I purchased a Race Pump mechnical fuel pump and installed it a few weeks ago. The strange thing is after about 25 minutes of driving around the car shuts down due to a lack of gas. The next day I took it out again for a ride and roughy 15 min into it I noticed the fuel pressure gauge down to 4.5. 3-5 min later down to 2 psi and even shaking the car I could not see fuel moving around through the site glass. 3-5 min later it stalled again. Once it rests for a little while I fill up the bowls and is OK until 25 min later.

http://www.racepumps.com/index.html

hose is a #8 line and brand new, but someomne told me that there was some more rubber suppply hose in the back going over the tank and that maybe the extreme capabilities of the pump is causing that rubber line to collapse by sucking all the air from the tank???? maybe....

 

I had the same set up on my nova and it did the same thing. I spent time on the phone with the owner of the company who is friends with my engine builder and he told me there is something wrong with my fuel system. after sending it back and having it rebuilt for free and going through the whole fuel system again it did it again. So its gone now. My fuel system is 100% new and 100% within spec of his diagram so whats the problem? Just a bad design it is not reliable. That is the only time I ever got stuck in my nova

 

I also have one of those pumps and went through the same problems. After many conversations with the designer of the pump I ended up plumbing a return line from my regulator and that has seemed to eliminate the problems. I've not put too many miles on the car since I ran the return line so I can't give a 100% on this solution but it's what he told me from the beginning when I bought the pump and worked for a few 40 mile cruises after running it. I'm using a -10an supply and -6an return. I placed a large holley metering jet in my return fitting on my regulator to help maintain pressure in the feed side so it doesn't try and divert a large portion of the main feed to the return. If you don't already have a regulator then I'd suggest buying their regulator and plumbing a return line.

 

Or you could just get rid of it instead of wasting more money on something that you just don't need. The stock pump will support 600HP+ easily.

 

That makes way too much sense

 

I gave up on my racepump because of this issue. The problem is vaporlock at the pump. I tried a lot of things to resolve this without much luck. Racepump has a bypass orfice that wil allow you to use a return line and keep cooler fuel flowing through the pump but it still overheats if you idle around too much.

 

Thanks Tshort, 78 vette, gyopp thanks for your answers...I know where to go from here.

Mike and Yellow, I was looking for answers on why something was not working not to be told I was wasting money to fuel my engine, but thanks for your opinion.

And yes this engine will be north of 700hp+ (with NOS) so no, I will not use a stock pump.

 

No prob 76 Sting. If you have any other questions let me no I put allot of time into making it work properly with no success.

 

You guys have your tanks vented, right?

 

mine is like i said my fuel system is 100% to spec.

 

I fought the same problem all last year, my fuel pressure was fine for the first 1/2 hour or so then it would drop down to next to zero. I had been using a mechanical edelbrock pump for several years that worked fine even running nitrous. Long story short, I tryed two new pumps and replaced the rubber hoses with molded then FI hose then with metal lines except for a very small amount of flex hose at the joints. None of this helped.
I finally emailed Lars, he said the problem is with todays blended fuels. Basically the alcohol lowers the boiling point to where once everything warms up the fuel will vapor lock in the line going to the pump. This problem is made worse by a high performance mechanical pump, since it pulls harder, creating more vaccum in the supply line. Since putting any liquid under a vacuum lowers the boiling point, this causes the fuel to boil. I think I made my problem worse in two ways by running a large 3/8 return line. First I believe by constantly returning a large amount of fuel from the hot engine compartment I was raising the temperature of the fuel in the gas tank. Second I connected the 3/8 return line to a existing fitting on the top left side of the tank, by returning a large amount of fuel from the top of tank I believe the fuel was becoming aerated since it have to fall about six inches into a half full tank.
Lars answer was to either add a small pusher pump at the tank to keep the whole system under a slight pressure therefore raising the boiling point of the fuel or go to electric pump, which I am in the process of doing. From reading some of this other articles on fuel systems it appears that he recommends a orfice in the feul return line between .020 and .060.
Hope this solves both of our problems.

 

There are numerous aftermarket conventional mechanical fuel pumps on the market that can more than handle your setup. Even a 130 gph free flow conventional mechanical pump has proven to be just fine for feeding 800 hp, 10.0 cars for years, in spite of what a lot of people may say. Its hard to argue with what works. If it were me, I'd go with the old tried and true. Sometimes it makes more sense to cut your losses and go with what works. Why make life more difficult than is necessary?

 

That is a funny question because most of my buddies mentioned that being the issue. all is vented on mine...

Unless anyone else has ideas I guess it was not all it was cracked up to be


Holley blue, red or black? I was thinking black?

 

Of course I should have thought about that, Lars does know a lot The explainations have all made a lot of sence. I really like to tests all kinds of new parts hoping it will be a wise invenstment...this one, we'll let's not talk about that it did look promissing.

 

I mentioned it since sometimes the simple things are overlooked. On '71 or so and newer, stock tanks are not vented...

 

There has to be some type of venting on any tank. If not you would suck the tank in after a few miles. My 72 was vented through the charcol cannister. The vent line comes off the tank and runs to the cannister and the fumes are sucked into the carb. At least that is the way it used to work. None of that is hooked up but I still use the vent line for a vent and it is connected to the cannister but not hooked to the carb. I think I even have a vented cap on mine also.

 

100% I just removed the canister and left the line there..but never had a smell of gas.

 

Recirc line is a great way to maitain constant fuel pressure and keep cool fuel in the line. Just a caution here when u fill up the tank the fuel and it sloshes after a turn the fuel tries to flow out that vent. Yes there is a check vlv in line between tank and canister. But ya know what Murphy says. Yep, mine became a flow loop and gas continued to pour out the canister vent - right next to my hot header pipes and again yes it was 100*F that day. Kinda like a gas shipon it wouldn't stop flowing untill i popped the gas cap. This also caused fuel mixed with carcoal to be feed into intake below the carb on the EVC vent line.
Well since that i replaced that little check vlv. Another story is that when i replaced my fuel tank that check vlv was not availible so i had to go with the original. I already had replaced the original canister before filling it with gas and now have a replacement canister ready as this reminds me to swap the secound new canister in (while i have my splash guard out).

Regardless i still preach using a recirc line for any mechanical pump - using a orifice restriction of course. Keeps the fuel in line cool enough for any weather and fuel pressure stays constant at idle or WOT. If u vent the tank right at the cap - like most of us - u will be fine (to switch to vented cap only requires a vented cap). If u still vent through the EVC becareful not to top off and make shure your check vlv is in good working order. Yes venting without the orifice restriction will make tremendous amounts of vapor inside the tank from the high return line flow rate.:bb

cardo0

 

I have had an Aeromotive A1000 on mine for years with no issues. I do have a return line.

I'm not a fan at all of the Racepumps. Looks neat.....but there are way more people that seem to have issues than anyone with anything else seems to have.


JIM

 

The venting on earlier models was through the gas cap, not the tank. Often times, someone would simply buy a newer design cap for the old tanks. It was a frequent problem when guys would be able to drive a few miles then the engine quit. When the went to check the gas level, whoosh! the air would rush in and they could drive a few more miles. In extreme cases, the tank would buckle inward...