Mercury EFI 150-1996 trouble

[Jmcfarland]

I have been having an issue with my motor just quitting while running on plane. It always seems it does it after I switch the fuel tanks from one to the other. I have 2 switches one by the seat and one on the dash console and switch them both at the same time. I am thinking it has to be a fuel issue as it seems it just starves itself of fuel and dies almost instantly. I cannot keep it running when it does it. The motor just quits and completely dies. It will crank right back up with the key after this happens and run just fine and then it will do it again. It usually goes away after doing it once or twice- almost like it loses its prime or something? but today it did it about 5-6 times and really was pis.... making me mad I had the same problem occasionally last year but just switched the tanks today and it really was acting up. It has run a 1/2 tank of gas on tank 1 and I switched it today as I always do when I get to half. Anyway thought you guys might be able to point me in the right direction. I will answer any questions about it if you guys think you might know what it is. Appreciate the help as always.

[Durand Dan]

Classic fuel filter problem. Change em!

[Mike S.]

I have a 97 150 efi, and mine will do that when I get under a quqrter of a tank.  I had FFJeff out on White last summer and it did it 5 or 6 times as I was trying to get on plane.  My filter was new then.  But, it only does it when I am low on gas.

[champion_206]

Have you checked your anti siphon valve in that tank ?

[Jmcfarland]

No, I haven't checked the anti siphon valve nor have I changed fuel filters.

[Lightningboy]

Start from the tank, and check each of the fuel components in order.  Make sure to check the grey hose leading to the motor.  I know this is a link to another page, but it explains the problems with fuel lines and ethanol very well:

http://www.bbcboards.net/zerothread?id=526471

I switched mine last year, and cut open the old line & found it cracked.  These pieces can get stuck in your fuel system and cause intermittent problems.  I'd change to the new fuel line just on principle, and don't forget the bulb; stuck bulb valves can cause similar problems. 

After the fuel line, follow the fuel line and check each component for obstructions.  Be systematic, and you'll find the problem.

[Jmcfarland]

I have a new fuel filter and primer bulb on the way and will get them installed tomorrow. I asked a guy in my club who told me to check the bulb right after it happens to see if it is soft or not. It was soft and he said it could be a bad primer bulb. Another mechanic recommended that if the filter and bulb doesn't cure it to check the screen on the pick up line in the tank. Lets hope the bulb and filter fix it.

[champion_206]

just another tip for ya, make sure the primer bulb is not pointing down from the tank to the motor, make sure the motor end is not pointing down, either level or a slight rise to the motor

[Jmcfarland]

Turns out that I am a bigger moron than anyone could have predicted. After changing the primer bulb and fuel filter I headed to the lake today. Same results but after troubleshooting on the lake I determined it must be an anti siphon valve or the screen was plugged on the pick up line. Put the boat on the trailer and headed home to work on it. After taking out the pick up line and seeing that there is no screen on my pick up line and I could blow air freely through the pick up line and the only fitting between the tank and the switch valve I determined it was the switch valve. Upon finding this out I call my uncle who is a retired certified Mercury mechanic. He comes over and takes a look at the switch and that is when he realizes the problem. I was simply (jeez i am a duma***)turning the valve to far when I switched tanks and it was only letting fuel flow at a 1/4 of what it should be. I really didn't want to have to tell this story but maybe it will help a newbie like me in the future.