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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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1988 Mastercraft ProStar 190, Ford 351 engine Symptoms: Upon

Customer Question

1988 Mastercraft ProStar 190, Ford 351 engine
Symptoms:
Upon initial start, motor will run strong but only for limited amount of time depending on increase in RPM. For example,
15 seconds @ 3,000
1 minute @ 2,600
3 minutes @ 2,300
6 minutes @ 2,100
Continuous @ 2,000
Strangely, after the motor has stopped a few times, the motor will begin stopping more frequently. For example, after a while, the motor will only run 1-2 minutes @ 2,000 rpm before stopping, whereas before it ran continuously. This eventually happens after the motor is start and stopped throughout a 1 hour period. Motor stoppage just seems to happen more frequently as the day progresses. And, hot starts are very difficult. usually require several throttle pumps or, must pour a small amount of gasoline directly into the carb. Motor then fires immediately.
At one point during the trouble shooting process, we wanted to determine if the issue was related to the carb not getting enough fuel. We were driving the boat, removed the carb breathe. When the motor began to stall, we sprayed WD-40 into the carb to see if the motor would continue running. It did not continue running and stalled. Was reluctant to attempt the same test with spray starter fluid for fear of fire or engine damage.
Engine temperature gauge reports 115-125F during operation. I understand normal operation is 140-160F
Replaced:
Fuel Pump
Coil
Relay
Submitted: 2 months ago.
Category: Boat
Expert:  Tan replied 2 months ago.

Hello Britton. My name is Tan.

Try running the engine on a different fuel source. Disconnect the fuel line at the engine coming from the fuel tank plug the line.Then with a gas can and a short piece of hose connect the hose to the engine. Secure the gas can. Run the boat does it run better?

You symptoms are of fuel starvation this could be debris in the fuel tank, clogged or kinked vent line, failing anti siphon valve or a bad fuel supply line.

We have to separate the engine from the boat side fuel system. This way we know if you have fuel supply issue or an engine issue.

Does this make sense?

Customer: replied 2 months ago.
I forgot to mention that we did run a temporary fuel line test where we ran a line straight from the tank to the fuel pump. No change.Should I try to inject some starting fluid when the engine begins to stall? (similar to my experiment with the WD-40)
Expert:  Tan replied 2 months ago.

Did you do the test as I outlined?

Different fuel tank?

Customer: replied 2 months ago.
I was just providing another data point about bypassing other in-line devices (fuel filter/gascolator). Will perform your "different fuel tank" recommendation then reply with results. Thanks!
Expert:  Tan replied 2 months ago.

Ok

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