150HPDI power loss

I run twin 2002 150HPDI units which started to missfire at high rpms. I thought this was a filter/fuel problem so changed all three engine fuel filters and changed the transom mounted filter/water separators for Racor Turbine 500s with elements of 2 micron filtration. One engine starts and runs with no problems while the other when started stops after a few seconds. If you keep starting the unit it will run for progressively longer times before it stops. This takes about 30mins to 1hr before it can be put into gear and move off, then over time it will rev to 2400-2800rpms and no further with a bad missfire and if pressed, severe surging as if the ignition was being switched on and off. If the unit is switched off and left left for a few hours it will start and run at low rpms with no problems; however the missfire and surging are still present. I have tested the fuel pressure in the fuel line between the vapour tank and high pressure pump and it runs at a constant 50psi at all times which I understand is correct. I fit new low pressure pumps each year and the engines now have 1450hrs each on them. Any help or suggestions would be appreciated. Thanks

Re: 150HPDI power loss

hello<br /> has the O2 sensor been serviced? and do you have access to a lap top or the yamaha dianostic lamp? all the yamaha sensors are usually testable with an ohm meter but will require test harness's. have you done a compression test? the list of things that could go wrong is long. but start with the basics. test the red plug caps with an ohm meter. do you have any test equipment and are you familiar with using it ?<br />are the engines equiped with the yamaha multi function tachs? are the engines operated in saltwater ?<br /> have you checked the ign timing at idle ?<br />when it does run what is the idle speed in netrual? in gear ? if it was an alarm issue both engines will trigger if either goes into a speed ruduction mode. assuming all rigging is yamaha and working correctly.

Re: 150HPDI power loss

Hello Rodbolt - Thank you for your time. The O2 sensors have never been serviced. How do you do this? as the workshop manual procedure (flame test) appears inconclusive. As of today I do have access to a laptop plus yamahas diagnostic CD and cable - but am unfamiliar with it; although it seems straight forward to use. Unfortunately the weather today stopped me from putting it to use. I have done a compression test and it shows 90psi on all 6 pots. I do have test equipment and am familiar with using it. Engines are equipped with multifunction tachs and are operated in salt water. I have used a spark plug tester on all cylinders and various rpms and everything seems fine. The idle speed in neutral is between 600 -700rpm. The same when in gear after an initial surge. No alarms sound and the other unit gives full power at all times. All rigging is yamaha. Once again, thanks for your interest.

Re: 150HPDI power loss

ok were not dealing with an alarm triggered. compression is good.<br /> have you tested the red plug caps? unscrew them and test, should be about 5Kohms. hook up the laptop. go to engine monitor. if it has a code set it will tell you when the program opens. do not erase stored codes at this time. the best test for the O2 sensor is to attach the test harness on the wires going to the ECM, not the heater side. remove the airbox and with the engine in the water and running and warmed up, cover the idle air bypass hole with your finger, the readings should climb to .8v or so. remove the finger and it should drop. at a warm idle the voltage should constantly scale between .35 and about .65 V. also a fuel system service is in order. test the low pressure fuel pumps for bad diaphams. I reccomend replacing them every three years. and on to the vapor seperator. there is a filter on the high pressure pump that needs periodic service. its a pain to get to but nessasary sometimes. <br /> your spot on about the flame test for the O2 sensor. its about as useful as a teat on a boar hog. dont use it.<br />try to acess the system with the laptop and let me know what codes,if any , are set.<br /> my findings with the laptop is its a quick test to find what is not wrong so I can move on to what is.<br /> also while testing borrow the TPS harness. place the voltmeter on the 5VDC refernce wire, its orange in the engine harness and red on the test harness. make sure it stays at or near 5VDC at all times.<br /> I just repaired an 01 175 that has had a pulser coil and ECM replacement and still would not run. wouldstart and die when the key was released from start to run.3 other dealers gave up and a friend that is a dealer called me. took me 38 min to find the problem . the laptop can do some static tests on the high pressure injectors to insure they are capeable of working. usually its something in the basics.<br /> dont let all the high tech stuff fake you out. also tell me what the ign timing does as your moving the engine RPM. if it locks at 7*BTDC you have a sensor problem somplace and the ign is defaulting.

