qd20 10hp wont rev up.

[jonesg]

I posted here about this 15 yrs ago, really , 2009, not wanting to dig up old posts I'll start again. I've been trying top get this engine to run throughout its range properly but no luck yet, I recently retired and have time to try to get this working properly.

Everything under the flywheel is replaced, it fires up and idles ok but then I put it in gear it doesn't really rev up, I'm guessing it sounds rich. Bogging at WOT.
I tried screwing the red needle all the way in, made no difference, same for the white plastic adjustment wheel, its doesn't seem to be reacting to mixture.
Carb was rebuilt, new float and rebuild kit.

any troubleshooting suggestions ?

 

[racerone]

Does spark jump a gap of 5/16" on both leads , yes or no ?----Post the actual compression test values you have.----Nozzle gasket is in place ?----Checked reed valves ?

 

[jonesg]

yes spark is bright blue snap and jumps the gap set to over 1/4 inch.

compression is 65psi on the top cyl, can't get the hose in to test the lower cyl, not enough room.

Whats the nozzle gasket ?

 

[racerone]

Remove bypass covers and look at pistons and rings.----Nozzle gasket is a donut around that tube sticking out of carburetor body.---Remove bowl to find it.

 

[jonesg]

i ran it again and tried troubleshooting,
in gear at wot i choked it for a second and it bogged even more, it tells me its not a lean bog, its just too rich.
stopped it and screwed the red needle in until seated and came out one turn, then ran it again, its starting to respond to needle adjustments better.

at this point it needs to go in the water but i haven't registered it yet.
its getting late in the yr, everyone around me is splitting firewood already.
i'm going to run it dry , oil it and call it a year.

 

[tphoyt]

Did you have a spare part when you did the carb? That nozzle gasket often gets tossed aside and over looked on reassembly.

 

[jonesg]

Did you have a spare part when you did the carb? That nozzle gasket often gets tossed aside and over looked on reassembly.

i rebuilt it with a complete kit including the updated float.

 

[jonesg]

Remove bypass covers and look at pistons and rings.----Nozzle gasket is a donut around that tube sticking out of carburetor body.---Remove bowl to find it.

piston and rings look ok, i recall installing the donut seal, its in there.

looking at the drawing of the carb i had confused the hi and low needles, bottom one is hi speed, so i was adjusting the idle all this time, duh.
i'm confident it will tune up just fine in the morning.

 

[jonesg]

fast needle was too rich, i leaned it in a bit more,
i think its ready for the lake tryout,

 

[racerone]

I don't think it's fine.-----I do not see any water coming out of exhaust relief.-----Best test in a deeper bucket !----Or replace pump impeller NOW.

 

[jonesg]

I don't think it's fine.-----I do not see any water coming out of exhaust relief.-----Best test in a deeper bucket !----Or replace pump impeller NOW.

its peeing fine until I open the throttle and throw all the water out, thats why I only ran it briefly.

 

[Crosbyman]

a recent case came up on the ETEC board where the impeller's brass inner sleeve was actually loose enough to cause problems.

at low rpm or temps the pump would work but at higher rpms and temp the impeller became totally useless in turning the fins.

see picture in this link

No tell tale, overheating

Hi! Third time in the workshop with the boat now, so I am looking for advice. Intermittent problem with no tell tale and overheating alarm. sometimes I have tell tale and cooling, other time I dont. The mechanic has gone through hoses, tried with pressurized air, checked impeller and housing...

www.etecownersgroup.com

 

[racerone]

OMC had that issue back in 79 with some of their V-4 impellers.------You just can't trust parts supplied by the lowest tender.------Did I say Boi%#%

 

[jonesg]

OMC had that issue back in 79 with some of their V-4 impellers.------You just can't trust parts supplied by the lowest tender.------Did I say Boi%#%

Water barrel filled to the top, pump is pushing water even at idle in N.