JaredAwells

I have a 1987 z-51 corvette with a stock L98 and sometimes it will start and run just fine sometimes it will turn over fire and then die I am out of ideas on what it could be causing it I plan on driving it to college next month and I’d like for it to be more reliable I have replaced the following, MAF, TPS IAC fuel pump fuel filter oil pressure switch I’ve disabled the VATS it has all new plugs and wires I’m tired of spending money on parts that don’t fix my problem my next route would be either new injectors or Ecu any advice would be much appreciated

Joe C

start with the basics - FUEL, spark , timing. have you run a fuel pressure test? do you have a FSM? BTW, quit throwing parts at the problem.

cadmaniac

When it won't start, check your fuel pressure at the rail. Could be a Fuel pressure regulator.

Sounds like a Fuel Problem. When it wont start, spray some starting fluid in the throttle body to confirm. If it starts, it's probably not a timing or ignition related problem. Diagnose, don't guess.

vader86

Sounds like fuel-issues. Check fuel pressure at rail first, with ignition in run but not started, then see how it behaves when you try to fire it.

JaredAwells

Yes I have checked the fuel pressure in the run position it made between 40-42 psi I haven’t tried it when turning it over

JaredAwells

I have a fuel pressure regulator on the way off run a pressure test as soon as I get home to make sure it’s what I need

cadmaniac

When it does start, does it run correctly, or sound lean or rich? Another words, is is it flooded or starving for fuel when it runs?

JaredAwells

When it does run it runs smoothly but it does smell a little rich

vader86

Hook up pressure gauge at rail, observe pressure when running. Turn off car or let it turn off by itself, watch FP gauge reading. Should hold.

Then best to hook up a scanner and datalog it to see what the computer is seeing before replacing any further parts.

JaredAwells

Do parts stores scan OBD1 anymore?

vader86

Parts stores scan codes, what you want to do is buy a scanner that will read OBD1. Mine is an Actron from Autozone with an adapter to let it read OBD1.

You can also buy an OBD1 cable and use DataMaster on your laptop.

JaredAwells

Okay I’ll pick one up is there a link to download data master? Or is it just a website?

xrav22

Put a paperclip in the top right 2 ports of the diagnostics connector and you can read the codes for free. Same codes as a tester.

vader86

He does not need to scan codes here, he needs to look at the datastream.

JaredAwells

Yes I myself do not have a laptop to get the data however in the next week or two I will use my cousins to find what is wrong

kael

Just to make sure, no codes? As in Service Engine light is off? Since you replaced the MAF, I'd be surprised no codes unless you spent $600+ for the Bosche.

JaredAwells

I have a Bosch in there yes but it does have a check engine light on but it goes off and on

vader86

Then what is the code set?

JaredAwells

I can’t recall the number but it’s just a O2 sensor fault

vader86

If your O2 sensor is dead or dying it can flood the engine and make it cut off.

Replace the sensor and check its wiring, that should've been the first thing you did.