Author Topic: Vapor locking?  (Read 6937 times)

Offline jeffrey.constance

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Vapor locking?
« Reply #15 on: August 16, 2017, 10:41:56 AM »
I tried that a while back but was only able to find regular non ethanol gas and it didn't run that great and still vapor locked...  The truck came with 2 air injection pumps that were removed and plugs welded in the factory stainless exhaust manifold (resemble shorty headers) and the EGR valve was blocked off with a plate.   I bought another EGR valve and installed it but it didn't seem to help any so I put the block off plate back on and gave up... also the vacuum line to the EFE was removed and it stays open all the time as best I can tell.  It is drivable now but it seems to be on the brink of stalling anytime it has to sit in traffic...  Also, the only time u can open up the secondaries on the old q- jet is a very cool night or when it has just come off the choke before the underhood temp gets very high... i don't know if any of that info is helpful... not a mechanic here diy-er so any advice is appreciated... This was my Dad's boat pulling truck and I went to pick it up from the transferring dealer on Saturday morning when I was in college.  My Dad loved this old truck and kept it even though he had several new trucks that we bought for the machine shop that we owned.  When I would ask him why didnt he sell it and just use his shop truck to pull the boat he would laugh and say it would be like getting rid of me or one of my brothers. I guess that was his nice way of saying the old truck was less of a pita than me and my brothers... My long winded point is that the truck feels like a part of my family and that as long as I have it I still have a little bit of my Dad. 


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« Last Edit: August 16, 2017, 10:56:59 AM by jeffrey.constance »

Offline bd

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Re: Vapor locking?
« Reply #16 on: August 16, 2017, 12:51:28 PM »
Sounds like you have a kinked hose or collapsed hose.  Double check them all carefully and make sure you have the hose properly routed from the valve.  I've seen all too often the hoses improperly routed.

First this ^^^^, then check/replace all fuel filters, then measure fuel pump draw, pressure and volume while cranking - should be >20" Hg, 7-9 PSI, and 1 qt in 20-30 sec of cranking, respectively.  Make sure the fuel tank is freely venting into the canister.  Single or dual fuel tank(s)?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)