Fuel issue after repairs

[OutlawBiz]

I was having some issues with my older 1999 GS over the 4th. It would idle and run at low speeds GREAT. But, when you accelerated it would bog down. Since we were at the lake and all repair shops were closed, I put 2 new spark plugs in and added fuel stabilizer in attempt to remedy with no luck.

So, last weekend I decided to tear into it to see what I could find. I soon realized the small internal fuel filter in the Mikuni carb was plugged nearly solid! Replaced that. I figured while I had the carb out I would also replace all the crappy gray Tempo fuel lines since I've heard they are bad. So, I re-ran all new fuel lines and sprayed carb cleaner into the fuel selector valves to clean them up as well. Got it all replaced and now it won't run. It doesn't appear to be getting any fuel (lost prime)!? I even labeld the fuel lines and replaced one-at-a-time to be sure I had them all in the correct spot.

I removed the supply line from the carb and blew air into the gas tank until fuel squirted out the line near the carb and it still won’t fire. Put a few drops of fuel in each cylinder and it will run for a second but then quit.

I finally filled the fuel line from the separator cup up front to the carb with fuel hoping that might “prime” it. Fires right up and runs long enough to burn the fuel in the line but then quits.

Any ideas? TIA!

 

[Jeffspx]

Couple things to start off
Are your vent lines clear?
Did you install the check valves in the vent line in the proper direction?
Is the o ring for the fuel filter in good shape and seated correctly?
Did you re install the pulse line to fuel pump while you had the carb off?
Your fuel pick up at the tank should have labels molded on them labeling each barb for vent, return, res, and out. Cant hurt to double check the routing.

Also I would consider bypassing the fuel selector temporarily. Cleaning the selector doesnt usually work real well, generally they should just be replaced with oem units and carb cleaner may have killed the o ring inside the selector causing it to leak air.

 

[OutlawBiz]

Couple things to start off
Are your vent lines clear? They are new / replaced...so I would assume so!?
Did you install the check valves in the vent line in the proper direction? ??? There were no check valves on the original setup!?
Is the o ring for the fuel filter in good shape and seated correctly? I will double check
Did you re install the pulse line to fuel pump while you had the carb off? Yes
Your fuel pick up at the tank should have labels molded on them labeling each barb for vent, return, res, and out. Cant hurt to double check the routing. Right. Yes, I looked that over again as well.

Also I would consider bypassing the fuel selector temporarily. Cleaning the selector doesnt usually work real well, generally they should just be replaced with oem units and carb cleaner may have killed the o ring inside the selector causing it to leak air.

Crap. Ok. What's the easiest method of bypassing it?

Thanks for the quick response!

 

[Jeffspx]

The fuel line on the OUT barb of the selector should go to the IN barb of the fuel filter/separator. Take that line and pull it off the selector and put it directly onto the ON or RES barb on the fuel tank baffle. So your fuel line when all finished should go from the tank-filter-carb IN.

 

[OutlawBiz]

The fuel line on the OUT barb of the selector should go to the IN barb of the fuel filter/separator. Take that line and pull it off the selector and put it directly onto the ON or RES barb on the fuel tank baffle. So your fuel line when all finished should go from the tank-filter-carb IN.

I will give that bypass a try!

Any chance the fuel pump is bad!? It ran (although not 100%) BEFORE I replaced the small filter / fuel lines tho! So I would imagine that it shoudl at least work the same as prior to tearing into it!? Unless that thin membrane / diaphragm can "dry out" etc.!?

 

[OutlawBiz]

Is the TOP or BOTTOM barb on the carb the IN. Pretty sure it's the top...but want to verify.

(the very bottom line is the pulse line)

 

[Jeffspx]

Acutally i think the lower is in and upper is out. And the pulse line is about in the middle on the fuel pump portion of the carburetor.

 

[OutlawBiz]

Acutally i think the lower is in and upper is out. And the pulse line is about in the middle on the fuel pump portion of the carburetor.

here's a pic I took BEFORE I replaced the Tempo lines. I have the pulse line correct FOR SURE. I was 99% sure I had #1 and #2 correctly labeled but now you got me wondering if I got those 2 mixed up somehow!? And I have no way of knowing now that I have the new lines in place UNLESS someone can verify which barb is the feed and which is return!? Are the barbs "labeled" somehow with arrows etc. Is there a drawing I can refer to online?

I'm not sure which model # carb I have...coudln't find any model #'s on it!?

 

[Jeffspx]

There should be arrows on the pump, you might be able to see them with a mirror.
Heres the parts fiche pic. If you look at the outter pump body in the fiche it has arrows on it. Looks like IN is the lower barb, I know on my carb the lower barb was IN as well.

