PM9 - Sportjet 90 problem...running on 2 cylinders

[PM9]

Hello all,

I've spent a couple of hours on this forum and found a lot of very interesting information...hopefully, I can get an answer to my question as like with most of you, I found there are not too many mechanics out there that know anything about these motors...even certified Mercury dealers..!!!

Here's the deal, I'm not a mechanic but I am dealing with a friend that know's his way around boats.

I just recently made the acquisition of a Sea-Ray Barracuda 1994 with a Sportjet 90 engine. This boat hadn't been running for 2 years.

After making the usual tune-up and inspection (check the impeller, clean all the carbs up, check battery, lubricate linkage and changed all 3 plugs to new ones), we checked the compression...140psi on #1, 145psi on #2 and 145psi on #3...all good so far!

Time to bring it in the water and there is where we found a problem. The boat had a tough time coming out of water and once it finally did (after having my friend sit at the front end), it would only get up to 20 mph at top speed. My friend took a look at the motor and the spark plug from the bottom cylinder was wet indicating this cylinder was not working, hence the motor was running only on 2 cylinders.

Here's my question, what's the next step and is this something one of you have seen with this motor??

Serial number is # 0E034610

Thanks in advance,
Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

First of all verify a no spark condition on #3 , the Sport jets are jetted rich on #3 due to engine heat . I really think you have a fuel problem with the carb vents/ stuck float/ bad needle and seat .. But Post up a spark test on #3 and we can get started.

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Hello Kend301 and thanks for helping,

We have indeed sparks on all 3 plugs...we were also thinking bad needle but before opening up the entire front end, I wanted to check if it could be anything else.

Let me know,
Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

I will post detailed info later but for now , run a fuel pressure test by taking the main fuel line off the lower carb , put the fuel line in a glass jar and crank the engine , It should NOT pulse just flow , do that an then pull the carbs as they are clogged without a doubt if the fuel pulsed you need to pull the fuel pump too .

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Thanks again...should I do this before checking the reed valve?

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Yes once you pull the carbs , post what you find , I really think you are going to find a bunch of varnish muck in the bowls from the vents which must be clear . If the carbs are clean then pull the intake and reed valves for inspection.

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

OK...Carbs are all good...bowls, needles, etc, everything was clean. The fuel flows through without any problems.

I guess the next step is to inspect the reed valves?

Thanks again,
Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Be sure the vents on the carbs are clean and flowing air good , And yes pull the intake and the reed valves and post up some pics of them .

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Hello kend301 (and others),

The plot thickens....

After removing the head (reed valves are all clean) and dissassembling the fuel pump (which is also in perfect working condition)...it appears the pistons have been changed by the previous owner.

At first glance, all 3 pistons have none of the 2 port holes that seem to be present on the original 700-819005A10 pistons. I suspect the previous owner could not find the original pistons so he simply had some wiseco jobers (with no port holes) put in.

Here's my question now, in your experience, would the lack of these port holes on the pistons bring the problem that I'm having?

As a second question, where can I find these original pistons?

I also suspect that some of the holes have been honed so I will most probably need some standard's and .030's.

Thanks again for your time...

Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

kinda confused about you are talking about , PLEASE post up pics , your first post showed great compression readings , I doubt a piston is the answer . I can find part numbers for you but would much rather find your problem with the motor

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

just to be clear...please see both pics.

The pic called 700-834800A6 is the original piston on my model Sportjet...you can see both port holes on the picture.

The pic called Wiseco 3151PS is the piston that is currently in my motor. See how the port holes are not present. Only the pin hole is there.

I know for a fact that the pistons were replaced by the previous owner as he left me with one of the defective original (in a box with several parts)...which this piston has the 2 port holes.

My question is...if you were to change the pistons for some jobers without the 2 port holes, would it have an impact on the motor? If so, I may have found my problem.

Thanks again,
Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

You need to call me , PM'd you my cell number

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

It was great to talk to you , Here is what you need to check ,
1 Ignition system , do you have 2 wires that bolt on to the coils ?
2 Wires from under the flywheel , do you have a green/white and white/green ?
3 Are any flywheel magnets loose ?
4 OHM test trigger , use white/black as ground , ohm purple, white and brown separately and post ohm readings
5 pull the # 3 coil and take it out of the rubber boot and see if the magnet is broken.

 

[dmball]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

just to be clear...please see both pics.

The pic called 700-834800A6 is the original piston on my model Sportjet...you can see both port holes on the picture.

The pic called Wiseco 3151PS is the piston that is currently in my motor. See how the port holes are not present. Only the pin hole is there.

I know for a fact that the pistons were replaced by the previous owner as he left me with one of the defective original (in a box with several parts)...which this piston has the 2 port holes.

My question is...if you were to change the pistons for some jobers without the 2 port holes, would it have an impact on the motor? If so, I may have found my problem.

Thanks again,
Pat

Did you figure out if those pistons are fine or not? I am getting a rebuild kit next weekend and assume they will be the same pistons

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

@ dmball: At this point, with the help of kend301, we may have found out that the problem doesn't lie with the pistons not having the port holes but perhaps with the stator...more to come soon. That said, I did find a source for these piston kits and from the pictures, they look like the originals (with port holes) unlike the Wiseco one's...http://www.teleflexmarine.com/

@kend301: It was great talking with you yesterday...thanks for all your help, it is much appreciated. I will be posting the answers to your questions shortly.

Thanks,
Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Sent you a PM , check it !

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Thanks again for your time Kend301,

For the benefit of others, we have now determined that I have a red stator. Also, we discovered that the coils have probably been changed before as I have 1 black and 2 blue coils.

Here are my next steps:

1. I will check coil #3 (problematic one) to see if the internal magnet is broken. If that's the case, I will be changing all 3 coils and put her back in the water to see if my problem has been resolved.

2. I will also OHM test as per Kend301's earlier post and show results.

More to come...thanks again Kend301.

Regards,
Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Remember the magnet will be on the outside of the coil but contained in the rubber coil boot .

 

[PM9]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Update...

So I checked coil#3 and as Kend301 had expected, it was broken. What I don't understand is that coil #2 was also broken???

Anyhow, please advise if you know where I can find these replacement coils.

Finally, I OHM tested the trigger, here are the results:

Purple: 544 ohm
White: 1240 ohm
Brown: 1252 ohm

As you can see, there seems to be a problem with purple...any advice, what's the next step?

Thanks for all your help,

Pat

 

[kend301]

Re: PM9 - Sportjet 90 problem...running on 2 cylinders

Buy 3 coils and a trigger .544 on purple is toast . As far as where to buy since you are in Canada I can only recommend I boats , If you need me to I can look them up and post up part numbers .

They can run with broken coil magnets but they can fry another part !