Mercruiser TBI Injectors interchangeable with automotive?

[Jughead22]

Hello,

I am having trouble finding out if I can replace the injectors on my 1999 4.3L TBI with 4.3L GM injectors.
The reason I am asking is Merc only sells as a kit and they want $1200 here in Canada!! All I need is an injector not the entire throttle body.

If anybody has any information I'd love to hear it!

Thanks in advance.

 

[Jughead22]

Re: Mercruiser TBI Injectors interchangeable with automotive?

Hello,

I am having trouble finding out if I can replace the injectors on my 1999 4.3L TBI with 4.3L GM injectors.
The reason I am asking is Merc only sells as a kit and they want $1200 here in Canada!! All I need is an injector not the entire throttle body.

If anybody has any information I'd love to hear it!

Thanks in advance.

Engine Serial number: OLO82558
Mercruiser lists the injector part # as: 852956A1

I have found 4.3L automotive injectors (part # 5235203) but they are made to operate around 12psi while the Mercruiser injectors are made to operate at 38psi.

Any ideas if the GM injectors will handle the higher pressure?

 

[Pete104]

Re: Mercruiser TBI Injectors interchangeable with automotive?

Not sure on the injectors themselves but I have cleaned them with good results. You'll need the TB gaskets that are the same, that I know.
I question that 12 psi, that ain't very much!

 

[Technorunner]

Re: Mercruiser TBI Injectors interchangeable with automotive?

The higher pressure are probably to get them to flow more then the auto. Unless they have a problem with steamlock in the injectors but i dubt it. Thats the 2 main reasons i can think of to have higher pressure. But my best guess are the Flow part.

 

[TilliamWe]

Re: Mercruiser TBI Injectors interchangeable with automotive?

...
I question that 12 psi, that ain't very much!

I agree, that *can't* be right. The fuel pump in a car produces WAY more pressure than that.

My 1997 5.7LX EFI Gen + had TBI and it was the same as the one in my 1987 and 1990 Chevy G20 vans. So if I were you, and you really think the injectors are the issue, I'd clean them. Then if that doesn't help, I'd get some from a junkyard and see how they work.

 

[fossill]

Re: Mercruiser TBI Injectors interchangeable with automotive?

Engine Serial number: OLO82558
Mercruiser lists the injector part # as: 852956A1

I have found 4.3L automotive injectors (part # 5235203) but they are made to operate around 12psi while the Mercruiser injectors are made to operate at 38psi.

Any ideas if the GM injectors will handle the higher pressure?

Vaguely remember that 35 psi was the regulated fuel pressure of fuel injected vehicles back in the day of twisting wrenches

 

[dan t.]

Re: Mercruiser TBI Injectors interchangeable with automotive?

Yes 12 -14 lb psi is normal for automotive tbi, on small blocks anyway, some 454 run up to 30 lb but the flow rate would be too high for a 4.3.

 

[TilliamWe]

Re: Mercruiser TBI Injectors interchangeable with automotive?

Yes 12 -14 lb psi is normal for automotive tbi, on small blocks anyway, some 454 run up to 30 lb but the flow rate would be too high for a 4.3.

So they are using an internal pressure regulator to reduce the fuel pump pressure down to that number at the injectors? If so, Mercruiser is using the same thing. In the form of a pressure regulator mounted on the "Cool Fuel" system.

The injectors "just have to be the same". that's got to be one of the only reasons Mercruiser used it, cause it was already engineered for them.