37L Mercruiser Dies at High speed

"This is my first posting on t

"This is my first posting on this site and I hope someone can help me.
I have owned a 1987 4-Winns with a 3.7 liter, 4 cylinder, 165 HP Mercruiser engine for about 5 years. It has always run well and is thoroughly winterized each fall including replacing the fuel filter at both the pump and at the carburetor (both are usually very clean). There is not a fuel/water separator installed. Fresh water use only.
Near the end of the season 2 years ago, the engine quit when attempting to reach high speed at full throttle. It restarted immediately but quit repeatedly under similar circumstances. I removed the flame arrestor and looked down into the carburetor while someone accelerated at full throttle and it looked like someone simply shut off the fuel supply to the carburetor at higher throttle. Flow from the jets just stopped. The engine will run all day at partial throttle (up to about 25 MPH) and will reach full speed for a number of seconds (the time varies) before it cuts out. If you pull back on the throttle quickly enough as it starts to die, the engine will continue to run, but will cut out again at faster speed.
I first thought fuel pump and replaced it the following spring with a factory unit. I checked the tank vent and the fuel line from the tank to the fuel pump and both were clear. It started right up, but the same problem continued. I then rebuilt the carburetor with factory parts - the problem still continues. I feel like I am missing something very simple but don’t know where to look next. If anyone has further suggestions, I’d like to hear from you.
Thanks,
Tom"

"Try a electric fuel pump. The

"Try a electric fuel pump. The only thing that comes to mind if you have done all that work,is the cam follower is worn and not giving the fuel pump full stroke. This would be rare to say the least. I've only seen this a few times over the years. Mostly in the ford 2600 V6 but who knows? The electric pump will tell if the other pump is at fault or not. Good luck."

Tom:

Bet you a beer you&#39

Tom:

Bet you a beer you've got the fuel filter(s) located BEFORE the fuel pump.

Jeff

Another overlooked problem can

Another overlooked problem can be in the fuel pick at the tank. Most boats have an anti drainback checkball in the fitting (talk about restricting fuel flow) and a screen in the tube in the tank. On my personal boats I lose the valve in favor of a brass 3/8 fitting and have had no issues as of yet. The srceen should remain but checked and cleaned.

"Just today 7/12/06 I solved t

"Just today 7/12/06 I solved the same problem on my boat that started last fall. It was the distributor. The mechanical advance inside the distributor was not advancing the timing of the spark at higher RPMs. Therefore bad performance at higher RPM. Mechanic did everything ignition wise like rotor, cap , wires , fuel filters. He finally put on another distributor and the boat started to run like a raped ape. 1979 Classic 211 with a Mercruiser MCM 228 (305 V8 4-bbl)."