Help!!!

So, did the cam swap. Installed new spring kit, 1.6 rr, new pan gasket, new alt, painted intake and rails, pushrods, motor mounts, pan gaskets etc.

Buttoned it up, crank- no start.

Pulled front cover, verified dot to dot on timing chain. Opti installed correctly. Plugged in correctly. New coil. New icm. Injectors getting pulses when opti spins. Fuel pressure at the rails is 44-48. ICM has proper voltage. Coil makes spark. Voltage present on opti plug. ICM ground present. Battery ground fine. Battery is charged. Scan 9495 showed only a low volt code on MAP and it is fine now. All fuses are intact. I've tried my known good opti and a new one.

Does anyone have even the slightest clue where to check next?

I'm at my wits end.

Thanks in advance (1995 car, console is out, 1993 intake and rails)

Do you get any popping like it's trying to start, or just dead silence? Spark at the plugs, or just at the coil?

It has spark. Fuel misted into the TB causes a firing condition. I'm not sure of the strength of it

Fuel pressure? Is there and injector pulse?

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44-48 (in OP)

check opti signals, just had one where a guy did a cam swap using a new accell and was getting spark but no pcm pulse for injectors

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It's sending pulses to injectors.

https://uploads.tapatalk-cdn.com/201...1d531a4ae7.jpg



Does it have compression? If not are the Valves adjusted too tight? Timing marks. Cam gear set at 12 O’Clock and crank gear set at 12 O’Clock is TDC on number one. Cam gear at 6 O’Clock and crank gear at 12 O’Clock is TDC on #6. In the attached diagram it shows timing marks at 6 and 12 with the cam pin at 3 O’clock. Rotor should line up with #6 plug wire. Also make sure your cam pin is out far enough to engage into the back of the distributor. You also state that by spraying some fuel into TB it tries to fire. If it was me I would pull the injectors and verify that they are indeed spraying some fuel. Just crank enough to verify fuel spraying. If you have a inspection camera you can stick it down the TB into a port and verify that the injectors are spraying fuel. Which would be safer. Fuel pump may be priming but not running when cranking, could be an issue with the oil sending unit. With No oil pressure pump cuts off. Bad sending unit can cause fuel pump not to run when cranking. Just giving some ideas to double check. Don’t get frustrated, take it one step at a time and double check everything. Keep us posted on what you figure out. Post up a video when it’s running.


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Attachment 38355

Timing is on. Oil pressure is present while cranking. I'll see if I can get a camera down in there when my brother gets back.

I measured the pin when I received the cam and it was within spec. I will back the rockers off a quarter after I verify fuel.

Thanks for all of the comments so far. This thing is being a PITA

How long does it hold fuel prime? Is the fuel pressure dropping off within a few seconds of initial prime? The time you got it to crank did you monitor rail pressure to make sure it held? I have 6.2l LS that drops fuel prime and takes forever to crank when it does decide to crank. That is why I ask.

I'll report back when the new fuel pump gets here Thursday. I went ahead and ordered one since the sender on the old one was jacked anyway.

I'm intrigued by the fuel pump oil pressure sending unit relationship. There doesn't seem to be an overall consensus about it. I don't see anything in the wiring that would cut fuel if it was jacked. However, the gauge goes to around 40 during cranking.

I set the valve lash according to shbox's directions. Took them to just beginning to drag when spinningg the pushed then 1/4 turn past.

Quote:

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Originally Posted by donfrye

I'll report back when the new fuel pump gets here Thursday. I went ahead and ordered one since the sender on the old one was jacked anyway.

I'm intrigued by the fuel pump oil pressure sending unit relationship. There doesn't seem to be an overall consensus about it. I don't see anything in the wiring that would cut fuel if it was jacked. However, the gauge goes to around 40 during cranking.

I set the valve lash according to shbox's directions. Took them to just beginning to drag when spinningg the pushed then 1/4 turn past.

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FWIW I DESPISE that method. Waiting to feel drag when spinning means you've got enough preload on them already to cause drag while spinning. You're past zero lash at that point already. Lift up and down until you have no play, then set lash past that. Very possible lifters are too tight.

Also, pulses from opti for injectors is good, but you need to verify the injectors are firing. The PCM fires the injectors by grounding the circuit. Could be a PCM issue, injector harness issue......shoot, have you checked the 7.5a injector fuses? That caught me once. Grab a NOID light and hook it up to see if you're actually getting injector fire signals too if those fuses are good.

