94 TEALBIRD

First off, let my say that the car is a '94 Z28 with 102,000 miles. The car will not start, it just cranks and every once in a while sputters a little bit. There is 48psi of fuel pressure while its cranking, there is no trouble codes on the computer, and there is spark at every plug, and the air filter is clean. I have absolutely no idea what the problem is. I did however just replace the O2 sensors and when I took them out they looked like they where two different ones, but the parts store said they were the same on both sides and sold me two of the same. Also before the car died completely, it was shaking really bad under acceleration and not wanting to rev past 2k. It tripped a code of left side O2 malfunction, so I replaced both and the car ran after that for about 10 minutes, and was doing the same shake and hesistation as before. Then it died an wouldn;t start back up. I reset the codes after installing the new O2 sensors and no codes have came up since. Any insight on this problem would be appreciated. Thanks in advance.

MyShibbyZ28

is the fuel pressure regulator ok? like shoebox told me, check to see if the vacuum line smells like gas or has gas in it. $81 at NAPA for the regulator. Mine had a really bad time starting and would crank over for a long time before attempting to start then would bog down, start again, bog down, and so on until it got enough momentum to actually stay started. replacing the FPR fixed the problem 100%

ShibbyZ

94 TEALBIRD

The regulator is definately okay, I checked it. It is also only about 6 months old. Thank you for the reply.

slopokrodrigez

Try squirting fuel directly into the intake while someone cranks it over. If it fires up, look for pulses to the FI's. If no luck, check compression.

94 TEALBIRD

I pulled a few plugs out to see if they looked like they were getting fuel and one of them didn't seem very wet so I took a noid to the fuel injector wire for that cyl. and it fired. I'm wondering if the injectors are not sending enough fuel. I was going to try some fuel in the intake this weekend and then check for compression. Thanks alot.

slopokrodrigez

My recommendations where based on the fact that EVERY plug was firing. Did you actually check all of them or just a few?

94 TEALBIRD

All of the plug wires were checked and all of them are firing. I am leaning towards the fuel injectors being glogged enough to not allow enough fuel into the cylinders. When I pulled the plugs they were not very wet with fuel. Thank You.

glfclubhaxsta02

Does the engine seem to spin over easily when trying to crank it. If it doesn't the motor may be trying to lock up. Try spinning it over with a ratchet on the front of the motor and see if it is hard to turn.

94 TEALBIRD

As a matter of fact,the engine is not spinning as fast as it used to. I even took off the belt to see if it would spin better but it didn't. If the motor is trying to lock up I'm going to be p_____. It was not making any noises. Thank you for the input.

miiso11

Have you disconnected the IAC at any point recently? If you have you will need to disconnect the battery cable for 30 seconds, then unplug the IAC, plug it back in, reconnect the battery, and the car should start. You then have to drive the car above 35 mph for at least 10-12 miles in order for the ECM to relearn the idle pattern. I just had a similar problem with my 95 Z because I had disconnected the IAC when doing the TB bypass. I ended up reading my repair manual front to back in order to figure this one out.

94 TEALBIRD

I havent messed with the IAC lately but I will give it a try. I took all the plugs out yesterday and did a compression test on all the cylinders. They were all around 190-200 psi except for the number one cylinder, it was reading 175 psi. With those readings I don't think that the motor is letting go. I'm about out of ideas. Thanks

slopokrodrigez

So what happened after you squirted fuel in the intake and cranked it over?

bcunny23

[well it might be the crankshaft position sensor, if yours has one. i had that issue

Dave89IROC

A:, a 94 z doesn't have one
B: crank sensor on LT1 has nothing to do with the engine running, unless the sensor fails in such a way as to pull the voltage feed to ground(compromises signals to other sensors)

Silver

i doubt enough of your injectors have all clogged at once to cut enough fuel off. unless you had some bad stuff poured into your tank all of a sudden, it would take a long, slow process to clog them that much. you'd notice it before they clogged completely.