boathead

Hello Everyone!
Since the start of the season, I have been experiencing the following problem.
After launching the boat and cruising long enough to get the engines up to operating temperature, if I stop somewhere and shut both engines down and later try to restart 'em they both stall out after running for a minute or so. They won't restart until I let them set for 1-2 hours. I've replaced both the oem Merc spin on separators(35-807172) these are between the fuel tank and the electric fuel pumps. I also replaced the inline (35-807174T)filters after the fuel pumps.

These engines have fuel coolers located just after the fuel pumps, but I am wondering if it could be a vapor lock problem between the tank and fuel pumps, the metal fuel lines on the engines all have insulating tubes on them and the lines coming from the tank don't run in any high heat areas. I've had the boat for 6 years, stored it with a full tank(with sta-bil)and NEVER had the slightest problem. Could lousy gas make this happen? I have added only about 30 gallons to the tank I stored the boat with(170 gallon tank).

Any Input is greatly appreciated,

Paul

t500hps

If they are 2000 500EFI's, a buddy had the same issues. He installed the mechanical AND electric fuel pumps like they used on the 2002 500's and the problem went away (vapor lock is the issue)

Trippin

I concur.

Big Block Billy

Talk to Dave N. you will see his messages posted on this board . He is an absolute genious.

boathead

Thanks for the help, guys!
This reinforces my "vapor lock" suspicion.
I see on the BAM website even the older OL 60100 serial number engines parts list has the mechanical pump added, this WAS NOT listed in my original parts manual, looks like Merc must have found the problem.......

Paul

Inspector

I also had what appears to be a vapor lock issue but on 502 MPI engines. One of the threads suggested using Marvel Mistery oil in the fuel. It makes sense if the additive raises the vaporization point of the fuel. I have added it to my fuel but have not had the boat out since. Good Luck...

KAAMA

So Paul.....when are you going to have your boat up and running again??? Now that you pretty much know what the problem is, do you think you'll have the parts installed and ready for this weekend?

carney

check if the fuel vent is plugged with a mud wasp nest. I have see this alot.

boathead

inspector:
it's funny you should mention that, I just went out and got a gallon, thinking that it might help!
KAAMA:
Still trying to verify for sure that this is it, just went to Van's an got a couple of outboard primer bulbs, so when it acts up again I can "pump 'em up". I thought this may be better than ordering the pumps then finding that this isn't the problem
Go Ahead, Laugh at me!!!!!! Have fun in T.C.!
carney,
checked that out already, no problem there.

Thanks for your help, everyone, have a great weekend!

Paul

Michael1

I'd be worried about coking the intake valves doing this.

Michael