LS swap Gurus

[jon316]

Back again! Now I am having fuel issues. Thankfully most of the gauges are buttoned up and working and I was able to clean most of the wiring up.

I am getting 90psi fuel pressure! I’m thinking for sure it’s the fuel filter regulator, as I unhooked the return portion and I’m seeing zero fuel come out. Issue is I installed it right after the tank, and then the inline pump down the feed line under the cab. Could the filter being before the pump cause this? I had come across a few builds that did it this way and no issues. Could it just be a faulty regulator is that common?


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[bd]

So, you installed the pressure regulator between the fuel tank and the pump on the pump's inlet side?  How did you expect the regulator to work?  The regulator should be located after the fuel pump and filter.

[jon316]

Shouldn’t it not make a difference if it’s pushing or pulling it’s the same direction. Anyways yea I swapped it and it worked. Weird because I’ve seen other setups that way. Oh well. Tomorrow is another day. Gauges are working and engine is running and idling great. Oil pressure is not working but that could be the sender I received or not making good contact perhaps.


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[bd]

It's a "pressure" regulator, not a "suction" regulator.   

[jon316]

It's a "pressure" regulator, not a "suction" regulator.   

Touché !


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[jon316]

So got all the gauges squared out thank God. Not trying to figure out the headlights and some wiring coming out of panel. The headlights were rolled up tucked into the firewall by drivers feet.

I stretched the harness out and made my best guesses. The headlights are inverted on drivers the high beam on top etc. filament ok drivers side bulb blown but has an extra wire?! Also found another wire coming from headlight harness with a rubber grommet not sure what for?


Look at this nightmare! That light blue wire what the heck is that for? There was a heck a lot if tapping in this truck. One tapping into main feed for wiper motor. Which I removed. But now when I turn headlights on or when I randomly start the truck wipers turn on and don’t shut off unless I cycle the wipers on and off.


This is that wire I mentioned looping into the headlight harness.


These wires come out on the lower side of the fuse panel. I can’t distinguish what the panel says from the other end.
Same as picture above.


And this one too, it goes from green to a black with a terminal plug on it?! I thought it might of been horn, but that’s in the headlight harness... so confusing!


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[bd]

Every question you've asked is answered by the Section 8C wiring diagrams of the factory service manual, linked earlier - wire colors & routing, circuit numbers, bulkhead connector map, etc.

[jon316]

Was it? Couldn’t find it up there. I’m using the mobile version of the app though that could be it.

Another curious question for the ls swap guys, are you running the steam ports still? Came across a few posts of people just capping them? I only have the one hose coming out of the front, the rears are plugged from factory. I did see an adaptor that goes on the top radiator hose and it connects to that. Probably go that route but if it’s not needed it would look much nicer without it.


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[bd]

Here is the link again:  1981 Service Manual.  There is a lot of useful information in that manual.

[ehjorten]

Run the steam ports, they are there for a reason.  The rear ones are capped from the factory in car applications because the engine is angled down in the rear.  Some people put the vent back into the top of the water pump.  Some people use that JTR (Jags that Run) adapter that goes into the top radiator hose.  Factory is a small port into the top of the radiator.  I had my radiator modified to add the steam port into it.

[jon316]

So far so good. Got all the wiring squared up just have the little stuff to wire up like cruise control. Now question time.

Truck is running nice, idling super smooth. Issue is sometimes it has trouble starting. Thought at first well it’s for sure ground. So added ground. That didn’t do much. I check the ground from the coils but figured it can’t be that if it’s running great WHILE it’s running. I would fiddle all the cables while it is and it’s good. So I got a scanner and ran codes WHILE it was running. It won’t throw any codes. But it has some in pending while it’s running. Not sure why it won’t store them maybe it’s just a minor issues.

Says mass air and cam sensors. But the cam sensor in the rear top of engine is new, ac Delco new, and the mas air flow is also new.

The only thing I’m guessing is that it could be the crankshaft position sensor. As I know those can cause starting issues. And it’s the only sensor basically that isn’t new!

It will sit there and crank and crank and crank. Occasionally when I stop cranking it’ll throw a backfire here or there but not every time. Any ideas?






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[jon316]

Changed mass air flow and the cam sensor and got better. Finally drove it but have a caliper that’s seizing up so had to park it again.


I’m having some issues with the trans. It keeps leaking out of the weep hole in the shaft. And it’s for sure because that tail is sitting way too low. I’m thinking maybe the crossmember is upside down. But then again it doesn’t look like it may slide in the other way due to the chassis. Any ideas??






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[bd]

You definitely need to check and set up the driveline angles. 

Regarding yoke weep hole seepage, read Leaking Driveshaft Yoke.

[jon316]

So the seal in the yoke is bad, or o-ring that is? What a weird issue! Ok I’ll get that swapped out then. As for the driveline idk what else to do!


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[JohnnyPopper]

Regarding your 'freezing caliper' it's more likely the flexible rubber line.

They deteriorate inside and will cause oil to be trapped, locking up the caliper.