2009 GM 4.3L vortech stalls over 3000 RPMS

[4.3 3rd time a charm]

OK guys I need some good advice here- just installed a new 4.3L GM Vortech w/ Holley 4BBL.600 CFM.
seems to run fine under 3000 rpms. timing is good all adjustmets to carb seem good - runs smooth---but when you do over 3000 RPMs acts like someone hit the kill switch-no sputter or nothin. no warning just dies.

this engine came with a Carter electric fuel pump P4389 6 psi max internal regulated.

the marina mech. is telling me that this fuel pump can not handle the 600CFM carb above the 3000 rpms. he says I need a higher pressure fuel pump 9 to 14 psi? I do not want a fire-- or is he correct?

just a little history when I installed this new engine of course as I said it has the electric fuel pump and oil pressure cut out switch. My other two 4.3L had a mechaincal fuel pump and an additioinal conventional fuel filer and fuel water seperator-- the new engine manufacturer told me that I had to much restriction and to throw the additional fuel filter away and just use the fuel/water seperator. I did and the problems still here.

lwhen I installed the oil pressure cut out swich and the oil sending unit-I had to add length to the 1/8 piping to fit them both--could that be a probelm that the oil cut out switch is about 4" high off ther block now?

Lastly-- is the fuel pump suppose to be mounted higher than the fuel/water seperator as they are about equal in height..

I think there is nothing wrong with this new engine ( God I hope not) I think it is in the fuel delivery.
any help ideas and what about a more PSI rated fuel pump.

PS- I aslo changed the fuel/water seperator just to make sure there was no reristions there., cleaned the fuel strainer on the Holley carb.

I am lost /please help? :
Thanks
Grant

 

[cooter2506]

Re: 2009 GM 4.3L vortech stalls over 3000 RPMS

run it on an auxillary tank and see if problem is still there. If it is then it is a problem in the tank or your fuel vent line is plugged

 

[4.3 3rd time a charm]

Re: 2009 GM 4.3L vortech stalls over 3000 RPMS

cooter, what about the fuel pump pressure 6 psi max.? do you think that is a problem?
I will get an external tank and run it on that also. will report back if the problem is strill there--anyone else wnat to weigh in on this one?
Thanks

 

[Rocky_Road]

Re: 2009 GM 4.3L vortech stalls over 3000 RPMS

Are you using a 10 micron water/fuel seperating filter?

If so...you might want to check the GPH flow for the filter that you are using. I know that RACOR has both 60, and 90, GPH models....

 

[4.3 3rd time a charm]

Re: 2009 GM 4.3L vortech stalls over 3000 RPMS

Thanks guys, I was going to purchase a fuel pressure guage and do that exact thing tomorrow-and take it back to the local lake for a test run.- I have been reading a lot on Vapor locking--any thoughts on that?. 98 degrees yesterdsay in Kansas on the lake-- I have been running the blower all the time when the engine is running.. Here is something I just thought about Celiberty 180 1992 dog house over motor compartment-I reinsulated that doghouse with a very good sound deading insulation--perhaps the new insulation is making the engine compartment to hot? according to the post I have read on vapor locking and the Merc bulliten some posted awhile back.? I will check that temp also. I am just pulling at all straws here and hoping that something will click for conversation.

I will also check the micron rating on the water/fuel seperator- good point.

any more you might think about please let me know--I think the vent hose is clear, at least fuel vapors and fuel came out of it when the tank overfilled. Would it help to insulate the fuel line from the fuel pump to the carb.? by the way the Carter 6 psi pump max is rated for 72 GPH free flow is that enough volume Bubba for this 600 cfm 4 barrell Holley when she kicks in? I will do the fuel line pressure test but what about a 6 psi with 97 GPH free flow (Holley pump) would that volume be better and still use the same 6 psi max pressure?
I will report back on the fuel pressure readings and the temps inside the engine doghouse.
Thanks again gentlemen.any more suggestions I am open..

 

[4.3 3rd time a charm]

Re: 2009 GM 4.3L vortech stalls over 3000 RPMS

UPDATE: installed fuel pressure gauge and ran engine on muffs at idle untril warm. saw even 4 PSI on gauge pump is rated for 6 PSI max. 72 GPH free flow rate.--then the gauge dropped to 1 psi and held inbetween 1 and 2 Psi for about 2 minutes flucuating( engine stalled out) then went back up to 4 psi. very slowly when I restarted the engine--- Bad fuel pump?

Vent hose is clear took it off the gas tank and blew it out nothing restricting , check anti syphon valve while I was there and all is good with the steel ball and spring reinstalled on tank.
changed the fuel water seperator higher flow rate one. so is it the pump anyone think?

 

[Fun Times]

Re: 2009 GM 4.3L vortech stalls over 3000 RPMS

UPDATE: installed fuel pressure gauge and ran engine on muffs at idle untril warm. saw even 4 PSI on gauge pump is rated for 6 PSI max. 72 GPH free flow rate.--then the gauge dropped to 1 psi and held inbetween 1 and 2 Psi for about 2 minutes flucuating( engine stalled out) then went back up to 4 psi. very slowly when I restarted the engine--- Bad fuel pump?

Vent hose is clear took it off the gas tank and blew it out nothing restricting , check anti syphon valve while I was there and all is good with the steel ball and spring reinstalled on tank.
changed the fuel water seperator higher flow rate one. so is it the pump anyone think?

You might want to run the engine on an auxillary fuel tank and with a new fuel hoes with the fuel pressure gauge hooked to see if problem is still there, This way you will Know if the problem is on the engine side or the boat side.

 

[Don S]

Re: 2009 GM 4.3L vortech stalls over 3000 RPMS

http://forums.iboats.com/showthread.php?t=167561