Quote:

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Originally Posted by donfrye

I'll report back when the new fuel pump gets here Thursday. I went ahead and ordered one since the sender on the old one was jacked anyway.

I'm intrigued by the fuel pump oil pressure sending unit relationship. There doesn't seem to be an overall consensus about it. I don't see anything in the wiring that would cut fuel if it was jacked. However, the gauge goes to around 40 during cranking.

I set the valve lash according to shbox's directions. Took them to just beginning to drag when spinningg the pushed then 1/4 turn past.

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https://uploads.tapatalk-cdn.com/201...1a60148751.jpg
After looking at the wiring diagram the oil sending unit doesn't appear to be tied into the fuel system. Sorry, I should have double checked before I mentioned it. Some GM cars have it set up that way.



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Quote:

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Originally Posted by Fastbird

FWIW I DESPISE that method. Waiting to feel drag when spinning means you've got enough preload on them already to cause drag while spinning. You're past zero lash at that point already. Lift up and down until you have no play, then set lash past that. Very possible lifters are too tight.

Also, pulses from opti for injectors is good, but you need to verify the injectors are firing. The PCM fires the injectors by grounding the circuit. Could be a PCM issue, injector harness issue......shoot, have you checked the 7.5a injector fuses? That caught me once. Grab a NOID light and hook it up to see if you're actually getting injector fire signals too if those fuses are good.

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^^ I agree with @Fastbird. This is how I adjust my rockers also. I always seem to over tighten when using the spin technique. Loosen rocker up until the push Rod is loose and you can rattle it up down between the lifter cup and rocker arm cup. Slowly tighten until you take the play out. Then I turn a 1/4 turn.




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The Corvette LT1 controls interlock fuel pump operation with an oil pressure switch, but not the F-Body. It’s done in the external fuel pump wiring, not through the PCM.

Quote:

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Originally Posted by Fastbird

FWIW I DESPISE that method. Waiting to feel drag when spinning means you've got enough preload on them already to cause drag while spinning. You're past zero lash at that point already. Lift up and down until you have no play, then set lash past that. Very possible lifters are too tight.

Also, pulses from opti for injectors is good, but you need to verify the injectors are firing. The PCM fires the injectors by grounding the circuit. Could be a PCM issue, injector harness issue......shoot, have you checked the 7.5a injector fuses? That caught me once. Grab a NOID light and hook it up to see if you're actually getting injector fire signals too if those fuses are good.

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Noted. I have my brother's inspection camera and will verify Thursday when the new fuel pump is here.

I'll get a noid light. The pulse sounds are there. The fuses are good. Pcm was fine when I tore it down but I can look for a known good one just in case.

Fuel pump relay seems to be operational and energizes the pump at key on.

Ok, so here's an update:

Have fuel. Have injectors firing. Have changed plugs.

As the pic shows, timing at chain is on. Plug wires are correct order.

Motor now tries to turn over first two rotations or so. I have likely destroyed my starter cranking.

I'm going to grab a better fuel pressure test kit at AZ this weekend and see what the cranking pressure drops to. Mine now fills with fuel after a few seconds and goes everywhere.

IDK what kind of FP gauge AZ has. I bought this one maybe 15 years ago, for 1/2 this $, but IMHO something that should be in your toolbox

https://www.summitracing.com/parts/h...e2-_-hypertech

Quote:

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Originally Posted by BALLSS

IDK what kind of FP gauge AZ has. I bought this one maybe 15 years ago, for 1/2 this $, but IMHO something that should be in your toolbox

https://www.summitracing.com/parts/h...e2-_-hypertech

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Funny.... that was one of the first tools I bought, right after I bought my Formula brand new in 1994. Exact same one in the picture, and I think under $30 back then, 23+ years ago. Still works fine, just a little grimy.

Yeah I was surprised to see how much they cost now. IIRC mine was about $30 from Summit back when

The FP gauge, IR Temp Gun, HH scan tool have more than paid for themselves over the years since I got a FI computer car

Like the old days you gotta confirm Fuel & spark

FP check will tell you immediately if that is, or contributing to, the problem before moving on to Ignition

Well worth the investment IMHO before blindly throwing parts at it

I have a theory and I hope it's plausible and ends up being the root cause.

Is it possible the starter has a bad motor that is putting far too much of a draw on the electrical system when engaged and not allowing it to allow proper spark during cranking?

