High Fuel Pressure

[ralt962 11]

I've done a complete engine rebuild with a mild cam.  I wanted to see if others had an issue with fuel pressure.  Finally getting to start the thing, running at break in around 2000 rpm.  I started getting fuel coming out the vents.  Tried all the float levels and cleaned the needle and seat.  (brand new Holley 600).  New Carter fuel pump.  Today I installed a pressure gauge to see if that is the issue.  Again at break in speed, I was getting up to 15psi.  Pump is rated at 6.5 max.  It started at about 8 or 9 and climbed to 15.  

I have a Holley regulator I'm going to install tomorrow.  See if that helps. 

I cant run it more than a couple of minutes before the fuel starts coming out the vents.  

 

thanks

[Brian Conway 270]

I am running a Holley 780 cfm with a Carter m6905 and a fuel pressure gauge.  Never have any problems and the gauge reads 6 ish psi.  The regulator may help ?  I have never had much success in the past using them.  I think a phone call or email to Carter stating your problems might be something to investigate ?  I have emailed Carter before and found them to be very responsive and helpful.  Brian

[1969_Mach1 334]

What Carter fuel pump is it?

Sounds like the motor is basically stock.  A stock fuel pump would probably supply enough fuel.

I think I'd select a different fuel pump before trying a pressure regulator.

 

[MN69Grande 203]

I would double check the specs on the fuel pump.  Some pumps are adjustable and there may be a way of changing it's output.  Otherwise if it is that far off spec switch it out.  I run a Holley fuel regulator with a Holley 7-11 pump.  The regulator keeps at 8.  Smaller Holley carbs supposedly can handle 9 over that it will over flow one way or another. 

Also the regulator will fix your problem I think but if your pump is pushing higher pressure, deadheading it may create a failure waiting to happen with the pump.  Just my 2 cents.

[ralt962 11]

I'm running a Carter M6588.  spec'ed for 5.5-6.5.  But running 15.  I just installed the Holley regulator.  That did the trick.  Its running around 6.5 and the issues have cleared up.  

But MN69Grande, you have a good point.  If its running such high pressure, is it a failure waiting to happen.  

Brian,  thanks also good suggestion, I will get a hold of Carter.  Certainly seems like this could be a different problem down the road.

I do have to give credit to the Holley regulator.  Working as it advertised.  

Thanks for all the quick feedback.  Great suggestions.

[1969_Mach1 334]

The Carter M6588 is merely a stock replacement fuel pump.  Something is definitely wrong with it.  When you get some time its worth replacing.  The regulator worked but is merely covering up the problem.  Like MN69grande mentioned, there may be a failure waiting to happen.

Between the pump and the regulator I'd guess you are reaching pressures of 15 psi.  Just be a little cautious if there are rubber hose and clamp connections in that section of fuel line. 

[ralt962 11]

Thanks,  totally agree something must be wrong with the pump.   I'm not on the road yet so I have some time and will contact Carter and go for a replacement.  

The guys building the Roush crate motors recommended the Holley pump.  Not sure which one, but I'm going to look into that.  

Have never seen so many new parts give such trouble.  Seems there is no more bolt it on and go.  Need to verify everything.  

[MN69Grande 203]

The other option would be to run a return line to gas tank.  Then the extra pressure would be released out of the system.  But i'd still worry about that fuel pump going crazy.

[Print Dad 58]

Hello all,

Just want to say I think the best solution is change the fuel pump.

I am not a big fan of the regulators - -especially the cheap models

Something is wrong with the pump = =change it or I fear you will have other issues in the future

 

Just thoughts from the old guy- -Print dad -Sam

 

[1969_Mach1 334]

5 hours ago, ralt962 said:

Thanks,  totally agree something must be wrong with the pump.   I'm not on the road yet so I have some time and will contact Carter and go for a replacement.  

The guys building the Roush crate motors recommended the Holley pump.  Not sure which one, but I'm going to look into that.  

Have never seen so many new parts give such trouble.  Seems there is no more bolt it on and go.  Need to verify everything.  

Contacting Carter might lead you down a circular maze.  First thing to try is exchange it from where it was purchased.

The Holley mechanical fuel pumps I've seen that have lower fuel pressures designed to be used without a regulator are fairly poor quality.  Purchased one once, opened the box, looked at it., then returned it.  Their high end stuff will need a pressure regulator.  The Carter pump you have is a good stock replacement part.  Unfortunately, you just happened to get a bad one.

[ralt962 11]

I ended up buying an Edelbrock pump from Roush.  They have tested many units and exclusively use these on their crate motors.   I also got some information on why the Carters have issues.  So I'm sticking with what has been tested.  Roush says they have had no issues since shifting to the Edelbrock pumps.  I bought the street version since my engine is farily mild.  

I'm going to install the pump this weekend.