Newbie needs help getting neglected Explorer Started

[pmacafee]

I just bought a '95 Seadoo Explorer (RIB jet boat) that has sat for 5-6 years. Although the owner sold it as running ok, when I pulled the plugs the forward one was completely carboned up and the gap filled. When I crank it with the plugs out that foreward cyinder pumps out large amounts of fuel like a fountain. If I leave the plug in then the cylinder gets filled with fuel to the point it wont crank. I assume that either I have a stuck float in the carb, or maybe a crank seal has failed. Only 48 hours on the engine. I am not very good at rebuilding a carb and do not have a workbench area for that sort of repair. Should I try to run some Chemtool through the carb from the fuel line or whack the bowl?
The carboned up plug tells me the owner had the problem before he let it sit so long. What other diagnostics should I be doing?

Philip Macafee

 

[Minnetonka4me]

I just bought a '95 Seadoo Explorer (RIB jet boat) that has sat for 5-6 years. Although the owner sold it as running ok, when I pulled the plugs the forward one was completely carboned up and the gap filled. When I crank it with the plugs out that foreward cyinder pumps out large amounts of fuel like a fountain. If I leave the plug in then the cylinder gets filled with fuel to the point it wont crank. I assume that either I have a stuck float in the carb, or maybe a crank seal has failed. Only 48 hours on the engine. I am not very good at rebuilding a carb and do not have a workbench area for that sort of repair. Should I try to run some Chemtool through the carb from the fuel line or whack the bowl?
The carboned up plug tells me the owner had the problem before he let it sit so long. What other diagnostics should I be doing?

PWC Carbs do not use floats...they use a pressure system to open the needle and seat.

Its not very typical to see the engine fill with gas. you sure thats what it is? Usually they stick closed when they sit.

If you want to take them off and send them to me I can go thru them. Rebuild kits are $55, and the N&S are about $20.

 

[Spimothy Leary]

PWC Carbs do not use floats...they use a pressure system to open the needle and seat.

Its not very typical to see the engine fill with gas. you sure thats what it is? Usually they stick closed when they sit.

If you want to take them off and send them to me I can go thru them. Rebuild kits are $55, and the N&S are about $20.

if its been sitting for that long and your in over your head, they definitely need to be sent out !

a word of caution, the carbs may be only part of the problem, but you really can't go wrong having them rebuilt, they will have some value then at least.

 

[SabrToothSqrl]

fuel

did those guys use the tempo lines?

6 year old gas needs drained and new put in.

new plugs

new battery

new lots of stuff! good times...

it can be done, get some pics!

before doing anything, do a compression test on that engine, if it passes yay, if not...

 

[pmacafee]

Thanks for all the posts.
I have siphoned all the gas out and put new gas in. Am using new plugs. BTW does the oil go bad over time? The guy who sold it to me gave me a couple of half filled jugs with the labels fallen off that he had for the boat.

If there are no floats and the needle usually gets stuck closed, then what are the symptoms of a blown crank gasket?

So we did a compression test and the rear cyl is 170 lbs. But when we go to test the front and crank the engine the cylinder fills with fuel quickly and the compression raises up to as much as 300 and then wont crank.
The fuel mixture shooting out of the plug hole is big droplets. Is there a way for the carb to malfunction and let large amounts of fuel in?

 

[purple_people_eater]

hmmm i wondering if there is a problem with your rotary valve... take off the carb( its going to have to be rebuilt anyway) then take the intake off. then you will see something that looks like this:

thats called the rotary valve. turn the engine by hand and see if its turning. if its not that explains why one jug is flooding with fuel.

 

[pmacafee]

Thanks purple_people_eater. Is this valve driven off the crankshaft? What would cause it to not turn.
BTW, is there any chance there is a problem with the fuel pump?

 

[pmacafee]

Oh, and how do I turn this by hand?

 

[purple_people_eater]

its on a gear thats driven by the crank, the "fuel pump" on these is vacuum driven by a diaphragm in the carb. to turn the motor by hand grab the disk on the back of the motor and turn it lol.

I've only had one or two skis ever come to me with rotary valve issues. the first was where the engine was starved of oil and sized the valve, the other was where the drive gear had striped. in your case i don't know for sure what the issue is, but the rotary valve's function is to direct the air fuel charge to the cylinder thats firing. if your's is stuck then all the fuel is going to just one jug...

 

[pmacafee]

Got it, thanks. If the gear is stripped, then I would need a new rotary valve and I guess a new crank. If I have to go this far, can I upgrade to a 720 engine? If so what would it entail?

Really appreciate your continued comments.

Phil

 

[purple_people_eater]

if i remember correctly not much, i had a 96 explorer for a while, but it already had the 717... i think if you found a non-dess 717 it will go right in without having to change the mpem, how ever the rev limiter will be lower since the 717 can handle more rpms that the 657. if you wanted to convert it; it would be best to find a donor ski thats been crashed ect...

as far as fixing your 657 you really don't know what the problem is until you get into it, take the carb and intake off and see what you got.:cheers:

 

[pmacafee]

Really appreciate the help. Will report back when I can see something.

