LLY new engine won’t start.

[gmduramax]

Well I might need a little help I have an 05 LLY and I dropped in a new engine. Callies crank(hopefully it doesn’t eat itself) Carrillos, AF cam, girdle, head studs, main studs, ported heads, 60% overs.

I cannot get the truck to start. It cranks over shows rpm on the scan tool. Has fuel pressure. Pours white smoke during cranking which turned to black. Has 7k fuel pressure. It does have a crank sensor code and fuel pressure sensor code but it’s for low voltage. I swapped sensors with known working ones and even checked to make sure I had 5volts at fuel pressure sensor. Crank sensor has 12volts is that correct? I triple checked the pin swap for the af cam and checked waglers and Dmax stores instructions. Also I swapped in an ecm from a running truck. The reluctor is gold. But I believe the callies crank came with a new one. It seems tight can’t move it with a screwdriver and it spins with the crank.

Not really sure what to check next any ideas?

 

[juddski88]

Does it have good compression?

 

[JoshH]

Did you get the cam and crank sensors mixed up?

 

[gmduramax]

Does it have good compression?

I haven’t done a compression test but turning it over with a ratchet it’s making compression. I’ll double check.

Did you get the cam and crank sensors mixed up?

I don’t believe so. I bought new sensors because the old ones had 180k on them. And I only opened one bag at a time to ensure I didn’t mix them up. They’re connected correctly I checked the wiring with another 05 I have sitting at the house.

 

[Duramax racer 8]

Did you swap the wiring for the af cam?

 

[gmduramax]

Did you swap the wiring for the af cam?

Yes and I triple checked the swap and looked at two different instructions.

 

[Duramax racer 8]

Did you Check all grounds to the block? Anything else acting funny like cluster?

 

[Chevy1925]

if you pull the FICM plugs and crank it, will it still huff smoke? maybe its way over fueling?

glow plugs in that thing? not that they are needed but you would think it would help fire it off with too much fuel

 

[gmduramax]

Did you Check all grounds to the block? Anything else acting funny like cluster?

The block was painted but all grounds were sanded then installed. Actually the ground at the back of the block might not have been sanded. I’ll check.

if you pull the FICM plugs and crank it, will it still huff smoke? maybe its way over fueling?

glow plugs in that thing? not that they are needed but you would think it would help fire it off with too much fuel

No smoke with the ficm unplugged.
And it doesn’t have glow plugs.

 

[JoshH]

I would double, triple, quadruple check for a cam/crank sensor problem. I fought an LB7 one time that was doing something very similar one time. On those motors, the bracket that holds the cam sensor is a metal bracket that isn't built into the body like it is on the newer motors. I had spun the bracket on the sensor trying to get a little extra clearance for connector to the belt (it was a swap that was only running an alternator we relocated down low on the passenger side of the block), and it would do what you are describing. Plenty of rail pressure and lots of smoke, but it wouldn't kick over and run. After spending a few days diagnosing things, I finally swapped in a different cam sensor, and it fired right off. I think it had it out of time somehow or something? I'm not really sure. Something to look at anyway.

 

[gmduramax]

I would double, triple, quadruple check for a cam/crank sensor problem. I fought an LB7 one time that was doing something very similar one time. On those motors, the bracket that holds the cam sensor is a metal bracket that isn't built into the body like it is on the newer motors. I had spun the bracket on the sensor trying to get a little extra clearance for connector to the belt (it was a swap that was only running an alternator we relocated down low on the passenger side of the block), and it would do what you are describing. Plenty of rail pressure and lots of smoke, but it wouldn't kick over and run. After spending a few days diagnosing things, I finally swapped in a different cam sensor, and it fired right off. I think it had it out of time somehow or something? I'm not really sure. Something to look at anyway.

I do believe it’s something with those sensors. When the built motor went in my lmm I had the same issue. The reluctor was bent slightly from being pulled off he crank when it was balanced. Would do the same symptoms only way that it was found was the dealer scoped the crank sensor wires and counted the pulses. I have a feeling I’ll be taking it to the dealer.

 

[juddski88]

Man a scope is so cheap, pick up a used modis or a used fluke for a couple hundred bones

 

[gmduramax]

Man a scope is so cheap, pick up a used modis or a used fluke for a couple hundred bones

I’m kind of dumb when it comes to that stuff I wouldn’t mind buying one I just don’t know what I need or how to use it :rofl: do you have a link for something that would work?

 

[RPM Motorsports]

If you used 06+ “LBZ” sensors on the LLY it will do this. Fought one for quite a while and it ended up being the wrong sensors installed. Even though they look identical, they are a couple numbers off on the PN#

 

[gmduramax]

If you used 06+ “LBZ” sensors on the LLY it will do this. Fought one for quite a while and it ended up being the wrong sensors installed. Even though they look identical, they are a couple numbers off on the PN#

I checked the PN on google and said they were for LLY. I’ll confirm with the dealer.

 

[dmaxfireman]

Get compression numbers, are you sure you have 7k of pressure and not just commanding it? Pull the glow plugs and crank the motor over with ficm disconnected to check for leaking injector.

 

[gmduramax]

Get compression numbers, are you sure you have 7k of pressure and not just commanding it? Pull the glow plugs and crank the motor over with ficm disconnected to check for leaking injector.

Actual is 7k. I got ghetto and sprayed starting fluid. It runs on that. If I try and start the truck after it runs out of starting fluid it does fire and die. Seems like something is telling the truck not to run. No security light and I turned off VATs in the tune just to be sure.

 

[dmaxfireman]

Smoke means its getting fuel from somewhere. timing is off. Check your sensors or swap with known good ones.

 

[juddski88]

Actual is 7k. I got ghetto and sprayed starting fluid. It runs on that. If I try and start the truck after it runs out of starting fluid it does fire and die. Seems like something is telling the truck not to run. No security light and I turned off VATs in the tune just to be sure.

Don't take this the wrong way, but have you ever run a built motor without glow plugs? For example, my race truck is a pretty loose lower compression motor and without glows it required starting fluid when ambient temp was below 50ish

 

[gmduramax]

Don't take this the wrong way, but have you ever run a built motor without glow plugs? For example, my race truck is a pretty loose lower compression motor and without glows it required starting fluid when ambient temp was below 50ish

Yes my LMM doesn’t have glow plugs but it’s 16.5:1 I’ll have to double check but I believe this motor is the same. I’m in California so it was around 70*