I have been having issues where I go to start my Force 800 and when I turn the key to start I get nothing.  If I remove the starter relay and replace it after a short period, it starts first time.  I only get the issue every couple of weeks or so. 

The battery is fully charged
Tank if full.
The dash lights up and the fuel pumps primes

When I went to the dealer they replaced the relay and said that should solve the issue.  It did not and now is out of warranty.  Anyone have any idea what the problem could be, and is anyone having the same issue?

Thanks

Sounds like the relay contacts are making intermintent contact with the relay receptacle.  Try spraying contact cleaner into the receptacle.

[2015 Z Force 800 53/Trail EPS]

I will assume you don't hear any clicking at all when you turn the key to the starter position so we will start with the relays. There are four relays and two switches involved in starter operation. First, the one with the battery and starter cables going to it, although CFM calls it a relay as it's load rating exceeds 20 amps we in the US call it a solenoid. I assume this is the one replaced and is obviously not the problem and is the last thing before the starter. Before that there AUX starter relays 1&2. Then you have the interlock or brake relay. Let's talk about it for a moment. This interlock prevents the starter AUX relay #2(as I recall) from getting power unless it's ground triggered coil is grounded through the gear selector switch...which just provides grounds for the lights in the dash and itself. It will be closed IF the Neutral, Park or Brake light is on. So when this happens, is the Neutral light or Park light ON? and if not and you have it in a gear, have you tried it with the brake depressed enough for the brake light to be on? And are the brake lights working? Try each. It is not common for this relay to fail but it is common for the gear selector to stop grounding which stops the indicator lights from coming on and the interlock from working. Now the next most common issues with CFM is the ignition switch and kill switch. The kill switch like all other rockers are not water proof and will get water in them and corrode. But the same circuit that sends power to starter position on the key switch also sends power to the fuel pump so you say you hear it prime. This would tell me that kill switch is OK...but never rule out a Chinese electrical part. The other thing that has been an issue in some had been the ignition switch itself going bad. Their life cycle is less then a third of others so I would think about it as well. OK, lets talk about some simple stuff like grounding. All the grounds go to the engine case. If for some reason one chassis ground is left off or gets broken, some things will and won't work normally so check those. On my 2015 they all are front side of the CVT cover.

In my opinion, if the brake/interlock system is function correctly and the grounds are all OK, then I would be looking at the key switch or one of the AUX relays. IF I was to hear a click when I turned the starter to the start position I would look ate the battery, all cables and a possible locking starter or one with a burnt commutator.   

Thanks you both for responding Correct, no clicking.  Thanks for all the information.  I will check what you have said when I am up at the cottage this weekend.  My wife and son inform me there have been no issues since I last pulled and put back the smaller of the 2 aux starter relays.  I just find it strange it starts fine once I remove the AUX starter relay for a few minutes?