I have a 69 half ton with a 390. The other day I was driving down the road, and the engine just shut off. So I pulled over and found the float bowl dry. I took off the fuel pump and manually operated the pump arm with fuel in the filter canister. The fuel did not squirt out, so I replaced the fuel pump and the problem wasn't fixed. I then disconnected the fuel line at the tank and blew through it to make sure it was clear. I also disconnected the line on the outlet of the pump and cranked the motor, nothing came out. I have just above half a tank of gas. I am wondering if the problem is the little cam that is bolted to the front of the cam shaft gear that the pump runs on, however, it seems odd to me that it would just all of a sudden quit working. If it were overly worn I should experience intermittent fuel deprivation problems over a long period of time, not just a sudden lack of fuel, right? I looked at the cam through the pump hole in the block, and it appeared fine. I tryed moving it with a screw driver, but it was nice and tight. The hole in the cam that the bolt goes through isn't slotted, is it? I don't need to prime the pump do I? I just have to bolt it up and turn the key, right?
thanks for any info
brad

 

When my fuel pump went out it didn't give any warning. I was in line at the dump and it just stopped. I did all the checks and found that I was not getting any fuel from the pump. A new fuel pump and off I went. No you don't need to prime the pump. Make sure the arm is going into the engine properly. If it goes in real easy then it is probably not in right. The bolts should be a little difficult to line up because of the presure on the arm from the cam. Once you are sure it is installed correctly then you can check for obstructions in the line.

 

I did a little more work on the truck and discovered something. I noticed that the input fuel line to the fuel pump wasn't drawing fuel from the tank when I disconnected it and held it below the level of fuel in the tank. So, I syphoned it through the line until it started coming out steady, and then I hooked it to the pump. I tried starting the truck, but had not luck. So I pulled off the line and found out that it wasn't drawing any fuel. I did the syphoning process again, but every time I tried starting the truck and then pulled the line, I found out it wasn't pulling fuel through. So, obviously it is drawing air into the lines and breaking the vaccum, however, I don't see any cracked lines or loose fittings and the truck doesn't leak gas.
any ideas?
thanks
brad

 

I still suspect the fuel pump. It has a diaphram inside that causes a vaccum to draw the fuel in. I would have a buddy turn over the engine while you check the intake side of the fuel pump for vacuum. If you don't have anybody to help you turn it over you can run a rubber hose to the front of the cab. When you turn over the engine you should hear or feel a vacuum at the end of the hose. If you don't feel a vacuum you should take the pump off and activate the arm manually. Again you should feel a suction on the intake side. If you do feel a vacuum then the pump is probably ok. Then look again and make sure it is installed properly. If you are sure it is installed properly and it still doesn't pump fuel then I would suspect the cam has a problem.

 

I had problems with my 71 also.... it turned out to be dirt/rust from the tank damaged the fuel pump. I replaced the pump and added a fuel filter between the tank & the pump and it's been working fine since then.

Just my 2 cents. : )

 

The inlet of the pump is the hole that sits higher up on the pump and is to the right as you stare at the driver's side of the engine, right? I forgot to look at the old pump to make sure which was the inlet and which was the outlet before I took off the fittings, and the directions for the new pump don't say which it is. I pulled off the hose that I believe to be the inlet and had someone turn the key. Instead of feeling a vacuum, it put pressure on my finger and when I let go, it squirted. So, I figured I had the lines mixed up and I switched them (put the inlet hose at the lower left hole). It still wouldn't start and when I put my finger over the fuel line at the tank I did not feel a vacuum or pressure. I know I have the fuel pump installed right.
If it turns out to be the cam, can I just install an electric pump since this is a junk engine? What type of pump should I go with and where should I mount it? I have an electric pump that I used on a 1600cc (1.6 liter) vw motor, would it likely be too small?
thanks for all the help
brad

 

Ok, I feel stupid. I had the input and output mixed up on the pump. I don't know how I did this since this is the 4th time I have replaced the fuel pump within the last two years (stupid Autozone parts), plus I have had to pull it off countless times when diagnosing problems. Also, I HAD to prime the pump by syphoning gas through the line and up to the pump because it would not draw the fuel itself.
I was beginning to think my old pump wasn't bad in the first place and that air just got in the lines and broke the vacuum. So, that means my Autozone pump lasted less than a month this time. Geez, I have had so much trouble with all of their parts.