Was cruising yesterday morning, about 70 degrees and sunny. All of a sudden, I pushed on the gas pedal and it sounded like I was running out of gas, that whoooaaaaa...the butterflies opening and no fuel there to make anything happen sound. I hobbled home and put the fuel pressure gauge onthe fuel line. It's supposed to be 7.5 to 9 lbs. I started the engine, and at idle I had the pressure gauge needle jumping back and forth from 3 to 6 lbs. like crazy and when I shut the engine down the needle went immediately to zero. I know that it should have held pressure for afew minutes after I killed it. Then when I took the clamp off the line on the gauge, there was no fuel in it. I was getting the pressure from air instead of fuel. The carb still gets some kind of fuel as the car does run, though terribly.
My many experiences w/ fuel pumps has always been that they go out all at once, and sometimes leak as the diaphram goes out.
I'm wondering if I have a dry-rotted rubber connection line, like the return line from pump to tank. My experience w/ dried out rubber connection lines, ie; tank to metal line rubber connection,has been that the car won't start. That's usually the situation.
So, anyone have this problem before? Let me know if you've had this experience.
I'm going to change out the rubber lines and if that's not it, change the pump. I'm also going to change the oil and filter as I know that if the diaphram goes out, that fuel can get in the oil w/ some pumps and I'm not going to take that chance. Is there anything in the 'Vette pump that blocks the fuel from the crank case? Thanks in advance.

 

Hi Texas Jim, you might want to replace ( or just remove to test ) the fuel filter if you have one in the carb.
At the fuel pump you can disconnect the supply side line and use air to be sure thats not clogged.
Then disconnect the line at the carb ( where you checked for pressure )and start the motor (pour a little fuel into the carb) you should get squirt after squirt into a can.
I think, but I'm not sure but 6 to 7 lbs of pressure should be OK.
If you have to replace the fuel pump, the rod falls out, to hold it in place look at the front of the block and remove a 3/8x16x1/2 inch bolt. Install the rod and turn the motor untill you are on the low part of the cam, then install a longer bolt JUST FINGER TIGHT to hold the rod while you install the new pump. Then use thread sealer and replace the original bolt.
One other thing, you could have a clogged sock in the tank.
Hope this helps, PG.

 

You also should run a hose from the fuel line at the carb to a jar. Crank it over and see what kind of flow you are getting from the pump. It should fill up pretty quick. This will also give you a sample of what is coming out of the tank. Water, dirt, etc...

 

Rich and pg,
Thanks so much f/ the input.
First thing I did was to check the filter, it's clean as can be. I get next to nothing from the fuel line when I put it in a coffee can,"nothing" like it should be, it is enough to keep the car stumbling though. I'm stating 7.5 to 9 lbs. from the GM 'Vette Manual, though Iknow thatthe standard isabout 5to 7lbs., like you said. The AFB and Edelbrock carbs are about 5.5 to 7.I've had many electric fuel pumps w/ regulators, and 5 1/2 to 7 lbs. is the usual. Pretty standard. I've replaced a million small block Chevy fuel pumps and I'm up on the "pain in the -ss" rod that U have to hold in w/ your finger and get the cam lobe down so you don't have to fight the spring pressure of the pump arm. You guys are here in the same boat w/ me, or I w/ you.
For the fuel return line, when I would havea vehiclethat "ran", if the system had the charcoal canister, I would use the tank vent line; and "T" off the fuel line just prior to the carb, hook the vent line (it's also the perfect diameter)in to that "T",and the vent linewill now be my fuel return line(to the tank) and using an electric pump and regulator, have cooler fuel going into the carb as it wouldn't be sitting there waiting to get into the carb in that hot engine compartment. The 'Vette pump and system has that return line already built in, but the fuel returns from the pump instead of "T"ing off just prior to the carb. This is the line that I'm wondering about as far as sucking air.
I just thought that someone may have had a situation like this w/ their 'Vette. The big (and only)difference in the regular mechanical pump f/ the small block Chevy and the 'Vette pump is that "fuel return line." I looked at the pump, saw the extra line, went to the GM 'Vette manual and read that this extra line is the return line. I have to say that this return line from the pump is a good "performance measure." I have no idea what year this thing was introduced, but until I saw the extra line and read about it, I had no idea that it existed.
Anyway, I'll replace the lines, if that's not it, replace the pump.

Rich,
No, I haven't messed w/ the tank and pick-up. There was absolutely no evidence of dirt in the line, filter or carb or when I pumped gas into the coffee can, etc.. I am going to spend the thirty dollars on the pump if the lines don't do the job before I drop that tank. LOL. If I did have any thoughts that the pick-up was clogged w/ crud, I'ddrop it.

Thanks again f/ the input. I'll post up the solution when I finish the job.
The weather here is breaking, was 84 yesterday afternoon and is going to be 41 degrees this afternoon w/ rain, as a cold front is settling in slow right now. It's supposed to be in the lower 60s tomorrow though, as the winds are going to turn back around. ...And so goes the "Central Texas" weather. I'll be under the 'Vette today. If it's like it is now, not too cold yet and only partly cloudy, I'll be outside rather than in the garage. As I've gotten older, I like the sun light, w/ the hood up,more than the bright lights of the garage. Although I have plenty of room, it's less confining outside on a smooth surfaceon a creeper if the weather permits and is a comfortable temperature. Also, even in "crumby" weather, being a 70s Airborne soldier, Pathfinderand French Commando School Honor Grad w/ the French Army, even at my middle age, I can handle some "field maint." LOL. Actually, I'm glad that I did tht when I was younger. LMAO.

 

A little tip.....
if you put a liberal amout of grease on the pump rod, the grease will hold the rod in place while you install the pump. Works for me.

 

Me too.

 

It sound like you just have a bad fuel pump unless the cam lobe is wiped out for the fuel pump. If this is a carb setup with a 2 line fuel pump the little 1/4 in line is not really a return line it's a vapor line for emissions. With fuel injection where the electric fuel pump runs constantly that is where you have an actual fuel return to the tank. Like you said first I'd check the rubber hose at the tank to the line incase it is cracked and your just sucking air. I would think you'd see a gas leak. Or maybe your guage is broke and your just out of gas! I can laugh because it happened to me. Thank God the the gas cap is so big on the Vette you can just look down in as see the pick up tube!