Engine redlining after starting

[Daviddaryl]

Hi, I have a mercruiser 4.3 v6. When I start the engine it immediately begins redlining. I have replaced the fuel pump and set the fuel pressure to 5psi and it still does the same thing. Does anybody have any idea what could be wrong?

 

[Grub54891]

More details needed. Did you look at the throttle cable at the carb? Is the throttle plate closed or wide open? Do you have a massive vacume leak??

 

[tpenfield]

Greetings and welcome to iBoats . . .

Well, you know it is not the fuel pump.

Go back to the basics - is the throttle position correct? Starting at little/no throttle? Are we talking a carburetor engine or fuel injected? Got a serial number of the engine to share?

 

[Bt Doctur]

We guess its a carb model with the 5psi
throttle lever fully advanced
incorrect operator procedure
gross base gasket/intake manifold gasket
missing pvc hose

 

[Daviddaryl]

Ok so it is a carburetor Setup. I have an edlebrock 4 barrel 600 cfm on it right now. The engine is a 4.3 v6 262 cu in. Could that be too big of a carb for the engine? I've seen threads say they use the 600cfm on this type engine, and I've also seen threads say that's too much. I recently used the carb calculator on summit and it said maximum of 500cfm.... I installed the intake manifold on myself with the gaskets and the gasket maker. So I don't think there is a massive vacuum leak. I don't know how to check if the throttle plate is open or closed. The throttle cable is not engaging the throttle linkage. So i believe it's closed?

 

[Paintman1960]

Ok so it is a carburetor Setup. I have an edlebrock 4 barrel 600 cfm on it right now. The engine is a 4.3 v6 262 cu in. Could that be too big of a carb for the engine? I've seen threads say they use the 600cfm on this type engine, and I've also seen threads say that's too much. I recently used the carb calculator on summit and it said maximum of 500cfm.... I installed the intake manifold on myself with the gaskets and the gasket maker. So I don't think there is a massive vacuum leak. I don't know how to check if the throttle plate is open or closed. The throttle cable is not engaging the throttle linkage. So i believe it's closed?

 

[Paintman1960]

Look down in the throat of carb, Plate will be closed mostly at rest,
Push throttle all the way, plates should be wide open ( WFO )

 

[Scott Danforth]

No, the 600 cfm carb is fine. However you have something wrong. Use posts 2 and 3 as guidance

 

[Daviddaryl]

Ok so the are the pcv valves supposed to be connected to the intake manifold by a hose? I just have them open with no hose on them.

 

[Grub54891]

Those hoses go the spark arrster< also called a air filter.

 

[Scott Danforth]

Hi, I have a mercruiser 4.3 v6. When I start the engine it immediately begins redlining.

Can you list your starting proceedure

 

[Daviddaryl]

I know I'm sounding dumb here, but I've been building this boat engine entirely by myself. I have had an incredibly hard time finding a mechanic that'll help me. Two shops have already turned me down due to certain parts not being available new for this boat anymore( it's a 96), and they won't install used parts. Another two individual mechanics have flaked on me...... with that said, I don't know what you mean by starting procedure. i just turn the key... the air filter i have on it is an edlebrock air filter, is that not the same as a flame arrestor? It doesn't have the connections like that picture... I'm gonna post a picture of the engine

 

[Daviddaryl]

This is the engine...

 

[Scott Danforth]

The air cleaner and fuel filter are not USCG approved.

 

[Daviddaryl]

Should I chuck that air filter and get an actual flame arrestor?

 

[Daviddaryl]

The air cleaner and fuel filter are not USCG approved.

The air cleaner and fuel filter are not USCG approved.

Oh OK ok, when I bought the carburetor, that was the air filter and fuel filter that the instructions recommended. But the instructions are not specific for the marine carb...I will get marine parts.

 

[Daviddaryl]

Any recommendations for the air filter and fuel filter?

 

[Scott Danforth]

You need a marine spark arrestor and a fuel water separator before the fuel pump

 

[Scott Danforth]

Which carb do you have?

 

[Daviddaryl]

Ok, I do have the fuel water separator before the fuel filter...I have the edlebrock 1409 on there