Engine won't start unless I use Wide Open Throttle

fespisito

Hey so I have a 2004 Rinker 5.0L volvo penta engine.  We have been doing some work on a bad head gasket as we are loosing a little compression and we are nursing it back to life to get some season out of it before a major repair.

Anyway, starting a few weeks ago the engine would turn over but not start.  If I use WOT to goose the fuel injectors it starts immediately.  Any ideas on what could be causing this?

212rowboat

that year/series of volvo had issues with the fuel pump on the front of the engine- it does both the lifting and the high pressure via separate chambers.  it's an expensive fix, but required.  the new model doesn't disintegrate as the old one does, launching little wads of black plastic chips throughout your fuel system.... the pending failure of this pump is usually accompanied by a high pitch whine.  

pistole

Did the engine start fine before? If so, look at what was done and work backwards.

FlyingBlind310

i had the same issue a few years back (5.0L merc)...i had cracked heads on both banks. coolant was seeping into 2 cylinders as the engine cooled and would not start without full throttle. she sounded ugly starting but eventually started. 

could your bad head gasket allow water/coolant in? 

fespisito

Thanks for your feedback guys. I may have all of the conditions you have mentioned. A whining sound has started to occur from the fuel pump. And you know we might have a water condition as well. Not sure of the extent.
Is there harm in letting it continue until failure, or do I need to jump on this? Trying to get through season without major costs

aero3113

A faulty IAC can make you use throttle to start also.

fespisito

Thanks, hadn't thought of that.   I will add this to my weekend work!!!