300 HPDI won't idle

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perryk123

Cadet
Joined
Apr 24, 2009
Messages
21
Runs kinda rough on the garden hose in gear at idle. Will accelerate to WOT and act ok, but when you bring it back to idle, it just dies. In the water it wont idle at all, had to rev it up to get it in gear and it will run wide open, but as you slow down close to and idle, she dies and will not restart for a few hrs.

drained fuel, replaced 10 mic filter

opened and cleaned vst (was very clean inside), replaced filter, fuel lines, and diaphragm pumps, check psi on vst all good 50 psi.

tried running on 5gal shop fuel tank same problem

YDS not showing anything unusual

cleaned air intake found some dirt and gunk stuck in there

replaced battery just to be sure it was not a voltage issue

compression is 120 psi on all cyl

checked spark with an in line spark tester, and all cyl are firing

was wondering if its a coil or injector issue, but wouldn't that make it act up in higher rpms rather than idle range???


vz300 tlrc 2004 model on a Skeeter bass boat w/40HRS

any help would be greatly appreciated.

We dont have a Yamaha dealer that really knows them around here, just part changers
 
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yellowfin31

Recruit
Joined
Feb 12, 2012
Messages
1
Re: 300 HPDI won't idle

I had the exact same problem 3 weeks ago with my starboard engine!!! I had my mechanic hook a computer to it, and he gave it a "clean bill of health". I was hesitant to go offshore grouper fishing with the engine not wanting to idle, but it was running great in gear...so I went. All day, both engines ran great WOT, no fluctuation on RPMs. And then it happened...I was running 5500 RPMs when the starboard engine blew!!! Later, I found out that the number 1 and 2 cylinders were gone. They said because those injectors were clogged. I would think the computer would have pick that up from the beginning, but it didn't. Those engines cannot run lean!!! I would definitely have someone pull and rebuilt all injectors before using the boat. I hope this helps you with your situation.
 
9

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,127
Re: 300 HPDI won't idle

If the high pressure rail has pressure in spec at all RPMs and there is good spark on all cylinders and timing is doing its thing then you are left with a injector problem in my opinion.
Those motors run on the lean side already, so any restriction in injector screens and you toast pistons.
Computer only sees high pressure on rail and decides how long to open the injector. it cannot see the injector has a restriction

I agree do not run a motor to see if it will get better, fix it
 
L

Ldavidgrover

Petty Officer 2nd Class
Joined
Feb 22, 2012
Messages
197
Re: 300 HPDI won't idle

If your saying you motor is a 2004 and only have 40 hr on it. Low hours and just as bad as a ton of hours Pull the vst and inspect. Chances are you have gunk that is clogging the filter on the high pressure pump and send you injector out for service. Look for water damage
 
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yamatech43

Petty Officer 2nd Class
Joined
Feb 9, 2011
Messages
188
Re: 300 HPDI won't idle

ok, looks a little simpler to me, but let's see....I would first have the linkage set and the TPS checked by a CERTIFIED veteran YAMAHA technician. The TPS will not send a code and If you live in some truly remote outback place that doesn't have a trained Yamaha tech you can be there while hooked to YDS and make SURE the fully closed throttle position give a TPS voltage of .60 volts(+ or - .15 volts). This must be attainable while the linkage is in place, that is by putting the boat in nueutral with the controls not by disconnecting motor from boat. I would do this first....and everything you've done till now would be to cure upper RPM problems, not idle....
 
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