RX DI sputtering at high end, eventually won't start

[DJDOttawa]

Hi All....my 2003 RX DI has been running great. This year needed a new battery and rectifier.

A few hours in it started to run rough at top speed. Quit all of a sudden at top speed. Got progressively worse, quickly. Finally it wouldnt even start. Turns over. After it sits for a couple hours, it starts and runs for 2 minutes. Then gets really rough and then wont start again.

Voltage is good at cranking. Ran great for 10-12 hours so far this season. Not throwing any Maintenance codes.

Any suggestions?

 

[mikidymac]

What is your compression?

 

[DJDOttawa]

I am getting 136-138 for both sides

 

[mikidymac]

That should be fine. Your next step on a DI is to check fuel pressure. It has to be dead on at 107 psi.

 

[DJDOttawa]

Ok thanks Mikidymac. Checking that next. Seems weird that it quits at top end and then gets progressively worse, then starts again after sitting for a few hours. I would think filters are clogged or not clogged, or the fuel pump would just give up.

 

[Boyd12]

how do the plugs look, light, dark?

 

[DJDOttawa]

Boyd12 the plugs looked ok. Dark but not oily or wet

 

[jhjesse]

When you check your fuel pressure go ahead and replace the fuel filter.
Remove the fuel pump cleane it really good and replace the internal fuel filters. They are most likely clogged preventing good constant fuel flow.

Airtex FS242 and FS220
I would cut the very expensive canister filter off the hose and replace with a wix 33095 along with two heavy duty stainless steel hose clamps.

 

[Boyd12]

most fuel pumps just fail. not the Di. I had one go bad over a span of several months. it would check it to be safe. good luck.

 

[Sportster-2001-951C-Stock]

IMO, new voltage regulators are suspect till proven innocent. Not saying your fuel pump is good b/c that's also a common issue.