Re: New to me Mariah 1993 diablo few ?'s
 

It would run weird if it only jumped 1 tooth. This doesn't happen often though. More likely the chain is stretched , if that is the issue. You gotta change the whole timing set or your peeing in the wind.
Ya gotta make sure that the timing is set right. I can't recall....did you already change the fuel filter?
Set the timing correctly and try her out.
Always attack the simple stuff first. Don't start throwing parts at it. It'll drive you nuts!

You can rent a timing light at Autozone , O'riellys, etc.

Larry

Re: New to me Mariah 1993 diablo few ?'s
 

No larry i have not changed the fuel filter as it looks brand new. The guy i bought it from said he found some water in the carb so he drained and cleaned the tank and replaced the filter at that time. Couldnt hurt to change it out i guess not like its a million dollars.

The guy i bought the boat from said he would go good on the parts if it doesnt turn into throwing 20 parts at it to get it right. Sounded more like he would give me 1 shot at it.

The local guy tony will come back out to the boat with me. I will ask him to check the timing and chain. We are beginning to wonder if there is an intake leak somewhere. We sprayed carb cleaner around the intake but didnt see anything noticeable. I will do a more thorough check when i stop and get some more carb cleaner. The backfire through carb, from what i understand is a lean condition, so it would make sense if it were a leak and feeding to much air.

I also need to check voltage coming from the coil and from the alternator. I still have concerns of the top speed of my boat. The fastest ive seen it run is 35 mph at 4k rpm. It takes 3k rpm to reach plane at 22 mph or so. I have not smelled any rubber burning that would pont to engine coupler, but there is a steady rotating noise coming from the shaft. It seems quite a bit louder than normal. I added some grease to it without any major change. May have quieted it a small small bit.

So we will check timing/timing chain, air leak somewhere, possibly distributor itself, voltage from alt to battery and coil. Accerator pump still ??? not sure though. Fuel pump could still be an issue although after carb set it does not surge anymore. I will order a new fuel/water filter. When timing we will have to check the advance make sure its working properly. Such a huge list of possible causes. Wish i had an obd II port hahah would at least give me a system to focus on.

Once again thank you so much larry for continueing to follow my story.

Re: New to me Mariah 1993 diablo few ?'s
 

Hang in there!!
You'll get it sooner or later. Hopefully , sooner.
I agree with you whole heartedly , it can be very frustrating.
Keep us up to date. I'm very interested in the findings. :)

Larry

Re: New to me Mariah 1993 diablo few ?'s
 

Well Larry,

The timing was way off! It was at 8 degrees ATDC or there-abouts. All the numbers had been scraped off, but Tony has set so many of these he said i know where 8 BTDC is. HAHA so it may not be perfect but i bet its damn close. The boat hops right up on plane and runs out great. I even reached 4600 rpm tonight with my wife and 2 small kids in the boat with me. I hit 42 mph with the drive almost out of the water riding just as smooth. Best part is i made 4 or 5 laps around the lake at 35 mph and never even moved the fuel gauge. I couldnt keep enough fuel in it before as it was just dumping down the cyliners.

I am concerned of how long it had been like this and possible internal engine damage from spark happening while the piston was on its way down. Guess that will be determined later, after my last month before it needs to be put away.

Thanks again Larry for following me through this crap, but i can breathe easy and focus on other aspects of the boat now.

Re: New to me Mariah 1993 diablo few ?'s
 

Good Job!!!
She'll be fine! Have a little faith!
Seriously though........glad it all worked out. These motors are very strong compared to others.
Nowwwww.........go have fun! :):)

Larry

Re: New to me Mariah 1993 diablo few ?'s
 

Now that its running good, have been whipping the snot out of my kids last couple days on tubes, i have a few other questions. Now i know Larry you are the only one really responding to this thread at this point, but thats ok because you have a similar boat to mine.

When we timed it the boat was left a little rich on mixture. Burned quite a bit of gas yesterday, so i leaned it out about 1/4 or a turn. Less gas smell from the exhaust but still there at times. The guy told me to lean it out based on fuel use but i really dont know what is normal. Yesterday i was out around 2 hrs or so and burned roughly 7 gallons maybe a bit more. Today about 3 hrs of tubing and went from 3/4 of a tank to 1/2 tank.

