Help Diagnose S2R that wouldn't and then would start.

Jonathan · March 29, 2015, 01:02:59 PM

Yesterday I rode my S2R 800 to the beach, about 70 minutes. The last ten was congested beach traffic. The bike maybe got up to 200 degrees but no more. After I stopped and had lunch with a pal I got back on the bike and got 5 minutes down the road when it died at a stop light. I check everything, made sure I didn't hit the switch etc. the bike wouldn't start. I pushed it to a garage, went for beers and waited for my wife to pick me up. The bike would tune over, it just wouldn't start. I tried to start it multiple times over the next 4-5 hours. This morning I drove back to the beach with a trailer and when I got there the bike started right up. It's kinda hard to diagnose a working bike. Anyone had this happen or have any ideas? I'm sorta nervous about taking a longer ride again.

The bike has no mods and only about 5000 miles. It's up on all services.

Jonathan · March 30, 2015, 04:29:09 PM

So I've had a chance to play with the bike. It's starting, but dies with any amount of throttle input. I also don't hear the fuel pump priming. Could the pump be almost dead and only providing enough fuel for idle?

ducpainter · March 30, 2015, 04:39:44 PM

What year bike?

It might need a fuel filter. Has it ever been changed?

Probably wouldn't start if the pump wasn't priming.

DarkMonster620 · March 30, 2015, 04:40:04 PM

Ok, key ON = no pump? But starts?

Have you ever replaced the fuel filter? A hose could be ruptured . . . Presure regulator could be "kapput" . . . Too many variables to think . . . TPS could be out of spec or damaged . . . Just thinking of ALL the issues I have faced . . . If it were the fuel pump it wouldnt start and idle . . . If if it idles and dies when you open it or give gas, that pulls me towards the fuel presure regulator . . . which I dont remember if you can replace on thia type of flange . ..
As of now, it's the most I can think of . . . of course, it could be something small . . .

Jonathan · March 30, 2015, 05:01:29 PM

Yes, it starts. I don't hear the usual pump sounds when the key is turned. Odd. It will only idle. I don't think the filter has been changed. The performance didn't decline, it just stopped.

DarkMonster620 · March 30, 2015, 05:56:37 PM

Quote from: Jonathan on March 30, 2015, 05:01:29 PM
Yes, it starts. I don't hear the usual pump sounds when the key is turned. Odd. It will only idle. I don't think the filter has been changed. The performance didn't decline, it just stopped.

OK, start by replacing the fuel filter and flange O-ring . .. while you're in there, check the hoses, if replacement is needed, replace with 30R10 hose, submersible/ethanol resistant and the clamps . . . also get the Orings for the quick releases, and lightly grease them before installing . . .

If you have a dealer close by you will be able to get the filter and flange oring . . . if you prefer to get the complete quick disconnects they should not be more than $40 for both . .. clamps, get them at the hardware store

Howie · March 30, 2015, 09:04:08 PM

If the fuel pump does not prime I'm thinking the fuel injection relay. Since the problem is intermittent diagnosis is difficult. Two easy ways. Replace relay and cross fingers or make a jumper wire. When the bike doesn't start jump from terminal 30 to terminal 87 after removing the relay. Bike starts? Relay bad.

brad black · March 31, 2015, 01:34:50 AM

check the rotation sensor and gap.

then check the fuel pressure. that will tell you if it's a fuel problem.

i wouldn't just start replacing stuff.

Yogi · March 31, 2015, 02:39:34 AM

+1 What Brad says.
I have had similar only on cars where the car was fine got hot then refused to start. Let it cool down fired up straight away like nothing had been wrong. Turned out it was a faulty cam sensor. If I poured cold water over it when it was hot and refusing to start it would fire up again. Obviously you don't have a cam sensor but you will have some other way of getting a timing signal, sorry not familiar with your bike.

Jonathan · March 31, 2015, 03:38:34 PM

I did start replacing stuff. It did have the original fuel filter from 2005 (I bought it last year with 480 miles) so I'm changing out the filter and orings because it's a good time to do that anyway and I need to stop putting that off.

I'll knock out the other suggestions when the tank is back together. The hoses and fuel line look good as does the pump.

This morning the engine started and ran without a load through the rpm range but this afternoon it would only idle and not rev above 2500rpm.

Thanks for the replies.

Jonathan · April 13, 2015, 05:51:56 PM

Update. I think I have this fixed. I tracked it down to a lose connection in the fuel pump flange. I scraped out the old epoxy, resoldered the connections and repotted with new JB Weld. Everything works great and the fuel level sensor is back Working too after re-soldering it's lead. The two weeks of down time even shrank the tank some.

koko64 · April 13, 2015, 07:25:32 PM

Good news. Glad you sorted it. A few people here have gone through this with the same solution.

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Help Diagnose S2R that wouldn't and then would start.