z28cam1993

Hi all. I'm a new member. Just bought a 1993 z28 slightly modified. Here is my issue and what I'm doing to fix but I need some more info if possible.


I'm changing the plugs. I'm swapping out the aftermarket fuel regulator for a stock one. I ordered a fuel pressure tester. I was thinking the fuel regulator went bad but maybe it's a stuck injector? The plugs so far aren't wet. Slight gas smell. Oil change literally was 2 gallons there was that much gas in it. Previous owner stated car ran before parked in winter. Any advice would be greatly appreciated.

Injuneer

Check the vacuum compensation line on the fuel pressure regulator for wet fuel. When you get the fuel pressure gauge, turn the key to "run". Fuel pump will prime for 2 seconds. Pressure should reach at least 40psi. When pump shuts off, watch how fast the pressure drops. If it drops quickly, could be leaking injectors, leaking fuel pressure regulator, or things that wouldn't put fuel in the oil - leaking check valve in the fuel pump, oil leaking fuel lines.

Scan it for codes, using a paperclip to short the ALDL connector pins, and flashing the codes on the SES light. You're looking for codes that indicate faulty O2 sensors, rich A/F ratio, etc.

For a more thorough analysis, download the Scan9495 software (also works for 93), and buy a cable to hook up a laptop. See the "sticky" at the top of the "Computer Diagnostics....." forum.

Don't drive the car with fuel washing down the cylinder walls, destroying the rings, and diluting the oil to the point the bearings are destroyed.

97WS6SCharged

Are you positive it's gas and not coolant? When you drained the oil which came out first, the gas or the oil?

z28cam1993

Thank you injuneer. I'll do everything you stated. I'm def not running the car at all until this is figured out.

To the last reply yes I'm positive it was gas. It was all over my arm and it looks like the gas came out first

97WS6SCharged

If that's the case then it probably wasn't gas. Motor oil is denser than gasoline so it should have been at the bottom of the pan, especially if you had 2 gallons of gas in the engine.

z28cam1993

That makes complete sense. Only thing I can say I mean I'm not positive what came out first because of the awkward position I was in and the force by which it came it and filled out I was in a rush to find another container but is stunk of gas really bad.

I'm waiting on my tester I ordered now. With these headers in not the easiest removing the plugs so still doing that.

97WS6SCharged

Well, look at it this way. There are only three fluids it could possibly be. Water, gas or oil. The chances of you pumping 2 gallons of gasoline into the motor without it exploding aren't very high. On the flip side a bad head gasket can push the contents of the radiator into the oil pan in a few seconds.

z28cam1993

Well explained that way it makes sense but what explains the gas coming out of the exhaust in liquid form and alittle white smoke?

Injuneer

If you are putting more fuel into the combustion chamber than it can possibly use, its simply going to vaporize, not be burned, and condense in the exhaust system, along with the water vapor formed by the complete combustion of hydrocarbons that did burn. The excess hydrocarbons are quenching the combustion process and cooling it down as well.

Do your plugs show excessive carbon buildup, indicative of running too rich?

Did you scan it yet?

Courtesy of Shoebox

http://shbox.com/1/dlc2.jpg

http://shbox.com/1/Dtcs.htm

Did you check the fuel pressure regulator vacuum line for wet fuel?

z28cam1993

I will take a better look at plugs soon so I can give you the most accurate description.

I didn't scan yet because I'm still working on plugs. Not the easiest to remove. I may order the obd1 12 pin to usb on eBay instead of making

Injuneer

You can scan if for codes without a scanner. Read the link. 93 is the only 4th Gen you can do this to. The engine does not have to be running to pull stored codes, as long as you have not disconnected the battery.

If you are looking for a cable for Scan9495, follow the suggestions in the thread. Gary no longer recommends building your own, because the Chinese components are inconsistent and unreliable. Consider the cables from ALDLCable or RedDevilRiver.

OBD Diagnostics

ALDL USB Cable

z28cam1993

Yes correct I worded wrong. I wanted to use scan tool eventually but not now. Next time I work on car I'll scan for codes on dash hopefully he didn't pull the battery. You guys are great. Thanks for the awesome info

z28cam1993

A little update. Removed all 8 injectors and sent out to be cleaned tested and repaired. 4 were dirty but now all 8 perform perfect. Will install soon. Also replaced fuel regulator back to stock. Noticed the vacuum line was missing to the aftermarket one so I will replace. Hopefully this solves it.