90 sport jet needs help (mharrngtion)

[mharringtion]

I need a guru right now before I blow the thing up.

earlier this summer the boat flooded out very badly, carbs were removed and cleaned and it started an ran great for the start of the day. We had shut it down to have lunch and swimming. When I went to re-start it would not and then the starter died. I replaced the starter but it still would not start. At this point it went to the boat mechanic, Might I add the only one in my area who will work on this thing, he rebuilt carbs, compression check, timing check and spark check. Everything checked out fine, he trailer tested the boat and gave it back. he stated it is smoking horribly and I had water in carbs. I drained the tank and started a new. No water was in gas that I drained???? I took the boat out and it started, smoked like a son of gun, figuring all of the raw fuel that Probably collected in the crank case is burning off. I took off from the dock. Boat idles well and is good to half throttle, once I stat to gain speed and WOT the boat bogs and starts to smoke, it will not plane or go over 15 mph. I have started it on land with flush kit it starts and revs like a son of gun. Is it just allergic to water. I am thinking fuel pump. bit I am an extreme novice. any advise would be greatly appreciated.

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

Was just about to copy and paste your pm to open a thread . It indeed sounds like you have a fuel problem , But the water issue makes me wonder , Give me a few hours to ponder this and I will post later tonight .... Never mind , I need to know the compression numbers , the HP of the motor , and where did he find the water also how long has it been since the boat has run prior to this happening ? We will get this sorted out .

 

[profade]

Re: 90 sport jet needs help (mharrngtion)

Fuel pump reading should be as I recall 3 psi idle and 6 psi wide open. You can get a $20 diaphragm rebuild kit from any boat store or online, easy to put in. If you take off the filter on the fuel pump, take out the screen with a pick lifting an edge and see if any junk is in there. Under load you could be having a misfire, that's why it runs good out of water, and is smoking, check you coils for cracks, plug wires, connections etc. Pull the flywheel check to make sure everything is good under there and clean as far as trigger, magnets, stator, etc. You may even try disconnecting the black/yellow wire from the rev limiter, those can be an issue when going bad. If you want to make sure its not the oil pump putting in to much oil disconnect it from the T into the gas line and remove the oil tank lid and put hose back into the tank, put a rubber band and sandwich bag over the top to hold hose and keep the oil clean, it will just cycle through then, plug the inlet to the fuel line with extra piece of hose and stick a bolt in it with clamp, its real easy to convert back this way. Then premix your gas to 50/1, if it is still smoking real bad then it means you have ignition problem somewhere with a misfire and the oil and gas is building up in the engine bogging it and making it smoke.

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

Good MIXED advice PROFADE , you have no idea if this motor has a 2 stage fuel pump or a single stage that runs at 6psi all the time, Also no idea if it is oil injected or a premix motor . That is why some more info needs to be posted by the owner of the boat .
Your advice is accurate for some Sport Jets, but since mercury has made so many changes to these motors in each year of production the owner needs to provide more info so proper diag procedures can be followed .

 

[mharringtion]

Re: 90 sport jet needs help (mharrngtion)

First off thanks for posting to my cry for help. The compression was cyl1-126,cyl2-130,cyl3-132 back a year ago they read 134,149,147 in same order 123. mechanic had checked spark, no issue. he found water in two carbs bowls. The boat was running great that day when it would not re-start. It flooded out the day before and that was when I removed and cleaned carbs, took it out the next day ran great, great speeds then would not re-start. Boat has been run about every two weeks during the summer and every day for one week while on vacation all with out issue.

It is a 94 sport jet 90 hp, oil injection system is disconnected mix 50:1 since I have owned it. Fuel is mixed in gas can and poured in, not oil in tank and then drive to gas station.

Stator, trigger, wires, plugs , switch box,and rev limiter are all new as of 5/09. When it would not start it seemed like it was not getting fuel. The other part I don't understand is the boat ran great, Mechanic states that when he took carbs off they were "way out of adjustment" if they were way out why the hell did the boat run so damn good, it had never started so quickly and run that good.)Anger toward boat and mechanic) I am not sure if it is a two stage or single stage and how do I tell.

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

It really does seem like you have a fuel problem , here is what you need to check .
1 take the air intake off the carbs and move the throttle to WOT with the drive engaged then look down the carbs and see if all the carb butterflys are perfectly open . You should only see the thickness of the butterfly ,they should be all horizontal .
2 Fuel pressure test , disconnect the feed line from the pump at the lowest carb , put that line into a glass jar and crank the motor ( ignition or plugs grounded) and check flow it should be steady not pulsing .
3 Your carbs should have a vent on them , small brass elbow close to the idle adjustment screw with plastic lines coming off them , blow through the lines and be sure they flow freely these are prone to clogging and will kill performance and flood the motor with fuel.
4 the proper adjustment for the idle screws for your motor is turn all the way in and then out 1 1/2 turns and leave them there no need for further tuning as long as the boat does not bog on acceleration.

You should have a 2 stage fuel pump , if you follow the fuel line from the tank to the pump on a 2 stage it wil go into a removable bowl and the pump will look like a sideways 8 , a single stage pump will be square and have no bowl for the fuel intake.
Your compression is great and this motor should sing if properly tuned , do the above tests and post results we can go from there !

 

[mharringtion]

Re: 90 sport jet needs help (mharrngtion)

The line goes from the tank to a circle on the fuel pump that is removable and a screen. Is that what you are calling a bowl?

