chuck3

Pump # 2 solid as a rock for over a year, allways read 14 to 16 psi at idle. yesterday I noticed a drop after a couple minutes of idling, down to 10 and then 5 to 6 psi for awhile then back up to 12, the thing is all over the place.
I checked it with my test gauge thinking it was something going in it, nope started truck both gauges up to 14 for about a minute then down to 11 incab gauge and 9 on test gauge. ???
Driving today same thing anywhere from 5 psi to 14.
Anybody seen this before? Its a new one to me. ???

Shovelhead

Fuel filter OK?

NAIL BENDER

I was showing 15idle, 12cruise and 10wot then the next day my Gage started jumping all over the place. Second day I hit the basement with all the numbers. I replaced the pump and everything went back to normal.

Tartarus

The checkball in your lift pump has popped out of the retainer and is "bouncing around" inside. Sometimes it comes part way out, some times all the way. When it happens, the pressure goes every which way, sometimes stabilizing for a time, and then going bad again. What's real fun is watching your gauge read 13 psi at 70 mph, and then 5 psi when you idle.

Common failure, probably caused by fluid hammering created by the VP44.

Palmetto_kid

[quote author=Tartarus link=board=4;threadid=23711;start=0#msg223510 date=1071451979]

Common failure, probably caused by fluid hammering created by the VP44.
[/quote]

explain "fluid hammering" to me por favor.

chuck3

[quote author=Tartarus link=board=4;threadid=23711;start=0#msg223510 date=1071451979]
The checkball in your lift pump has popped out of the retainer and is "bouncing around" inside. Sometimes it comes part way out, some times all the way. When it happens, the pressure goes every which way, sometimes stabilizing for a time, and then going bad again. What's real fun is watching your gauge read 13 psi at 70 mph, and then 5 psi when you idle.

Common failure, probably caused by fluid hammering created by the VP44.
[/quote]




I bet your right, I had forgot about that checkball, seems the likely cause the way its jumping up and down.

Thanks for the replies.

chuck3

[quote author=Palmetto_kid link=board=4;threadid=23711;start=0#msg223813 date=1071512551]
[quote author=Tartarus link=board=4;threadid=23711;start=0#msg223510 date=1071451979]

Common failure, probably caused by fluid hammering created by the VP44.
[/quote]

explain "fluid hammering" to me por favor.
[/quote]


Its Like water hammer, but in both directions.