Engine only starts at full throttle.

Here is another data point for this problem.
After starting the engine and letting it run for 15 seconds or so I shut it down. If I immediately restart the engine, it starts at idle just like a normal engine. However, if I wait 10 minutes to start the engine, then I must again use full throttle. This sounds to me like a leaky injector mentioned above.
If this is the case, can I find the leaky injector and replace it, or replace all eight injectors on that engine?
As I mentioned above, is this something I can do myself?
 
Flytrade said:
Here is another data point for this problem.
After starting the engine and letting it run for 15 seconds or so I shut it down. If I immediately restart the engine, it starts at idle just like a normal engine. However, if I wait 10 minutes to start the engine, then I must again use full throttle. This sounds to me like a leaky injector mentioned above.
If this is the case, can I find the leaky injector and replace it, or replace all eight injectors on that engine?
As I mentioned above, is this something I can do myself?
Click to expand...
Read this first. The weakest link on an injector is the electrical connector. Be very careful removing the clip on connectors, and very careful connecting up to new injectors.
go to the fuel delivery section to see what you are up against.
https://www.dropbox.com/s/x84y48g0spxe64m/Mercruiser_Service_Manual__31.pdf?dl=0
 
Little tricky on the install, easy to pinch an O-ring . Don't throw any old rings away until your done
 
Most injector issues can be fixed by cleaning/rebuilding. As noted above, at 16 years old, this would be a good idea to do regardless of whether or not you're having an issue. The good thing is that there MUST be fuel injection shops near you. In fact, I think there's a guy names "injector man" (or something like that) that does online stuff, but is in Florida. But there has to be others.

The question will be, what's the wait time right now. However, some places may have rebuilt injectors that they can swap for yours. I would definitely look into rebuilding rather than replacing - rebuilding is a fraction of the cost of replacing.
 
At this price I think I should order a set and then hire someone to install them. What do you think?

From Amazon
(Set of 8) OE# 0280156081 885176 12567905 Fuel Injectors For Marine Mercruiser V8 350 MAG 5.0L 4.3L 6.2L
Brand: Luyuan

Price: $75.99
 
Don't even think about going there, Chinese junk. Problem with cleaning what you have is that poorly designed injector plastic gets very brittle and break off real easy. Talk to John he'll tell you all about cheap knock-offs.
 
Maybe someone has said this but have you seen if you are losing fuel rail pressure by checking the Schrader valve. This will tell you if you have a leaky injector.
 
dvx216 said:
Maybe someone has said this but have you seen if you are losing fuel rail pressure by checking the Schrader valve. This will tell you if you have a leaky injector.
Click to expand...
I do not have any way to check the fuel rail pressure, but I do understand it could be a pressure regulator problem versus an injector problem. It looks like I will need to get in touch with Mobile Marine Mechanic. Can anyone recommend someone in the Bradington Florida area?
 
Another thing to consider. Our fuel tanks have anti siphon switches on the tanks rather than valves. They close when the engine switch is off and open when the engine switch is on. If one is stuck open, after you shut down the engine fuel can back flow back into the tank. Not sure why SeaRay does this other than as a safety feature. I am having issues with mine and at times need to do exactly what you are having to do. It is the end of the season, so on the troubleshoot list for the off season.
 
Korkie said:
Another thing to consider. Our fuel tanks have anti siphon switches on the tanks rather than valves. They close when the engine switch is off and open when the engine switch is on. If one is stuck open, after you shut down the engine fuel can back flow back into the tank. Not sure why SeaRay does this other than as a safety feature. I am having issues with mine and at times need to do exactly what you are having to do. It is the end of the season, so on the troubleshoot list for the off season.
Click to expand...
Wow, I have never heard of that. This adds complexity to finding a solution.
 
Korkie said:
Another thing to consider. Our fuel tanks have anti siphon switches on the tanks rather than valves. They close when the engine switch is off and open when the engine switch is on. If one is stuck open, after you shut down the engine fuel can back flow back into the tank. Not sure why SeaRay does this other than as a safety feature. I am having issues with mine and at times need to do exactly what you are having to do. It is the end of the season, so on the troubleshoot list for the off season.
Click to expand...
Basically any engine that employs an electric fuel pump will have a way to shut fuel off. Sea Ray employed Parker Skinner 1/4" NPT 12vdc solenoid driven valves. As long as you have power to the valve, it is open. I personally have had a hard time with that as my engine room is routinely 180 degrees in the summer runs, and these solenoids are rated lower than that. There is a knurled knob on the side of the valve that lets you bypass the solenoid should it fail.
This explains it.
http://clubsearay.com/index.php?threads/parker-skinner-fuel-solenoid-manual-overide.23308/

Be aware that on my boat and maybe yours one of the valves is mounted upside down, so you may not be turning it on when you think you are.
 
Advancing the throttle on a cranking engine does nothing for fuel delivery. The fuel pump engages with the ignition in the on position to pressurize the fuel rail.
 
I just checked OEM injectors on mine, they are $350-$400/ea. Yikes :eek:

NjIyMjU0-74fe9c17.jpg
 
Flytrade said:
I do not have any way to check the fuel rail pressure, but I do understand it could be a pressure regulator problem versus an injector problem. It looks like I will need to get in touch with Mobile Marine Mechanic. Can anyone recommend someone in the Bradington Florida area?
Click to expand...
Harbor freight tester is $19. Would get you through this diagnostic and help guide you.
 
This doesn't help you, but to correct the earlier posts, this is not indicative of an IAC valve as you now know. If faulty IAC, the motor would not idle. Full throttle back to idle would stall the motor.
 
Not sure if this is the case with Mercruiser MPI, but with other EFI systems I've worked on ...

If you crank it over at WOT, the ECM will purposely not fire the injectors even though the fuel pump came on and you have fuel pressure. I think this is so you can start even if flooded.
 
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