hpdi intermittent starting issue

[skeeter7]

Re: hpdi intermittent starting issue

I looked at my shift cable and it seems to be adjusted properly. Could a dirty o2 sensor be causing hard starts on the water? As far as I know the sensor has around 800 hours on it and has never been cleaned. Also the last time we cleaned the vst the o ring broke and we used some type of sealent to complete the seal. There isn't any fuel leaking through there but could an air leak at the vst cause problems?

 

[jeffersondodson561]

Re: hpdi intermittent starting issue

The O2 sensor only makes ajustments at top end rpms, now if some of that sealent dripped into the VST could have a restriction to the high pressure pump...Don't do that again. I would check the schrader valve at the VST you may have some sealent floating that is covering the medium pressure filter inside you may have to monitor it while you have the problem. Do you have equal distance throw between fwd N and reverse at the control box?

 

[skeeter7]

Re: hpdi intermittent starting issue

Thanks for the continued replies Jeff. I really appreciate it. I have an appointment in two weeks with a really good yamaha tech, but I'd like to do as many inexpensive tasks as I can before then. Especially if I can resolve the issue myself. I did another spark test today on the hose. It's firing on 4 in N and all 6 in gear, just like it should. I'm pretty sure the sealent was dry before we reasembled the vst, but that doesn't necesseraly mean there isn't any in there that may have come free. I'm going to replace it with a new gasket, but I'll check the medium fuel pressure as well. I don't know if the throw is all equal at the control box. I can't remember from when we installed the new cables and it is a major pita to access it. The control box is flush mounted and very difficult to get to. It would be worth checking though. The problem has to be related to being under load. It still cranks everytime on the hose and never right on the water. This makes me believe your shift interupt switch theory. Could a fuel restriction be this sensative to being under load?

 

[jeffersondodson561]

Re: hpdi intermittent starting issue

As a mechanic you want everything to be in the right paramenters before diagnosing something. The electronics operate on the theory knowing that all the mechanical devices on the motor are functioning properly i.e. fuel pressure, proper fuel pressure regulator operation, fuel pump output, VST float level etc. And then you have to factor in the fact of the back pressure of water. So yes a restriction could be the problem or part of a numerous problems. The mechanic should verify all of these things first before attempting to troubleshoot. Here's the problem with way shops operate, most mechanics are trying to race through and meet/beat flat rate time. Something could very well be overlooked. It is the shops responsibility to troubleshoot with you the symptoms, chances are they won't. So it is in your best interest to give them as much information as possible, maybe even write a few paragraphs of what you are noticing. After they determine that their is no problems from the boat side, they can use the shop tools to fix your motor.
Good Luck keep us informed.