Alright, I just installed my second lift pump on my 86 6.9 I say "second" because I believed to put the first in incorrectly. The first one registered no pressure on the guage. So, $33 later the second one goes in with greater attention to the cam position. Guess what? Still no pressure at the schraeder valve. I even put in a new fuel filter and filled her up with power service. Nothing.
Can I get it started? Sure with some starting fluid. The white smoke coming off of it makes the cars stop to see that my house isn't on fire.
Here's the list of what has been replaced: Fuel pumps(x2), fuel filter(x2) Injection pump,all the return lines,all the glow plugs,all the fuel injectors and one fuel line.
You're the experts, but here's what I think:The first fuel pump works fine, as does the second. This motor has so many miles on it that the cam is worn and no longer contacts the fuel pump's arm to get the fuel going in the first place. The odomoter SAID 99,000 miles when I bought it as did the title, but I think that's B.S. It now says 100,364.
Replacing a cam sounds unpleasant.
Let's hear the opinions of what is wrong with this truck.

 

TJC, man I have to give you credit for hanging in there on this!! I pulled up all your old threads to review what may be going on here, and I see there was the second tank removed. My thinking here is that your lift pump may be sucking air from somewhere in the supply side, are all the hoses in the right place on the tank selector valve, and in good condition or are the monkey rigged for some other problem. Also the supply line from the tank clear through to the lift pump could have a "pin hole that is allowing air in under vacume of the pump, but not letting fuel out. Also check that the flex hose connecting to the liftpump has no sharp bends which could kink off during operation.

It seams doubtful to me that you could ever get enough wear on the pump cam for it not to work, unless the rest of the engine was just as bad, NOT. However, given the problem you are having, I would get a inline self regulating electric pump way before pulling a cam shaft! This may be a bit of a stretch, but are the replacement lift pumps the right ones for the application?? Did they physically look like the original, ie arm length, position etc??

Another thought is you may have an air lock between the tank and the pump, can you put a pound or two of air pressure into your tank to get the fuel flowing freely up to the lift pump, with the hose disconnected, verifying unrestricted flow??

We'll keep at it till this things going- Good Luck

 

If you can see in the pump hole you will confirm that it's good or bad. If you do not wish to putzz with it anymore...... put an electric in line.

Does the (FSV) fuel selector valve work..... does it make a ziiip noise when changed... does the fuel guage change tanks.

 

I will check the supply line from the tank to the pump to make sure it is still good. I will also get some air in the tank and see if that changes anything. Uh, how does one get air in the tank correctly?

I would like to get the second tank back on this truck. I don't know why the previous owner took it off in the first place. Maybe this is a good excuse to not only replace the line, but get started on putting the second tank on. What size is the line to the tank? Is there a good place to buy the tank and the guts or is this a salvage yard type of job? Thanks for all the help from everyone on all my questions so far.

 

I would make sure your supply line is open at the pump, then with an air compressor available, stuff a rag around the fuel tank inlet and insert a blow nozzel into the tank. VERY GENTLY puff, puff, air into the tank while someone watches for fuel. It shouldn't take much air to make the fuel start flowing, too much and you can stretch the tank- NOT good -too much air, thats why if just use a rag loosely stuffed around the air hose you should not overpressurize the tank. I think this would fall into the shade tree mechanic area, I doubt there is a "correctly" for this procedure FWIW!!