Fuel pressure goes from 55 to zero.

[67ChevyRedneck]

00 Z71, 5.3L w/126K.

A couple weeks ago the truck started to not start on the first hit. It was totally random when it did it, sometimes when it sat for a day or two, sometimes right after I just drove it, ect, but it would also sometimes kick right off in the same scenarios.

I put a fuel pressure gauge on the truck today. With the key on, the pressure gets up to what I'm guessing is around 55psi because by the time I get back around the hood to see the gauge it QUICKLY falls to about 20, I haven't waited for it to go to zero, but it starts falling really slow after around 20. I pushed the release valve on my gauge and repeated this several times.

So, is this a fuel pressure regulator or am I looking at a new pump? Does the regulator maintain pressure or hold it back from the pump (keeping it constant)?

Supposedly, a sign of a bad regulator is gas in the vacuum line. Mine is completely clean/dry.

Also, while running, pressure bounces from 54 to 56.

I just did the fuel pump on my s10, am I in for more fuel pump fun?

[clinebarger]

Originally Posted by 67ChevyRedneck

00 Z71, 5.3L w/126K.

A couple weeks ago the truck started to not start on the first hit. It was totally random when it did it, sometimes when it sat for a day or two, sometimes right after I just drove it, ect, but it would also sometimes kick right off in the same scenarios.

I put a fuel pressure gauge on the truck today. With the key on, the pressure gets up to what I'm guessing is around 55psi because by the time I get back around the hood to see the gauge it QUICKLY falls to about 20, I haven't waited for it to go to zero, but it starts falling really slow after around 20. I pushed the release valve on my gauge and repeated this several times.

So, is this a fuel pressure regulator or am I looking at a new pump? Does the regulator maintain pressure or hold it back from the pump (keeping it constant)?

Supposedly, a sign of a bad regulator is gas in the vacuum line. Mine is completely clean/dry.

Also, while running, pressure bounces from 54 to 56.

I just did the fuel pump on my s10, am I in for more fuel pump fun?

Bad check valve in the fuel pump. Yes, more fuel pump fun.

If your bed is empty, Remove it to get to the fuel pump.

[67ChevyRedneck]

I 99% figured it was the damn pump.

[67ChevyRedneck]

New issue. Went to order new pump, apparently there's 2 versions for VIN T:

1999-2003 CHEVROLET SILVERADO 1500 5.3 VIN T w/o Evap Emissions Sensor Stamped TCU

&

1999-2003 CHEVROLET SILVERADO 1500 5.3 VIN T w/ Evap Emissions Sensor Stamped TCU


Ummmmm, any insight on this?

[DirtyLarry]

Originally Posted by 67ChevyRedneck

New issue. Went to order new pump, apparently there's 2 versions for VIN T:

1999-2003 CHEVROLET SILVERADO 1500 5.3 VIN T w/o Evap Emissions Sensor Stamped TCU

&

1999-2003 CHEVROLET SILVERADO 1500 5.3 VIN T w/ Evap Emissions Sensor Stamped TCU


Ummmmm, any insight on this?

Buy whichever is cheaper. One has a little EVAP pressure sensor on it and the other doesn’t. If you truck requires the EVAP sensor just finish drilling the hole template in top of the new fuel module and move your old sensor over to it. Usually the fuel modules without the sensors are cheaper. I just did this on my ’04 Hoe.

Here is the pressure sensor that will be on top of the EVAP fuel module. It is basically the same sensor as a MAP sensor…..It just senses pressure inside the tank. These sensors seldom fail so I would feel comfortable using the old one to save a few bucks.

AC Delco 213-4429

[67ChevyRedneck]

Cool. The seller answered me back. If it says federal emissions it doesn't have it, if it says evap emissions (california requirement, maybe?) it has it. Mine says federal. If he's wrong, or I read the wrong thing, it's good to know I can fix it.

[truckdude239]

i would not cheap on on these pumps order an ac delco pump i've seen way to many after markets fail with 6 months to a year . and ac delco being the only ones to last

[truckdude239]

btw you can get the vin and call the dealer they will tell you which one u need

[Boog]

Originally Posted by 67ChevyRedneck

00 Z71, 5.3L w/126K.

A couple weeks ago the truck started to not start on the first hit. It was totally random when it did it, sometimes when it sat for a day or two, sometimes right after I just drove it, ect, but it would also sometimes kick right off in the same scenarios.

I put a fuel pressure gauge on the truck today. With the key on, the pressure gets up to what I'm guessing is around 55psi because by the time I get back around the hood to see the gauge it QUICKLY falls to about 20, I haven't waited for it to go to zero, but it starts falling really slow after around 20. I pushed the release valve on my gauge and repeated this several times.

So, is this a fuel pressure regulator or am I looking at a new pump? Does the regulator maintain pressure or hold it back from the pump (keeping it constant)?

