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James, Marine Mechanic
Category: Boat
Satisfied Customers: 4111
Experience:  12 years Certified marine mechanic, performance boat builder
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We have a 1996 ford 351 5.8L EFI engine Volvo Penta in a 1996

Resolved Question:

We have a 1996 ford 351 5.8L EFI engine Volvo Penta in a 1996 26 ft. striper. When the RPM's reach about 2900 on the tach and we are not quite planing yet the engine surges rapidly and it holds the rpms at 2900 and will not ggo any more. We have changed the plugs, wires, fuel regulator etc. Could the problem be in the ECM? Thank You for your time. LOUIE also where can I get a reasonably priced ECM ,will an automotive one from a parts house work? the problem is we are at the bottom of Baja, Mexico...
Submitted: 6 years ago.
Category: Boat
Expert:  James replied 6 years ago.

Hello, welcome to JustAnswer.


I doubt this is your ECM.


First, make sure you are getting good gas. You must use the premium grade in Mexico.


The surging indicates that you have a vacuum leak in the motor, or air in the fuel lines.


Check that all of the fuel lines are tight on the vacuum side of the fuel pump. Notice any cracks in the rubber or any pinched hoses.

Replace the water separating fuel filter, water in that can cause fuel starvation as well.


You need to check your fuel pressure when the problem is occurring. That will require a fuel pressure gauge attached to the fuel rail and running the boat, in the water, until the problem occurs and you can get a reading. You are probably going to find it is dropping off. If this is the case, replace the fuel pump.




Customer: replied 6 years ago.
we did check the fuel pressure on the rail while running it. Fuel is good and the high grade. The RPM's are always the same they always cutout at the same RPM and it always smooths out with just a small pull back out the throttle but is not enough RPM"s to make the boat plane. The rapid engine surging is very consistant in its very rapid rythum and and does not even make the tach move the needle as it holds the RPM"s constant. all vaccum hoses and fuel hoses have been checked and are good they have been sprayed with propane to check leaks as well. ?????
Expert:  James replied 6 years ago.

Check your for loose ignition coil ground wires, and the coil(s) for cracks or signs of carbon tracking.

Otherwise, you are going to need to have the ECM read for fault codes. You may have a faulty knock sensor, cam or crankshaft position sensor, or throttle position sensor.


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