175 xr2 engine problems

[Forrest_g]

Hey everyone, I have a 175 xr2 sport jet and it seems to only be firing on 5 cylinders and It will only rev to 4900, iv replaced the coil on the cylinder that’s doesn’t seem to be firing and it is still only revving to 4900, after it wasn’t revving out I swapped the spark plug wires from that cylinder to a different one and ran it for a couple minutes to see if i could chase the problem down to the spark plug wire, but by that time it was starting to get dark so I headed home, will check it all out again after work, any help would be greatly appreciated

 

[—Яiвs>]

Do a full compression test to rule out any internal faults.

 

[Forrest_g]

Will do, have day off tomorrow!! Ended up being busy after work, someone told me I have to disconnect coils when doing a compression test is this true?

 

[—Яiвs>]

Correct. Easiest way is to disconnect the lanyard if equipped.

 

[Forrest_g]

No unfortunately it’s not

 

[Forrest_g]

Correct. Easiest way is to disconnect the lanyard if equipped.

What would be the next easiest way?

 

[—Яiвs>]

Unplug each one

 

[Forrest_g]

Unplug the green wires or the black? Just wanna make sure I do everything correctly

 

[—Яiвs>]

Either or you are just breaking the loop so it can’t ignite any fuel vapor.

 

[Forrest_g]

Alright sorry it took me a couple days but I finally got the compression test done and all seemed to check out what would be my next step?

 

[—Яiвs>]

What are the readings? The coil you put on did you check it for spark? Could be losing the signal to fire. Other then compression and spark you just need fuel so maybe the reeds for that cylinder but I’d lean towards checking the spark.

 

[Forrest_g]

Like 121 on the left side and 116 ish on the right, the hole in question is the bottom left of your facing the rear of the boat, and no I didn’t but it was a brand new coil, I will check that next and post my findings

 

[—Яiвs>]

Is it the triple carb? Possible clogged jet to that cylinder.

 

[Forrest_g]

yes it is a triple carb.

 

[Forrest_g]

any chance you know where i could find a pdf for a service Manuel for this thing? the internet doesn't seem to have one for me! its a 99 sportjet 175xr2 0E368912

 

[—Яiвs>]

I don’t know where to find the Manuel. I’m betting it is the carburetor feeding that cylinder. Each of the carbs only feeds 2 cylinders so very likely the jet to that particular one is clogged with varnish or deposits.

 

[Forrest_g]

alright ill take a look as soon as possible, you don't think the bottom cylinder on the other side would be showing the same symptoms if it was a carb issue? the bottom left plug looks almost new except in the center, it gets black, and the plug almost seems to have raw fuel on it then the other 5 all show signs of being used/ look the same compared to the 6th

 

[—Яiвs>]

If it’s wet with fuel then it’s a spark issue

 

[Forrest_g]

now that i am thinking of it one day when testing, from all the humidity in the air it gummed up my carbs with white muk from the oil mixing with the moisture, i keep a can of carb clean in the boat, sprayed the white stuff out from everywhere i could fired the boat up let it idle for min or so then after getting up on step trying to see if it would die again feathering throttle all of a sudden the boat went right to 5500 rpm on the gauge and it felt like it to, let off cause i wasn't sure if it was about to blow up, it didn't, then i couldn't get it to happen again just the usual 4900, so im thinking maybe your onto something with the carb issue, but the wet plug idk about

 

[Bilmon]

any chance you know where i could find a pdf for a service Manuel for this thing? the internet doesn't seem to have one for me! its a 99 sportjet 175xr2 0E368912

Here's your service manual. Boatinfo - Mercury Service Manual for 175xr SportJet