zxtce

Hey everyone my son has a 1993 z28 auto, last night he found out how far off his gas gauge was(read 1/4 tank but it ran out of gas). Now it will not start because no spark,running codes using the service engine light just shows a 44 and 55, no opti codes. Swapped out the icm and coil with a known good ones,grounds are good, the short opti harness is good,also no blown fuse. Other than checking the opti with a voltmeter does anyone have a clue? Thanks in advance

Injuneer

Are you sure it's "no spark".... sounds like the fuel pump failed when the tank ran low.

Check for signal from the ECM to the ICM.... white wire:

Courtesy of Shoebox

4th Gen LT1 F-body Tech Articles

http://shbox.com/1/93_ign_system_schematic.jpg

zxtce

We will check that again probably tomorrow. I will post what we find. Thanks

Fatdog2

The gas gauges in these cars are not accurate.The fuel pump relies on gas to keep it cool.He maybe fried the fuel pump.Happens to most cars I think.Does he still here the fuel pump noise working in the back when you start the car?There is a site(shoebox) I think,That shows how to not have drop the gas tank to replace the fuel pump.Hope this helps.

zxtce

Thanks for the reply, but the fuel pump primes, I just have to have him check out the no spark issue tomorrow night. Funny thing is that I did warn him about the fuel gauges on these cars many times and he knows about the gas cooling the pump. He's too hard headed for his own good.

GaryDoug

Just because it primes does not mean it has good pressure. The only good way to tell is to measure it. Many auto parts stores will "loan" you a tester. The code 55 means it ran lean of fuel somehow (empty tank). Also could be a partly clogged fuel filter caused by sucking up sediment.

zxtce

Thanks Gary, I probably wont get over to his place to help him with the car until this weekend. It just seems odd that when the car died from no fuel he had it towed home, then put in a couple gallons of gas, wont start because of no spark. When I get over there I will again go through everybodys suggestions and post here what was wrong. Thanks

Fatdog2

First thing I would do is change the gas filter.Might be some crud at the bottom of the tank.I think shoeboxes sight can show you how to do it yourself,or just buy a gas filter and have a jiffy lube change it out.If you do this yourself you will need to jack the car up(evenly) as to not bend the frame on the drivers side of the car.Release the gas cap and once you are under the car you will see the gas filter next to the gas tank.Get 2 wrenches and hold one with one and unscrew the gas filter with the other one.Wear gloves and have a pan ready to catch all the gas that splurts out.Put the new gas filter in and tighten it up.The gas line is plastic or something so it bends real easy .You will get the hang of it when you see it.Hope this helps.

Fatdog2

And even though the car is fuel injected,after the fuel filter change ,don't be afraid the pump the accelerator a couple of times to get it going.Whew.I'm done.My02.

zxtce

That is a good idea, never hurts to change it out,who knows when or if its ever been changed anyway. Thanks, I just did that on my car about two weeks ago also, it looked old enough to be the original.

Injuneer

The fuel filter is nowhere near the fuel tank. It's in front of the rear axle, on the driver's side rear frame rail, about even with the LCA connection on the outer rail.

You also have to relieve the pressure in the lines, which you can't do by opening the fuel fill cap. You have to release the pressure at the Schrader valve.

"Pumping the accelerator" does not cause fuel to flow in the LT1 fuel system.

The fuel filter has a GM quick connect fitting on the inlet side, so you need to squeeze the nylon clip to release the plastic feed line. The outlet line is steel.

My fuel filter is not stock, nor are the lines, but it is mounted in the stock bracket, in the stock location..... right side of photo, just above the turndown on the exhaust pipe.

Fatdog2

Wow.Your set-up is beautiful .

zxtce

Hey guys, he did check the opti(followed instructions on shoebox's site, and he needs to replace it) also I guess the fuel pump is ok but he will also be doing the filter. Thanks for the help. Also Fred the bottom of your car looks sweet, nicely set up.

Injuneer

What was wrong with the Opti? If it was the optical cam position sensor, it should have set codes (DTC 16, DTC 36). The code for loss of the low resolution pulse signal from the sensor (DTC 16) causes the PCM to shut down the fuel system.

The bottom is not as clean as the top......

https://www.camaroz28.com/forums/mem...olish-5661.jpg

zxtce

I guess he got a code 16 when he scanned it. It's funny tho that using the service light and jumper wire there wasn't any opti codes when I checked it , just the 44 and 55. And by the way Fred, really, really nice job on your car.