No fuel coming from the fuel pump

HARLEY CRADDOCK

MEMBER
1992 CHEVROLET SILVERADO
5.0L
V8
2WD
AUTOMATIC
289,000 MILES

I recently bought the truck from my uncle and he wanted to keep the 350 in it because it was his grandfather's. I bought a 305 and put it in there. It ran after we got it in there and we got the timing set good, but it was dark so I did not test drive it. I came back the next morning and it fired right up fixed a water leak from the thermostat housing and drove around the block it seemed like it was starving for gas. By the time I got back to his drive way it died before I could put it in park. I can hear the fuel pump kick on, but I is not getting any gas to the tbi or even the fuel filter does not even have a drop of fuel. The tbi has two gas lines one is a feed and the
other a return and the return line got bent. I do not know if that is the problem or what is going on with it, but I checked all the grounds and they are good. Hope someone can help me.

3 Replies

CARADIODOC

MECHANIC
33,870 POSTS

Actually, if the return line is kinked and blocked, it could cause a problem. I am speaking from experience with my Dodge products, but I have a suspicion most other brands are the same. In my 1988 Grand Caravan, I had to replace the gas tank due to rust and was trying to understand how the system worked. The pump and pickup screen sit in a bowl welded at the center of the tank. That is so about a quart of fuel will not run away from the pickup when you go around a corner. If it did that when the fuel level was low, it would stall at every corner. That part I understand, as well as when filling with gas, the filler tube is shaped to dump the gas into that bowl. What I could not figure out is what pumps gas into that bowl while you are driving.

Turns out there was a real nice description in the service manual. The fuel coming back in the return line rushes past a port that creates a venturi action, and that picks up more gas from the tank to keep the bowl full. I scratched my head for a long time, and I am still not entirely convinced, but it does seem to work.

As a point of interest, I have a similar setup in a 1994 Grand Voyager, but after running out of gas, (on purpose), I found that one appears to not dump the gas into that bowl very well. I have to put in almost five gallons, (quarter tank), to get it up high enough to spill into the bowl before the engine will start. Once started, it will keep the bowl full all the way down to "empty".

If my story is right, you should not have this problem if the tank is over about half full. Keep in mind though you have a fuel pressure regulator on the engine, and the excess fuel has to be able to flow back to the tank. If the return line is blocked, fuel pressure can go too high and cause running problems from an excessively rich mixture.