99 E-150 5.4 Triton - Wont Start

[Pollarican]

Hey guys I know a lot of you on here have other Ford trucks and Vans, and I'm stuck with a dilemma. I pulled the 4.6 triton V8 out of a van I am working on and swapped in a 5.4 V8 triton, which is the same motor with a different bore/ stroke.

Upon trying to start it, I cannot for the life of me get the starter motor to turn the driveplate - I can turn the crank by hand so I know that works, I have all the wiring on the starter correctly, the starter and battery I know are both good.

I attempted to turn the motor over by jumping the battery directly to the starter then running a test lead from the positive cable to the smaller positive enacting lead on the starter. Upon doing this, the solenoid on the starter engages, but it will not spin. With the same test being ran out of the car on the bench, the starter motor spins freely and easily with less than a 1 volt voltage drop. Attempting this test in the car, I have about a 5 volt drop, with either of two good batterys that will turn over an explorer first attempt.

I am lost- Could the torque converter be locked up due to some Neutral Safety Switch connection? What would cause such a resistance or voltage drop when trying to jumper the battery directly to the starter? Any help is greatly apprectiated!

 

[TedJ]

Are you sure those batteries are really good? (maybe take them to be tested) 5v drop is like 7v, usually I'd like to see 9v give or take while cranking.

Is the engine grounded well (check the resistance between the block and the negative battery cable)?

I'm assuming the engine ran in the vehicle it came out of, but if it was sitting outside for a long time before you got to install it, maybe the contacts inside the starter solenoid have oxidized / corroded and cannot pass enough amperage to run the starter under load.

I doubt that the torque converter can be locked without hydraulic pressure created in the trans while the engine is running. How hard is it to turn the engine over vs. say the old 4.6? Maybe the torque converter is not seated properly in the trans and is binding up?

Or one of your accessories has seized (take the belt off and try to spin them all)?