Topic: Weak fuel pump?

[sharpxmen]

Gave the fuel pressure gauge a shot this morning.   Tested it engine off/pump on, idle and then drove around on city/highway roads at different speeds -- 25mph to 75mph -- for about 45 minutes.    I took some photos of the idle readings on the gauge and then some phone-cam video of the readings on the gauge (still hooked up) while I was driving. 

I ended up just running the hose under the left side of the hood so the gauge was sticking out upside down above the left front fender.  Then drove around with it like that with the phone cam taped up and angled to record it and me hanging my head out the window periodicalloy for a few seconds at a time to see how it was reading.

Idle it looks like its around 31-34lbs.  When I was on the throttle, pressure consistently ascended to what looked like about 44lbs (due to adjustable FPR, presumably).  I didn't see any difference in pressure while I was on the thottle on highway-grades with the engine under load.   Regardless of the speeds, roads, or load on the engine, no pressure drop-outs anywhere on the part of the fuel pump as far as I can tell.

I'll get some of this photo/video stuff together and post it

if you have 44 at wot or with vac line disconnected you should have about 34-36 at idle, you would get 31 probably in engine brake while decellerating with throttle closed (you get more vacuum in the intake that way)

doesn't sound like your pump is weak.

you could run a test with the vac line disconnected, should be constant pressure that way all the time, otherwise it really depends on throttle position and rpm.

[chrisfranklin]

34lb is shown in a couple of the photos I've got of it reading at idle.  



Turn the sound down on the video in the link if you watch -- the wind noise is terrible.  

The fuel pressure gauge is upside down but needle bottoms out at idle pressure around 34lbs and under acceleration appears to hit around 44lbs.  

I drove all over the place, up highway grades in 4th and 5th at full throttle and it was still the same reading: 44lbs or approaching that under accelerations/full throttle acceleration.   Cruising seemed to keep the gauge needle fluctuating between roughly 34-44 lbs.

Tried to embed this.  Here's the link at least

<a href="http://www.youtube.com/v/RO38yyPe6h8" target="_blank" rel="noopener noreferrer" class="bbc_link bbc_flash_disabled new_win">http://www.youtube.com/v/RO38yyPe6h8</a>