kcpope

@Zed Head If I had another gauge handy, I definitely would, but I don't. I'll ponder the headache of buying another gauge to check my guage🥴

Unfortunately it's not the original Bosch pump. I'm 99% sure this is the pump I have. Mine appears identical: https://www.autozone.com/p/trugrade-electric-fuel-pump-a1188ep/303038?searchText=fuel+pump&productPartGroupId=azpg1436&productBrandId=HTTT&productUniqueId=8870929706 And because the Autozone page doesn't list any specs, I searched RockAuto and came up with this pump, which also looks exactly the same, and probably is, despite the blue color. They actually list the specs: https://www.rockauto.com/en/moreinfo.php?pk=11528713&cc=1209260&pt=6256&jsn=3412 As you can see, here's my pump setup...

@Zed Head It's a brand new, Aero motive gauge. Known for high quality fuel injection components. Not a junk brand. @zcardepot.com , any comment on this? Here's the pic of the gauge with the fuel pump running (engine off). Should be 36 PSI but is showing 41 PSI...

Running the fuel pump without the engine turning over shows about 41 PSI.

Looking for input… It’s running and idling OK, but I want to get some input on the following gremlins: Replaced the FPR. Getting 34PSI at idle. Still seems a bit high to me. Might be related to my 2nd bulletpoint. Can anyone chime in with their reading at idle? I’m getting 16 inHg of manifold vacuum at idle. This seems low. Anyone want to chime in with their engine’s vacuum at idle? Mine is steady, no surging. Sprayed brake cleaner to check for vacuum leaks. Nothing. I’ll start by checking the EGR. Set timing at 10 deg. BTDC and idle at 800 RPM, just fyi. Thanks for any suggestions. First check will be the EGR…

Half of the enjoyment I get in this process is using bits and pieces that I already have, researching youtube and forums for hours to figure something out, and never paying "the pros" unless I've exhausted all other options. I dunno what that is, but it sure scratches some itch in me. 😅

Well, out of principle I refused to pay the $130 they want for a 78 FPR😅. So, I opted for the zcardepot $70 FPR that's technically for the 75-77 models. Still expensive for what is it, but I digress! I'll just plan on capping off the second fuel inlet. For those who may not know, 78 FPRs only have 1x inlet and 1x outlet, while the 75-77 FPRs have 2x inlets and 1x outlet. Internally, they function the same though. Zed, I agree, any "used but functional" FPR is going to have a 50 year old diaphragm inside that could be hanging on by a hair, so I opted to go the "new" route. I'll report back with the results, along with some fuel pressure readings.

Yes, I saw those and was tempted. But felt like the idle PSI it claims was a bit too high, right? Shouldn’t it be more like 20PSI at idle?

Following up to my own question to help anyone in the future. Here's some good discussion on FPRs that are the same spec, but don't hurt the wallet as much...

@Zed Head Nice call! Sure enough, very slow dribble of fuel coming from the vacuum port on the FPR. Too bad the only source for these FPRs seems to be zcardepot and MSA at well over $100. Woof. Anyone got a clever solution? I also finally understand (from much reading of the FSM) that proper fuel pressure is critical to achieve a correct A/F ratio. The ECU is essentially "dumb" and simply opens and closes the injector based upon a set amount of time, regardless of how much fuel pressure is being applied. Too much fuel pressure = rich condition. Too low fuel pressure = lean condition. Proper fuel pressure should be MANIFOLD VACUUM PRESSURE (a negative number) + 36PSI For most healthy engines that will mean you should see about 20PSI of fuel pressure at idle. Mine is showing about 38PSI at idle. Way too high, which would explain my rich idle condition. The little bit of raw fuel entering the FPR vacuum line also isn't helping. Anyways, I think I'm understanding that correctly. Off to source a FPR...

@redondozee Nice looking 280! Where abouts is the car located? Auto or Manual? Thanks👍

Makes sense. I’ll do that tomorrow and report back. Thanks👍🏼

I removed the FPR vacuum line. No evidence of liquid gas in the line, but it does smell like gas inside the tubing. Is there any sort of on/off vehicle test for the FPR?

Quick question. Got the car running today and I’m going through the basic tuning procedure. FUEL PRESSURE. I’m at 38PSI at idle. Also, it drops to zero immediately after turning off the engine. I know that’s not technically correct. Would that indicate a faulty fuel pressure regulator? Or is it more likely my aftermarket fuel pump that might not have a “check valve” like the OEM pump? Lastly, would this fuel pressure scenario possibly cause an overly rich idle mixture? I can tell she’s running very rich at idle. Or is it completely unrelated?

Cold.🥶 And by that I mean an ambient temp of 95. I know it’s not the absolute most thorough option, but this was just a “make sure the valves weren’t grossly tight or loose” situation. Which thankfully, they weren’t.