So 1996 z28 lt1 auto(VIN 2G1FP22P0T2115740)...has been sitting at the mechanics for 4 years because he said it needed an engine, after it shut down on the road and would not turn over. Same mechanic had just replaced the front main seal the week before. Well he had a shelter and I didn't have the cash to put a motor in it. So I finally had it brought back home with the intent to clean it up enough to sell. However, when I started looking at stuff, the first thing I did was check the oil....It had 1.5 qt's in it. It's worth noting that the seal is still leaking, now that I've had it started a time or two and it's full on oil, >_<.


Now I had taken the mans word that it needed an engine, based on him starting it to move it inside, and said the engine "sounds horrid, somethings broken internally" . He did confirm it started right up but didn't recommend driving it based on how it sounded. So I of course, topped off the oil and attempted to start it. I had put 5 gallons of fresh premium in it, gave it a couple squirts of it in the intake(removed all plastic) and sure enough it fired right over for 4-5 seconds.

With oil in it, I could not hear anything from the motor that sounded off even remotely, but it's hard to say in 5 seconds. Later I had a friend help out, and was able to keep it going on squirts for a good 15 seconds, but fuel would never catch. Those 15 seconds sounded like pure heaven, beautiful. That was as far as I got at that point, with help. Back to working solo I cracked the fuel filter, nothing but old gas smell, not quite varnish, but not far off.

After checking the fuses, (I still can't find the fuel relay) I saw a thread here about the bypass wire above the pcm on drivers side for pressure testing, and that's easy solo so I gave that a go. I didn't get anything at the rail, no catch trying to start it that way at all and cracking the line at the filter produced no more fuel beyond that bit that came out the first time, I can put a hose on it and blow air back into the tank, so it's not varnished shut.


Does that bypass wire confirm for sure that the pump is dead? Money is tight and I really want to confirm if there's anything else I can do solo before going ahead and replacing that pump, doing the panel cutout..

If so, I've read here that the HP10036 is the correct pump, but parts sites tend to disagree and suggest something about the size of a start solenoid...?

What do you think?

If it matters, there's 131k original on the engine and turning over and short starts on squirts sound great, no hard knocks for sure, but I figure I won't be sure on the internals till I can get it going and give it a little torque.


Am I on the right track? Also, please lmk if this isn't the right board for this post, I looked around and it seemed the right place. Thanks in advance!

 

lots of possibilities:

Did you hear the pump start when you applied 12 volts to the prime connector near the PCM?

The 96/97 cars are a bit different, in that the prime connector does not connect directly to the fuel pump. It goes through a 5th pin on the fuel pump relay. The relay is behind the driver side foot well kick panel. (Photo is 95. Location same in 96)

http://shbox.com/1/fuel_pump_relay.jpg

Have you actually measured the fuel pressure?

Did you change the “varnished” fuel filter?

After sitting for that long the injectors could be plugged up.

When it only runs for a few seconds when trying to start, it can be a result of the PCM not receiving the “fuel enable” signal from the VATS system, part of the body control module. There is a code that sets in the PCM if it detects the crank position signal from the Opti, but does not receive the fuel enable signal from the BCM.

 

I hear nothing from the fuel pump when bypassing with the wire.
don't have the pressure gauge but I do have a hose with the correct shrader fitting on it, when applying power to the bypass no fuel was produced.

So the relay can still affect power to the pump on the 96, even with the bypass is what you're saying?

Just got done putting new filter on, no change. Also turned key on while filter was off, no fuel from line coming from pump.

So, fuse tests, relay test, and then start trying to figure out how to test the VATS/BCM?
​​​​​​​

 

I answered each one at a time but for some reason it said comment had to be approved by a mod...

No sounds from pump at all when bypassing with 12v jumper..

 

I approved” the post. Not sure why the system puts some posts in the moderation queue. Might be the length of the post plus low post count. I also had to approve your first post.

To clarify the comment on the prime connector circuit going through the fuel pump relay - in 93-95 models the prime goes directly to the pump. In 96/97 it goes through the relay. But the significance of using a 5-pin relay is that when the relay is “off” the switch that connects the 12 volts from the battery to the pump relaxes and opens the circuit to the pump. But the 5th contact allows the switch in the “off” position to close the circuit that sends 12 volts from the prime to the pump. If the relay is working properly, prime will activate the pump. But, if the relay is not functioning correctly, the circuit might not be completed. Hence, in 96/97 there is an outside possibility that a defective relay could prevent the prime from connecting to the pump.

You could pull the relay and check continuity between relay pins 30 and 87A. If you have continuity the relay is connecting the prime to the pump. Next check the pump harness connector on the body in front of the rear axle:

http://shbox.com/1/fuel_pump_wiring.jpg

With 12 volts on the prime connector, make sure you have 12 volts between the gray wire and ground. That would narrow it down to a failed pump.

http://shbox.com/1/fuel_pump_connector.jpg

As far as the pump, I believe that part number is correct, but it is the complete sending unit - support frame, wiring, level sensor, pump, pump bucket, sock, etc. You should be able to replace just the pump. Make sure you get a “genuine” AC Delco pump, from a reliable source. Seems like most of what’s available mail order are cheap Chinese counterfeits that can be dead right out of the box, or soon after.

To check the PCM for the “fuel enable” signal code (P1626) you need an OBD-2 code scanner with GM Enhanced Parameters capabilities.

 

If you want a good fuel pump try this one:

Airtex Fuel Pumps
https://airtexasc.com

Amazon has the one you need:

Airtex Fuel Pumps E3739 https://a.co/d/18ZS6o9
97-96 CHEVROLET CAMARO V8-5.7L Fuel Pump and Strainer Set

Or RockAuto if you trust them

I put an Airtex in my '95 Z28 back in September 2019
It has never ran this good in 10 yrs i have owned it.
Before it would cutout @3800 RPM and only got 18MPG Highway, now i can redline without cutting out and last year i got 22MPG on a trip out of state.
Chevykid