Engine dies after 3-4 mins at low Idle

[redmen62]

Haven't had to post for advice in a while... apparently the boat thought I was due!

Engine: 1983 Mecrusier 228, 305 v8, ~1550hrs

Went out last weekend and while on plane cruising across the lake lost an engine, limped back on one and dung in the next day.. found my fuel pump was bad. I replaced the fuel pump and once I got fuel all the way through the system it ran great and fired right up, problems solved... not so much

It will run great when you dump some gas down the carb and run on it's own for 3-4 mins at 700-1000 rpm, when i bump it up to 1200-1500 rpm it will run for 5-6mins and then kill... dump gas down the carb and it'll fire right up and do the same thing all over again.

I used an automotive fuel pump for a chevy 305 because I couldn't track down an merc pump, and I also noticed that the temp gauge for the engine in question is now pegged to the max even when the engine is stone cold or not running

Any ideas what might be going on?

 

[Leardriver]

When my dirt bike did the same thing, it was a plugged vent in the gas cap that eventually caused fuel starvation. I would be tempted to take your gas filler cap off and see if it restarts.

 

[redmen62]

When my dirt bike did the same thing, it was a plugged vent in the gas cap that eventually caused fuel starvation. I would be tempted to take your gas filler cap off and see if it restarts.

I don't think that's the issue... there's the vent line from the tank that's clear. We filled up the other week and it spit out the vent just fine

I'll loosen it up and give it a try, I'm at a loss otherwise

 

[Rick Stephens]

If you pull the fuel line off the carburetor and stick it in a clear soda bottle, does fuel come out when you crank the motor, thus running the fuel pump?

• If yes, then the problem is probably crud in the carb, like maybe a plugged needle valve.
• If no, then you have a problem in fuel delivery to or from the fuel pump.

You need a marine fuel pump just for the ruptured diaphragm port. Important protection. Get one from iboats.