Fuel rail pressure

[SeaRenity]

I have had this problem since I owned this boat. The engines are 350 mag horizons, and the issue is that if the boat sits for a few days they have to crank for 5-7 seconds before they start. If I just energize the fuel pump 3 times by cycling off the switch it appears I pressurize the rail and they almost start right up. While running my fuel pressure at idle is 40-42 psi.
My question, is it possible to lose rail pressure when the boat sits? Is there a check valve not working, does the fuel regulator control loss of pressure? Any ideas or help?
thanks
Rich

 

[ttmott]

Hey Rich - It is desirable the fuel rail pressure remains when the engine is not running. The worst thing is an injector that is leaking and unfortunately usually the most common issue. A leaking injector not only affects performance but will wash down the cylinder walls of lubricant and then consequently also contaminates the oil with fuel. However there are issues with the cool fuel systems contaminating the fuel system causing the pump check valve to not seal or the pressure regulator not seating. The injectors themselves have screens in the inlets so the most common cause of injector leakage is corrosion. With all that said, there isn't much volume in the system so any minute leakage will drop pressure rapidly.

 

[paulswagelock]

It is odd it is both engines (your description suggests it is). If it is both, then it is likely something that’s common between the two motors like fuel lines, fuel pick ups, etc. rather than the same failure on both. However, given the age of the boat, it could be any of the things Ttmott suggested.
Watch for fuel dilution in your oil. That would be the only real risk with the issue.

 

[SeaRenity]

I don't think it's the injectors as the starboard engine have been replaced.
It is both engines that have the same issue, do other owners of a 350 mag have similar issues???
The cool fuel module has been replaced on both engines and I did notice sludge ( dissolved paint ) around the regualtor -- do you think the reguator could be the reason for losing rail pressure????
I know owners of older 340s with larger engines that just start up like cars - immediately!
If I am not losing pressure via fuel injectors than where???
thanks
Rich

 

[scoflaw]

Fuel injected motors take a little bit longer to catch. Normal. Maybe your exaggerating with the 5 to 7 sec.

 

[ttmott]

These FI systems start almost instantly. All they need is the cam position sensor to roll over the pickup and the ECM will fire the engine as it now knows where the firing sequence is.
As you could imagine it wouldn't take much of a leak to bleed down the pressure so quite possibly the pressure regulators....
It's odd that both engines are suffering from the same symptoms.

 

[Lazy Daze]

I see this quite a lot with these engines, whether 5.0L, 350MAG or whatever. Some tend to start a little faster, some take a couple more seconds after sitting for a while. I honestly wouldn't worry about... especially since you have said it's been happening for a long time and, it sounds like, it has never gotten worse. Unless it starts to change and gets noticeable worse, don't worry about it.

 

[Espos4]

http://clubsearay.com/index.php?threads/delayed-start-on-5-0-normal.98237/#post-1134356