I am looking for some guidance on a hot start issue...I have no mechanical experience or talent...I have a 2001 150 HPDI that fires up when it is cold very nicely. However, after it has been running for awhile and then shut down. It will turn over but takes quite some time to fire up. It then smokes for about 20 seconds or so and eventually starts to run smoothly. It acts like it has been flooded or something. I changed the plugs and fuel filter to no avail. The engine has 142 hrs. Anybody have any ideas? Thanks in advance.
Sounds like you have some sort of fuel system issue.
I would start with a fuel rail presure check at the medium pressure valve,test for compression and spark. test the plug cap resistance and if all look good have a look at it while cranking with the laptop.
also test the lift pumps for leakage,if a diaphram is leaking it can create an excessivly rich fuel mix at hot restart.
What is the maint history on your motor?
Low pressure fuel pumps, VST filter, pressure reg screen, medium pressure filter, inline check valve removed, thermostats, water pump, tech bulletins, etc?
the Z motors are run at the ragged edge of lean to start with and wont tolerate much of anything going wrong and they will detonate a piston.
That is a great start CousinAbe; I took the boat to an authorized Yamaha repair dealer. They want me to spend about $1K to do all the maintenance which is replacing the items suggested but there is no guarantee that the maintenance will fix the problem. I don't mind spending the money but I certainly want to make sure the problem is fixed. Yes, I do trust the repair dealer as they have done right by me in the past. They are concerned that we wont be able to get an accurate test because our water temps are still in the thirties up here...
ask to see some actual training certificates, if they dont have at least fuel and electrical training certificates on the wall take a mulligan and find another dealer.
water temps are ABSOLUTLY IRRELAVENT.
first clue your dealing with monkeys.
does your car start flawlessly every day regaurdless of ambient temps?
your HPDI, if it aint broke, will do the same.
thats why it has coolent temp sensor feed back and ambient (intake) air temp sensors and can adjust.
it also has a barometric pressure sensor to aid in altitude corrections.
the maint must be done however I dont think its gonna fix your issue.
that motor will start and run fine with or without the high pressure belt even being attached to the high pressure pump. top end wont work but they will actually start and run low speed just fine without the high pressure pump.
the computer may or may not display a code, it will however tell a TRAINED tech what may be going on.
I took the engine to a second Authorized Yamaha Repair shop. The problem has been resolved. The dealer first popped it on the computer and thought it was a shift issue. He then called Yamaha who told him to check the VST. One of the needles in the VST was very worn (he said) and replaced it. That did not seem to do the trick. He then pressure tested two pumps (might be lift pumps?) and the diaphragms both leaked. He replaced those two pumps and the problem is now solved. I also had the filters replaced in the engine, all new plugs, and the shift thing that was intermittently acting up. All told I spent (with tax) $876. The engine runs better than ever.
Thank you to those that made suggestions. Send a PM, I have a fishing trip on Oneida Lake for you.
your second shop is staffed with monkeys too.
to check for a leaking VST needle/seat( only one) you simply dissconect the VST vent line from the intake manifold and squeeze the primer bulb, if fuel wont flow from the vent tube the needle is fine.
second test is simply pump up the primer to see if it will stay hard or go soft with steady pressure, if it goes soft it either has a leak or a diaphram in the pump is blown.
above checks can be made simultaneously and take about 5 min.