radar502

Anybody know any early signs of fuel pump going out .04 Z 70,000 started about a month back go to WOT and motor just turned off let off gas pick back up and run fine did it a few times 04 been sitting till now .Just wrapped headers jacked up 04 did work went to start no fuel in starrer nothing tried to crank nothing tried it over and over a few times a day for two days then bam cranked has press. in starrer runs good but if try to pass another car just motor stops and let off gas bam picks back up and drives good .No I have not checked Presser ,it acts like pump going ,anybody seen this before ..Thanks...

0Anthony @ LGMotorsports

No error codes?


I would check pressure first before going to far if you don't have any check engine codes popping up.

radar502

NO Codes.. Yep the pressure is next ,going to have to check wile driving to get it right pressure sitting in the garage it will rev to 6000 no prop. but on the road easy drive and hit the gas a little motor dies and when let off gas comes back to life ,had an 96 GS do the same thing ,bad pump .. Have to check it out for sure .. Just getting some in put I don't even want to deal with a pump replace I do my own work looks like pain the rear or in the wallet..

radar502

I checked pressure running sitting 58 Lbs. give it a little gas driving and the pressure drops to 50 lbs. and prop beyond if held the gas down let off gas and jumps back to 58 LBS so I thinking the pump going ... NO CODES.. ????

radar502

NO I have not checked the voltage on fuse #13 , big NHRA race in Houston had to put the 04 on hold great race weekend was fun now back to the pain in the rear 04 at times .The 04 has new Battery and Battery cables and DA DA Alt. has power if its going to were it needs to go ?? Will check #13 and I hope that is it I don't even want to pull the tank out heck no.. If right volts going across the #13 fuse I guessing bad pump some people said the filter may have trash in it ???? Thanks..

BLUICIDE

radar502

NO power to the fuse nothing I guess its the switch ,taking it out in the morning and going to open the switch using the write up and check it out and I hope just a clean up will do.. ..Thanks

radar502

Yes I had the ignition in the on position no pump noises no fuel in fuel rail nothing tried to start turned it over for a few min. rechecked nothing ..The pump is not pumping why looks like no power ,I turned the switch on checked nothing turned off nothing put in new fuse nothing replaced the relay nothing .. Bad ground ??? Well Fry . it cranked and I drove it about around the block with the gauge taped to the windshield to check the pressure looks like sometimes it will pump it comes and goes ,that's when I seen the pressure drop to 40 + - from 58 as I pressed the gas now nothing so I just don't know ,well I do know I have on pump pressure no fuel in lines I looks like no power to the pump ??? Thanks

BLUICIDE

8VETTE7, even without the slightest "ambient noise" OR a added ("Boosta-Pump"), shouldn't you be able to hear the FP pressure-up?

Something similar to a "small whine"? Something similar to a small dc motor "gearing-up"? If it's silent, and there's nothing at the shrader, it must be two things, right? Power/connectivity to the pump, (whether it a a GND/continuity) or, once that's proven, no +VDC to the other end of the ckt.? If that's true then, two things remain to be checked. The GNd/connectivity to/thru the tank/fuel pump, (given no interruption in continuity) or the VDC supplied and isolated from the power source.

Certainly you DO NOT want +12VDC near the fuel. So, one would run a GND (continuity) to the mechanisms in the tank(s). Add a relay, a regulator (isolation) and seemingly, that would work, yes?

The problem is, how can one determine if the pump is getting the VDC required without playin' "SPARKY" near the tank. Especially with no codes.

Down to this. If/when the car doesn't make a damn noise (other than the preliminary ~bing&bongs~, AND there's no VDC at F13, then might it easily be the IGN switch? I'd have to say YES. Until that's proven otherwise, nothing can be proven, otherwise. The hell of it is, where to begin.

