Optimax studdering

[prodjsaig]

My 150 optimax won't go WOT and stutters drops from 3400 rpm to 3100 then picks up again. Sounds like a fuel delivery problem. All my coils and coil drivers check ok on the multimeter and the only alarm I get is engine guardian active due to certain conditions. Engine power limited.

I'm replacing the fuel pump diaphragm kit after the low pressure pump. Also replacing the fuel regulator that has a Crack on one side. Should still work but maybe it cracked and failed. I'll start it up tomorrow and try to get a reading of fuel and air pressure from the shraeder valves.

 

[prodjsaig]

Think I found the problem. I just replaced number 6 air injector due to too little resistance. Now I see this alarm I missed number 5 has too much resistance. I have an extra injector looks like I'll be putting it in tomorrow. Fml one thing after the other.

I rigged my trailer lights up and the next day I noticed my license plate fell off. Can barely stay ahead of the game. Fun times owning a boat I found a bottle of gibsons finest whiskey in the garage tho

 

[DuroBoat]

Lol yup that’s owning a boat.

 

[ryanb]

Your symptoms sounds just like the low pressure fuel pump. I had a 200 optimax sportjet on my riverboat before and the low pressure fuel pump was a known weak point. When mine went I had the exact same symptoms.

 

[Pursuit Of Hogs]

Check your VST filter, my yamaha 250 last year would cut out randomly with the same symtoms, I couldn't get a new filter in time due to covid but simply took the filter out, gave it a clean and never had the issue again. Spent so much time replacing and checking everything to do with fuel and it was a wipe of a filter the size of a loonie that fixed everything!

 

[prodjsaig]

Your symptoms sounds just like the low pressure fuel pump. I had a 200 optimax sportjet on my riverboat before and the low pressure fuel pump was a known weak point. When mine went I had the exact same symptoms.

I replaced the original merc low pressure pump with an ebay chinese one. Maybe it does have the flow? My coil driver on 5 and 6 was .7 ohm below .99 ohm spec so the fuse was blowing either from that or the mercury low pressure pump. Ill bench the original pump and maybe put it back on. Replacing the low pressure crank diaphragm with the kit they have in stock as well.

 

[prodjsaig]

Check your VST filter, my yamaha 250 last year would cut out randomly with the same symtoms, I couldn't get a new filter in time due to covid but simply took the filter out, gave it a clean and never had the issue again. Spent so much time replacing and checking everything to do with fuel and it was a wipe of a filter the size of a loonie that fixed everything!

Thanks for that ill pop it I have the top seal for the hp pump maybe that's cracked but the gasket for the vst is $230. Hopefully I can reuse it.

 

[prodjsaig]

I opened the vst clean as a whistle there is a screen on the hp pump inlet. The diaphragm pump is behind the vst. I'll replace that next. Original lp fuel pump works np. So the failed injector took out the coil driver which blew the ecu, injector fuel pump fuse.

Also replacing the fuel regulator and tracker.

 

[Blen]

You need to find out what is putting it into guardian mode. Once in guardian your RPM will be limited to around 3000 /3500 to protect the engine. There is a finite number of sensors that will do this such as Low oil lvl or oil inj pump fail. Look in your manual for a list that will put you into guardian. Guardian will signal the ECU to interrupt spark to lower RPM the motor will run really rough and sound like poop. I think Smartcraft also list what will put you to guardian don't think a bad coil or low fuel pressure is on the list.

 

[prodjsaig]

You need to find out what is putting it into guardian mode. Once in guardian your RPM will be limited to around 3000 /3500 to protect the engine. There is a finite number of sensors that will do this such as Low oil lvl or oil inj pump fail. Look in your manual for a list that will put you into guardian. Guardian will signal the ECU to interrupt spark to lower RPM the motor will run really rough and sound like poop. I think Smartcraft also list what will put you to guardian don't think a bad coil or low fuel pressure is on the list.

My new oil tank the sensor doesn't work will that cause it?

 

[Blen]

yes

 

[Blen]

The little tk on the motor that is not the large 3 gallon one.

 

[Blen]

Hi-temp, over-rev I think also low volts. I tried to attach a list for you but was unsuccessful just do a Google search.

 

[prodjsaig]

Sweet I'll jump the tank tomorrow see if that solves it I still have the oil tank I can put on.

 

[prodjsaig]

Tank sensor works I took a magnet and multimeter when there is level i get a reading when the magnet is pulled away no contact. This means the wire on my outboard is damaged. My cowl ripped the port coolant sensor clean off as it was hanging loose. I ordered two new coolant sensors now I have to find the wire for the ecu for the oil level sensor and run new wire. I have solder seal connectors so Ill just wire it in.

This explains why it trolls fine runs good reaches only 4500 rpm. max rpm is 5500. so guardian was screwing me around. fuel pump diaphragm new coolant sensor and new tracker and fuel regulator all going in. Ill get it going just a pia.

 

[prodjsaig]

The coolant sensor fixed it much thanks all. I will stay one step ahead of this peppy optimax. 740 hours 2002. I have a spare air injector ill get a spare coil and fuel injector for the shelf. Been running her hard from all the talk you run these things full out. I'll do 50% full bore rest cruise.

Every 300 hours you must pull the rails all injectors and have them ultrasonic cleaned. Don't ask me how I know. Engine cut out and bashed into some rocks. Kicker was brand new and not ready to go depended on the opti. They are finicky af.