Mercury optimax shuts down periodically

[wildsteelhead]

I am having trouble with my optimax. It fires up perfect at the dock then usually you can get out of the break water and cruise then it dies flat on its face. I have replaced the antisiphon valve the fuel lines the fuel filters, ignition switch, spark plugs, batteries, primer bulb, checked the relays trim and ignition. had the local shop check it out and they ran it for 5 hours and it never died, then I took it out the very next weekend and it died 8 times in a quarter mile. (every time it dies it fires right back up). Left it in the marina and went back to the shop on Monday and told them to go for a run with me. We had it hooked up to the ddt and fuel and air pressure gauges and when it did die it did not lose air or fuel pressure, also it did not throw a code, and the computer did not die. they called mercury and mercury was very adamant on this grommet on the high pressure pump in the vst, replaced it went halibut fishing and ran for about 5 miles then died, and died a few times after that. on the way back in it died about 9 times. the next day it died about 9 times going out then only 2 times coming back in. I am starting to think that it might be the crank position sensor getting warm or shorting out.
any help would be great.

 

[Haarukka]

Re: Mercury optimax shuts down periodically

Hello from Finland.

I have exactly same problem with my Optimax 90. After shut down it allways starts well.

Yesterday I drove 30 minutes and it shuts down twice. It works perfectly, but it shut down suddenly. It seems to be some kind of eletrical problem (ECU ?).

I have checked every wires and cabless many times. Everything is in perfect condition!

Did you solve your problem or is there anyone who can help us?

Best rgds,

AH

 

[scrat]

Re: Mercury optimax shuts down periodically

Having the same sounding problems with my optimax 190. It shuts down just like the emergency cut off was thrown. starts right back up with no problem. Any one have any ideas?

 

[quicktach]

Re: Mercury optimax shuts down periodically

Sudden repeated stops like you're getting makes me think of an intermittent fuel cut off problem. The fact it starts up right away makes me think it's not an ignition problem. Are your injectors clean ? Are they original injectors ? Getting any overheat signs .... injectors lean ?

 

[Haarukka]

Re: Mercury optimax shuts down periodically

Hello

I think too that it is fuel problem. I already tested an other ECU, but same problem with engine.

When I drive quietly with 4000 rpms, it works, but when I raise rpms over 5000, it stops.

Injectors are original, never checked. No overheat signs.

I think that engine is too lean (not enough rich fuel mixture).

Is it possible to adjust mixture?

Any other ideas?

Ari

 

[scrat]

Re: Mercury optimax shuts down periodically

Sudden repeated stops like you're getting makes me think of an intermittent fuel cut off problem. The fact it starts up right away makes me think it's not an ignition problem. Are your injectors clean ? Are they original injectors ? Getting any overheat signs .... injectors lean ?

Injectors cleaned in service at beginning of summer. No overheat alarms on mine.

 

[schematic]

Re: Mercury optimax shuts down periodically

Gents. Optimax is a fairly complex system and requires operational understanding and troubleshooting skills to properly diagnose. Although several people are complaining of shut-down, the underlying cause could be different.

You must be capable of testing and monitoring:
-fuel pressure
-air pressure
-TPS voltage and linearity
-Temp sensor voltage
-system voltage
-ignition components
-stored codes
-computer outputs

If not, you will likely replace expensive parts with "roll of the dice" results.
Sometimes you just gotta take it in......IMHO

 

[scrat]

Re: Mercury optimax shuts down periodically

I'm just going to hope to deal with it for the next week. Hopefully I won't get stuck 10 miles out. End of next week it'll be shop time for the ol girl I guess. 'll mark the exact time it hiccups.. might help them in locating and error codes in the system??

 

[sirstriker]

2000 merc 150 optimax temp light comes on several times ( each time dropping motor to idle )when I take it out over night , but the second day it doesn't come on . I changed the pump and both thermostats . Any help !

 

[jamescerano5]

Re: Mercury optimax shuts down periodically

Hello from Finland.

I have exactly same problem with my Optimax 90. After shut down it allways starts well.

Yesterday I drove 30 minutes and it shuts down twice. It works perfectly, but it shut down suddenly. It seems to be some kind of eletrical problem (ECU ?).

I have checked every wires and cabless many times. Everything is in perfect condition!

Did you solve your problem or is there anyone who can help us?

Best rgds,

AH

Has anyone ever figured this out? I had the same issue for two seasons. I have noted so many similar complaints but not one solution... I'm about to give up and repower with a Suzuki.