Twin Solex pa44 1, volvo penta Aq151B

[dave7575]

Hello

After a carb rebuild I am experiencing some issues. I can get engine to start and idle good. Upon accelerating the engine will die around 1500 rpm. I can get it past this point by pumping the throttle but it will not hold the high rpm. It will eventually drop the high rpm and die.
I've set idle and idle mixture screws to workshop manual, I've got accelerator pumps squirting as I throttle.
Has anyone experienced these symptoms. I would d be very grateful if anyone could point me in the right direction.

Thanks David

 

[Scott Danforth]

something in the carb is plugged up in the main circuit. you are running out of fuel from the idle circuit. hence the reason it dies. check the main jet to the emulsion tube

did you pass a bit of fishing line thru every passage to make sure they are clear before re-assembling the carbs?

 

[dave7575]

something in the carb is plugged up in the main circuit. you are running out of fuel from the idle circuit. hence the reason it dies. check the main jet to the emulsion tube

did you pass a bit of fishing line thru every passage to make sure they are clear before re-assembling the carbs?

Hello Scott

Thanks for your reply.
I Blew compressed air through all passage ways. Like you say I may have a blocked passage way. Would there be a way to identify which carb may have the blockage? While running.

Thanks David

 

[Scott Danforth]

I wouldnt run it until you get the carb sorted. running cylinders lean will make them eat themselves from detonation.

 

[dave7575]

I wouldnt run it until you get the carb sorted. running cylinders lean will make them eat themselves from detonation.

Yes I'll make sure I get them checked out.
Regarding the setting up of the accelerator pump, at what point should they squirt? Just before throttle plates open or the exact same time?

Thanks David

 

[Scott Danforth]

Yes I'll make sure I get them checked out.
Regarding the setting up of the accelerator pump, at what point should they squirt? Just before throttle plates open or the exact same time?

Thanks David

The linkages are connected. So they should start squirting as the throttle plates are opening.

 

[dave7575]

Hello

Has anyone experienced these issues before. Engine will idle nice, around 900 rpm. It will rev to 1500rpm but between 1500 and 2000 rpm it wants to die. Once above 2000 it will rev but won't hold the revs. I've took video. If someone has ever had these issues please get in touch.

Thanks David

 

[dave7575]

The linkages are connected. So they should start squirting as the throttle plates are opening.

Hello Scott

Thanks for your reply. I've had the carbs apart and checked with compressed all passage ways. I've backed off the nut on the accelerator pump and both squirt but still seeing the same issues.
One observation I did make was if I cover the small Hole on top of carburetor which is the pilot air for idle circuit the engine rmp speeds up and seems to hold the higher revs. In your opinion what's that telling me? It happens on both carbs.

Thanks David

 

[kenny nunez]

Are you sure that the throttle plates are synchronized ? If one is opening more than the other it will act like that. If the carburetors are working correctly the idle mixture screws should be a 1.5 turns out from lightly seated. Any large deviation from that then the carburetor has a problem.

 

[stresspoint]

need a background story , was the motor running before work was done to the carbs ,
any other recent works done on the motor that would cause bogging , IE: timing adjusted , points replaced etc.

 

[dave7575]

need a background story , was the motor running before work was done to the carbs ,
any other recent works done on the motor that would cause bogging , IE: timing adjusted , points replaced etc.

Hello

Engine was running fine before carburetor rebuild. I decided to rebuild the carburetors because they had never been touched in the 10 years I've owned the boat. Wish I never disturbed them now. I ran the engine the day I removed carburetors with no issues.
The only other recent work was resealing oil cooler a few months ago.
I will confirm ignition timing with a strobe.
Also I think I've managed to acquire a vacuum flow gauge to help me make sure throttle plates are opening together. I've currently done it by ear.

Thanks David

 

[dave7575]

Are you sure that the throttle plates are synchronized ? If one is opening more than the other it will act like that. If the carburetors are working correctly the idle mixture screws should be a 1.5 turns out from lightly seated. Any large deviation from that then the carburetor has a problem.

Hello

Hopefully I've manage to borrow a vacuum gauge to identify if plates are in sync. I set idle mixture screws to 2 turns out from seat to start but the mixtures screws ended up way more than 1.5 turns out in the video above.

Thanks David

 

[Scott Danforth]

Thanks for your reply. I've had the carbs apart and checked with compressed all passage ways.

check with a piece of fishing line.

usually with compressed air, you cant tell where its going or if its partially blocked.

another trick I use is a can of WD-40 and making sure the oil comes out the correct passage. however that doesnt ensure the passage is fully clear.

 

[Bt Doctur]

if your interested in those cabs I think I have 2 of them from a inline 6
PM me if interested

 

[dave7575]

if your interested in those cabs I think I have 2 of them from a inline 6
PM me if interested

Hello

Thanks for your reply. I wouldn't be Intrested in buying, but thanks anyway. Also I'm in Scotland, wouldn't want to cover the cost of postage.
David

 

[kenny nunez]

Did you remove all the threaded plugs in the Venturi body? Some have fine mesh screens on them. I have had good results cleaning out those carburetors in the past. The Volvo service manual is very good and helpful with setting the throttle levers evenly.

 

[dave7575]

Did you remove all the threaded plugs in the Venturi body? Some have fine mesh screens on them. I have had good results cleaning out those carburetors in the past. The Volvo service manual is very good and helpful with setting the throttle levers evenly.

Yes I removed all the jets and cleaned the fine mesh filter on the feed to accelerator pump housing. My next port of call is confirming the ignition timing is correct. Hopefully get Down to boat in the next couple of days.

David

 

[dave7575]

need a background story , was the motor running before work was done to the carbs ,
any other recent works done on the motor that would cause bogging , IE: timing adjusted , points replaced etc.

Hello everyone

Checked ignition timing with strobe and was set approximately 6°. I loosened distributor and adjusted to see if i could get it closer and engine sounded better after a move in the slot. But to my horror I had turned it the other way. I increased the degree to approximately 15 ° and engine would run better. Why would this be the case?
I ve also checked timing marks on the the timing belts and all line up.
I'm running out of ideas.

David

 

[Scott Danforth]

your motor will always run better at idle with a higher advance. it will also pull water in from the exhaust and hydrolock.

what did you set the dwell to on the points prior to the timing?

 

[dave7575]

your motor will always run better at idle with a higher advance. it will also pull water in from the exhaust and hydrolock.

what did you set the dwell to on the points prior to the timing?

Hello

Only ran for a minute at higher degree's. It's electronic ignition inside distributor. I removed heat exchanger to confirm timing belt timing marks. I'm going to replace timing bekt and tensioner while I'm that far.

David