I'm currently running a Holley 80 GPH mechanical fuel pump with an Edelbrock 600 CFM carb on my mostly stock 289 engine with the exception of being bored .30 over in my 65 fastback. According to Holley specs. the pump puts out 7.5 psi of fuel. I'm told that Edelbrock carbs run best at about 5.5 psi. I did notice after I ran the motor for the first time the other day that I am smelling some fuel and upon shutting it down after 10 minutes of idling I was unable to start it back up due to it being flooded. I pulled my plugs and they were a little wet and smelled of fuel. I plan on trying to tune the carb tonight but did notice when I ran it last I was idling right at 1000 rpms and when I had adjusted the idle screw on the carb I wasn't getting any change in idle. FYI, the carb is brand new. I am running stock mechanical fuel pumps on both my 66 stang and 70 Bronco with Edelbrock carbs and have no problems with flooding. I know Holley says that a fuel regulator is not required with this pump but I wanted to see if anyone else had some insight on this??

 

yes. get a regulator and gauge.
i ran my edelbrock with only 4.5 psi. holleys need 6+

 

7.5 is not much pressure for a Holley carb, but it may be enough to blow past the float seats on an Edelbrock...I do not know. I run 6.5-7 in my Holley HP carb using my Aeromotive fuel system with no issues. I have run as much as 10 with out floading it at idle.

Do you have the bowl level set correctly? Is your idle set correctly? Do you have any unplugged vacuum ports?

You could put a pressure regulator on this, but I am not convinced that is your issue.

 

I haven't messed with the bowl level although I had a factory mechanical fuel pump on for a bit and had no issues with that. The reason I changed to the holley pump was because of the chrome finish. My entire underhood is chrome as I plan on using this car for shows. If I could have found a factory pump in that finish I would have never swapped it out.

As for the idle, I am working on that. I couldn't get it to idle below 1000 rpm's the other day but it was still pretty cold and hadn't had the chance to warm up before it shut off.

No, I don't have any unplugged vacuum ports. I made sure to double check this before I started it.

 

that seems like a lot of pressure for a street engine. IMO I'd get a regulator and run it no more than 5 psi.
JLG

 

A pressure regulator is always a good idea. It does two things
1) It keeps too much pressure from being sent all the way to the carb to prevent seal blowout as already mentioned and fuel bowl flooding as you shut down (That gas smell)
2) It keeps your power consistent so if the pressure does dip when you're flooring it you won't notice.

 

I was wondering if this is why my 65 seems to run rich. I have an Edelbrock 650.

I got this Summit fuel pump that puts out 8 psi.

http://www.summitracing.com/parts/SUM-250024-1/

I was wondering if I should have gotten this Edelbrock pump. It puts out 6 psi.

http://www.summitracing.com/parts/EDL-1725/

Sorry for the thread hijack, but I figured it is all related info.

 

Do what you want, but I would first check your bowl fuel level. It should be right below the sight port. If you cannot get the level to stay there while the engine is running, then maybe the fuel is blowing passed the seal due to too much pressure. That is the only way a fuel pump could cause a carb to run rich. If the fuel bowl fuel level is consistent, then you have another problem.

As for the advantages of a regulator, yes they can help keep your pressure from being too high, but it does nothing for low pressure so they really do not help even out your pressure unless your pump is capable of high pressures like 18-20psi. Regulators are also not pin point accurate. I notice a .5psi swing on mine from month to month.

So, do what you want, but I would start by checking the fuel bowl levels go from there.

 

I would absolutely run a fuel pressure regulator. If I remember correctly, when I ran an Edelbrock carb, it required 5-5.5 PSI. If you run more pressure than the carb is designed for, you're going to have issues with flooding and blowing seals/gaskets.

 

tx65coupe: leave the pump as you have it and put a regulator inbetween to put the pressure to around 4.5 or 5psi, adjust your floats to that. that's at least the idea