Factory fix for vapor lock

[ZooMad75]

I was out at a junkyard yesterday looking for some front axle parts. I came across a factory big block 1986 K30. I noticed a big difference to the size of the fuel line and the routing.

With some of the guys having issues in the heat in Moab I thought it was interesting to see.

First off they moved the fuel lines from inside the frame c-channel to the outside of the frame rail. Next thing they did was increase the size of the feed line to a much larger size like 7/16” or 1/2”. It’s really big.

They also added additional heat shields on to of the frame where it comes over the top to get to the stock fuel pump. The end of the pipe necks down to a smaller more normal size to allow a regular rubber fuel line to connect to the pump.

Here’s a couple of pics. (Yes there is a small block in there now, but the spid label confirms the big block).




Interesting to see what the factory was trying to do to address the vapor lock prior to Tbi.

 

[cheavyk10]

Very interesting, I don't think I've ever noticed that before looking at a K30.
Nevada Gold too!! Ah man

 

[ZooMad75]

Very interesting, I don't think I've ever noticed that before looking at a K30.
Nevada Gold too!! Ah man

I never noticed it before, but I hadn't looked that close either. I just thought it was interesting with all you guys vaporlocking out in Moab and then see this truck. Routing fuel lines inside the frame rail was a dumb idea to start with so I'm betting that GM had been getting blasted with complaints and high warranty costs over the issue. Why they only did it to the K30 is a mystery. The change to TBI happened the next year and the fuel lines went back inside the rail again.


The truck cab was pretty hammered for sure. But it was gold! I'll be taking a piece home from that truck soon enough.

 

[Wes Harden]

that isn't a 7.4l in the pictures

 

[ZooMad75]

that isn't a 7.4l in the pictures

Yeah, I know. I pointed that out ahead of the pics.

 

[Wes Harden]

you nab the d60 ?

 

[ZooMad75]

you nab the d60 ?

Maybe....

Deal made, need to go get it.

 

[Wes Harden]

right on ! I was afraid it purloined before it arrived to public pick and pull

 

[Big Ray]

I put a 4v and headers on my jeep with a 304 wayyyyyy back when. Started vapor locking.
Added a small electric fuel pump right about where the firewall is.
No more problems after that.

 

[Truckman4life]

My factory big block '81 C30 crew cab has the big fuel line down the outside of the frame. Mine has a single driver side saddle tank and the line runs across a crossmember at the back of the cab and up the outside of the pass rail.

 

[86454K30]

I believe when they went to HD5 emissions in 85/86 they re-routed. Both my 86 K30's were that way.

 

[Chickntrk]

The lack of rust on the frame rails is disgusting, on the plus side I’m glad you found a 60 front….sure beats changing the spindle on a 10 bolt…

 

[ZooMad75]

The lack of rust on the frame rails is disgusting, on the plus side I’m glad you found a 60 front….sure beats changing the spindle on a 10 bolt…

What is this rust you are speaking of?

The spindle is in the middle of getting fixed. I want to go through the 60 prior to the installation.

 

[ktmoutfront]

My 84 C30/P30 is routed outside of the frame starting at the back of the cab and is 1/2" feed line. Goes through a grommet in the frame right at the pump. My vapor locking issue was in between the water pump and timing cover.