Thirsty 302

[kevin73]

I'm going nuts here! My '73 2 barrel 302 usually runs fine but every now and then (now) it seems to stop pumping fuel to the carb. I put a clear filter before and after the pump and I see the one between the pump and the carb go dry. pressure drops from 5 down to 2-3 and pinching the return line seems to help some. I have replaced fuel pump twice in two years but the problem is intermittant so I don't know if it really helped. I want to go 4 barrel when mama lets me dump the cash. Any tips on what's happening and what I can do now?

 

[bax]

I am not a big fan of rubber gas lines. Would your set up happen to have a rubber line from the pump to the carb? I know from your post the you must have a filter and a presure regulator/ guage before the carb. Do you happen to have the old steel line that goes from a manual pump to the carb. If you do, take the current setup off and try the steel line. If your problem goes away, great. If not it's time to check the pump and other lines. Fuel presure readings at idle or in park and reving the engine is not a good measure of presure even if your # are good. The question is what is my fuel presure under a full load? If you have 5 pounds of presure under load you dont have a fuel problem unless your presure unit has a filter up stream of it. You want fuel presure readings at the carb inlet. if your filter is in front of your sending unit then change your filter location. Be a good plumber
Good luck, sorry I talk too much.

 

[agent_orange_71]

It sounds like a fuel pump diaphragm but since youve recently replaced it that may not be it. Check the filter between the tank and pump. Is it flowing OK? Does it have alot of junk in it? An excessive amount of crap in the tank may be plugging the line or restricting flow in the filter(s).

 

[Mr Joe]

I eliminated the '73 return system after having the same issues. I also replaced all the old rubber lines and cleaned the pickups in the tank. My problem hasn't happened since.

 

[kevin73]

What do I have to do to eliminate the return system? I was just going to clamp it off but was affraid to blow the lid off the carb or kill the mech pump.

 

[kevin73]

BAX, all old steel is in place I just added the extra filter\guage\regulator between hard line and carb for diagnostic. Is there some kind of valve in the bypass or is the crimp of the tube all that regulates how much fuel returns?

 

[bax]

filter /regulator/guage in that order to carb. keep the return line for now.

 

[Mr Joe]

What do I have to do to eliminate the return system? I was just going to clamp it off but was affraid to blow the lid off the carb or kill the mech pump.

I just capped it off for testing purposes. It alone gave me 2 pounds of additional fuel pressure. My carter mechanical pump won't pump more than 6-7# at deadhead. Not enough to hurt anything. Ford stopped the return system after 1 year ('73) because it didn't work.

 

[73stallion]

i remember someone not too long ago having a similar problem. take your gas cap off and drive it, see if it happens then. you may need a vented gas cap.

your gas tank may be creating a suction not leting the fuel pump have enough fuel.

 

[kevin73]

i remember someone not too long ago having a similar problem. take your gas cap off and drive it, see if it happens then. you may need a vented gas cap.

your gas tank may be creating a suction not leting the fuel pump have enough fuel.

First thing I tried. Funny I was just at JBG lusting after a couple big new tanks as a first step in a whole new system (without the return).

 

[broncow72]

To me it sounds like your By-pass reg. is acting up. Which regulator are you using?
Does it have a vacuum port on it? If so is it hooked up?
I am using the Mallory by-pass, My brother uses the same one. I have never hooked up the vacuum port, he has. He had an issue like what you are describing and simply removed the vacuum line, plugged the port and and vacuum source and never had the problem since.

 

[kevin73]

To me it sounds like your By-pass reg. is acting up. Which regulator are you using?
Does it have a vacuum port on it? If so is it hooked up?
I am using the Mallory by-pass, My brother uses the same one. I have never hooked up the vacuum port, he has. He had an issue like what you are describing and simply removed the vacuum line, plugged the port and and vacuum source and never had the problem since.

Not shure what I have. I have hard line from the pump up to something that looks like an oversize (black) tylenol capsulefrom that I have a hard line continuing to the carb and a little stub that appears to be crimped for restriction that 5/16ths to the return hose. No vac or other connections.

 

[broncow72]

I don't know what regulator that is. How old is it? Did you replace the filter? Where is the regulator located on the fuel line?

 

[Mr Joe]

The factory '73 regulator is hard piped in the fuel line. I'm not sure there's any spring in there. I'm not sure it's even a regulator. When I took mine off I could blow threw it with zero resistance.