Anybody know LT1 engine?

[48builder]

Finally getting to where I can try to start my '95 Lt1-powered '48 Chevy. At first it would not crank, traced that to a bad VATS relay. Then I had no spark, cleaned up the connectors at the optispark distributor and now have spark. I found out the hard way today when I accidentally touched my spark tester while cranking the motor. Got a good shock.

Bought a noid light kit and the injectors are firing. I have the recommended fuel pressure at the fuel rails.

Seems to fire if I spray a little starting fluid in it but I suppose that could be the ether igniting from the compression.

I've read that the tach needs to read over 100 RPM for it to start, which I don't have, but I also read where if I have spark then that's not an issue.

I'm wondering if all the injectors are plugged from sitting for 25 years. Seems to me that if at least a couple of them were squirting it would try to start.

My next step is to take the fuel rails out, stick the injectors in jars and see if any gas is coming out.

Things are so much easier with my carbureted '39. The '95 Camaro's came from the factory with OBD1 computer but OBD2 test connector. I found a OBD1 tester on eBay that will be here next week so I can check to see what codes I may have.

Any Ideas

[WZ JUNK]

I think you are on the right track.  My throttle body engine sat for 10 years while I was working on the car.  It started with a minimal amount of problems but fuel was the source of those.  My guess is you have some deposits that are causing the problem.

[kb426]

Enjenjo is knowledgeable on those. He has posted about the ignition systems before. It's common for people to ultrasonic clean injectors. Because e10 based fuels cause corrosion and deposits,it's very possible that the injectors could be stuck or slightly plugged. Have you considered using a squirt can and a little fuel to see if you can get it running for a little to see if there's air in the fuel lines or something along that line just as a further process of elimination. I'm not familiar with the ignition system on those but can it be 180 out on time?

[chimp koose]

I drove a 96 silverado with a 5.7 vortec onto the car trailer using insect repellant sprayed into the throttle body to fuel it when I determined the fuel pump was toast .       If it runs on bug spray/carb cleaner/brake cleen you found your problem .

[enjenjo]

Several things could be in play here. First the Opti-spark, If it was good GM would have used it much longer. The 94 and 95 models suffered with early failure of the Opti-spark. Water vapor would seep into the distributor from the crankcase and corrode up the insides in no time. In 96 they modified it with a vacuum line into the plenum that would pull the water vapor out to slow corrosion. The last time I looked Summit had the 96 type distributor at a reasonable price. The plug wire terminals are made of Unobtainium and hard to find separate, so buy the premade wire kits.

Next we get to the ignition switch. Most ignition switches will not supply spark through the computer while cranking, or while running as they only have one output to the computer. So you may have to use a relay on the ignition wire from the ignition switch so you can supply power in both modes, cranking and running. With some starters you can provide the 12 volts from the starter solenoid while cranking.

Now we get to fuel. There should be a timed output to the relay that runs the fuel pump for 5 to 10 seconds when the ignition switch is turned on, but before cranking starts. Once cranking starts the fuel pump relay drops out until the engine starts. No fuel pressure, no start.

And it's good that you are getting a reader because there are several sensors that can cause a no start including TPS, Crank sensor, Cam sensor and others but those are the big three.

What are you using for a wire harness

[48builder]

My engine has that vacuum line for the opti. Since I'm getting spark at the plug I'm assuming it is working properly. I'm using the complete original harness I pulled from the donor Camaro.

I hope the reader points me in the right direction. I have the factory service manual and I've been doing the tests for all the codes that indicate no start, but I'm really just throwing darts doing that.

The manual says 2 seconds on the pump relay, which does work. I have pressure in RUN and START

[kb426]

The orifices in the injectors are very small. If you have blockage, it will be inside where normal cleaning may not be effective. Is there a chance you find some injectors to swap out and see if that cures the problem? Anytime I'm starting an efi engine and it doesn't start within a few seconds, I'm pretty sure something is wrong. Finding it takes a little time sometimes. Most of us have forgot many of the items we need to be looking for. Fire, fuel, compression. Have you pulled a plug to see if there's any sign of fuel?

[48builder]

I ended up taking all the injectors off, and will probably send them out to be cleaned. I found a site lt1350.com and the guy who runs it told me to apply power to each injector and I should here a "click". If not, the injector is plugged. I did not hear any clicks so took them out. I saw no sign that gas was getting into the manifold so I'm pretty sure that's the problem.

Watched a lot of videos about how to clean them myself, but if they are stuck I think my best bet is to have them done by a pro.

[48builder]

Sent them off today to a place called InjectorRX in Houston. They clean and verify proper operation for $22. I thought about trying to clean them myself but I don't want to screw them up and don't want to go to all the trouble of putting them back on, etc. unless I know they are 100%. Looks like it will be another couple weeks before she's running. Time to finish up some AC lines, wire up a relay to send 5V to the PCM for my AC temp control, wire up the moonroof. Always something to do on a custom build.

[kb426]

Positive movement.

[48builder]

WOOOOOOOOOOOOOOOOOOOOHOOOOOOOOOOO!!!!!!!!!!!!

It is running! Put in the cleaned injectors and it fired right up. Was running a little rough until I discovered I forgot to hook up the EGR connector when I put the fuel rails back on.

Had a leak in a heater hose and took it to my local NAPA to have it crimped again. Problem solved. A couple little leaks in tranny line and power steering at the box, tightened up the fittings and all is well there. Had to replace a spindle that was somehow bent, so I could get my new Power Stop front calipers on. Put the driveshaft and torque arm on, just need to bleed the brakes and then try backing it out of the garage for the first time since 1997. Whew.

[kb426]

Great update.

[58 Yeoman]

It feels good when things start going right.

[chimp koose]

congrats on getting it running ! I have a model T project that is near that old and nowhere near done .

[wayne petty]

 many years go.. an LT1 Camaro pulled into the shop with a misfire. the shop owners said they were going to work on it. i pointed out the coil was the cause of the misfire.. it was leaking high voltage externally. so they replaced the optispark and water pump.. still misfired..

 i said replace the coil . nope we are doing this.. so 2 sets of delco spark plug wires and a set of spark plugs and 2 days later it still misfired..  frustrated they were over at the repair info computer trying to figure out what was next.. i kept new ignition coils on my tool box. took me about 10 minutes to install the new coil and wire brush the ring terminals above the bracket.. i reached thru the window and started it up.. idling perfectly..  what did you fix.. i handed them the old coil.. i told you it was a coil causing the misfiring..

 warning Optispark ... the short extension harness from the weatherpack to the optispark gets green corrosion and must be replaced.. or 2 new connector pigtails and build your own..  the green is the wire being dissolved.. cleaning won't help where the corrosion is deep in the wire strands.  somebody online sold replacements for 30 bucks years ago.. gm wanted 10 times that. .