Super Jet Superjet low end bog

[schicks]

a ton of ways to make a leak tester. You can use a bike pump (similar to mikuni n/s popoff tester), you can barrow an air regulator from work that use 1/8" line and plug it into the pulse line (i usually use the pulse line to leak test my motors, which only works if you are running a 38 manifold with the cross over which pressurizes front and rear at the same time; if you are running a 44 manifold w/o cross over you need to do front and rear cylinder seperate) To seal off the engine, you can use radiator style plugs available at menards or you can duct tape the manifolds off and use the carb and exhaust manifold to clamp and hold the tape in place to maintain a seal. Only pressurize up to 10-15 psi and go slow when using an aircompressor as a supply.
Also, if you engine block is clean, you can usually see some sort of oily blow by where its leaking.

 

[Blue]

If u can get it to idle down long enough to do a test u can spray carb or starting fluid along the sides of the case and around the seal area. If it revs up or dies when u spray it u may have a leak.

 

[motozachl]

You can make one easily using plumbing plugs and cheap hf tools. See here
http://www.x-h2o.com/index.php?threads/leak-down-test-kit.110441/

and here
http://www.x-h2o.com/index.php?threads/pressure-test.1303/

 

[djkorn1]

Check ALL fuel line connections. Check all fuel lines for tears, etc... Tighten down the cylinder to cases, Tighten down the intake manifold to the cases and the carbs to the manifold. Restart and test. Look for any oil coming out at the base gasket.

FOR SURE air leak.

 

[mthomps]

I have a gauge, all we need is a thick piece of rubber to block carb and exhaust.

 

[SmittySX]

Just got my gaskets. Going through the whole intake side and making sure all surfaces are flat and clean. I notice that the bottom of the carbs looked like someone drug the across the concrete...
although they were some what flat, one of the gouges was almost .004 deep. The surface plus a crappy gasket might have caused a leak?

 

[SmittySX]

So i thought i had fixed it by smoothing out the base of the carbs and all new gaskets on the intake side... Also started it up after and let it idle and sprayed starter fluid around the base gasket and head.
It starts fine and revs as it should on the trailer. Took it to the water and it has the same "off idle bog"..... WTF.
It still acts as if it has to "catch up to itself" while being started out of the water.
It only bogs heavy when its in the water but i can work the throttle and get it to a high RPM.

RECAP.

-New gaskets on intake side of the engine
-New plugs
-Sprayed starter fluid around base gasket while idling.

 

[SmittySX]

I just replaced all the fuel lines and pulse line and started it up in the garage and it instantly ran away.

Now what do i do?

 

[Quinc]

Have you done a leak down test?

 

[SmittySX]

Have not done that yet... Looks like ill do that next. Where and what are the plugs called that i plug the exhaust and intake mani?

Note: the previous owner replace the crank seals in april.

 

[Quinc]

I used packaging tape..

 

[SmittySX]

I used packaging tape..

Really? That will withstand 15 psi for 10 min...?

 

[King Kang]

Now it might be something you can't see like a bad crank seal or lean low screw.

 

[TheBuzzard]

have you opened up the carbs and checked for plugged internal filters or hard needle n seat diaphram? if it revs to the moon, that means its running out of fuel. i seriously doubt you have an air leak. more likely you have a carb/fuel delivery problem. that rusty ass screw leads me to believe you never took the internal filter side apart.

 

[Quinc]

Really? That will withstand 15 psi for 10 min...?

I only went up to 10psi, and it lasted for 10+ minutes.

 

[SmittySX]

have you opened up the carbs and checked for plugged internal filters or hard needle n seat diaphram? if it revs to the moon, that means its running out of fuel. i seriously doubt you have an air leak. more likely you have a carb/fuel delivery problem. that rusty ass screw leads me to believe you never took the internal filter side apart.

I was hoping you would chime in, buzzard. I have not taken the carbs apart. "Supposedly" the previous owner had rebuilt the carbs completely in april.

Im also running a seperate mechanical fuel pump. I think thats what its called? Ive always only ran pump bodies on my carbs. Could this be taking a poop?

 

[SmittySX]

Just tore into the carbs and they are clean as can be BUT I did find that the body under the diaphragm had 1 loose bolt...?
could this be my issue!?

 

[SmittySX]

I don't think anything changed... Going to water test tomorrow morning.....

 

[mthomps]

the ns not grooved? I agree that it's fuel delivery...

Spray wd40 all over the engine and look for a bubble.

F*** with the screws now after taking carb apart. Is it better or worse

 

[TheBuzzard]

is the diaphram that runs the needle and seat TOTALLY soft with no crispy spots? i run the remote fuel pump on a bunch of my setups and never had a problem. they are easy to test, if you suck on the pulse line to the pump it shouldnt leak air and you can hear / feel the pump diaphram working. check the internal carb filters. that loose jet plate aint good. just have a squirt bottle with gas handy for if it revs up.