mannix91

Hi I have a 91 Z-28 305 TPI, just bought it after being off the road for 10 years. It just developed a problem when driving where it will run at idle and drive but as soon as I give it gas there is nothing there. Foot to the floor it feels like it is not getting gas. No codes, starts fine and does this right after starting before it has come up to temp.
The guy I got it from installed the fuel pump wrong and was leaking from the seal so I just finished pulling the tank and replacing the fuel pump. While the tank was out it was dry and I vacuumed out some rust and junk before putting it back in.
It was running great until just a day or so ago when it started the giant bog feeling.
I am also noticing an increase in noise (buzzing) from the fuel pump.


I wanted to ask for advice on next steps. I am thinking check the fuel pressure but am not sure where the Schrader valve is or what to hook up to it to check it. I am probably going to pull the filter and replace it since it is easy.
Is there anything else I should look at that might cause this? Will the fuel pump get noisy if it can't move gas (like a plugged filter) or is it simply a bad fuel pump? (I think it was a Denso pump)
Sorry for the long post and I appreciate comments.
Thanks

Bob88GTA

iTrader: (2)

Don't mind the comment. This is your location for the Schrader valve. Passenger side rear fuel rail

mannix91

Thanks great photo. Can you get to it without taking the plenum off? Also is there a "special" fitting I need to hook up a pressure gage? Maybe stupid, but would a 100 psi tire pressure gage work???

Bob88GTA

iTrader: (2)

Easy access. Just get a gauge from the auto parts store cheap. It will have a flex hose on it and will screw right on. NO on the tire gauge.......!!!!

cuisinartvette

^^^^this

wrap a towel around it when you go to unscrew you can get a little fuel spray sometimes. Or just barely crack it let it seep out then finish unscrewing

Nice to have, can tape to your windshield see whats going on under load.
They arent much long as you own an EFI car youll use it
Better than paying someone $100 to diagnose it for you.

mannix91

Just thought I would provide an update.
I checked the pressure and it was running around 40 at idle and then dropped off when I drove the car, so I pulled the outlet line from the filter and hooked up a hose to drain my tank and observed that the flow would start strong and then taper off and at the same time the noise increased in the pump. So, I dropped the tank and think that while there was still some rust and "stuff" in the tank, the filter that came with the new pump had more of a "cloth" type of material rather than the fine mesh on the original pump and it was restricting the gas available to the pump and starving it.
So I reinstalled the original pump with the screen filter thinking that as long as the filter catches the larger particles that would mess up the pump it would pass through the fine stuff that would be caught by the in-line filter which is serviceable.
I will probably replace the tank in time but so far, not many miles on the car, but the pump is quiet and running well.

Bob88GTA

iTrader: (2)

Great to hear.