Fuel pressure bouncing????

[lucky7's]

I have a 2002 Mercruiser 6.2mpi. I have been trying to solve some engine problems for some time now in like 2 other dead threads.... I have a fuel pressure gauge hooked up to the fuel rail. I turn the key over to let it prime and the gauge goes up to around 43 psi and holds then drops to like 38 when it shuts off... When I crank the engine the fuel pressure gauge bounces back and forth really fast between 32-38psi... What in the world would cause this..

 

[lucky7's]

Re: Fuel pressure bouncing????

Im sorry the fuel pressure need bounces between 38 and 43 psi at idle..And it goes up a little but still bounces when i pull the vacuum line off the fuel pressure regulator..

 

[Fun Times]

Re: Fuel pressure bouncing????

Im sorry the fuel pressure need bounces between 38 and 43 psi at idle..And it goes up a little but still bounces when i pull the vacuum line off the fuel pressure regulator..

Well your fuel PSI is with in specks. Key on engine off will go up to 43psi, With the engine at idle with vacuum hose ON will be 38 psi pull the vacuum hose off it should go back up to 43psi. Is the gauge bouncing from 38 all the way up to 43 psi at idle? I have seen them bounce befor if I rember right something like 1-3 psi. THE BIG ??? IS what does it read while under a load all the way up to top RPMS.

 

[lucky7's]

Re: Fuel pressure bouncing????

The reason the fuel pressure was bouncing was because of two burned up intake valves. The compression was leaking back into the intake and making the fuel pressure go up and down.

 

[Fun Times]

Re: Fuel pressure bouncing????

The reason the fuel pressure was bouncing was because of two burned up intake valves. The compression was leaking back into the intake and making the fuel pressure go up and down.

Thanks for the info, Did you get it running right yet?

 

[lucky7's]

Re: Fuel pressure bouncing????

Yes I had the head reworked at a machine shop and it runs like it always has.