1999 sugarsand tango

[Kimber]

We have cleaned the carbs, replaced the spark plugs, drained old gas, sea foamed and new gas. Can get it to fire and start when on trailer and hose hooked up.
Take to water and not able to get it to start without starting fluid. Once started she goes like a champ. If you shut it off and try to start again it won't start.
This has a 175hp inboard. The jets have been placed back to manufacturer specs.

Any and all ideas welcome

 

[biffdotorg]

Its actually the 175hp Mercury sportjet correct? Not an inboard?

 

[biffdotorg]

I will make an assumption that it is the Mercury SportJet. If so, these engines are truly finicky when it comes to power. A good battery with full charge is always necessary. Next would be to find a service manual and check all head temp sensors. I do believe the 175hp is similar to the 200/240/250 as they had head temp sensors that could fail and would cause issues like you are experiencing.

There are plenty of things to check, but you are going down the right road. Fuel, Air, Spark. Get a service manual if possible.

Good luck,

 

[Kimber]

Yes, it is the 175hp sportjet. We have the manual and it does not have anything listed in it similar to this issue.

 

[biffdotorg]

Find the location of any temp sensors, specifically head temp sensors. It can cause the issue, but it won't be the only potential cause. Lots of variables with a carbed engine, so those sensors may not even exist with an non-efi version of the old SportJet.

Sorry to have lead you astray.

 

[Kimber]

thank you

 

[Bilmon]

enrichment valve? No experience with the carb sportjets, just a wild guess http://www.boatinfo.no/lib/mercury/manuals/175xr_sportjet.html#/138

 

[Kimber]

Thank you. Great manual. I am trying a few things this weekend and will post results on if they work or not.

 

[Bilmon]

I know @biffdotorg touched on it earlier and I don't know if it applies to the 175 but with the injected motors batt. voltage is critical, if voltage drops below I think 11 volts it will crank but not run. I have had my son's 240 where it would start on trailer fine but put in water and the added drag would cause the starter to pull more juice and it would not start even though it was cranking fairly well, had him replace the batt and all was well. Again I don't know if the 175 is that touchy, my 240 has a lot more electronics

 

[Kimber]

TY @Bilmon . That sound definately like what is happening here, once in water will crank but not start unless you shoot it with starting fluid. then runs like a champ until you shut it off and then it won't start again.