I'm pretty sure it's the fuel pump, but I would like another opinion.

02 Caravan, 240,000 miles 3.3 Litre engine

Van died on our driver after running just fine all day. Hauled it to the shop and hooked up the scanner. P0171 code meaning it ran lean. Checked vacuum and it's right up there at 17-18 inches.

Checked fuel pressure and the first few times, the pressure came up to 60 PSI immediately, then dropped to zero in about 10-15 seconds.

I did this a few times, then started the engine and it ran fine holding 60 PSI even under load. Cycled the key off then back on and it went right to 60 PSI, but after about 30 seconds it had only dropped to about 40 PSI.

I did this a few times, then had to run a few errands and came back and now when I cycle the key on, the relay always clicks, but sometimes the pressure doesn't come up at all, sometimes, it only comes up to 20 PSI from zero, or sometimes up to 40 PSI from zero. When it does this, if I crank it, the pressure comes right up to 60 PSI.

Last year, I replaced the fuel pump relay which was definitely dead, but the pump seemed to make alot of noise. The noise went away as did my concern.

If it were electrical, why would the pressure drop like a rock to zero sometimes? This is why I am leaning towards a fuel pump.

Also, I watched the O2 sensor and at idle it is showing very normal, but under load, it gets whacky. This again sounds like a fuel pump problem.

Am I right in my thinking here?

 

Evening bump for any advice.

 

Any suggestions before I drop the tank?

 

sorry bro, you are correct on the fuel pump is junk. They should hold the pressure for quite some time after key off, if it goes down quick, get a new one.

 

The times that I recall noticing, when I turned the key off, it seems like the pressure stayed up. It was just those first few times that I turned the key on and the pressure jumped to 60 PSI, then - with the key still on - the pressure dropped quickly to zero.

I guess it doesn't matter. The tank is out and a pump is on it's way back in.

Thanks for the reply.

 

have fun!!

 

Now, with the pressure bled off, I cycle the key on and pressure comes up to MAYBE 15 LBs. and in similar increments with each cycle of the key with the expected longish crank time. I can live with that because it gives the oil about two seconds worth of pumping before it starts. That's my story and I'm sticking to it.

Also, the pressure drops to 40 PSI in about 30 seconds but it doesn't drop all the way down.

I can jumper the relay (30 to 86) and the pressure comes up just fine, but with the key, the relay only cycles on for less than a second, so it only comes up a little bit. If 2.5 seconds of cranking time is the cost of a reliable pump (and a working fuel gauge) I'm OK with that.