Yamaha f 150 hiccups every 35 sec. regardless of RPM

[snorkelbob]

I have a Triumph 215 CC with a 2008 Yamaha f 150 . Problem is that it hiccups every 35 sec.[exactly] regardless of the RPM. From idle to flat out. Any ideas?

 

[glehav]

it might be a gas problem, water in gas.dirty fuel filter, a leak in your fuel line I would start there . hope this helps

 

[FrankCloud]

Could also be caused by a fuel flow problem. What is the condition of your primer bulb, and does it appear to collapse about the time of the skip in the motor. Otherwise, glehav had some good suggestions. Good luck.

 

[Harper]

I don't know.....the way you describe it....EXACTLY every 35 seconds regardless of throttle position or load.....doesn't sound at all like a fuel issue to me. Sounds like something in the engine control system, some sensor that has a timed or sequenced input. I can't for the life of me think of anything that would send at such a long interval, though. Most such things are done many times a second. Sorry I'm not beng much help, but I'm still thinkin'......

 

[Chad@MerrittMarine]

i would have the IAC or MAP sensors checked out

 

[snorkelbob]

Thanks for the reply. I have sat there and squeezed the primer ball and kept it hard and it still hiccups every 35 sec.. I have a 2 micron filter, instead of the factory 10 micron and I just changed it as the problem began. One thing I did change was to start using premium gas, don't know if this can set off a sensor. My friend has a 210 cc and he has used high test for years to lessen the fuel injector clogging problems he went through. The time interval is the really strange thing. I have put 40 hrs.on the motor sense the problem started and nothing has changed ? Any thoughts appreciated.

 

[Harper]

I still think it's something in the engine control system. Get it on a diagnostic computer. Not every problem throws a fault code on the CEL.

 

[snorkelbob]

Thanks Harper, after reading all these replies ,I am eyeballing the YDS diagnostic package, maybe it can point me in the right direction. $62.00 on ebay ,not much of a gamble.

 

[Dipnet]

I think I'd follow Chad's suggestions as that's what he does for a living!

 

[snorkelbob]

Thanks for that Dipnet, Those sensors will be top of my inspection list.

 

[snorkelbob]

Well the f150 has about 50 more hours on it and still hiccups every 35 sec. regardless of RPM. I installed a new Intake pressure sensor [map sensor]and no change. Any ideas? I have the diagnostic software and it shows nothing unusual at idle. Next step see if it can pick something up at speed. A real head scratcher. thanks

 

[mr300s]

VST Filter could be a problem but I agree with Harper seems odd for a fuel problem if it does it exactly at 30 seconds ...

I changed the ones towards the back of the motor that I could see and that didn't do it. It turned out to be the VST which is buried in the engine

Here a is a video this is the 115 however its the same on the 150...https://www.youtube.com/watch?v=gY2RFaahio4

 

[Harper]

Still doin' it, huh? It's a real head-scratcher, all right. In searching the web, I see you've been on other forums looking for input, also with little help. The guy, vihn, who had a 2003 carbed motor, mentioned the CDI. I believe that he was referring not to your ECU but to a capacitive discharge ignition on his carbureted engine. So unfortunately, I would be suggesting that you not rule out having to replace the ECU itself. It seems that something that clocks is causing your problem, and the only thing that I know of that clocks would be the ECU. Of course, before dropping a whole wad of cash on a new unit, I would try like crazy to find a used ECU, or a real good friend who would let you swap the ECU out of his motor to try. Cheapest used ECU that I can find after a short search runs $435.

I do have one other idea, but with the exact 35 second interval that you face, it's a long-shot ... but here goes. Your injected Yammie has two fuel pumps; a low pressure pump that feeds fuel to a vapor separator tank. Inside this little tank, sits your high pressure fuel pump, immersed in fuel. This is the pump that pressurizes the fuel rail for your fuel injectors. If the low pressure pump is weak or damaged, then every so often, the vapor separator tank may get low enough for just a second to cause the high pressure pump to cavitate, causing your hiccup. The low pressure pump's out put would be relative to RPM, as would the regulated fuel volume needed by the high pressure pump, so the hiccup interval might stay very close to the same at all RPMs. I'm not convinced at all by this suggestion.... like I said, a long-shot.

 

[snorkelbob]

Mr300s and Harper, Thanks for your thoughtful and rapid replies. When I bought the boat there were only 93 hrs on the Yamaha. I immediately installed a 2 micron filter, so I think the filter might not be the issue. The whole problem started the day after a tropical storm blew rain sideways, 50mph, into the air intake of my engine. I thought nothing of it until the problem showed up on launch. So there it is water and electronics , fresh water but still. Still have to run with the diagnostics for the final check before putting out the big bucks for a new ECU. Keeping my fingers crossed that a simple fix shows up. Thanks again

 

[Harper]

sBob, even after using your YDS and finding nothing, I think you'd be wise to take it to a competent Yamaha service center for their opinion before dropping the bucks on another ECU. I hate throwing parts, especially expensive parts, at a problem when I'm not sure that the part will solve it.

Those DIY computer diagnostics programs are very useful and good for finding most problems, but sometimes are not quite as comprehensive as the systems used by the factory authorized service centers. They might find something the YDS program wasn't designed to check.

 

[snorkelbob]

Thanks Harper, may have to go that route. The problem is that I am 600 miles from the US, in Baja and the logistics of bringing the boat to a dealer for mucho labor and full cost for parts will have to be factored in to my decision There are some respected mechanics in the area and who knows one may have an ECU for testing purposes. I found a New one for 900.00. I will keep you guys informed of any progress with this head scratcher. Thankyou all for your informed input. Much appreciated.

 

[Harper]

Ah, I see your problem.... but you never know, there seem to be quite few good, well equipped mechanics in other countries. Hope you find a cure soon.