Supposedly, a sign of a bad regulator is gas in the vacuum line. Mine is completely clean/dry.

Also, while running, pressure bounces from 54 to 56.

I just did the fuel pump on my s10, am I in for more fuel pump fun?

Sounds like I have the same issue with my 00 Z71. It seems to run fine except the first start of the day or numerous times a day. Hit the key and it fires but dies immediately. Hit the key again and it spins over a lot like it is flooded or something. It does seem to idle slower than it used to. I have not checked the fuel pressure yet. Isn't operating pressure supposed to be around 65 psi?

[67ChevyRedneck]

Originally Posted by truckdude239

i would not cheap on on these pumps order an ac delco pump i've seen way to many after markets fail with 6 months to a year . and ac delco being the only ones to last

ac delco or delphi?

The delphi's are about $50 more. I just put a delphi in my S10. I think the delcos are made by delphi.

[Legend56BC]

Originally Posted by truckdude239

i would not cheap on on these pumps order an ac delco pump i've seen way to many after markets fail with 6 months to a year . and ac delco being the only ones to last

I will agree 100% with the above statement!!! I have a aftermarket one here on my shelf for emergency only I wouldn't even put it on craiglist to sell to someone...

[67ChevyRedneck]

Don't worry fellas. Waiting on my order from GM parts direct.

I've read about the same issues on S10forum.com and GM-Trucks.com. Some lasted as little as 3-6 months!

[truckdude239]

good old flow Chevy gmc dealer i deal with the dealer thats runs gm parts direct. good guys over there

[67ChevyRedneck]

Yeah, I sent them my VIN on tues night and they answered early wed morning.

[Boog]

How about an update Jesse.

[67ChevyRedneck]

Ummmmmmmmmmmmm, still haven't fixed it

Been busy with work, house, s10 needed some lovin, and now that we have spending cash, been having some fun going out on the weekends finally!!!

I've been driving my S10 everywhere. The truck was hooked to the boat for a couple weeks, my tarp got a hole and I had to air/dry the boat out so I moved it around every couple days to the sunny areas of the yard so I didn't kill my grass. So she still got a little exercise.

I bought the pump like 5 weeks ago??? Just drove it to wally mart and back. Weird how it seems nothing is wrong. If it's nice this weekend I may finally get it done. Trying to get the gas as low as possible, it's down to 1/8 tank now, but that's still like 6-8 ish gallons. I do miss driving it. I used to drive S10 to work and Z71 on the weekends.

[Jacfourteen]

I've been having intermittent pump problems on mine too. Dropping the tank isn't alot of fun, but I'm getting better at it! I've had the tank out 4 times in the last month and now I can have the pump out in 20 minutes (if the level is low enough that I don't have to siphon gas out). My problem is that against advice on here I replaced the bad factory pump with a cheapy pump only (not module) and I'm getting a bad connection on the plug that attaches to the pump. So I pull it out clean connection, put some dielectric grease on it, put it back together and it runs good for week or so then dies. If it dies again I'm gonna bite the bullet and get a Delphi. Sorry for the long post but just sayin you made the right choice getting the oe pump.

[Boog]

Jesse I know you have already checked the vacumn line to the fpr for gas but I had done so also but it was after the truck sitting over night and mine was dry. The gas had drained back and the line was dry. This past Saturday I pulled the line just after shutting it off and gas poured out of it. By my post below you see I replaced the fpr curing my hard start problem. Way easy. 5 minute job for less than $50. It's back to it's old self again.
Maybe run yours a bit then shut it off and pull the line again.

[67ChevyRedneck]

Thanks, I'll check that too. I already got the pump and I guess for a GMT800 it's overdue for a new pump anyway. Going to NY in about a month, don't want to be on the side of the road in the mountains of WV in December.... I'll do another pressure test with the new pump on and check the regulator after I've run it for a while too What's funny, is the last 9 or 10 times I've started it, it's been fine (starting on first hit)

[67ChevyRedneck]

I finally fixed the damn thing. What a pain in the ass... Pressure is now holding.

I freaked myself out. After I got it done, I put the tank up in and left everything loose for a test. Turned the key and nada... no ZZZZZZZZZZZZZZZZZZZZZZZZ, crap. Started checking and swapping fuses... nada... put on my old thinking cap. Nada Started looking under truck and I see fuel filler ground wire hanging down... ah ha! The fuel pump ground and filler ground are on the same bolt and I had to loosen it to get the filler neck off! Tightened it down and it fired right up.

[Boog]

Well good deal Jesse. Be glad you put in an AC unit.

[67ChevyRedneck]

Originally Posted by Boog

Well good deal Jesse. Be glad you put in an AC unit.

Me too, there's no way in hell I want to do that again!