Re: 150HPDI power loss

Hello Rodbolt<br />I have tested the red plug caps and they are within spec. Tried to hook up the laptop and got error message about a problem with the cable, are you aware of problems with USB diagnostics and Windows 98? Have obtained another laptop with Windows XP installed and will try that tomorrow if possible. Where is the filter on the high pressure pump? Can't see this on the parts diagrams. Thanks again.

Re: 150HPDI power loss

hello<br /> the filter is on the bottom of the pump. you have to remove the VST from the block and remove the phillips headed screws and seperate the top from the tank to access them. if not bad they can be cleaned. the diagnostic lamp can be used on the HPDI as well as the laptop for code checking. also while the engine is running poorly take a voltage reading from the orange TPS enigine harness wire to ground. do this with the TPS test adapter. make sure the sensor 5v reference stays between 4.75 and 5.75V.

Re: 150HPDI power loss

Hello Rodbolt... Sorry for the silence.. I was called away for a few days. Managed to get the diagnostics to run and all the sensors show normal. The diagnostic record only shows battery voltage at 701 hrs and atmospheric pressure sensor at 237 hrs. Total hrs shown: 1401 as oppossed to 1450 on the tacho. Why? I did the static tests on the injectors, spark plugs etc. - all show normal. Got confused by the filter in the high pressure pump, Yamaha call the belt driven pump high pressure and the VST pump medium pressure on HPDI units. On EFI units I believe the VST pump is called high pressure so yes, I have put the new filter on the base of the electric pump plus new diaphragm pumps. I understand there was a filter fitted to the belt driven pump but it was removed in later units because it caused 'problems'. I do not know what model year this occurred in. So, as you rightly say its back to basics. Any thoughts? Thanks again in advance.

Re: 150HPDI power loss

how old are your spark plugs. what brand? have a yamaha dealer run your model/serial number for any required updates. what is the cca rating of your batteries. how are the battery cable/comnnections? have you checked your tps voltages?

Re: 150HPDI power loss

hello<br /> test all the basics. insure the spark plugs are correct. if the computer shows all is normal its going to be either somethiong the computer does not monitor,or an in range sensor failure. your also going to have to run the engine at the RPM its missing and look at the data. the fuel pulse with information may be helpful. sometimes the ECM will try to correct a running problem and not set a code. the above referenced 175 ended up with 2 problems. the first was the splice on the key on 12v yellow wire about a ft down from the main connector. its a cheesy splice and when it fails will turn off the ECM. the ECM will see it as a shut down and wont set a code. the second problem was a failure of the harness between the driver and the ECM. some of the other more minor problems were previous tech induced.<br /> I got the motor after 3 other dealers had quit. its running now. we wont go into hours and methods. suffice it to say it was a time consuming learning curve that showed up the many defects in the service manual,especially the wiring diagram. mostly the lap top will only ID what is not wrong. takes a long effort with a multimeter and a knowledge of what is going on to find some of the problems. test the pulser coil outputs with a peak reading volt meter and the test harness. once you verify the basics as being good, all sensors are working and the connection for the power feed at the starter is working its time to chase the harness.

Re: 150HPDI power loss

i love my boat in a box

Re: 150HPDI power loss

boat in a box wont find main engine harness problems nor problems with the ECM to driver harness nor pulser coil to ECM harness. all have failed on several HPDI motors. its the cheese bone splice they use. its not water tight and the black tape will allow water in and not back out. it sets up a failure. I have had some fail in less than 9 months of use. but before hunting any spices in the engine harness check all other problems sorces. and keep a DVM on the 5V refernce for the TPS. if you lose the 5V reference while trimming or especially while toggling the manual oil tank switch you may have a harness issue.<br />but its a process of elimination now. the laptop told you what was not broke so dont chase that rabbit.