The title says it all. I had to get a universal electric pump because my replacement engine doesn't have the cam for a mechanical one. There is fuel in the tank and I can hear the pump switch one, but I get no fuel. Any suggestions?

 

Some later GM carbureted vehicles had an electric feed pump in the tank to prevent vapor lock at the inlet of the mechanical pump. Generally you can pull sufficient fuel through this electric pump to run the engine without having to remove the old pump. But if the intank pump is locked up, you may not be able to do this.

Even without the intank pump, if the car has sat for some time you may have a clogged pick up.

Make sure that you can draw fuel through the line from the tank before you connect the external pump. Also, be sure that no packing material or plastic has gotten into the inlet or outlet of the new pump. Be sure that you double check polarity. If you connect the pump backwards, it will pump backwards.

 

The block isn't the same mechanical pump style (4 bolts vs 2) so I put in a cut off plate. It has sat in the weather since April, so it could be plugged up. There are two fuel lines... which should I be using? The bigger one? I know the flow is correct, I tripple checked that.

 

The larger line is the outlet from the tank and should go to the external pump. The smaller line is the return line for an FI motor, the vapor return line for a carbureted motor. You may end up using it if you have vapor lock issues. If you are sure that the pump is wired correctly and not itself restricted by foreign material, use compressed air to blow back through the large line to the tank, with the fuel cap removed. Be aware that you may get fuel spray from the fill tube, so have clean rags handy to wipe down the fuel from paint. Once you clear the restriction in the pick up tube/filter sock, install an inline filter before the pump to protect the pump from debri.

If the fuel sock is clogged with sediment, you may end up dropping the tank to flush it out as the sediment will find its way back to the filter sock and eventually clog it up again. For a clue to the condition of the tank, look at the fuel that runs out of the line once the clog is cleared. Run a cup or two into a glass jar and look for it to be milky or rust colored.

 

Well, I don't have any compressed air handy to try that right now, but I did blow into both lines as best I could and I am still getting nothing. Maybe my float got stuck and I don't actually have fuel? Is 8 months long enough for all the fuel to evaporate through the open fuel lines? The new lines smelled like fuel after running the pump, but no liquid was present, just vapor. I am going to work on some other stuff and then come back to the fuel pump later today, maybe I will pick up a gallon of gas and see if I get anything.

 

Fuel,atleast the cat pee that I'm used to seeing will not evaporate over time. It will lose its combustibility. If you have fuel in your tank that has sat unsealed for 8 months, you may need to clear it out as your engine may not want to run on it. There are products such as HEET that will help clear out water contamination. If you find your pick up is clogged, find yourself a cheapo air compressor or even an air tank that you can charge up at a local shop.

 

This same topic has come up twice recently and there are many posts on both of them that may help. I replaced my in-tank fuel pump this week, not because the pump was not functioning, but because the fitting connecting the pump to the line was disintegrated. I could hear the pump spin but had no/little pressure at the carb because of the disconnection. You may have the same problem, a disconnection between the pump and the line in the tank. The only remedy is to pull the tank and fix it.

Regarding the blocked line, I could blow into the fuel line at the carb and hear gurgling in the tank without any compressor air. Blowing into the line as if you are blowing into a balloon was sufficient.

Me, myself, I don't think 8 month old gas is the problem.

 

I added a gallon anyway, just to eliminate the possibility of a stuck float and empty tank, and still nothing. I will have a friend bring a compressor by if I can to blow into the tank and eliminate the possibility of a clogged pickup. I simply do not have the money right now to replace anything else unless it is $19 or less. I had zero fuel problems before the car sat, so I am hoping that it is just a clogged pickup. I am going to look into it a little further. Is pulling the fuel tank usually a pretty grueling process on these? It is an 84 with a T5 if that helps. The tranny and driveshaft are out right now. I am going to do a couple searches to get an idea, but if I have to pull the tank I am not sure I want to put the drivetrain back in yet.

 

Pulling the tank is not fun but it isn't as bad as some think. Of course it would be easier on a hoist where you can stand under the car. The key to it going smoothly is first detatching the rear shocks from the axle so that the axle can hang down. Remove the bolt that attaches the rear most brake line bracket to the body to gain some slack there so that you don't stretch the rubber hose. Loosen the exhaust clamp just in front of the axle, detach the rear exhaust hangers and rotate the muffler down out of the way. Detach the fuel lines by the left side frame rail and bring the tank down. Take care removing the fill tube from the rubber grommet in the tank. A little WD40 will help here. When you go to put it back together, apply silicone grease to the tube to help it slide in easier.

 

Will I need any kind of special equipment to put the rear end back together if I start taking stuff off? I have basic tools along with a 2 and a 3 ton floor jack and 2 7 ton jack stands, that's about it. Based on the reading I have done, it is looking like I am going to have to pull it. Also, if the electric pump in the tank is bad, is there a way to plug it off or something instead of replacing it since I am running an external pump? I really can't afford a new pump right now

 

Little update, I stuck my mouth on the fuel line and sucked on it, and my filter resorvoir filled up with fuel. Thus I have determined that clogging is not the issue. Will the pump not pump fuel if there is no pressure in the lines? Is it possible there is an issue with the pump itself, even though it is brand new? I can hear it going, but it is very loud and vibrates a lot. When it is hooked up, it clearly is pumping air through the line. Or does this sound like it is related to the in-tank components?

 

Hmm, now I see. You have air in the lines. Most any electric fuel pump needs to be primed in order to pump. That's why we try to mount the pump level with the bottom of the tank and as close to the tank as possible. Electric pumps generally push much better than they pull. Where is your pump mounted?

 

It isn't technically... 'mounted' anywhere yet, because I wanted to make sure it is functional first... I was just holding it up and connecting it to the battery... which I guess is like 2 feet above the top of the tank, cause it is pretty lifted. Let me put it down near the ground and I will get back in a few minutes.

 

Okay, I put it on the ground and ran some wires up to it... and lo and behold, it works! Thanks so much ASE doc, you saved my a**. Thanks for being patient with my unfortunate lack of knowledge about fuel pumps!

 

I'm sorry for the round about way we found the solution. Should have thought of priming right away. Good luck bro.