Engine Stalls at low revs

taza

Engine starts first time, leave engine running RPM approx. 600 after a while just stalls   Starts back up fine same again happens if I keep the revs above 900rpm its OK VOLVO PENTA 5.7Gi- G

Engine Serial No 4012215965

Out Drive DPS-A No 4202203870

Dream_Inn

Sounds like a possible IAC valve issue.  I'm not too familiar with the Volvo, but I know on the Mercs the valve is located on the aft side of the throttle body.  Couple allen head bolts and one hose to remove and it's off.

212rowboat

you're starving it of something... could be air (and the IAC a prime candidate as the issue) or it could be fuel (dirty filters-doesn't matter how old they are if the fuel is contaminated).  Also, check for a vacuum leak. 

taza

Cheers Guys
But why only at low Revs, runs great above 900rpm

Liberty44140

When the IAC went bad on my 310's 5.0 Merc it was intermittent at first but always hit me when I was at idle or neutral. 

212rowboat

at idle your engine's throttle body blade(s) are closed- not enough air making it past the plunger/passage on your IAC to allow it to run.  when the blades are open on your throttle body, it gets plenty enough.  the idle air control's purpose is to regulate the air, and allow enough to pass to maintain idle (600~650rpm)... they can get pretty nasty and gunked up, which limits its ability to provide the air even if the plunger/needle is fully extended from the seat. 

MarkB

Yeah, 212rowboat has it right, you're starving it. If it doesn't bother you, you could always just adjust idle to keep it above the stall point (although I wouldn't want it to idle anymore than 700).

Taz

Guys
replaced IAC Valve and still stalls 

Taz

Also checked fuel pressures
low pressure pump 18psi. Manual says 8psi
high pressure pump 52psi Manual says 50 to 60 psi
i also checked fuel regulator and fitted the e Clip mod that Volvo recommend

but still stalls at 600 rpm

212rowboat

way too much fuel at idle... bad regulator.  is this engine tbi or mpi?  

Taz

My Engine has the fuel rail with 8 ejectors,EFI Engine
Going back the boat this Friday with a new Fuel Regulator 

will keep you all posted

Taz

Fitted new regulator and it still stalls at idle

rasbury

And the filters?

rasbury

How long since plugs and stuff?

aero3113

It's possible your RPM gauge is faulty,when reading 600 it could actually be lower causing the engine to stall. 

taza

Guys

Plugs,Dissy,Rotor,Oil,filters,Leads all been replaced  600rpm is the correct speed, 600RPM on dash gauge also on Rinda Scan tool showing the same

rasbury

cleaned flame arrestor? Have not heard that mentioned....beyond that my mind says your not getting enough juice/voltage to the plugs at low rpm or a fuel restriction...new boat to you? Looks like your a new member....ask PO if this has been an issue in the past?

rasbury

and I'm very new to figuring this stuff out and usually equate to a car which I know does not always apply---if you have a bad/failing alternator is it possible it is draining the batteries/electrical system so at low rpm it is not getting enough juice to keep it running? Or bad batteries? Does the alternator provide power to the engine or does it go through the battery and then the engine? Just talking "out loud" here looking for ideas. He has done everything I have seen in other posts with similar issues...

dalek

With reference to Rasbury's posts above, is it possible you could try running the engine with the shore power plugged in and the charger on?

rasbury

someone will chime in that knows way more than me...I'm probably way off base as normal!

taza

Replaced the arrester with a new one, and I have had the shore power connected, battery voltage is OK and alternator is fine.

Going the boat this weekend to have another look

dalek

Did your scan tool show sensible air intake and coolant temperatures?

raybo3

Is it possible that the neutral safety switch is out of adjustment????? 

Taz

i sent the new faulty fuel cell back and they sent me a new one back, fitted the fuel cell and so far it's been running OK not stalled once, going back tomorrow to try it again, The pressure readings for the new fuel cell are
Low Pump 10psi Old pump 18psi
High Pump 50 psi Old pump 54 psi 

My thinking is to much fuel being delivered and flooding the Engine at low revs ?????