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

Yes that is the bowl , you have a 2 stage pump and I really think the diaphragm is bad . as stated it needs to be at 3psi for idle and operation to 2000 rpm then at 5 to 6 psi for wot operation .

 

[mharringtion]

Re: 90 sport jet needs help (mharrngtion)

Well not only do we have a two stage pump we had a two stage problem. The choke butterflies were at about 1/3 closed at idle and WOT, which is not fixed, the interior butterflies are perfect at WOT. The fuel pump was pulsating pretty bad and it appeared that every second cycle it pumped nothing, I am guessing that there is a hole in the diaphragm.

By the way, not that I am complaining and I am sure anyone else that you have helped, but why do you do what you do? There are not many people left in this would that will offer professional advise for free. I myself enjoy helping others, i am a social worker by trade. I just don't find many people like you.

Thank you!!!

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

OK , seems we have found 2 potential causes , first adjust the choke tiebar so the choke butterflies are horizontal when not in use , simple adjustment , undo the top carb pinch screw and set the top to horizontal then lock that screw and check and adjust the other carbs as needed .
You do need to rebuild the fuel pump , the part numbers you need are as follows :
f438747 ... diaphragm
f658803 ... block gasket
820490 .. pump body gasket
823606 .. bowl gasket
It is much easier to pull the pump off and rebuild it on the bench vs trying to seat the diaphragm while the pump is mounted on the block . If you have a spring to hold the diaphragm inside the pump , use a 1/2" putty knife to hold the diaphragm and spring down while assembling .

I do this because when I got mine I could find no help , these boats are not hard to work on once you know what parts are on the motor as there are several upgrades. There is no one manual that covers it all . Most marine mechanics refuse to work on these because of this . I did so much research to get mine running that I just decided to help those who could be misled by info that does not apply to their setup . besides it keeps me sharp for when I work on mine .

 

[mharringtion]

Re: 90 sport jet needs help (mharrngtion)

I have adjusted the butterflies already. I am also glad to hear that my theories are not far off. From the beginning I have thought that the fuel pump was bad.

I know on a car fuel pump old style that there was a piece in the block that made the pump work. Is there anything in the block that I have to re-align on re-assembly?


I had called Five repair places in my area when I first had issues with this boat and they all just about laughed at me. One guy said he would work on it and when I brought it down told me to get it off his lot. The one guy who would work on it is about 35 miles away an dis reluctant, nor will he test drive it off the trailer. I had asked him how to replace the gear oil, he replied and I quote, "you have to take the engine out, remove the drive place it upside on the bench and fill i. That is to do it properly. It would cost me about 1500.00 to have him do it. From advise on this forum and the sea-rayder forum on yahoo I found out how wrong he was.

KEND Thank you for what you do!!!!!

 

[calledinsick]

Re: 90 sport jet needs help (mharrngtion)

I know you've already adjusted your carbs, but here's an extra note for adjusting the butterflies. I know it's difficult to see down the throats on my setup, so I was using an 'extendo mirror'. However there is another way.

On the side of the carbs with the synchronization linkage there is the "L" shaped connector (1 for each carb) that connects the linkage to the carb. If you look closely at these "'L" connectors, they each have a line on them (engraved) that represents the position of the butterfly. This line can be used to facilitate adjusting the carb synchronization.

 

[calledinsick]

Re: 90 sport jet needs help (mharrngtion)

Here's a picture of the engraved line that matches the position of the butterfly:

 

[mharringtion]

Re: 90 sport jet needs help (mharrngtion)

That was some good thinking on the engineers part. When I take of the fuel pump is anything gonna pop out at me or is there anything I have to line back in place?

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

Nope , just pull the 4 bolts around the small end and take it off the block , the last 2 are body retention screws and can be removed when you have it on the bench.

 

[mharringtion]

Re: 90 sport jet needs help (mharrngtion)

Hopefully I can get this ordered this weekend and put in. However I will not be able to get it in the water until spring it is getting quite cold here. 34 this morning.

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

Oh common , show a little backbone , water does not freeze until it is 32 degrees .

 

[mharringtion]

Re: 90 sport jet needs help (mharrngtion)

I've hit a snag, I have removed three of the four bolts, The forth the top one closest to the carbs will not budge. I have soaked it with penetrating oil and have attempted several times at removal. I have used a pry bar to apply forward pressure pushing screwdriver into slot and vise grips on screwdriver to turn and nothing. I am dreadfully afraid of stripping the slot out of it. any suggestions?

It is apparent that this unit has been removed once before, paint is off the screws and two screws are missing the lock washers. I can not get a visegrip on this screw for there is no room to attach. A bit concerned about adding heat since it is the fuel pump. Might add a bit too much, BOOM. Why the hell did they use slotted screws.

 

[twu928]

Re: 90 sport jet needs help (mharrngtion)

I would try to use a 1/4" ratchet with a large blade screwdriver bit that inserts into a socket. You will be able to apply steady inward pressure on it with one hand while your other hand applies the force to unscrew. Hopefully the head of the screw is still in good enough shape.

 

[kend301]

Re: 90 sport jet needs help (mharrngtion)

Slotted screws have pissed me off about this motor since day 1 , my only advice is to be sure you have a very large bladed screw driver ( I bought a craftsman that was like 2 feet long cut it off then put a wrench on it ) it has to fit the slot. Your next step it to figure the fuel pump is cheaper than the block , break the housing then with the fuel pump and fuel out of the mix , heat try and vice grips if no luck then cut it off , drill and tap it then do what I did , repalce ALL slotted / phillips screws with stainless steel allen heads .