787 wont start unless fuel is dumped down the plugs

[ghost183]

hey guys...

weird problem that im not sure how/where to start...

its a 97 GSX....

whenever i want to start the ski, either hot or cold, i have to dump fuel into the sparkplug holes, im sure the same would happen if i dumped into the carbs, but its easier to pull the plugs than the arrestors.. after that , the ski would start and run great, until i shut it down, holds idle nicely, great out of the hole and follows thru till the limiter with no hickups..

carbs were rebuilt by a reputable local ski shop to oem specs to the tune of $410, no expense spared, middle of the last season but the problem didnt go away...



where do i start guys?

 

[ocod]

If you know carbs are right check next obvious thing that is known to cause fuel issues.
#1 Fuel selector
#2 Grey lines

Check compression either way to know motor is healthy.



http://www.seadooforum.com/showthread.php?40380-Carburetor-Adjustments

 

[Dr Honda]

If he had leaky N/S.... putting more fuel in the engine would make it worse.

My guess is that you have high clearance in the RV, and you don't make very good vac at cranking speeds.

Check the RV, and compression... and we will go from there.

I guess an easy fix would be to install a primer kit. THen you can just give it a shot a fuel to get it going. (Assuming it is running well otherwise)

 

[ocod]

If he had leaky N/S.... putting more fuel in the engine would make it worse.

My guess is that you have high clearance in the RV, and you don't make very good vac at cranking speeds.

Check the RV, and compression... and we will go from there.

I guess an easy fix would be to install a primer kit. THen you can just give it a shot a fuel to get it going. (Assuming it is running well otherwise)

That would make sense.:thumbsup:
Then when leaky and warm it floods making it hard to start.

 

[Minnetonka4me]

Check compression b/c low pressures will have trouble starting when cold. That and weak crank seals cause low vacuum pressure like the Doc said. The fuel pump assembly may have had a mistake when he put it back together. flapper may have been flipped...

 

[ghost183]

thanks for the input guys.. compression is great at 156 and 162, fuel selector has been replaced as well as ALL the fuel lines and pickup tube inside the tank, the carbs are OEM to this ski, i too am suspecting the rotary valve but i dont know how to check it to see if its in time, but. after it starts it runs great, plenty of nuts and shoots out of the water, very healthy, the problem is only there when i shut down and go to restart.. the crankcase was pressure tested and passed, i dont know exactly how it was done or if it was pressure or vaccuum that was applied, or even what "passed" means cause i wasnt there, but the same guy who rebuilt the carbs did the check

now.. minnetonka4me, you lost me when you mentioned the fuel valve might be flipped? how do i check that? and would the ski run "nuts" out if it was?

the killer for me is as long as i dump fuel into the cylinder, it starts, either hot or cold, it runs with no issues, pulls hard and revs out forever, ive lost count of the hours invested in trying to figure this out fellas.. and with my luck, its probably something thats right in front of me and due to aggravation, i cant see it..

 

[Minnetonka4me]

I was talking about the flappers in the fuel pump..the round discs. They have a blue line on them to tell you what size goes down.

I have had a rotory valve on a 800 off one tooth and it ran like crap. The clearance is possible...worth a check. Smash some solder in between the mani and the case and measure.

 

[ghost183]

Oh, well that part of the pump wasnt touched, so ill have to look into the RV, but like i mentioned above, would these symptoms be from a mistimed RV? Again, once i start it itll idle and run great...



Dr Honda? Or anyone? How do i check the clearance on the rv? Is it safe to say that if i replace the RV with new would remove that from the equation as a problem?

 

[Minnetonka4me]

Its not the valve itself...its the clearance between the cases and the Manifold. Take the RV out, smash some solder in between the case and the mani, and measure.

The one I worked on that was out of time started but ran like crap.

 

[ghost183]

ok, got an update fellas...

after several attempts to time the engine i need some more in depth help guys..

i checked the clearance of the rotary using a procedure the local shop told me, dab of silicone and reinstall the cover, when dry (next day)peel and measure thickness of the silicone, i did and came back within specs i was told, i didnt make note of the measurement cause they were on the phone with me when i pulled the cover and measured using a digital caliper

when i was putting the piston at TDC, i noticed the RV was turning almost 3/4 " during the pistons hang time on top, is that normal??? that equates to 11-14 degree change in timing

and also, when i was fiddling with the RV, i did notice that the valves teeth arent symmetrical, they are off a little on one side and cause of this i was able to get the valve to 144 degress and when flipped, 150 degrees and tried both ways to no avail

when exactly should the RV be put at the speced 147 degrees? the start of the hang time? end? or approximation of middle?

but in all of this i am progressing somewhat where it is now at the prementioned 150 degrees where i left it cause it was closer to the 147 spec...

now i can start it on its own without dumping fuel into the cylinders, but im getting massive backfiring thru the carbs!!! im talking violent explosions not just a pop and some flames

 

[ocod]

ok, got an update fellas...

after several attempts to time the engine i need some more in depth help guys..

i checked the clearance of the rotary using a procedure the local shop told me, dab of silicone and reinstall the cover, when dry (next day)peel and measure thickness of the silicone, i did and came back within specs i was told, i didnt make note of the measurement cause they were on the phone with me when i pulled the cover and measured using a digital caliper

when i was putting the piston at TDC, i noticed the RV was turning almost 3/4 " during the pistons hang time on top, is that normal??? that equates to 11-14 degree change in timing

and also, when i was fiddling with the RV, i did notice that the valves teeth arent symmetrical, they are off a little on one side and cause of this i was able to get the valve to 144 degress and when flipped, 150 degrees and tried both ways to no avail

when exactly should the RV be put at the speced 147 degrees? the start of the hang time? end? or approximation of middle?

but in all of this i am progressing somewhat where it is now at the prementioned 150 degrees where i left it cause it was closer to the 147 spec...

now i can start it on its own without dumping fuel into the cylinders, but im getting massive backfiring thru the carbs!!! im talking violent explosions not just a pop and some flames

While helping some figure out their back firing he found the woodfuff key on the crank was broken in half. Take flywheel off and take a look.