Shot in the dark is, IF the IGN SW is intermittent, then couldn't it be that ANYTHING is "possible"? I'd say yeah, for damn sure. Once the key is inserted and turned to "ON", the IPC lights, does it's sweep(s) etc.. ~Bing/Bong~ etc.. Car might run but for only long enough as to what seems to be fuel starvation. Once that occurs, pressure is checked at the front of the LS6 FR Left fuel rail shrader. Notta. SO, either there's a connectivity issue, or a fuel pressure issue. Sometimes it "works", sometimes it doesn't. It's either/or. I think the op has a decision to make. Which is less costly? IGN switch rebuild, and IF that doesn't reveal some codes, then, the dreaded "drop th tank(s). It kinda makes sense that if the IGN SW is intermittent, and, cycles serial-comms to/from the BCM & PCM, there would be no codes, until after several successful start/run cycles. Just my .02. As mentioned, new key (car ran) new battery, new ALT, car's in great shape. Best part is, everytime it fails, it's in the garage. (lucky son-of-a-gun)

BLUICIDE

Is there any type of inertia switch involved (mercury switch or spring) not included within the schematics? If so, could you point them out? GM has a "funny" way of excluding small details as such. Also, do you have a (layman's) diagram of fuel flow from tank-to-tank for the '04Z? IF so, might you also have a throttle pedal position schematic? Yeah, we checked the oil.

radar502

Thanks for all your help pulling the ING. switch in the morning ,the only way to know for sure and with 70,000 miles prop. needs a little TLC anyway and I will have pulled the console out a even 14 times . I here 13 is an unlucky number..LOL Just an FYI I put a new fuel pump in my 03 Audi 30 MIN..

radar502

As stated in your drawing pin 1-2-5 should be down in crank mode #2 is not going down ,tried to push it down no way ????? Bad switch??

BLUICIDE

Yes, turns out the switch seems to be ok. Depends on how it's positioned. The pin was releasing, it was simply orientated wrong. Guess what happened next? Thanks for your assist.

radar502

As you can see myself and BLUESIDE removed the tank ( NO I did not bench test the new pump in a hurry trying to make a show Sat. NO will not work nothing so hot wired it, still nothing coming back out .We did all the test over and over got power all over checked ground cleaned it and reinstalled it and the switch has been cleaned looks good we used new key I had put away ,so no key prop. Now I have lots new tools LOL.. I think we got this C-5 tank removal thing down will remove any body's tank for one arm and a leg or Kinney and where dog and how much money you got can you get more .. Thanks for your help we going to make it work ..RIGHT

radar502

No not yet ,when we get it out we will check everything out . We were thinking about connectors and the like being the prop.. Will keep you posted had to take a weekend break..

radar502

Update : Dropped the driver side tank NO GAS in it not drop ?? have not checked the pump yet am still in shock over no gas deal ..The pas. side had gas in it when we first started I guess it pumped the gas over from the driver side to the pass. side but not pumping it back I put 6 Gal. in it ,I really don't know how it works ?? Thanks..

BLUICIDE

8Vette7, dropped the DRVR side tank AGAIN and tested the new pump. Purrs like a kitten, yet, all the fuel we put in (appx 7-gallons) is in the PSGR side tank. No comprende' that AT ALL. Sooooooo, gonna reinstall the DRVR side tank (with new fuel pump) and see if filling both tanks might "re-sync" the floats/senders messaging to the PCM. Checked ALL fuses, swapped relays, the whole-9... Whacky-weird twilight-zone stuff going on. Theoretically, when filling the tanks, the DRVR side tank fills 1st, then, via the cross-over tube, fills the PSGR tank. HTH does 7-gallons of fuel get to the PSGR side tank without the DRVR side tank being full to cause the crossover flow? Dumbfounded at this point. Any possibility that the "system" needs to be "re-sync'd" with both floats/senders communicating with the PCM? Appreciate any input. Thanks!

BLUICIDE

So, gonna "fill'er up! See if once both floats/senders (if operating correctly) will make a change. If that doesn't bring any joy, then, I guess it's replace the PSGR side internals. We now have a pressure gauge on the fuel rail shrader (shrader valve removed) to assist in pressure checks. fyi

radar502

Today dropping the right-side tank going in .. after that checking the oil ( inside joke ) .Thanks for all your help..

radar502

New pump new siphon pump nothing has changed ,no pump pressure nothing any ideas??? Thanks