Backfiring through carbs

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goldfishdude04

goldfishdude04

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I have a 98 seadoo gs 717 motor. I had the famous green goo clogg the internal filter in my carb. I cleaned the carb and got the gunk out. When i replaced it i found that my fuel selector was clogged. I cleaned the selector and still it is gunked up somewhere. I have since bypassed the switch and ran new fuel lines. Its running but when i get up to about 70%-wot it starts to back fire through the carb. I had reset the factory settings of all the way in for the high side and 1 and 1/4 out for the low-side but that didn't change anything. The plugs are new and when i look at them they seem to be good, i used Snipes write up about the plugs. I did not remove the RV cover and not messed with anything else timing wise. I have read the post but haven't really figured anything else out. When i by passed the selector switch i ran the ON line to the fuel filter under the hood up front, would that have anything to do with it backfiring? I haven't had it on the water since i don't have a truck handy, but have been running it on the hose. Becoming frustrated as all get out! I haven't had any problems with the ski until it sat for a couple of months while i was at school. I'm trying to sell it to pay for said school but want to have it running right to get more money HAHA.
 
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carb base sealed?

Any carb gasket sealant? Air could get into the flange manifold. Incorrect fuel/air mix will cause backfireing, as well as:
A lean carburation condition, rev limiter in mpem malfuncion, Bad crank seals, rotary valve timing, ignition timing from sheared keyway so flywheel position dislocated, Stator 9:30 alignment marks off, Too much build-up of Carbon on piston and head, the square 0-ring at water separator filter is failed.
Metal particles in stator coil(s), intake leak, Bad Gasoline.wrong combination of mpem-flywheel-stator.



RV BRASS GEAR STRIPPED? (and it is backfireing)
It is always wise to set the closing timing to 65 degrees. Why ? because Sea Doo makes 3 different duration RV's. for use on 3 different engines they produced. All three will allow the motor to run if you use the closing timing number of 65 degrees when setting the valve, not the opening timing mark.

At quick glance at the RV positioning when the mag piston is at TDC will show the lower edge of the valve ( closing timing ) is about a half inch below the mag port in the cases.

The only other reasons it could backfire is non resistor sparkplugs are installed, or you have a faulty or wet coil, and water is in the rear E-box. and in some very rare instances, an overly lean condition can create a misfire. Corrosion or water is in the AMP connection mpem pins or fuses.

Bills86e
 
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Thanks Bills86e! This gives me a place to start. Another question, if the fuel lines are too long is that a possibility to create a backfire?
 
No never had a problem with the backfire until i replaced the lines and cleaned out the carb. I didn't take off the RV cover when i pulled the carb it came off easy. I did replace the coil, rectifier, and the starter solenoid. I also had to replace the battery as it would hold a charge but as soon as a load was put on it it would drop volts to like 6.5. I am going to use some RTV on the carb gasket to see it by chance the gasket isn't sealing everything right and allowing air to go into the carb. Sudden thought i bypassed the selector switch and ran the ON to the filter under the handlebars, and the bowl fills all the way to the top, almost like it TOO full. Would that cause excess gas to get to the carb and make it backfire?
 
I would guess the backfire would be b/c of the rectifer or the stator, not the carbs.

Engines get too much gas from leaky needles and seats. Usually if they are it will bog...either right away, or after it warms up.
 
Yes it was a new one off of e-bay. I haven't had a chance to mess with it but will tonight. I may put the old rectifier back on and see if that changes anything. I'm growing frustrated with this ski haha. I'm also gonna try and bypass the fuel filter under the handle bars and see if maybe that's allowing air into the lines. I appreciate all the help Minnetonka4me
 
Yeah they will give you fits....Believe me I have seen my share of "WTF" moments after trying 18 things and getting no where.

I had a HX I was about to give up on...my brother had one he worked on where for some reason the pickup had a crack in it. Well we pulled it out and someone had drilled a hole in the pickup tube and glued it over....and the glue had let loose.
 
I put RTV on the carb base along with the gasket but its still backfiring. Gonna take the mag cover off tomorrow morning before work and check everything in there. i read that its possible that i could be hitting the rev limiter? I have not tried it on the water because of no truck is there a chance that it would run right with a load on the water?
 
Hey guys, The tuned pipe has two welded plugs and one of has a small hole in the plug, i didnt notice the water leaking out of it until today, it might have gotten bigger and allowed more water to spurt out. Could this be my problem???
 
Well hell! Gonna clean up the area and put some JB weld on it. I noticed that when it idles and you apply throttle that it boggs and thenwill clear up. Im guessing that the needle may be stuck. I have the low speed setting at 1 and 1/4 can i go anylower with out messing up the motor?
 
What would constitute a actual back fire? It's not real loud just a popping noise through the carbs and has little bits if smoke that puffs out when it happens. Thanks again for your help and patience!
 
Remove pipe, Tig weld the four welsh plugs. before they rot thru. NO......its just another problem.
 
Crap and crap haha. Unfortunatly I don't have access to a tig welder, or the money to pay someone to do it. Plus my friend who can do it is about 3 hours away from me. I read about using Jb weld as a temporary fix will do that tonight.
 
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