Thread: LT1 Engine stopped while running

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Yes, Your LT1 PCM does control your Fuel Pump and your ignition if it is wired to do so. Some PCM wiring does not while others do. I would suggest that you get ahold of a scan tool for OBD1 and scan your PCM while turning it over. You can likely get an indication of what is going on. It could be something as simple as a fuse (I have three that control the PCM) or a ground for the PCM let go. Since you don't get your Fuel Pump activated while the switch is on but prior to the switch in the start position, these are the most likely things that can happen on your LT1.
Jerome

A simple check to isolate whether its fuel or spark is to spray some starting fluid, brake clean or even inflamablr hair spray into the intake--if it starts and then dies after the spray is burnt-===its fuel===if nothing, probably spark


and try a different key!!!!!!!!!!!!

simple check.....Koeo...does the check engine light come on? If no Start there..If i does, check for spark on two differant plugs. Should be a BRIGHT plug spark..IF not start at the opti spark. Check for Injector pulse..

The Opti is no easy change, it is buried under the water pump and you must remove Lots O Stuff to access it. It's a better part of the weekend to R & R it.

Keith

Thanks again. I'm learning the hard way. I did spray starting fluid into the intake hopeing to start the engine. I found that I did not have to drop the gas tank and replace the fuel pump. I tested the one I pulled out. The black wire is ground the gray wire is hot and the purple wire is the gas gage. My check engine light comes on whenever the key is in the run position and the engine is not running so that is no help. As I said my car is 75 miles from home so I have a limited amount of time to work on it. This past trip I started to remove the optical distributor. I did not have a harmonic balancer puller with me so the distributor is loose but not out. Like you said it is a real pain to remove. All the comments are appreciated. Hope this helps others.

I have NOT been able to remove the harmonic balancer so that I can replace the optical distributor. The puller that I have used to remove many chevy balancers does not work with the LT1 engine because the threads in the LT1 are 7/16 - 14 and previous models have 3/8 - 24 threads. I went to AutoZone and found their balancer puller will not accept the larger 7/16 bolts. I purchased a puller from Harbor Freight. The puller did not work because I could not keep the engine from rotating when I tightened the puller. I tried unsuccessfully to use a slide hammer to remove the balancer. I did remove the 7/16 -20 x 2 inch bolt and heavy washer from the crankshaft nose. It appears to me that this bolt does not do anything. Does this bolt hold anything or is its purpose to keep the threads clean??? Is the 1.25 keyed hole in the balancer a thru hole??? The reason I need to know this is that my next try will use a hydraulic puller that will push on the crankshaft nose with a 1.20 diameter rod. Thanks again for the help.

I've never worked on an LT1, other than helping my Son with minor things on his Camaro. But, if I remember right the harmonic balancer is a 2 piece bolt together unit. The balancer part can be removed without needing to use a puller to remove the hub part. The hub that stays on the crank snout isn't in the way = no puller needed. I could be wrong, like I say my son works on his car and I just assist if he needs an extra pair of hands now & then. Someone will chime in I'm sure & let us know if it actually is a 2 pc. unit.

the hub on the crank of an lt1 cannot be pulled with the normal dampner type pullers---the hub is a closed unit the bolt goes thru and it doesn't use the big thick washer of earlier stuff---

Dozer, have you Googled "LT1 Harmonic Balancer Removal"? There are a lot of discussions out there that give tips to the process, and explain what does and does not work. Most seem to point to a three claw puller for the pulley, then pulling against the loosened bolt or some smaller tool (one says a socket extension??) for the hub, if you need to pull the hub. Here's one - I cannot attest to it being right or wrong, just posting a link to get you started:
http://www.lateral-g.net/forums/showthread.php4?t=2770

This is what it looks like after you get the balancer off.

Dozer. Sorry I did not show the side view. It is a press on that does need a claw puller to get off. Should be easy with that!

You don't need to pull the balancer hub off to change the Opti, just pull the balancer/pully itself off. One other note on the LT1 balancer hub. It is not keyed like a normal SBC balancer is, it is just pressed on. You can't manually adjust the timing like on the old SBC due to once the relationship between the crank and cam is established via the timing chain, your timing is set. The Opti has a drive pin on it that indexes the timing off the camshaft. The computer does the rest. Are you gonna put a new seal for the Opti in the timing cover? Make sure before you install the Opti that the teflon seal and the Opti seal running surface are super clean. The teflon seals don't like any lube when installed, if there is they will leak.


Keith

Originally Posted by sfort

This is what it looks like after you get the balancer off.

I did not expect that. The picture says it all. Thank you.

I have acted on all the good advise. The voltage tests show no voltage. The relays and fuses were replaced. The harmonic balancer was particularly dificult because of the rust from the salt used in the area in the winter. I had to make a hydraulic puller to remove the balancer as the pictures showed. I replaced the opti spark distributor, still no joy. I have just aquired a cpu from a suppositly runnable junk yard car. I will install it next time I am able to drive the 75 miles to where the car stopped. If this does not work I am going to pull the LT1 engine and replace it with an older engine. I am allowed to do this because the Chevy is a 1994 that does not require a computer scan to pass New York state inspection. Possibly I should have given up on this car, but I like older cars.

Dozer

Wow! This has been going on for almost seven months and it's still 75 miles from home with occasional trips to work on it? Have you considered towing it home, maybe on a two wheel dolly or getting a friend with a trailer & winch?