94 lt1 problem in a 96 roadmaster

**bigontray** · 01-11-2017, 09:31 AM

I just put a 94 lt1 in my 96 roadmaster. It started right up and ran for 3 min then died as iff it has died of gas. Now it will only crank. I have swapped the timing cover and knock sensors and opti from the 96 motor onto the 94 motor. Please help need my baby back

**Catmaigne** · 01-11-2017, 10:16 AM

Did you use the 94 harness? The pins for the knock sensors are in parallel on one pin with obd1 and series on separate pins with obd2.

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**Injuneer** · 01-11-2017, 12:08 PM

Did you check the fuel pressure?

**bigontray** · 01-11-2017, 12:30 PM

The knock sensors were switched over so I can keep everything 96

**bigontray** · 01-11-2017, 12:31 PM

I dint have tools to do that so I was going to troubleshoot all else first.

**Catmaigne** · 01-11-2017, 01:30 PM

You could've switched the knock sensors but the wiring could still be different. What year harness did you use?

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**bigontray** · 01-11-2017, 10:02 PM

Used a 96. It ran for 3 min tho.

**BALLSS** · 01-11-2017, 11:47 PM

Originally Posted by Injuneer

Did you check the fuel pressure?

Originally Posted by bigontray

I dint have tools to do that so I was going to troubleshoot all else first.

well you may be checking quite a bit until you do get around to checking fuel pressure. That should be moved to the top of the list.

If your local auto part store does not have a "loan-a-tool" one, buy one

Not saying it is fuel pressure related, but highly possible,.....its just the basic step on any "no start" issue. Check fuel and spark. That later is more involved because of the several areas of a ignition system that can cause no start

**bigontray** · 01-12-2017, 12:00 AM

I was just told that a caprice lt1 will not work in roadmaster apparently roadmasters arnt compatible with the other lt1s

**atlantadan** · 01-12-2017, 05:06 AM

Originally Posted by bigontray

I was just told that a caprice lt1 will not work in roadmaster apparently roadmasters arnt compatible with the other lt1s

You were misinformed. An LT1 is an LT1 - they didn't make different engines for Roadmasters. (There is a 4.3 LT1 and a 5.7 - did you check to see which one you have?)

If the car ran for three minutes, you have other problems. Check the fuel pressure as stated before and then check for spark. Do you have any way to scan it and pull codes or see what the PCM sees? R&R'ing an engine means you unplug/plug a lot of different connectors. Its entirely possible that something you connected gave up the ghost.