The reason I ask is this: I can get about 1-2 cranking sessions of about 8-12 seconds before I need to recharge the battery. Yesterday after about the third session, the starter began making the dreaded high pitched noise. Additionally, that starter sat there for God knows how long while I changed motor mounts and the cam. This would answer why voltage is correct, fuel pressure is correct (before my gauge went tits up), and all checks out normal with KoEo but I get no start.

Is possible. After my stroker was complete, seemed to extend the cranking tine quite a bit. A assumed it was just a function of the engine build and the aftermarket ECU. The shop assured me it was taking less torque to start the stroker than the stock engine. I upgraded the stock starter (which had been replaced under warranty at about 30K miles) to a CVR Pro-Torque starter and it returned to the almost instantaneous start that was normal for a healthy LT1. But, problem was extended cranking, not "no start". I think the heat from my headers had toasted the stock starter.

What is the system voltage on the dash gauge when the starter is cranking the engine?

It drops considerably. From the 12-13 down into the 6-8.

I pulled the rail and physically verified the spray pulses as it cranked.

After I rent/buy the pressure gauge and new starter, I'll give a better update.

I switched to a 93 intake and rails plus a 52mm TB when I did the cam but everything appears sealed and functional.

We will see where it goes.

Quote:

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Originally Posted by donfrye

Ok, so here's an update:

Have fuel. Have injectors firing. Have changed plugs.

As the pic shows, timing at chain is on. Plug wires are correct order.

Motor now tries to turn over first two rotations or so. I have likely destroyed my starter cranking.

I'm going to grab a better fuel pressure test kit at AZ this weekend and see what the cranking pressure drops to. Mine now fills with fuel after a few seconds and goes everywhere.

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Just to clarify, timing marks are correct as seen in your picture and at that alignment position you are at TDC on number 6 cylinder. I’m asking if you verified that the distributor rotor was aligned with the number 6 terminal position on the cap. It’s is possible to install an opti wrong. If you google it many people have done it. Just making sure you checked everything. I attached a picture below. https://uploads.tapatalk-cdn.com/201...27235cf709.jpg



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Quote:

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Originally Posted by 1QUICKZ28

Just to clarify, timing marks are correct as seen in your picture and at that alignment position you are at TDC on number 6 cylinder. I’m asking if you verified that the distributor rotor was aligned with the number 6 terminal position on the cap. It’s is possible to install an opti wrong. If you google it many people have done it. Just making sure you checked everything. I attached a picture below. https://uploads.tapatalk-cdn.com/201...27235cf709.jpg



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And yes, a starter going bad that spins slower will pull more amps from the battery and this creates more heat in the starter. It basically fries the starter. 100% Fully charged battery Is 12.6-12.7 volts. 11.9 to 12 volts is at zero percent state of charge. So cranking a vehicle with the battery in a low state of charge can and will damage the starter over time. Remember Amps starts a car not volts. As the starter spins slower it pulls more amps to which will drop the voltage. This will affect electrical devices in a car.


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6-8 volts while cranking is not adequate for the PCM. Voltage that low will set a code. With low voltage, the injectors and fuel pump get lazy, coil may not generate required voltage for a decent spark.

Try starting with a jumper battery in parallel with vehicle battery. Don’t overdo it.... high amps will start damaging wires and contacts.

Op

your battery may just be to tired now, especially after sitting during the cam swap time, to hold a charge and put up with extended cranking time.

Also if your battery cables are original...consider replacing with better than stock ones

Sounds like the starter may have fell victim to this situation.

Many, including me, got the "corvette" starter. It is a gear reduction type, smaller and cheaper than a stock one. Autozone is where I got mine. Given the starters look different...might want to return your "core" a day later

Quote:

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Originally Posted by Injuneer

6-8 volts while cranking is not adequate for the PCM. Voltage that low will set a code. With low voltage, the injectors and fuel pump get lazy, coil may not generate required voltage for a decent spark.

Try starting with a jumper battery in parallel with vehicle battery. Don’t overdo it.... high amps will start damaging wires and contacts.

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I've been using a charger with a jump setting along with it. Are you saying to wire in another battery or would running another car in a "jump" capacity suffice?

I'm not sure that starter is going to have too many more cycles left in it now.

BTW, thanks to everyone for taking the time to respond. It means a lot.

Just "jump" the battery with cables from another car with a healthy battery, engine running. This is just a quick test to see if keeping the voltage high helps it start.

Update:

Starts and runs with the tps unplugged. Buying a new one and then cleaning up all the crap I tore apart troubleshooting. Yay.

I did replace the starter and battery btw.

Thanks so much, again, for the help.