454 EFI does not like to restart...

[jarrett]

I have a 96 454 EFI Mercruiser inboard/outboard BRAVO. It’s a strong running engine with one exception. Once I run it at RPM (3K for over 5 minutes) if I shut down it never wants to start again. It’s very similar to vapor lock, but since its fuel injected I've kind scratched that one off. The crazy thing is once it’s cooled down (4 or 5 hours) its starts right back up on the first crank. <br /> The way I've been solving this problem of not restarting is I've been putting the throttle in neutral and manually giving it gas and turning the starter over & over & over. Doing this it finally catches and cranks up. But, now my starter burned out and I've replaced it but the problems with the fuel/starting still exist?? I have no idea what the problem is? I want to start with the fuel pump but before I started I wanted to get some different looks??<br /><br />Thanks,<br /><br />jarrett

 

[Elk Chaser]

Re: 454 EFI does not like to restart...

First off, believe it or not, check all your wiring connections for any corrosion. Focus on the battery, ignition and ECM wiring. Read a few things on this and many times the problem stems from corroded wires not providing good connections. <br /><br />The next items on the list are things that can not function properly when hot (as equipped) but work fine when cold: the coil, ignition amplifier, fuel pump relay, as well as any sensors the ECM may use.<br /><br />It does sound like a fuel delivery problem so checking your fuel pump is a good idea as well. Check the pressure when it's hot and that will quickly mark off that as the problem.

 

[jarrett]

Re: 454 EFI does not like to restart...

I'm going to attack the fuel pump this weekend should be a fun job. Do you think I can handle replacing the fuel pump? <br /><br />How big of a job is it? 1 -10 (10=huge *** pain) Keep in mind I work on the 3 : 1 ratio. For every 1 hour a normal person would take to work I need 3! <br /><br />Thanks,<br /><br />Jarrett<br />--if anyone else you like to post in please I'm not tearing into it until Sat (11 Sep)...

 

[tommays]

Re: 454 EFI does not like to restart...

dont just replace the fuel pump you need to test it with a pressure guage when the problem happens it could be fine <br /><br />being able to check the fuel pressure is very inportant on a fuel injected motor<br /><br />its costly to change parts with out haveing any idea if there not working correctly<br /><br />tommays

 

[jarrett]

Re: 454 EFI does not like to restart...

So let me get this right? I'll check the fuel pressure before cold crank up and then run the engine at speed to a while then shut down. At this point check the fuel pressure. If the pressure is the same after shut down as it was before crank up, I can rule out the fuel pump???

 

[tommays]

Re: 454 EFI does not like to restart...

efi is great but it is not user friendly when its not working it is a complex system with a lot of parts working together<br /><br />you need<br />1 manual<br />2 fuel pressure guage<br />3 code reader to see if the engine is putting out faults<br /><br /><br />you need to make or by a safe fuel pressure guage to go inline after the fuel pump<br /><br />and efi motor needs a very tight fuel pressure range you need to no what it should be for your motor ???37 min to 42 max??? what every the manual calls for<br /> after the guage is in you can use the boat and see if it is staying in the correct range i dont no if your boat has a way to return fuel back to the tank if the pressure goes to high again you really need a manual to no what to look for but with out a guage your just takeing a wild guess at the problem<br /><br />tommays

 

[Dunaruna]

Re: 454 EFI does not like to restart...

A leakdown test should also be done when testing fuel pressure. If the system does not hold pressure when shutdown it will present vaporlock type symtoms. Your manual will give you the specific test. ie: 250kpa for 10 minutes. If it doesn't hold pressure you could have a faulty pump, faulty return valve, faulty pressure regulator, dribbling injectors. <br /><br />Aldo

 

[jarrett]

Re: 454 EFI does not like to restart...

wow! Thanks for the insight guys! Really good info and I really wish I knew what the heck most of it means no really I do understand and reading the manual (which is back at the marina) will help. <br /><br />Has anyone ever had the same problem with this type of engine not starting after it heats up? Its just so crazy that it starts up when cold as if its a brand new motor... Well, I know what I'll be doing this weekend!

 

[Dunaruna]

Re: 454 EFI does not like to restart...

jarrett, the problem you are describing is common for ANY e.f.i., not just boats and not just mercruiser 454.<br /><br />Just to throw another spanner in the works, often heat related problems are caused by faulty electronics (ignition module/crank angle sensor etc). Usually the first test to do is code checking, then fuel pressure and so on.<br /><br />Good luck.<br /><br />Aldo