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Discussion Starter · #1 ·
I have a 98 Sonoma that was previously a 2.2/5speed and now has a 5.3/4l60e that I cant seem to fire up. I'm near the end of the swap and have finally gotten to the point where I can attempt to start it. I got it to crank but its a slow crank and sounds sluggish but wont start at all. I have been trying to figure out why it wont start, checked over my wiring and everything seems right. I have a suspicion that it could be the oil pressure switch since the fuel pump doesn't seem to prime. Also thought it was the clutch safety switch but I tried the paperclip bypass thing and it did nothing so I'm completely out of ideas of what it could be. This is my first ls swap so don't be too hard on me lol
 

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Just starting with easy to overlook basics...
Is the battery in good shape/fully charged?
Are the battery terminals clean and tight?
Do you have a good ground going to the engine block?

The sluggish crank makes me think it's a low power issue, either due to the battery or connection issue in between causing a voltage drop.
 

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I've never seen an LS oil pressure sender that was tied to the starter. They are either 97-02 1 wire direct to the gauge or later 3 wire to the PCM and sent by serial data, but that doesn't work on an S10. Oil pressure is about the only gauge on an S10 never tied into serial data.
Is the engine filled with the correct amount of oil? I've seen guys forget it. So busy doing other stuff it got overlooked.
Did you ever hear the engine run before you bought it? I had an LS that turned over slow because it had a bent rod.
 

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2004 Avalanche. 2001 V6 Extended Cab ZQ8.
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So first off you mention that the fuel doesn't prime. Well start there. If you are using the 2.2L pump it will start the engine but may not make enough volume to feed it at higher loads or speeds. Did you change the pump? If so did you get the ground back on right? How about the fuel pump relay? That is going to be the next place I am going to look. Make sure it's getting power and also the signal from the PCM. It should power up for about 3 seconds then shut off, powering up again when the engine cranks and runs. It will then shut off when the PCM loses the tach signal. Will the pump prime or run if you bypass the relay?

Make sure it's getting all the basics, fuel, spark and air is almost a given.
 

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Discussion Starter · #7 ·
Just starting with easy to overlook basics...
Is the battery in good shape/fully charged?
Are the battery terminals clean and tight?
Do you have a good ground going to the engine block?

The sluggish crank makes me think it's a low power issue, either due to the battery or connection issue in between causing a voltage drop.
The battery is new and terminals are clean too. I have it grounded to the chassis as of right now. Should I ground it to the engine block instead?
 

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The battery is new and terminals are clean too. I have it grounded to the chassis as of right now. Should I ground it to the engine block instead?
That's the way the factory does it.
 

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You want a ground to the chassis for all your lighting and accessories etc,

Then you want a heavy ground to the block specifically for starting and charging, as well as just general engine operation
 

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Discussion Starter · #10 ·
That's the way the factory does it.
You want a ground to the chassis for all your lighting and accessories etc,

Then you want a heavy ground to the block specifically for starting and charging, as well as just general engine operation
Sorry for the late reply but, I finally had some time today to work on the Sonoma. I took your advice and just decided to give everything a once over. I grounded all the engine harness grounds to the engine, including the battery and it fixed the slow crank issue. It sound ten times better and it stays cranking till I let go of the key before it would just die out within a sec or two.

All that’s left to do is to fix the fuel pump wiring that my dog decided to play tug of war with. Lol

Thanks for the help!
 

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Discussion Starter · #11 ·
So first off you mention that the fuel doesn't prime. Well start there. If you are using the 2.2L pump it will start the engine but may not make enough volume to feed it at higher loads or speeds. Did you change the pump? If so did you get the ground back on right? How about the fuel pump relay? That is going to be the next place I am going to look. Make sure it's getting power and also the signal from the PCM. It should power up for about 3 seconds then shut off, powering up again when the engine cranks and runs. It will then shut off when the PCM loses the tach signal. Will the pump prime or run if you bypass the relay?

Make sure it's getting all the basics, fuel, spark and air is almost a given.
I’m not sure on the
So first off you mention that the fuel doesn't prime. Well start there. If you are using the 2.2L pump it will start the engine but may not make enough volume to feed it at higher loads or speeds. Did you change the pump? If so did you get the ground back on right? How about the fuel pump relay? That is going to be the next place I am going to look. Make sure it's getting power and also the signal from the PCM. It should power up for about 3 seconds then shut off, powering up again when the engine cranks and runs. It will then shut off when the PCM loses the tach signal. Will the pump prime or run if you bypass the relay?

Make sure it's getting all the basics, fuel, spark and air is almost a given.
I switch the old stock fuel pump with a Walbro GCA758-2, but I figure out why my fuel pump wouldn’t prime. My dog decided to chew my fuel pump wiring that runs along the drive side of the chassis. Kinda surprised he could get under there since I have a 3” drop on it.
 

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I’m not sure on the


I switch the old stock fuel pump with a Walbro GCA758-2, but I figure out why my fuel pump wouldn’t prime. My dog decided to chew my fuel pump wiring that runs along the drive side of the chassis. Kinda surprised he could get under there since I have a 3” drop on it.
That kinda goes along with the dog ate my homework line... lol keep us informed on how it goes.
 

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Glad it solved the slow crank. One step closer to it running!
 

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Discussion Starter · #14 ·
hey guys, sorry for the late reply, been real busy with work and stuff lol
Finally gonna have some free time next week and wanna get this thing running so all that it seems to be missing is the fuel pump wiring. I still can’t figure out where these wires go and if I even need to hook up all of them just to start it.

This is what I have so far have no clue what the rest do or where they go.
Any help is appreciated, thanks!

Purple - fuel level signal
Green -
Orange/Black - low reference
White??? or Tan??? -
Gray - fuel pump power
349951
 
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