assist the bad battery. Is this in anyway affecting my trouble shooting? I ordered a new one off Amazon, just waiting for it to arrive.

I too believe this could be injector related. Just not sure how to go about cleaning it. Also I will note that the plug is wet with fuel every time I remove it for inspection.
You're reading 10v to 17v at the spark plug? Normally there is supposed to be something like 30,000 volts at the spark plug. Have you tried grounding the spark plug against the engine housing with wire attached and then turning the engine over to see if you can detect a spark in the gap of the plug?
Yes. That's how I know there is spark by grounding the tip of the plug on the frame. When I said "at the spark plug" I meant at the wire. But coil is what amplifies voltage, correct? So at the wire should be 100v minimum according to the service manual.
Yes, the coil amplifies the voltage, but the engine must be turning over so that pulses reach the coil in order for the coil to amplify them. The coil can't do its job unless voltage builds and collapses. The black/red wire attached to the coil is what delivers the 100 volt pulses to the coil. The coil then amplifies voltage to something like 30,000 volts to the spark plug wire. When you say "at the wire", I don't know if you mean the black/red wire or the spark plug wire. Please restate for clarification.
At the spark plug wire. I was miss reading/using my multi-meter which maxs out at 1000v anyway, so the 10v-17v statement is false. Blue spark should be enough evidence that the coil is functioning properly I would think?

I checked timing in a sense. Put the motor at TDC and both rockers had clearance of the valve. Not sure there is any other way without removing the front case and looking at the timing marks on the cam?

Also the injector and fuel pump seem to be fine, I removed the injector from the TB and the spray was sufficient to at least start the motor. I believe I'm going to bite the bullet and order the new ECM. I hate to throw parts at a machine but I have no way to properly hook up a diagnostic tool if that's even available on these machines.
I agree that you can rule out spark. You're getting a good spark, and ignition timing must be correct because there is no way to adjust it.

I know you did some extensive testing on the fuel pump and injector, but I still have some suspicion about the fuel pump since it does run for a while when you squirt some starting fluid in the throttle body. I'm leaning more toward the fuel pump than the ECM.
If I run a jumper wire to the fuel pump do you believe that would be beneficial and give us more information?
The jumper wire to the fuel pump is not a bad idea, but it might be easier just to attach your volt meter to the fuel pump. Get the engine running by squirting starting fluid into the throttle body. Then, stop squirting starting fluid and watch the volt meter as the engine sputters and dies. If it shows a solid 12 volts all the way until it dies, then that supports the thinking that the fuel management system is working as it should, but the fuel pump is not.
No change with the jumper wire. One of two things is happening, either I'm getting way too much fuel or the spark isn't sufficient enough to ignite gas. Even after running on ether when I pull the plug its soaked in fuel. I know spark plugs pulse but how timing sensitive is that? Is my spark not igniting when the fuel is being delivered? Or is the fuel just drowning the spark?

I Can't decide if I should drop the money on a voltage peak test or just a new coil. Also I noticed there is a fuel regulator according to the service manual. So maybe I buy a coil and fuel pump assembly and rule both out?

I did disconnect the CPK sensor to see if the motor will still run on ether, it does not. So that kind of makes me think the ECM is ok. Still not 100% convinced its not ECM related either...
I could be totally wrong here, but if you can run on ether and fuel, then if there is excess fuel in the combustion chamber, it would get burned up (from the burning ether if not from the spark) and you would see a huge cloud of black smoke coming out of the tailpipe. Since you didn't mention any black smoke, I would have to say that you do not have excess fuel, but just the opposite. There is not enough fuel being supplied by the fuel pump for the engine to be able to run. With the mixture being too lean, it doesn't ignite, and thus the fuel remains deposited on the spark plug. It seems like a weak fuel pump or clogged intake filter to me, but like I said, I could be totally wrong. It would be nice to have all the proper diagnostic equipment in order to do a thorough job.
No black smoke. I never would have though a symptom of lean fuel is a wet spark plug. But the way this thing is acting that could be very true and seems to be a more reasonable solution . I've had the filter off the entire time so no lack of air.

I do have a new Rancher 420 pump still in the box I never used. I wonder if I can rig it up just in the meantime while I wait for a new pump to arrive.
You can bet that if you don't have black smoke, you don't have an excess fuel issue.

When I mentioned the filter, I did not mean the air filter. I was referring to the filter on the intake of the fuel pump (I assume it has one).
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