Low Fuel Pressure, Pump? Regulator?

[jmgtp]

well this isnt 60V6 so thats why I put it in off topic but figure someone around here might shed a lil light.

1991 Plymouth Grand Voyager
3.3L (pushrod) AWD
105,000 miles

My father has been driving this vehicle and today told me that the engine sputters and pops under acceleration. He says it happened all of a sudden, ran fine and then out of know where this condition began.

I went to go for a test drive around the block to duplicate the symptoms it lacked all power and felt as if it couldnt make it out the driveway so I shut it down. I measured fuel pressure at the fuel rail and it tops out at 20 psi (supposed to be around 45 psi) and dips when throttle is opened. I suspect the fuel pump, but before I jump the gun and go buy one I wanted to know if there is any valid way of testing the fuel pressure regulator? I did pull the vacumn line off and had a sniff and did not detect a fuel odor so it appears that the diaphram hasnt ruptured. The fuel filter is about a year old and I dont think it can get clogged so badly to cause this condition but I will replace that before tackling the pump.

I actually found a forum for this engine and posted the above there. The only response I got told me that all signs were pointing to the o2 sensor and that just seemed way off base to me. How could a bad o2 sensor cause low fuel pressure at the rail? Even if it could, can an o2 sensor go from good to bad in the matter of 1 second? On top of all of that, if the chrysler ecm works anything like our OBDI ecm's it would ignore o2 data at WOT (but I dont know if it does).

thanks for any info and advice.... I'm pretty sure its the pump just dont wanna blow $100 of the 'rents cash without being certain first.

[Cliff8928]

The fuel pump failure is not uncommon on the chrysler vans, I sell plenty of them at work (if i remember right, it's the whole sending unit for around $150 or so? with lifetime warranty)

Cliff Scott
89 BerettaGT
89 Volvo740

[jmgtp]

I actually just stopped at advanced auto - $168 for the fuel pump, didnt check about warranty info because I was just getting a price (the rear tire of the beretta blew out on the highway on the way there! yikes did it get squirrely for a few seconds!!)

I think its the fuel pump too... but didnt wanna jump the gun before exhausting other possibilities. I think the guy on the other forum specific to the engine is very much incorrect. He thinks its the o2 sensor yet cant seem to explain to me how the o2 sensor is related to fuel pressure. He is convinced the fuel pump is good because he is from the school of thought that a fuel pump either works 100% or 0%, in this case it has enough pressure to start the van and idle (although a bit rough) but with the application of throttle it farts and pops. So safe to bet the pump is bad and I should go ahead and change it?

thanks for the response!

[93LuminaZ34va]

In my experience, yes, that has been the problem. And yes, they can work half way..... I've seen them do that just as you are describing. However, Its still possible its something else...... something wierd always has a way of showing up at times!

[jmgtp]

To bring this back up... does anyone know if this vehicle has a fuel pump test lead?

1991
Plymouth Grand Voyager
3.3L

[jmgtp]

Found the relay and jumped it from there.

[geoffinbc]

Pinch the return line (on a rubber part) if the pressure increases the pump is doing its job

[jmgtp]

I replaced the fuel pump last night. It was $218 for the pump (they originally quoted me $170 but then when I told them it was AWD the price went up). Took me a few hours, was really very easy. Runs like new now. Thanks for the input guys!