Volvo Penta Stalls

A

alastair1956

New Member
Joined
28 Jul 2015
Messages
12
Visit site
1993 Sealine 270S - Twin Volvo Penta 250's (AQ151) twin Solex Carbs per engine - Engines start fine & run fine, planes perfectly etc - engines stall consistently after 45 mins as soon as I carry out the following manoeuvre - Come off plane, cruise 5 knots for 2-3 mins then slow to carry out 'mooring' procedure : forward dead slow, neutral, reverse, neutral, forward, revs drop... Starboard engine stalls ( smell of petrol)... try to immediately moor with port engine, within two minutes same procedure, revs drops, Port engine stalls, can't start engines for 30 minutes until flooded carbs clear ( then engines start perfectly ) . Have had the following work professionally carried out by respected marine engineers ( who are now pulling their hair out as well...) New : plugs, leads, rotors, condensers, coils, fuel lift pumps, Carb service kits including carb accelerator pumps & venturi etc, fuel filters, carb air filters etc - Fuel good - Checked petrol tank vent, clear - no evidence of vapour lock ( bypassed boat fuel system with separate petrol tank and hand pressurised pump to maintain fuel line pressure etc ) - Strange how it seems to be always after 35-45 mins of running - Has anyone had similar and if so what is the advice please - or any other suggestions welcomed !!!
 
Hi Richard, Thanks for the reply, yes, as I said in my question they both start perfectly after about 30 mins ( after flooding clears ) and I agree with your 'common' theory. Also have had a look at the links, which are useful. Will post some more later after I share them with the engineer. Thanks, Al !
 
First thing is, are the float heights in the carbs set correctly?
Second thing is both engines are good and warm after running for 45 mins, were the mixtures and idle speed adjusted when the engine is warm, or when it was cold as in just idling?
 
Hi Spannerman, thanks for the reply - Float's, not sure - I'll contact the engineer and mention it. It seems as if it only happens when I go into a slow manouever when I either go from reverse, neutral and then try to throttle to go forward again - or if I have been on say, dead slow and then throttle - but in each case its when the engine is warm and at low revs - but in both cases the carbs flood and I have to wait about 30 mins to clear before I can restart ( usually with no problem ) - next weekend I'm going to try running it at a constant speed for an hour ( with a friend on his boat along side just in case I need a tow ! ) to rule out if there is something like a fuel vacuum in the tank etc - I'll report on the outcome. ( The current engineers I'm using in Cardiff (CMG) are vey thorough )
 
Last edited:
Hi . I have twin VP 1993 500B engines and when I had an episode of engine stalls whilst slow speed maneuvering the issue was fixed by setting the carb mixture by colortune and reseting the ignition timing?
 
alastair1956 said:
( The current engineers I'm using in Cardiff are vey thorough, but are diesel specialists - I'm trying to find someone who are good with petrol engines, but as yet, to no avail...)
Click to expand...
Hopefully not Wigmore! I've just moved from Penarth otherwise I would have been able to give some help. I used to have a fariline Targa with Penta petrol engines which I rebuilt and overhauled the carbs etc etc. Are they Holly's? If so I have the workshop manuals somewhere if SWMBO hasn't thrown them out. Lovely carbs, tricky to set up but once done ultra reliable. It does sound like the float level - they are sensitive to the heat if you've been running for a while, either flooding or evapourating depending on how they are set.
 
Thanks Boating dave : No, CMG - they have been very thorough so far - its just one of these problems that we have to do by elimination - the Carbs are twin- Solex
 
Just a thought to throw into the mix and happy to be contradicted..
Are the idle jets clean?
Just wondering if there is a partial blockage thereby the mixture adjustment has been made at cold, so starting wouldn’t be affected- but may cause flooding when hot.
Easy to check with a soft copper wire in the nozzle and carb cleaner with the idle jets removed.
What filters are being used? As I believe some of the old Volvo’s used the CAV296 type and the petrol with ethanol can break up some CAV filters causing muck in the carb bowl.
Good luck.
 
Hi moresparks, thanks for the reply. : Twin Solex - We have stripped the carbs, re-jetted, gaskets, diaphragm, etc - our plan now is to bypass the fuel system and connect up a 25 ltr outboard tank with a hand primer to maintain pressure and to eliminate any vapour lock. I'll report after ! Thanks
 
Just a thought, has one of the fuel pumps leaked petrol into the oil? This would 'fume' after the engines got hot, and the subsequent venting give you the fuel odour....

Used to see this a lot.
 
Hi No Regrets - It seems that the fumes are directly after the engine stalls and when it fails to start - so we think its just excessive flooding.
\
 
You must log in or register to reply here.

Share this page

Top