New LS3 won't fire
Thread Starter
Teching In
Joined: Jul 2012
Posts: 7
Likes: 0
From: Santa Clarita, CA
New LS3 won't fire I've read most of the related posts here and haven't found anything to solve my problem.
My situation: New LS3 in a 67 Camaro. Engine has never been started. Engine cranks but there is no fuel or spark.
What I've tried (the short list):
Checked all fuses
Verified ECU grounds
Verified voltage and ground at injectors and coils
ECU has roughly 11-12 volts in ON and START positions
Fuel pump runs - 55 psi at the fuel rail
Removed VATS
Verified connections at all sensors.
All sensors and connectors are brand new.
ECU is seeing 185 RPM during cranking.
I am suspicious of the new Painless harness I'm using which is for an automatic trans, and I am running a manual. The guy at Painless told me this would be OK, just don't use the TCM harness. (They do not sell a harness for this application for a Manual trans.)
The items that might cause issues have been taken care of in the ECU - Park-Neutral switch, brake pedal switch, etc. The tech that built the engine also flashed my computer and took care of the auto trans issues. There maybe something else here that we missed???
I have checked everything I can think of and now I'm completely stumped. I would like to use solid diagnostics rather than randomly replacing parts, but I don't know what else to check.
I am new to all of this and would really appreciate any suggestions.
Thanks,
Mark
My situation: New LS3 in a 67 Camaro. Engine has never been started. Engine cranks but there is no fuel or spark.
What I've tried (the short list):
Checked all fuses
Verified ECU grounds
Verified voltage and ground at injectors and coils
ECU has roughly 11-12 volts in ON and START positions
Fuel pump runs - 55 psi at the fuel rail
Removed VATS
Verified connections at all sensors.
All sensors and connectors are brand new.
ECU is seeing 185 RPM during cranking.
I am suspicious of the new Painless harness I'm using which is for an automatic trans, and I am running a manual. The guy at Painless told me this would be OK, just don't use the TCM harness. (They do not sell a harness for this application for a Manual trans.)
The items that might cause issues have been taken care of in the ECU - Park-Neutral switch, brake pedal switch, etc. The tech that built the engine also flashed my computer and took care of the auto trans issues. There maybe something else here that we missed???
I have checked everything I can think of and now I'm completely stumped. I would like to use solid diagnostics rather than randomly replacing parts, but I don't know what else to check.
I am new to all of this and would really appreciate any suggestions.
Thanks,
Mark
Launching!
Joined: Dec 2011
Posts: 242
Likes: 4
From: Alabama
Are the injectors old or new . If using used injectors these ls injectors are bad to get gummed up and plug when sitting around for a while . If you have 12v at the injectors and spark I would seriously consider this . I built a homemade cleaner to cycle them with carb cleaner running thru them . Look at youtube if you want to do this . Theres several ways . I used the syringe method and a 12v battery .
Thread Starter
Teching In
Joined: Jul 2012
Posts: 7
Likes: 0
From: Santa Clarita, CA
Thanks for the suggestions. The injectors are new.
UPDATE: We bricked the junkyard computer by trying to load a newer operating system. Bought a brand new ECU, disabled all of the same things that could keep the car from starting including VATS, and still no spark or fuel
The tech from Painless had me try disconnecting the cam sensor which would have allowed the engine to fire for a short time is the sensor was bad. Didn't work. Still no spark or fuel.
Has anybody had this problem and solved it?
Thanks!
UPDATE: We bricked the junkyard computer by trying to load a newer operating system. Bought a brand new ECU, disabled all of the same things that could keep the car from starting including VATS, and still no spark or fuel
The tech from Painless had me try disconnecting the cam sensor which would have allowed the engine to fire for a short time is the sensor was bad. Didn't work. Still no spark or fuel.
Has anybody had this problem and solved it?
Thanks!
Teching In
Joined: May 2015
Posts: 4
Likes: 0
yes, had the cam sensor and crank sensor plugs reversed. would't fire or open the injectors.
also check your resistance to the ecm on the cam and crank pins. depending on the tune you put in the crank sensor sometimes has different pin locations on C2 or X2
also check your resistance to the ecm on the cam and crank pins. depending on the tune you put in the crank sensor sometimes has different pin locations on C2 or X2
Thread Starter
Teching In
Joined: Jul 2012
Posts: 7
Likes: 0
From: Santa Clarita, CA
Thanks for the suggestion Q-W. The Painless kit won't allow the cam and crank sensors to be connected incorrectly.
I'm not sure, but I think if my crank sensor pins were incorrect, I would not get an RPM reading during cranking.
I really want to get this thing running. I appreciate any suggestions.
I'm not sure, but I think if my crank sensor pins were incorrect, I would not get an RPM reading during cranking.
I really want to get this thing running. I appreciate any suggestions.
Trending Topics
Thread Starter
Teching In
Joined: Jul 2012
Posts: 7
Likes: 0
From: Santa Clarita, CA
I appreciate the suggestions from the 3 people that responded, but i must admit that it is disappointing how few people responded to an LS engine problem on an LS forum. Is there a better sight to talk about LS engines or am I posting in the wrong place on this forum?
I am completely stumped and would be very appreciative to hear suggestions from anybody who has had, and solved this problem.
Thanks,
Mark
I am completely stumped and would be very appreciative to hear suggestions from anybody who has had, and solved this problem.
Thanks,
Mark
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TECH Regular
Joined: Dec 2011
Posts: 448
Likes: 2
From: SoCal
Mark,
It's tough to be patient when you are at the goal line. I've experienced it and to a certain degree I am again now. What I can tell you is there is a ton of knowledge on this forum and sometimes it takes awhile to get traction. Some of the best insight comes from people that are not looking at every new post every day. Keep asking and even when you don't get replies explain what you are trying to keep the thread moving and popping. I promise someone will have an answer if you stick with it.
Give the guy a bump and help him out! And while your at it pop on over to my thread on PCM Diagnostics and Tuning do a little comment.
It's tough to be patient when you are at the goal line. I've experienced it and to a certain degree I am again now. What I can tell you is there is a ton of knowledge on this forum and sometimes it takes awhile to get traction. Some of the best insight comes from people that are not looking at every new post every day. Keep asking and even when you don't get replies explain what you are trying to keep the thread moving and popping. I promise someone will have an answer if you stick with it.
Give the guy a bump and help him out! And while your at it pop on over to my thread on PCM Diagnostics and Tuning do a little comment.
Thread Starter
Teching In
Joined: Jul 2012
Posts: 7
Likes: 0
From: Santa Clarita, CA
Problem solved. The problem was with the cam sensor connector. I had been told that the cam sensor would not prevent the engine from firing, but it did. Engine is running and sounds killer. Thanks,
Mark
Mark
