Won't restart for 30 - 60 minutes

[Cobalt226]

1999 7.4L MerCruiser with Alpha One - Serial number OL362290 - engine runs great and always starts instantly on initial start. After cruising and stopping it will fire to restart and then die and will not start again for 30 - 60 minutes. I have replaced water pump impeller and have added a check valve to cooling system to keep water from backing up into fuel cooler. Any ideas on issue and fix?

 

[alldodge]

You have a 99 7.4L with an Alpha drive? Your serial number says its an MPI and I would bet you have a Bravo 1 drive.

What your getting into sounds like vapor lock. The check valve and also installing a booster pump is what Merc recommends, that and along with running your blower and letting the motor idle for a while to cool down. All these things help including the check valve as you mentioned.

The only one I know that really works is routing the return line from the fuel filter back to the tank. Some have another fitting in the tank and others Tee into the gas tank fill hose.

 

[redneck joe]

my solution was a rebuilt carb for that exact issue

 

[KJM]

had a similar problem and it turned out to be a very clogged up spark arrester starving the engine for air (I think). I also changed the rubber fuel lines in case they were cracked and sucking some air. at least if the motor runs good for the first half hour then its probably not something too drastic and/or expensive!

 

[redneck joe]

had a similar problem and it turned out to be a very clogged up spark arrester starving the engine for air (I think). I also changed the rubber fuel lines in case they were cracked and sucking some air. at least if the motor runs good for the first half hour then its probably not something too drastic and/or expensive!

yeah that helped mine; took a whole can of carb cleaner

 

[Cobalt226]

AllDodge, you are correct and my mistake. I do have a Bravo One, not Alpha.

I took the boat this week to my local marine which is also the Cobalt dealer. They could not get boat to do what I have described. It ran great and restarted every time no problem. They have no ideas for me on how to keep this from happening again. Very frustrating!

Redneck Joe, I have fuel injection and no carb.

AllDodge, since I have already installed the check valve, can you tell me more about the booster pump and steer my in direction of what I would need to buy?

Sure do appreciate the help!

 

[KJM]

could also be clogged vent to the tank creating a vacuum after the gas level starts to drop. if it happens again loosen the gas cap and see if it helps.

 

[Cobalt226]

Thanks KJM, I have actually tried that and no help.

I called Mercury and was told about service bulletin 99-7 on vapor lock issue. http://www.boatfix.com/merc/bullet/99/99_07.PDF
Also found out about the booster pump kit #862264A7 that can be installed. I have read on other forums that this helps most of the time. The kit is expensive at around $400 and I am hoping that my son in law can install.

 

[alldodge]

Looks like Merc advised of the kit. Hear it does help but its also not a 100% fix. The kit has all the instructions of how to install and should not be a big issue. Another thing I have found that helps, and IMO helped me before re-routing my return line. I use only E-0 gas with no Ethanol. Only issue with E-0 is availability in your area