need help 200 hpdi does not idle good

[bayranger1]

Yamaha hpdi is shutting off when going to neutral from in gear and sometimes when at idle. Changed plugs did not help a lot. A loss of rpm on top end.

[ncdrew03]

sounds like a fuel problem. mine has been a pain as well. lucky to hit 5400 these days after it used to rev 5800 consistently. mechanic is stumped.

[SIM]

bayranger1 - 5/30/2007 4:31 PM Yamaha hpdi is shutting off when going to neutral from in gear and sometimes when at idle. Changed plugs did not help a lot. A loss of rpm on top end.

If it runs fine otherwise, there is a electrical switch that aides the engine getting out of gear. It actually cuts theignition for a second.It could be bad, stuck or the mechanism that it is mounted to needs to be greased.

Look where the shift cable(under the cowling)attaches to the engine control. Its under that mess of stuff.[img]../images/emoticons/biggrin.gif[/img]

If you had YDS (diagnostic software) you can actually see within that program,that switch connect.............and then disconnect while shifting.

Andy

[pbruce66]

We've had a lot of dirty fuel filters that are not normally changed during routine maintenance, specifically the filter inside the VST (part number 68F-13915-00-00) and the filter right after the VST (part number 60V-24251-01-00). We have now started changing these filters on all HPDIs and OX66s (doesn't have the filter after the VST) annually. There is also a screen inside the regulator section of the VST that may need replacement. Yamaha does not recommend cleaning these screen because the mesh is so fine that cleaning them does not work well. We had a couple of 150 HPDIs that were down about 600-700 RPMs which came back as soon as we replaced those filters.

These filters are often overlooked but are part of the published annual maintenance schedule. You wouldn't know it to look at them but the filters are not cheap (around $60 for the first and $80 for the second), but they solved our loss of RPM problem on at least 6 engines so far this spring.

[SIM]

bayranger1 - 5/30/2007 4:31 PM Yamaha hpdi is shutting off when going to neutral from in gear and sometimes when at idle. Changed plugs did not help a lot. A loss of rpm on top end.

oops!.....I missed that comment at the end. You very well could have multiple problems.

A simple inexpensive fuel pressure gauge can go a long ways in helping diagnosing a possible fuel delivery related issue on all EFI engines. Also trying to diagnose a running issue with an HPDI without at least verifying the ECMsensors ect (via YDS Software)is like trying to shoot skeet with a blind fold on. Ya......you might get lucky.....[img]../images/emoticons/biggrin.gif[/img]

As mentionedVST cleaning is a periodic maintenance item along with the med pressure fuel filter replacement.[img]../images/emoticons/thumbsup.gif[/img]

Andy