Another Sportjet 90 Starting Issue

[nate2k5]

So I bought a 94 Baja Blast a few weeks ago and we can't get it to run. i've done nearly everything that i have read in the threads regarding this here so i don't know what i am missing.

- fuel is pumping smooth and consistent
- there is spark
- carbs have been disassembled and cleaned and have new gaskets
- there is fuel in the bowls, well at least the bottom easily accessible one
- old gas was drained and new put in
- oil injection system seems to be working fine
- replaced all old fuel/vent lines
- starts with starting fluid but will not stay running

any ideas would be greatly appreciated.

 

[aksor]

Re: Another Sportjet 90 Starting Issue

Compression, timing, reeds

Check the compression I hope you did before purchasing, if good then take out the spark plugs and place a screwdriver in the top cylinder sparkplug hole and turn the flywheel until the screwdriver is pushed out then check the flywheel timing mark and make sure it lines up with the 0 degree mark if not tthen the key is sheared under the flywheel.

Check to make sure your magnets are not loose or broken

using a timing light check the timing

Check the reeds make sure none of the petals are missing and they close properly

 

[nate2k5]

Re: Another Sportjet 90 Starting Issue

checked the reeds today, the reeds seem to be in good shape but the stops are corroded pretty heavily

 

[nate2k5]

Re: Another Sportjet 90 Starting Issue

so i worked on the boat a little more tonight:

compression numbers:

Cylinder 1: ~150
Cylinder 2: ~145
Cylinder 3: ~110

we got the boat to run and stay running by pulling the fuel enrichment thing out, the fuel was being pumped in with the fuel pressure past the carbs so it stayed running. the carbs were dry past the butterfly.

not really sure what to do from here. either it is not pulling enough vacuum or the carbs aren't letting it through.

 

[aksor]

Re: Another Sportjet 90 Starting Issue

The bottom cyl is a bit low but make sure the carb vent elbows and lines are gunk free else the carb bowls cant breathe

 

[nate2k5]

Re: Another Sportjet 90 Starting Issue

the vent lines were replaced and the elbows cleaned

 

[aksor]

Re: Another Sportjet 90 Starting Issue

did you check for loose or broken magnets under the flywheel?

 

[nate2k5]

Re: Another Sportjet 90 Starting Issue

would that affect the fuel not being sucked into the engine? isn't that ignition related?

there is no problem with the ignition, it runs fine with the enrichener removed.

 

[aksor]

Re: Another Sportjet 90 Starting Issue

Check this link then. http://forums.iboats.com/showthread.php?t=557911

 

[nate2k5]

Re: Another Sportjet 90 Starting Issue

i don't think the enrichener is the problem however. it will start and run with it out but when you press it back into it's hole the carbs are not picking up the slack and the engine dies.

 

[aksor]

Re: Another Sportjet 90 Starting Issue

I'm not really familiar with the electronic enricher as I have a solenoid choke on mine but it sounds like you might have a vacum leak trough the enricher and once u plug up the hole it actually starts using the carbs to suck in the air .

 

[nate2k5]

Re: Another Sportjet 90 Starting Issue

the motor will not start when the enrichener is in place and bolted down, only when it is out

i took the flywheel off last night and all of the magnets were loose and one broken. i've cleaned it up and jb welded the magnets back on so we will see if that was the problem after it sets up.

 

[aksor]

Re: Another Sportjet 90 Starting Issue

If one of the magnets was broken you will need to locate a spare one from someone who has one because once a magnet breaks it becomes two magnets, they now both have a N/S pole, You can contact a member named "venxxxx" he seems to have a few for sale from his old flywheel. And you have to make sure all of the magnet polarities are aligned the same way

Here is a quote from my thread:

"Default Re: Mercury Sport Jet 90 Engine Problem need advice

I got a few loose magnets around from my previous flywheel. I couldn't find any to replaced my 2 broken ones, so i bought a used flywheel. Let me know if you want one, I'll sell it to you. Pm me."

Contact him and see if he still has them otherwise you will need to purchase a new flywheel and make sure you get the right one for your ignition type CDI or CDM there have different center magnet config for the trigger.

 

[nate2k5]

Re: Another Sportjet 90 Starting Issue

i have a 94 sport jet 90, with a flywheel from a 95 sportjet 120 work? they look identical.

 

[aksor]

Re: Another Sportjet 90 Starting Issue

Looks like the same part# acording to the microfiche so it should work!