 

[Minnetonka4me]

I bet i know..the diaphram in the fuel pump is rotted out and gas is siphoning into the pulse line.

I had a guy bring me one he rebuilt and gas was filling the mag cyl. Pulled it apart and he had not put that diaphram in.

 

[pmacafee]

Given the low hours on the machine and the length of time it sat, the fuel pump diaphram idea seems a more likely bet. It is also probably easier to check. Can you tell me how to do test that, can I pinch the pulse line or something like that?

 

[Minnetonka4me]

the pulse line comes off the cases and runs into the side of the fuel pump. It says pulse on the plate. unhook it from the carbs and then pump all the gas out of the motor.

When I had that one in I had the carbs OFF and it started 50 times (shut off right away so it didnt run away) before it burned up everything.

 

[pmacafee]

Minnetonka4me; I was a little over my head getting the carbs off etc. So I drove about 2 hours to the Central Valley south of Sacramento to a dealer that does Seadoo right. I printed out this discussion and gave it to them. They called back today and said you were right, it was the fuel pump. They are currently rebuilding the pump and both carbs. Thanks for the help.

 

[pmacafee]

Well, the shop got into it and found that the cylinder was filling with oil, not gas so I need a new crank. Thinking about putting a 717 into it. Does anyone have any ideas about how practical this would be. One of the posts above says that the revs would be limited, and if so would I really get the benefit of the larger engine?

 

[Minnetonka4me]

Oh yeah!! Nailed it!!


Oil in the cylinder is not an absolute deal breaker. When they sit they do get oil in the motor. It gets past the crank seals from the RV cavity.

If it was mine I would crank it with the throttle wide open and get all the oil out. Put a towel over it. It will take a lot of cranking.

Once its out, pour a little gas down the cyl and get it to fire. You'll prob have to unfowl the plugs a few times to get it to run.

Once its running get it warm, then brapp it a few times to get the last of the oil out of the cases.

The real test is to see if oil fills the cases in a few weeks after you get it running. Tired seals def leak when they are stored, but it usually isnt too bad if used a few times a month. If it fills up again in a couple of weeks, it needs a new crank.

The other thing....if you are an environmentalist...it may spew a bit of oil.

One last tip on this issue....LISTEN UP PEEPS!!! A theory I have is the oil tank will build up pressure b/c of the one way valve. 2-3 or more PSI. With tired seals what is gonna give??? The seals.

My easy fix...just keep the oil tank lid cracked open so it cannot build up pressure. Its worked on my GFs 93. That machine leaks out of the fittings on the tank into the hull...and again if I crack the tank I get little to no oil in the hull.

 

[Minnetonka4me]

Now on the engine swap...

the 720 will drop right in there, but PPE was saying the MPEM would limit the RPMS...so you would also need to replace the MPEM.

I did this swap on a 93 last year and heres the main issues:

#1...carbs. You will need the 720 carbs. The 657s will not work. Luckily yours has the newer airbox so that will not be an issue...on the 93 I had to modify some parts to make it work.

#2 MPEM...no biggie on yours...you could just get a module and swap it out in your box. Be aware though some of the 720 MPEMs can be programmed to use a DESS key, and once programmed it cannot be changed. On 94 and earlier, you need to swap the whole box and replace the stop with a start/stop

#3 prop...I put a prop out of a 96 SPX which from the list says its the same prop they used in the 720 explorer but I found it to be too steep. I am gonna try a prop out of a 94 XP this spring and see if it brings the Revs up.

 

[pmacafee]

Really appreciate all the comments here. I am worried that the guy that sold it to me knew the engine was bad. When I pulled the front plug it was completely carboned up with black fuzz filling the gap. He also had about 20 spark plugs under the seat and in his box of boat accessories.
I don't think I will get an honest answer out of him regarding the history or condition of the engine.

As newbies we made the mistake of hooking up a hose before it started and hydrolocking it with either water or oil. I could be the one damaging the crank myself but that doesn't account for the gummed up spark plug.

Also not sure if I can get the shop to follow the instructions of a unknown third party.

About the swap:
So if I do the swap, I need a 720 with good compression, MPEM, and my 94 prop is just about right. The shop rate is $120/hr, and there is a 720 on ebay for $800. What should I budget for a swap?

 

[Minnetonka4me]

I would search craigslist for a small guy. I work out of my garage and all my work comes from CL. Look for people who will actually talk with you, and who doesnt "work on everything" As is life...there are always idiots...but there's guys like me out there who want to be their own boss,and live and breath seadoos.

I'm $60/hr in the summer....and after its said and done it might be cheaper to bring it to MN...lol