 

[OutlawBiz]

1st off...THANK YOU Jeffspx for your time / advice this morning...much appreciated!!

2nd...is there anyway to find out what model # the carb is if I did want to order a fuel pump rebuild kit so I know what part # to order?

 

[Jeffspx]

Sea Doo PWC Carburetor Reference
I believe you have a super bn40. The chart can confirm.
Also, this has a nice pic of fuel line routing and pulse, although carb setup a little different.
Mikuni Carburetor Test & Rebuild Info
Glad I could be of help. Good luck. Once you get it running I'd advise replacing that fuel selector with an oem one. And change out those oil injector lines, they look original in the picture.

 

[OutlawBiz]

Sea Doo PWC Carburetor Reference
I believe you have a super bn40. The chart can confirm.
Also, this has a nice pic of fuel line routing and pulse, although carb setup a little different.
Mikuni Carburetor Test & Rebuild Info
Glad I could be of help. Good luck. Once you get it running I'd advise replacing that fuel selector with an oem one. And change out those oil injector lines, they look original in the picture.

So in the pic of the Mikuni carb in the link you sent...the TOP lines shows Fuel OUT and LOWER one shows fuel IN...

To clarify...one of those lines runs back to the fuel pick up tube in the gas tank and the other runs back to the fuel filter / separator correct!? To be sure I don't have them flip-flopped...which one SHOULD go where?

Also...are the oil injector lines you refer to the small "clear" ones down under the carb coming off the crankcase?

 

[Jeffspx]

Yes. Assuming you keep the fuel selector hooked up, here is the routing:

So for IN which is the lower barb on the carb the order will be fuel selector OUT->filter/seperator IN-> filter/separator OUT->carburetor IN.
Out will be carburetor OUT-> fuel tank pickup RETURN

And of course the other remaining barbs on the fuel tank pick up will be vent which just goes to your vent lines and ON from the tank will go to ON on the selector and RES from the tank will go to RES on the selector.

 

[OutlawBiz]

Last question and I'll leave you alone (for now). What's the chances the fuel pump went bad while I've had it tore down working on the rest of it? Could that be the reason I'm not getting any fuel to move through the system?

Wondering if it was weak before (why it ran crappy) and now it finally crapped out on me!? I just assumed (hoped) it was that clogged filter in the carb that was my issue...

 

[Jeffspx]

You had the fuel pump apart? Or no?
If any off the diaphragms ripped or there not making seal, it will not pump. They can get weak too. I would attribute your poor performance to the clogged filter inside the carb though.
Have you confirmed the lines are correct? Are you still having a problem?

 

[OutlawBiz]

I had to take the cover off the fuel pump to get at that tiny filter that's inside. So, yes...I had the fuel pump apart in that I opened it up and set it aside to replace the filter. BUT, I did NOT disassemble any of the pump components (like a rebuild). Basically just carefully set it aside while I put the new filter in and put back together.

The attached pic shows the nasty little filter I swapped. In the background you can see the exposed fuel pump.

I haven't been home from work yet to verify my lines are run correctly. I will check that out tonight or tomorrow morning. I printed off all your notes / advice so i can double-check my work.

 

[mwat65]

Your going to have to dismantle and rebuild your carbs with oem kits and needles and seats. Once the green goo goes through your carbs there’s little chance of getting away with cleaning them. Btw the arrows for fuel flow are on each side of the pulse line fitting on the carb.

 

[Jeffspx]

Your going to have to dismantle and rebuild your carbs with oem kits and needles and seats. Once the green goo goes through your carbs there’s little chance of getting away with cleaning them. Btw the arrows for fuel flow are on each side of the pulse line fitting on the carb.

This exactly, and you definitely need to use genuine mikuni rebuild kits. This will include a rebuild kit for the fuel pump as well. I just was shooting for you to get the ski at least running before pulling the carbs again and rebuilding.

 

[OutlawBiz]

***UPDATE***
Fuel lines were run correctly. I filled the separator / filter cup FULL of fuel and screwed back on.

Hit the start button and fired right up and ran strong!

Put it all back together, dropped it in the lake this afternoon and ran decent but not 100%. Would cut out at high speeds.

Flipped the fuel selector switch to RES and ran much better (95%). If I feathered the choke button when it started acting up it would run perfectly.

So...any thoughts on what I may have going on now!? At least it runs now!

 

[Jeffspx]

Well using the choke would suggest its running lean. Now that you got it running I would suggest:
New fuel selector, oem only
New fuel filter and o ring for the separator cup
Carburetor rebuild kit, genuine mikuni only with needle and seat

I would also advise doing a compression check just to make sure the top end is healthy and replace the oil injection lines and injection filter since they looked original in the pic.

 

[mwat65]

A lot of times when u have fuel selectors going bad they also have air leaks.