When you install the "T" inline, it gives you the same result as using the service port. If the fuel pressure regulator is working properly, fuel pressure readings taken at the service port will be the lower of maximum pump output or whatever the regulator is set for. For example: If the regulator is set for 62psi, the regulator will not bypass fuel/pressure until pressure is at least 62psi and it will not allow pressure to exceed 62psi. If the pump can't build 62psi, the regulator will not bypass fuel/pressure.

 

Im sorry for the post. what is Facebook? good luck

 

Finished up diagnostics today. Dead end fuel pressure is appx. 32 psi with key on, way too low. I ran this test appx 20 minutes after the car was running to simulate when the issue happens. Checked the connector at the fuel pump, both grounds are good. Grey wire has appx. 12 V, purple wire(sending unit) read 5.10V with full tank of gas.

Sure seems like the pump is failing which surprises me, is should be either an AC or Delphi in ther now and was replaced appx. 25,000 miles ago. The fuel gauge is acting wacky also.

 

You understand the gray wire need tested with pump running.

But even good brand pumps CAN fail 'prematurely' .. just you should be aware when I replaced my pump it was good, the {2x2} harness connector failed.

 

Tested the grey wire while I had someone turn the key to second position to prime pump(runs for a few seconds). Read 12V. (actually 11.95 or so with key on, and 12.1 or so right after key off, pump priming) Also, when testing the pump(dead end test) never got above 35-40 psi even after repeatedly turning the key on and off.

 

Well. It's tank droppin' time, fer sher! Careful with that front vent.

 

I may have the shop up the street do it, they did the last one. I'll just get the new pump first myself. I was going to do it last time but was sure that I'd break that vent bung,as the hose was real tight on it, and there wasn't much room to work under there without the vehicle up on a lift. Besides, I can't seem to find the time to do it, and as I get older, the less I want to do bigger jobs like this.

Thanks for everyones help!

 

Just for grins and giggles, take a few pictures, (different angles) of the old pump and post them. One angle in particular, from the top down into the module. If the pix have enough detail, we should be able to tell if it's an AC Delco/Delphi, or some el cheapo knock off from across the pond. If you get a new module from Ebay or Amazon, you really have to be careful to make sure you're getting a genuine AC Delco or Delphi pump. They can be very deceiving in the way they word their description. After you get the new module, check maximum output pressure. In post #7 I mentioned 78psi as the minimum, actually 73psi is the minimum, and 108psi is the maximum, sorry. Brand new AC Delco/Delphi pumps usually build very close to 100psi or slightly above.

 

Captain, I have been checking them out on Ebay, and I do know that a certain place in Miami sells bogus AC pumps so I will stay away from them. There is a place I believe in Cali that shows a photo of a packaged in a bag AC pump with a realistic looking AC label, but the price seems to low at appx. $170. to be genuine. It seems that genuine AC pumps should sell fo over $200.

Also, If I do this myself(possibly with a helper), am I able to just drop the back of the tank down by removing the rear strap and loosening the front one? Yes I do know that i need to have a nearly empty tank and remove all hoses and such, but will there be enough clearance to get the pump out?

And yes, I will take photos of the old one.

 

These seem legit. Also, I do see some listings for a "Robust" version costing over $300, are these heavy duty or severe service?

GMC Chevy Blazer S10 4 Door Gas Fuel Pump & Sending Unit Module AC DELCO MU1733 | eBay

ACDELCO OE SERVICE MU1733 Electric Fuel Pump | eBay

Although no too sure about this second one.