Regarding a Lean running issue

[ddanster]

I Have a 1998 gtx Limited in which I have replaced the fuel lines, Cleaned the fuel filter and cleaned out both carbs and pop out tests good. I did have to repair the Fuel pump diaphragm as it tested bad..found a small leak but replaced diaphragm and all was good. Anyways I dug into it due to some running issues while on the water..hard to start sometimes.

I replaced all the grey fuel lines and found a lot of grey gunk in the fuel selector valve..i flushed it out. Carbs were exceptionally clean of residue considering the amount of grey gunk I found. Had the carbs out, rebuilt and reinstalled with new base gaskets.

Started it up and it instantly wanted to run away...based on what I've read here that's a lean running issue meaning too much air. I have verified I don't have a throttle cable that is too tight, Checked for air leaks around the carb base and swapped gaskets with the same results. I did manage to keep it from running away after installing the carbs back on a second time. However It races at about 4200 rpms and that is with the idle screw all the way out..and it does seem like it wants to race away but I don't let it run long enough to find out.

I don't understand how the motor can race to 4200 rpms with the throttle plates all the way closed. I didn't mess with the low speed jets when I had it apart..should have I?? Possible Fuel selector issue??

Thanks for any assistance.

 

[SabrToothSqrl]

High idle isn't too big of an issue, if you are aware of it. When it's in the water, the idle will be much lower.

However, I usually set the idle to 3k out of water.

So, you played with the carbs. And your SURE the throttle cable is adjusted?
There is an adjuster on it as well, remove the front under hood bin, it's near the fuel filter.
Also, where the cable meets the carbs it can be off as well.

Also, is the air box on? That will affect it some.

Did you set the needles to stock spec? L1.5 out. H closed.

New plugs?

Yes, if it runs away, pull out the choke.

However, is it actually running away? Holds 7K even if you pull the lanyard? Or is it just a high idle issue?

Are the carbs in sync? Perhaps one is being held open due to the link being out of sync.

 

[ddanster]

Yes pretty sure cable is adjusted correctly...the throttle plates are basically closed at idle and yes I actually had the jets out 2 turns...I didn't touch the H jets though so those are as they were when I took the carbs off. The Carbs are also in sync. Before I took carbs off I had no issues setting idle speed..it was 3K out of the water and 1.5K in the water. Also the Airbox is attached but seems to effect it little. Engine should die with throttle plates closed or at least a minor idle...doesn't seem to matter. Perhaps I need to double check my internal carb work.

Yesterday it did run away even though I had pulled the lanyard..I backed off though as I was waiting for a blowup lol so I dunno if it reached 7K

 

[vettepilot_6]

How did you check for air leaks? (usually use WD40 see if revs drop) Are the base of carbies flat not curved from over tightning of bolts/screws? doe's it have a plastic spacer between carby and block that maybe split or cracked? some carbies have a bleed hole for vacuum to crankcase after throttle plate towards back of carby...does this engine have anything like that? these are things I check when rebuilding any 2 stroke..I have not worked on these but 2 strokes are basically the same....just a few thoughts put out there for your consideration.. Dave

 

[ddanster]

How did you check for air leaks? (usually use WD40 see if revs drop) Are the base of carbies flat not curved from over tightning of bolts/screws? doe's it have a plastic spacer between carby and block that maybe split or cracked? some carbies have a bleed hole for vacuum to crankcase after throttle plate towards back of carby...does this engine have anything like that? these are things I check when rebuilding any 2 stroke..I have not worked on these but 2 strokes are basically the same....just a few thoughts put out there for your consideration.. Dave

I used Carb cleaner to check for leaks..WD40 better? It does not have a plastic spacer, Yeah there is a bleed hole in both carbs which I believe to be the low speed jet. After reading this I did an inspection of the intake area and the Oil inject actually could be a cause of a vaccum leak. It has been converted to premix and the old oil connections, which are under each intake port still has the old hoses attached. I removed them and placed caps on them...so I'll see if it helps any soon.

 

[ddanster]

I have the issue resolved but I'm not sure what the actual cause was. I reseated the fuel lines on the baffle. Took the carbs apart again and flushed them out...I did do the extra step of removing the low speed jets and replacing the seals on them As I hadn't before. I checked the Pulse connection and Capped off the oil feeds right on the intake ports. It is premix so that isn't an issue but I did wonder if my extra air was getting sucked into there. Anyways got a steady idle now.

 

[manolocross]

It was the uncapped oil port holes... That's an air leak straight int motor!

 

[ddanster]

It was the uncapped oil port holes... That's an air leak straight int motor!

Yeah quite possible..there were still lines attached all the way to the oil pump. I'm willing to bet removing the carb and replacing the fuel lines I probably struck one and cracked it causing the tubes to leak.

 

[donkey]

i have a 951 ski that runs away every time i start it,out of the water,hopefully i'll find the same issue with mine.
im about to reinstall oil injection,so its a good time to check.