My fuel gauge is all over the place so i hardly ever know where its at. It seems where i set it today is a reasonable amount of fuel usuage for 3 hrs of pulling 2 tubes wouldnt you think?

I also wonder if pulling 3 tubes is to much for this boat/motor combo. I think it will do it easy enough, but may be difficult to get on plane. Once there i dont think it will be bad. Is it safe to pull 3 tubes smaller kids off the ski hook? Or should i move the outside tubes to the stern hooks?

Re: New to me Mariah 1993 diablo few ?'s
 

Gas usage doesn't seem to bad to me. I run at anywhere from 4500-7500ft altitude though , and use about the same as you do , so maybe a tad rich but be careful. Running the motor to lean will kill it. You might play with the jets a bit but I think your close by the sounds of it. If you idle the boat for a long time it will load up and you will smell fuel too. Tubing sucks the fuel also.
As far as towing 3 kids on seperate tubes , the hook will handle them easy. Mariah boats have some of the best backing designs in the business for their ski rings , grab handles , and cleats. I have pulled 2 large tubes with adult men on them with bungee tow lines with no issues.
3 in the water too me is a little scarey , but I hate tangled lines with a passion.
Does she come up on plane quickly? What is your WOT at now? What pitch is the prop? Is it a 3 blade or 4 blade or do you have a high 5 prop(5 blades)?

Larry

Re: New to me Mariah 1993 diablo few ?'s
 

I dont truely know what pitch the prop is. I am assuming it is whatever came stock on these boats. 19 would be a safe bet i guess. Need to throw some goggles on and check it out. It is a 3 blade prop with 400lbs in the boat and 3/4 tank fuel i hit 4500 at wot which was 41-42 mph by the speedo i didnt have my phone with me that night as i have a gps speedo app on it.

Yesterday pulling 2 tubes it came up on plane pretty decent didnt snap right up but i didnt hammer it either with the kids on the tubes. It was difficult to plane at times based on where the weight was in the boat. If i had 2 adults towards the back it wouldnt plane for obvious reasons. If 1 of the other adults went to the front she would come right down.

I agree if i were thrashing them around pretty good on the tubes 3 would be scary, but the tubes i currently have all have holes in the middle with a floor so my kids sit down in the hole. The tubes are pretty stable and they only fall out when the bump and tip going over the wake, which isnt really all that often. I dont even have 3 good tubes to pull right now anyway i was just wondering your thoughts. I have one double tube and 2 singles but i dont think the mix would be all that great.

Re: New to me Mariah 1993 diablo few ?'s
 

Pull your prop if you have too , and it should be stamped something like this on the nut side of the prop usually. WOT on your motor is 4400-4800rpm , so your in range with your current prop.

http://i271.photobucket.com/albums/j...ss/prop001.jpg

If you want to get more speed go up 2" in pitch , if you want more holeshot go down 2" in pitch. You can also go to a 4 blade and that will get you outta the hole faster. Or you could put these on and it will make you think your on rails and have a drag boat coming out of the water. They work awesome.

Smart Tabs SX Trim Tabs

Larry

Re: New to me Mariah 1993 diablo few ?'s
 

I have the smart tabs in my garage right now. Not in any rush to put them on, it may end up being done beginning of next season at this point.

Larry the boat has done something weird to me again. I went out the other day pulled tubes for an hour or so everything was fine and dandy then all the sudden at 20mph or so it just quit. Without spuddering or anything almost as if you were watching tv and someone unplugged it. No noises just a rapid cut of everything. Its been sitting out there for 3 days and i havent even gone to look at it. Frustrated figured i would take a break from it. I had work to do on my truck so i just did that to forget the boat for a bit.

I restarted the boat 2 or 3 times but it would not stay running. I started and quickly put into gear and same thing cut right out before hardly and forward movement.

So im leading to believe this is electrical and possible water in my fuel. Is there any switches that would cause this I just need a direction to start in. Neutral safety switch oil pressure switch? I did have the boat at 1/4 tank of fuel so i suppose something could have been sucked up, but i dont think this is likely with the way it cut out and restarted.