Need advice on a 81 k5 that won’t run

[mattsettle]

Recently helped father in law replace a fuel tank and sending unit in 81 k5 blazer. I don’t think the sending unit is getting power. It will crank with gas in the carb. There is no visible writing on the fuse box and I’m not sure if there is any type of fuel pump relay. Any info would be fantastic. Thank you in advance.

 

[Wes Harden]

81 was mechanical pump from the factory. it should be on passenger side front of block @ frame level. If the pump is there, inspect all of the soft fuel hose from pump to tank. Look for soft squishy, melty, hard, cracked, frayed, chewed. Replace any suspect. If the pump needs replacing come back here and we'll give the tips and tricks on that.

If the mechanical pump is not there or not hooked up then someone put an electric pump on this truck. If they did it right it should be near the tank, and we'd just be guessing on how it would be wired.

Welcome to CK5 @mattsettle

 

[mattsettle]

81 was mechanical pump from the factory. it should be on passenger side front of block @ frame level. If the pump is there, inspect all of the soft fuel hose from pump to tank. Look for soft squishy, melty, hard, cracked, frayed, chewed. Replace any suspect. If the pump needs replacing come back here and we'll give the tips and tricks on that.

If the mechanical pump is not there or not hooked up then someone put an electric pump on this truck. If they did it right it should be near the tank, and we'd just be guessing on how it would be wired.

Welcome to CK5 @mattsettle

Thanks for the reply. I’ll check hoses when I go back over. I know he said it had a new mechanical pump installed.

 

[Fastereddie]

Your title says won’t crank, but after reading your post, it sounds like it’s cranking fine. I believe you mean to say it won’t fire/run.
It can be confusing when the wrong terminology is used…

 

[mattsettle]

Your title says won’t crank, but after reading your post, it sounds like it’s cranking fine. I believe you mean to say it won’t fire/run.
It can be confusing when the wrong terminology is used…

I apologize for any confusion. Is there a way to edit the title to correct it?

 

[Wes Harden]

As for the sending unit, even if it is not getting power it should still run. The tan-ish wire to tank sender is the gauge wire, there is also a ground wire. Sometime these get damaged when a tank is removed and installed. Be sure it connected near the sender, and normally the cross member between the tank and differential. Good clean connections

 

[Fastereddie]

I apologize for any confusion. Is there a way to edit the title to correct it?

No worries, just trying to help clarify.
Looks like you already changed it!
Your in good hands with Wes helping you!

 

[mattsettle]

81 was mechanical pump from the factory. it should be on passenger side front of block @ frame level. If the pump is there, inspect all of the soft fuel hose from pump to tank. Look for soft squishy, melty, hard, cracked, frayed, chewed. Replace any suspect. If the pump needs replacing come back here and we'll give the tips and tricks on that.

If the mechanical pump is not there or not hooked up then someone put an electric pump on this truck. If they did it right it should be near the tank, and we'd just be guessing on how it would be wired.

Welcome to CK5 @mattsettle

Hey Wes I know you responded to this last year but wanted to see if you thought it could be a vacuum issue? I see a port on the 4 barrel that doesn’t have anything attached.

 

[Wes Harden]

any open vacuum ports should be capped or have a hose attached.

Have the fuel lines been inspected ? Do we know what style pump is being used ?

 

[mattsettle]

any open vacuum ports should be capped or have a hose attached.

Have the fuel lines been inspected ? Do we know what style pump is being used ?

I may have to inspect the lines myself my father in law tells me he replaced some. It is a mechanical fuel pump.

 

[Wes Harden]

if any of the lines are cracked, it could be sucking air and not drawing fuel from tank.