96 Vortec fuel pressure

[dirtautoguy]

Last night I checked some things out. There was some **** on the negative batter terminal so I took the connection apart and cleaned it up and made them all shiney. I did the positive side as well.

I checked all the grounds I could find and made sure they were clean and snug.

I cleaned and sanded the fuel pump ground till it was clean and shiney then i put some grease on the connection to help deter moisture and such.

My results. Before I did those things the battery would hold 12.2 volts is all Right after engine off. Afterwards it had 12.6 volts right after engine off and with it fully charged the pump sounded normal key on engine off.


This morning I checked it before I went to work and it was down to 12.0 volts and the pump was loud. The battery is 4 years and 3 months old so I’m thinking it’s time for a new one either way it probably won’t live through the winter.

 

[Hogg]

Pressures on the Central Sequential Fuei Injection(CSFI) is 60-66psi, pump running. This is the base fuel pressure after which the vacuum referenced FPR pulls down fuel pressure when manifold vacuum is high, like when idling. Basically a VRFPR keeps the pressure differential across the injector valve as near a constant as possible. Then at WOT, intake vacuum is lowest(pressure highest). Engine off, fuel pump running and engine running at WOT should yield very similar pressures.

12.6 volts on a battery is a good sign, whilst running it should be over 14 volts.
4 years in NOT an old battery.

peace
Hog

 

[PlayingWithTBI]

This is the base fuel pressure after which the vacuum referenced FPR pulls down fuel pressure when manifold vacuum is high

I may be wrong but, I thought only the 74.L had VRFPR? OP said he has a 5.7L.

 

[dirtautoguy]

Around here batteries generally seem to last 5-7 years. We have very cold winters and my truck lives outside. Iv had this truck since 2010 and put 3 batteries in it.

1.I put a interstate battery in to replace the one that came with it

2. Napa legend battery that failed after 6 months

3. The warrantied battery that’s in it now.

the interstate battery lasted the longest of about 5 years and I feel like it was much more reliable and strong than the Napa battery.

anyway Started and running my truck is generally 13.6-14.1 volts but after sitting for any length of time it drops to 11.9.

I played with it some more it’s stumble/hiccup seems to have cleared up a lot to where I can’t hardly notice it now and when I do I have to question if it’s just me looking to hard.

when I get some time I think I’ll pull the dist cap and take a look at the ignition system it’s been a while since I visited those.

I also was thinking it might be time to clean the throttle body as well I have done it before but it’s been quite a while.

 

[Schurkey]

Started and running my truck is generally 13.6-14.1 volts but after sitting for any length of time it drops to 11.9.

Killing batteries due to parasitic draw?

 

[96-2D-Hoe]

after sitting for any length of time it drops to 11.9.

Def needs replacing. Fully charged should not be below 12.6v after sitting.

Just got mine replaced with a month left on the 3 year warranty.

 

[Schurkey]

Def needs replacing. Fully charged should not be below 12.6v after sitting.

This might not be a battery fault. Could EASILY be a problem with the vehicle--failed alternator diode(s), parasitic drain in one or more circuits.

Point being, need to TEST the vehicle, and TEST the battery before squealing for a warranty replacement.

 

[96-2D-Hoe]

If the battery is charged and doesn't sit at 12.6v or higher it should be replaced, especially if it's under warranty. How can that not be a battery fault?

No squealing involved and nothing to do with a parasitic draw when it's not installed in the truck.

 

[dirtautoguy]

I’m pretty sure it’s not a parasitic draw. The truck can sit for a week and still be at 11.9 volts, I would think if it were a parasitic draw the battery would be dead.

I didn’t squeal about a replacement I had to jump through a bunch of hoops to prove it was no good it really sucked

I can turn on every electrical accessory in the truck including my electric fans on high and I can still get about 12.7 out of the alternator (the fans draw way more than anything)

 

[Schurkey]

If the battery is charged and doesn't sit at 12.6v or higher it should be replaced, especially if it's under warranty. How can that not be a battery fault?

No squealing involved and nothing to do with a parasitic draw when it's not installed in the truck.

Point to the place where he says it's not installed in the truck. If it's installed, a parasitic drain could discharge it.

For that matter, I've seen parasitic drains right through the conductive slime that builds up on the battery case. Takes cleaning the battery case to fix it. In that case, the battery wouldn't have to be installed.

I’m pretty sure it’s not a parasitic draw. The truck can sit for a week and still be at 11.9 volts, I would think if it were a parasitic draw the battery would be dead.

Perhaps.

I didn’t squeal about a replacement I had to jump through a bunch of hoops to prove it was no good it really sucked

Shouldn't be any need for "hoops". It's very straightforward--Test the battery, test the vehicle, if the vehicle is OK, and the battery isn't...warranty the battery. The process is tougher if a vehicle fault caused the battery failure. When it was us, if the customer had the vehicle fixed, (replacement alternator, wire harness repair, starter, voltage regulator, etc.) we warrantied the battery.

I can turn on every electrical accessory in the truck including my electric fans on high and I can still get about 12.7 out of the alternator (the fans draw way more than anything)

Sounds like the alternator is under-sized. I'd want at least 13.5.