Full spectrum help

C

Colby

Location
Harvey's Lake PA
I’ll start by I got this set of fs49s from a ski sitting for a couple years. 3-4. Decided to rebuild them.
While they were still together I tried a pop off test. They leaked in the fuel pump side.

I rebuilt the carb (working on one carb at the moment) and it still leaked. Base gasket between fuel pump and carb. New oem gasket.

I pulled the other one off used the fuel pump section and the o ring and base gasket and put it on the leaking carb. (3 year old gaskets) and it sealed.

So now I’m on the other carb working on it. Trying to figure out what’s going on. New gaskets same thing leak in the same spots... I’m under the assumption that the fuel pump may be warped.

Question I have is can I just use like a 46 fuel pump and I put it no with the restrictior still? Trying to get the carbs done and dialed before dropping into the ski.

Sorry long post hopefully someone can help me out!
 
Jr.

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
Most all performannce carbs, including full specs start life as 46 SBN, so yes, a SBN fuel pump assembly will work on your 49’s

look at how your orientating your fuel pump gaskets? Its fairly easy to assemble them incorrectly, and have the leak your describing
There is an index pin that is there to aid correct assembly
Lastly, wet the gaskets with a light oil, such as WD40. This will soften the gasket, and make for better sealing
 
C

Colby

Location
Harvey's Lake PA
Jr. said:
Most all performannce carbs, including full specs start life as 46 SBN, so yes, a SBN fuel pump assembly will work on your 49’s

look at how your orientating your fuel pump gaskets? Its fairly easy to assemble them incorrectly, and have the leak your describing
There is an index pin that is there to aid correct assembly
Lastly, wet the gaskets with a light oil, such as WD40. This will soften the gasket, and make for better sealing
Click to expand...
Yeah I pulled there gaskets out and put them in the exact same way. Unless person before me didn’t do it right. I wasn’t sure if Ed modded the fuel pumps or not since I have another new fuel pump I can try and see if that one works.
 
Jr.

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
Ed prefers a remote pump, and normally just blocks off carb mounted pumps.
so, no they are not modified
 
C

Colby

Location
Harvey's Lake PA
Jr. said:
Ed prefers a remote pump, and normally just blocks off carb mounted pumps.
so, no they are not modified
Click to expand...
I figured my fuel pump issue out but the ski back fired as well as cuts out after I rev it a little bit. It just dies out. I keep having inaccurate pop off issues. Inaccurate reading and I had a leak on the diaphragm by the needle and seat and jets. Any suggestions on how to get my pop off accurate?
 
Jr.

Jr.

Standing Tall
Staff member
Site Supporter
Location
Hot-Lanta
If your having back fires ? You could very well have multiple issues going on? probably ignition related

for pop off, going to state obvious first. Verify both needle and seats and springs are identical, and oem Mikuni?
make sure the float arm and pin are not damaged and bent? Make sure seat O-ring is not leaking?
if all is good and true? Make sure float arm pin is fully seated and screw is tight. Try swapping out springs until you get a set that match.
 
C

Colby

Location
Harvey's Lake PA
I bought brand new needle and seat as well as springs. I have an old gauge that when I use it. It reads different almost every time. I ordered a new one so that will definitely help to see if the one I have is shot. I agree the backfire issue sounds like ignition as well as the ski cutting out after running for 5 or 10 seconds seems ignition related. It came off a running ski the only thing that changed was the zeel tune. I’m going to try to figure the carbs out and get them dialed and see what happens.
 
C

Colby

Location
Harvey's Lake PA
JC-SuperJet said:
Excellent.

Genuine Mikuni is the only choice.

Also, inspect the Throttle Plates for wear. Look at the Throttle Plate Sections near the Shaft. There should be no gaps. Also test the Shaft Bushings for slop by lightly pushing/pulling on the Shaft.

Common Story is Brand New Top of the Line Carbs like Novis and Full Spectrums are installed in a Ski. They work like a Champ for a couple of years. Then Carburetion becomes slightly erratic. Carbs get rebuilt with Genuine Mikuni Rebuild Kits. Carbs operation improves. Year or so later, Carburetion worsens. Another full rebuild but the erratic metering is worse. Unable to identify cause, Owner sells highly-coveted used Carbs at a discount. Happy New Owner installs Carbs and can't get the Carbs dialed-in either, even with another rebuild. Frustrated, 2nd Owner turns around and sells them to another Happy Unsuspecting Jetskier, who probably will also suffer from the same Tuning issues. Chances are that the Carb Throttle Plates and Bushings are worn allowing additional unwanted unmetered Air to pass thru corrupting the Fuel Mixture. Replacing them would solve the Tuning Problem.

But installing new Throttle Plates, Shafts and Bushings are not as common as the standard Carb Rebuild, so many tend to think that replacing Internal Gaskets and Diaphragms are the only thing necessary to a have good working Carb.

I know I used to only pay attention to the Throttle Plates for Synchronization. Now I always look for Throttle Plate wear too.

Specially with the Guy at the Lake that just scored a nice set of used Blingy Big Bore Carbs and can't get the Carbs to tune consistently.
Click to expand...
I inspected the butterfly on both carbs which seem tight on the sides of the carb. I also checked for play at idle which is none and at wot theres the smallest bit of play very minimal but doesn't matter at wot throttle anyways. The shafts feel tight and seem to be in great shape. Im pretty sure im close to figuring it out. Just slowly crossing things off of my checklist that is used. The carbs and electronics are the only used pieces. Once I get the new kill switch I believe thats the main cause of the backfire. The carbs are definitely too rich but I'm at 1.5 turns out on each,
 
C

Colby

Location
Harvey's Lake PA
My issue was that I had a extended pop off spring jamming my needle and seat and binding. But id either email ed. Or ask jetmaniac. I emailed Ed on Sunday and got a response yesterday. He seems pretty quiock with emails.
 
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