what do you guys think?

[benno440]

as some of you guys know i have a "racepump" brand mechanical pump on my 505 BB, i have just run 1/2" fuel line all the way with a inline check valve that was recommended by racepumps i also ran a 1/4" return line to the tank off the regulator, the car is a 68 charger so it has the single vent line that goes upto the tank.

now my question today i tried priming the line by putting compressed air into the gas cap and i noticed no fuel going through then i noticed that the retainer ring that holds the fuel sender in had popped out, (damn that check valve must have some pressure) so i refitted it and applied some rtv around the rubber for a better seal, i retried priming and noticed some air was still coming out around the rubber and fuel sender unit, are these tanks supposed to be super air tight? may my problem go away once my pump starts sucking instead of me trying to blow fuel through the line? maybe pull one way valve off until line is primed??

what do you guys think?

 

[67 coronet]

you should be able to prime it by sucking on some extra hose attached to the fuel line just before it enters the pump.(dont suck up any gas)putting air over fuel is a fluid dynamic that would require a huge amount of presure to move the fuel up that line.

 

[RustyRatRod]

I've never had to prime an electric pump.

 

[WP29440SE]

I've never had to prime an electric pump.

xs2 ... never once

 

[67 coronet]

I've never had to prime an electric pump.

its a mechanical pump guys.

 

[Meep-Meep]

The tank should hold a little pressure but but keep in mind the forces when you pump it up with air. I wouldn't go more than about 5-10 PSI. An area of 2' x 2' (576 square inches) will have 2880 lbs of force at 5 PSI! The sending unit seal should be compressed otherwise it will leak, so if you notice air escaping chances are it will leak. Also, don't use any RTV on that gasket. In my experience RTV does not hold up to gasoline.

Did you have the line connected to the pump inlet while trying to move the gas? If so perhaps that race pump won't allow any fuel to just pass through so you are just compressing air in the line. Try disconnecting it. Or try filling the line from the pump side using a small funnel. Just a little standing gas in the line may be enough of a seal to get things moving. Normally mech pumps do not have a problem puling fuel but I have no idea about the race pump. Also make sure your vent is completely clear or leave the gas cap off during this operation.

 

[RustyRatRod]

its a mechanical pump guys.

I know. That was my point.

 

[747mopar]

I fired mine last weekend, I didn't prime the fuel line (never have), I filled the float bowl threw the vent. It fired right up and had fuel to the carb in no time.

 

[benno440]

i expected that rusty haha, no going back now.

thanks for the help guys

 

[anmracing]

Convert to an electric pump. You'll be a lot happier when you do...

 

[benno440]

nah hell no.

my mechanical will outpump most electrics and theres no annoying noises and no extra wiring i have to put in.

main reason i ddidnt go electric is i rewired whole car then i have put matting and carpet throughout so you can understand i dont wanna rip it up to do more wiring

 

[747mopar]

You no what they say "keep it simple stupid". I'm with you on that, two bolts, two hoses, walla done.

 

[66 coronet deluxe]

Make sure your tank is still vented, try pulling that vent line off the tank, otherwise you will create a vapour lock. Don't ask me how I know. A good mech pump replaced and a thousand hairs later, I found my ramcharger had one because the bozo I bought the truck from removed the charcoal cannister and decided to plug the line with a bolt. Need venting to move the fuel from the tank.

 

[HT413]

If your sender grommet is blowing out it seems to me your tank venting isnt working, the grommet was never installed correctly, or both. Besides, I know my carter mechanical 'musclecar pump' is no racepump, but it's self priming like I thought all mech pumps are. Other thing to look at i suppose is maybe you installed the check valve backwards?

 

[383man]

Convert to an electric pump. You'll be a lot happier when you do...

He is right. If you have any vapor lock problems with this cheaper pump gas we have now the electric pump will help. Also the pump gas has more ethenal in it now and the fuel will boil on very hot days. The electric pump will also help that. It will help both problems because it is pushing fuel from the tank and fuel under pressure will have a high boiling point and the fuel under pressure will help fight vapor lock better. Its much better then having the fuel being pulled up under a vacum to the eng. It just works better as thats why I went right to an electric pump. And heck its a hotrod so whats a little noise right ? LoL ! But being a hot rodder all my life I always liked to hear a little fuel pump noise when I turn it on so I know its working. And they are making the pumps much quieter today. Good luck what ever you decide. Ron

 

[benno440]

thanks ron for the advice, honestly i have invested neally a grand in the pump, lines and regulator etc. for this mechanical, they reckon it will out perform any electric and is good for upto 2500hp which i definetly dont need but anyway, shouldnt have a problem with fuel here we get fuel from 92 - 98 out of the bowsers and sunoco 100 is readily available if i need it.

- - - Updated - - -

i have just ripped out the tank, filler neck and got them acid dipped i have bought fuel tank sealer,i am looking for new seals and lock ring, so once all back in i hopefully wont have a problem.

any recommend a place to get a good lock ring, seal and filler grommet?

 

[Jeremiah]

For some of that did not catch the "Racepump" part:

http://www.racepumps.com/

My experience with these pumps is that they do not like pull fuel from a stock sending unit. They are almost always unreliable with a stock style sending unit. In my red car (fuel cell with a bottom feed at the sump) the race pump works awesome. I think this is because it has a little fuel pressure to prime the pump.

If you are looking for a fuel pump that will keep up and work reliably with a stock fuel tank setup I would get a Clay Smith six vane deal and grind the hell out of it to fit your block.

The other thing you can do is add a sump to your stock tank however I am not a huge fan due to decreased ground clearance.

Hopefully this helps. The Racepump should be called "not a street pump" lol

 

[RustyRatRod]

Has it outperformed an electric pump yet?

 

[Propwash]

With you running a return line Benno, use of a bypass regulator will work well to alleviate vapor lock/fuel boil issues. I've never had a priming issues with mechanical pumps. Sounds like it's that space shuttle pump giving you all the flak. I also have the Clay Smith 140GPH 6 valve mechanical pump for my 512. 10 minutes of clearance work and it fit fine. Good to about 1300 HP according to George "Honker" Striegel over at Clay Smith.

 

[Jeremiah]

Has it outperformed an electric pump yet?

I can't say for sure. I keep trying to get the Racepump and Holley Blue pump to line up but the Holley want some spots and the hit and the race pump isn't giving up any land.

Seriously I only like mechanical pumps because they are quiet. If I had a stock tank I'd be putting an electric in the tank itself to damped the buzz. I am going to test both on the dyno if I ever get back to the machine shop to work on my 511's. Must.....stop.....buying...more...projects!