'94 350: good cold starts, struggles to crank when restarting or still warm

Schurkey · Nov 24, 2020

thinger2 said:
Cranking slow is exactly the reason to look at a hot start kit.
Thats why they were invented

No.

If the starter motor RUNS AT ALL, the solenoid is engaged, and that means there's enough power to the "S" terminal.

When the starter DOES NOT CRANK, the "hot start kit" you describe may be useful.

Perhaps I missed it:
What is the battery voltage when the engine cranks slowly? For that matter, what is the battery voltage with no load? A fully-charged "12-volt" battery had better have 12.6--12.7 volts with no load, and at least 9.5 when cranking, but more likely ~11 volts. More is better.

Frank Einstein mentioned voltage-drop testing; but neglected the ground side. Here's a diagram:
https://www.chevelles.com/media/starter-voltage-drop-tests.48355/full

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badco · Nov 24, 2020

I use 2ga battery cables on all my rides, i also run extra ground from engine to frame and engine to firewall. Although i haven't done it to my 96 yet i use a ford solenoid and get all my hot wires away from exhaust or anything in way. Header wrap on starter helps alot also.

usar17 · Nov 24, 2020

Schurkey said:
No.

If the starter motor RUNS AT ALL, the solenoid is engaged, and that means there's enough power to the "S" terminal.

When the starter DOES NOT CRANK, the "hot start kit" you describe may be useful.

Perhaps I missed it:
What is the battery voltage when the engine cranks slowly? For that matter, what is the battery voltage with no load? A fully-charged "12-volt" battery had better have 12.6--12.7 volts with no load, and at least 9.5 when cranking, but more likely ~11 volts. More is better.

Frank Einstein mentioned voltage-drop testing; but neglected the ground side. Here's a diagram:
https://www.chevelles.com/media/starter-voltage-drop-tests.48355/full

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Schurky, when I get an assistant I will do this!

But for now I have planned a heat shield, replace battery cables, and clean up those connection points

Are all these heat shields pretty much the same thing?

Also, thoughts on these battery terminals for GM side posts? The theory seems nice and simple for running larger gauge wiring to everything.

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usar17 · Nov 25, 2020

Or what do most do? Stack lugs on a bolt? Custom cables?

Or factory cables and just add the big 3 on top of that?

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PlayingWithTBI · Nov 25, 2020

usar17 said:
Or factory cables and just add the big 3 on top of that?

@5vortec7 makes a great "Big 3" setup for our trucks which includes cables for the alternator (with a fuse to replace the fusible link) and fuse box and battery teminals.

Schurkey · Nov 25, 2020

Replacing a fusible link with a fuse on the alternator output is NOT an upgrade. In fact, it's a significant DOWNgrade.

Fuses, even so-called "slow-blow" fuses, pop FAST. Fusible links take a sustained overload without damage, but protect against catastrophic damage.

A suddenly-open circuit on the alternator is a fabulous way to create a voltage surge that pops the alternator diodes, perhaps even the alternator regulator.

usar17 · Nov 25, 2020

Agreed. I think I'll install a factory set of cables. Then add some additional grounding cables.

thinger2 · Nov 25, 2020

Schurkey said:
No.

If the starter motor RUNS AT ALL, the solenoid is engaged, and that means there's enough power to the "S" terminal.

When the starter DOES NOT CRANK, the "hot start kit" you describe may be useful.

Right up untill the solenoid kicks out because of low amperage at the s wire.
This is often why you get one turn, let off the key hit it again and get one turn etc..
The hot start bridges the power wire to the s wire so that the power wire triggers the the solenoid.
The s wire is relocated and used to trigger the ford solenoid.
It is well worth the time to put one on and making your own is cheap and easy to do

Perhaps I missed it:
What is the battery voltage when the engine cranks slowly? For that matter, what is the battery voltage with no load? A fully-charged "12-volt" battery had better have 12.6--12.7 volts with no load, and at least 9.5 when cranking, but more likely ~11 volts. More is better.

Frank Einstein mentioned voltage-drop testing; but neglected the ground side. Here's a diagram:
https://www.chevelles.com/media/starter-voltage-drop-tests.48355/full

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thinger2 · Nov 25, 2020

Its just a grounding problem.
Or at least you cant diagnose it untill you check out all of the grounds.
Take a look at the ground strap from the back of the passenger head to the firewall.
It shares a common lug with a strap that goes to the frame.
A real ***** to get at which is why they never get checked.
Your ecm and sensors have a ground to a stud right next to the manifold temp sensor.
check those out, not with a meter, continuity doesnt mean **** of of the meter.
Pull them all apart, clean em up put new good quality heat shrink connectors on.
The starter grounds to the block, the block has a few grounds but they ground in different "planes"
In other words those grounds are providing a path for different sources.
If you are missing a ground or have a weak or intermittant ground, The path then goes through whatever other ground it can find.
It just wants to go back home.
If you have no grounds, it will go through the transmission cable or the throttle cable or even the main bearings or the transmission.
So, before you go too nutty brother.
You cant diagnose a gm tbi unless all of the grounds and power are good and solid.
Crawl up and under and all over it and fix all of that every damn bit of it.
Live data does not mean **** all of anything if it is from an ungrounded or intermittantly grounded systen.

thinger2 · Nov 25, 2020

Heres an example for you.
I pulled this out of a friends k1500 a few months ago.
Totally destroyed.
And it still worked, kinda sorta
but it started the truck.
Because it had a friggen hot start kit on it so the solenoid engaged off of the battery hot.
People have crawled underneath Chevys to stick a screwdriver between the Bat terminal and the s wire since they built the damn things.
Its wires and grounds

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'94 350: good cold starts, struggles to crank when restarting or still warm

Schurkey

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badco

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usar17

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Schurkey

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