A little fuel system info

[Mr.Mopar]

Just for kicks, I installed a Carter high performance mechanical fuel pump for my small block 340. It was advertised to flow 120 gph at around 6 - 7 psi. When I installed a fuel pressure guage on the car, at start-up, it was around 6 psi, just as advertised, but when it got warmed up the reading fell to 4 psi! I checked all fuel filters and they were fine. I did have a Carter electric fuel pump still on the car mounted back at the tank. It was to flow 72 gph at 6 - 7 psi. I spliced it back into the system and ran both the electric and mech. pumps. Now I have 6 - 6.5 psi at all times. I had no idea that the mech. pumps were that bad. I am going to keep it that way for now, with both of them operating. I wonder what the psi would have went to when I hit the Nitrous switch! Ouch! I could see the melt down ahead. If I wouldn't have installed a fuel pressure guage on the car, I could have mis-diagnosed problems for a very long time. My suggestion to everyone is to never take the factory specs for granted on anything and always check for yourself what is actually going on. There are too many variables on some equipment and I have just proved it. Now, what else can I dig up that I've been wondering about....mmmmmmmmm.

[JVMopar]

I've had stock mechanical fuel pumps drop to 2 psi with a 2bbl on the dyno. I thought it was a bad pump so I replaced it with another and it did the same thing. The spec. for the pump was 4.5 psi

[charger_dan]

I hear ya!

I once installed a brand new Carter Street Mechanical Pump 6903 on my 440.
It was factory rated at 120gph and 6psi.

I checked cold pressure at start up, and it was putting out 7-8psi at idle
and flooding my carb!

I wound up having to run a regulator at the carb (a good idea anyway).
Got 5 years of intermittent use out of that pump before I had to replace it.

In my opinion, Carter's quality control has gone downhill.

[cuda66273]

Just remember that fuel pressure is a measurment of resistance in the system and not a true indicator of volume.

Let's face the facts...what kind of quality can we expect from a $69.00 pump......Summit probably pays around $48.00 or less for them, the fctory makes $20.00 so the true manufacturing cost is probably around $25-30...you just don't get much for that kind of money these days...

Have a look at the new BG220RR pump, now available, it has a bypass at the pump like the BG400's and only requires a short
-10 return line from the pump to the tank. Allthough not recommended for a daily driver, for a weekend cruiser and bracket racer it's great and will handle 450 HP easily.

Priced at $269 it's a great pump and until the Enduro's come out in Oct of 2002...(and that's not a typo.....still waiting, factory say's maybe Oct 2003 now)...the RR pump is the way to go.

For more continuous duty cycles the BG220 HR pump would be a better choice but requires a -10 from the carb back to the tank.

[Ausydad]

My daily actually ran dual Holley 450's with a Holley blue pump rated @ 110 gph and 14 psi with an Aeromotive regulator set at 6 psi according to the gauge at the carbs. Never had a problem, but also never trusted advertising....