A little late to the discussion, but glad I stumbled on this thread regarding in tank fuel pumps in GM products. It seems that Tickerguy has done an in depth analysis of what seems to be parallels issues that I am having with my 2004 Chev., 1500 Express van with 5.3L vortec engine. The van has about 185, 000 miles on it, and save for the normal wear and tear replacement things and a transmission o'haul about 5K miles ago has been a good running machine. However, on a recent round trip from Austin, TX to Albuquerque, NM via southern Colorado and TX panhandle, and back, without warning engine begin to stumble and act if running out of gas, but with about 1/2 tank of gas, and finally just stopped running.
This occurred in Post, TX on a Sunday evening....talk about a bad places to have trouble...and with only a Zone about to close. Based on past experiences as past owners of several late '90s Jimmys and Blazers, I immediately suspected the fuel pump, but had no way to verify as Zone didn't have a fuel pressure tester and even if they had one, getting to the test port in the van is impossible without dismantling part of the lower dash in order to remove the interior engine shroud.
Anyway, after waiting a bit, and figuring how and where I was going to get towed and what would be involved in the fix, I attempted to start the van and ta da, it started right up, idled OK and we eased around a bit and all seemed to be fine, so headed on down to Austin and van continued to run without a hiccup.
So, once at home base with tools and a fuel pressure tester, dismantled the dash and remove engine cover, attached tester to port and got these readings:
Ignition on, no start - Pressure goes to 63 PSI and in few seconds drops to 53 PSI
Ignition off - Pressure holds at 53 PSI and after about 15 minutes drops to 50 PSI
Ignition on, start engine - Pressures goes to 60 PSI and varies between about 57 - 62 PSI, depending on throttle.
At the same time, I wanted to make some checks of the fuel pressure regulator and I searched hi and lo on each fuel rail in the area as is shown in OEM Helm manuals for this model Express van, and NO pressure regulator. So where is it?
After much searching on line, I found some guy on U Tube that had the same experience with a Suburban and had found that it is now located in the fuel pumpin the gas tank. I have since found some critic notes that in about '03, for certain models of GM (which apparently includes my van) they relocated the fuel regulator to the fuel pump assembly....great, now we have at least 3 functions buried in the damn fuel tank that can go wrong....fuel pump, pressure regulator, and stupid fuel tank pressure sensor, all requiring dropping of the fuel tank to fix. Geeezz.
In the video on U tube of the guy I referred to earlier, he showed installing a fuel regulator module on to the pump assembly, that is identical to the one that used to be mounted on the driver side fuel rail of the engine. In his installation sequence he did not connect anything to the vacuum port on the regulator.....so how does this work without vacuum?
Anyway, after several weeks of tooling around town and several hundred miles, van still running fine with no hicups. However am a bit leery of taking it on an extended road trip and having the fuel pump and associated parts go out in the middle of no where, and so am going to replace the fuel pump....after I chop a hole in the floor of the van over the fuel tank and fuel pump....no more dropping the tank for me!
And so am about to order a fuel pump from Rock xxxx and find that the fuel pump for my van doesn't have the regulator in, but regulator sold separately. So I'm still puzzled about the relocation of the regulator in to the pump, and how it works and what the pump part number is for the pump that has the integral regulator???? Someone in the thread, mentioned a Delphi pump with an improved return fuel cups and such. Would welcome anyone with ideas, suggestions, etc. addressing pump part number with regulator, brand (Delphi or AC Delco}, and how it works and if it will fix my problems. So tnx in advance for any and all info.
