Hi guys. Please let me make a couple of comments. ALBISULOU, you said you can hear the pump running, so don't waste time with voltage readings. What you should hear is it hums for one to two seconds when the ignition switch is turned to "run", then it turns off. If you hear that, the pump, relay, and wiring are working. The automatic shutdown, (ASD) relay, and the fuel pump relay turn on again during engine rotation, (cranking or running). If that doesn't occur, suspect a missing signal from the crankshaft position sensor or the camshaft position sensor. When this is the cause of the problem, you will still get close to normal fuel pressure from those one-second bursts each time the ignition switch is turned on.
What you didn't mention was how much gas you put in the tank. That's why I felt the need to stick my nose in here. The fuel pump pickup sits inside a plastic housing and draws gas from in there. That way there's still gas flooding the pickup when the level is low and it sloshes to the side of the tank when going around a corner or up a steep hill. While running normally, that housing is kept full by fuel being pumped to the engine, going through the pressure regulator, then returning to the tank. One of two ways keeps that housing full. The returning fuel can be directed straight into the housing, with any excess spilling over into the tank. On older models the returning gas flowed rather forcefully up a ramp as it went around the outside of the housing. That created a venturi effect that drew in more gas from the tank as it went up that ramp and into the housing.
How it's done doesn't matter, but you have to start out with enough gas in the housing for the pump to pick it up. In the case of my '88 Grand Caravan, when you pour gas into the tank, it dumps right into the housing. A quart is plenty to get the engine started. That's not true with my '94 model. In that one, the gas misses the housing and just fills the gas tank. This one needs a minimum of five gallons for the level to get high enough to spill into the housing, and flood the pickup tube. That's when the engine can be started. Once running, all of that five gallons can be used up, like normal.
I should mention one more thing that I'm not proud of. Due to living in the rust belt, I had the gas tank out of my '88 twice. There's two rubber hoses running to the pump housing that had to be disconnected. The return hose is always a smaller diameter than the pressurized supply hose, yet, both times I accidentally switched them. Pressurized fuel feeding the regulator won't work as that is a spring-loaded one-way valve. At first I found no fuel coming out of the supply hose at the fuel rail on the engine. Pulling the hose from pressure regulator is where the gas showed up. Switching the two hoses at the tank back to their proper ports solved that.
I'll be waiting to learn what you fellows find to solve this.
Monday, March 31st, 2025 AT 6:21 PM
