What other issues can mimic a vacuum leak?

[Joe67]

Originally Posted by Triple_Se7en
One time with my Chevy S10 4X4, I was stumped as to why my defrost and floor heat cycles didn't work, at any blower speed. All that worked was the bi-level setting.

Turns out there was a damaged hose right at / near the transfer case, underneath the vehicle. Once that was replaced, all my defroster, bi-level and floor heat settings began to work again.


Indeed the Ranger's cab HVAC controls are via vacuum, but it all originates from one tee off the intake next to to brake booster line. Easily capped off for testing and eliminated as a source of trouble. Great thought tho as the HVAC control / manifold vacuum connection is easily overlooked.

 

[FordBroncoVWJeta]

Originally Posted by Triple_Se7en
One time with my Chevy S10 4X4, I was stumped as to why my defrost and floor heat cycles didn't work, at any blower speed. All that worked was the bi-level setting.

Turns out there was a damaged hose right at / near the transfer case, underneath the vehicle. Once that was replaced, all my defroster, bi-level and floor heat settings began to work again.

My step dads 1999 S10 has the same problem. Ill have to check it.

 

[Joe67]

After a few hundred miles with Seafoam in the crankcase my situation has greatly improved. Of course, we've also gotten past the winter cold, so Seafoam or warmer temps? Whichever. I'm pretty certain at this point that I have recessed exhaust valve seats but still mild/early on and not yet catastrophic, so if the lifters bleed down freely then it doesn't produce symptoms. My hope is that the Seafoam cleaned up the lifters allowing them to bleed down faster and this will remain a non-issue come next winter. Or, it's just warmer temps and generally thinner oil in which case I spend next winter having to give it a 10-15 minute warm up.

Details of the "improvement" are just that it hasn't thrown a misfire code (used to throw a P3001 often, even just at idle on warm up), and hasn't stalled or run rough with cold engine when coming off throttle. I have been babying it at first since I hate those bad misfires as they're just unhealthy. But my son, who is just learning to drive a stick, and my wife, who can't handle light throttle -) have both driven it without issue.

 

[brages]

My Ranger is still chugging along on the old MAF and not throwing any codes. So all's well, I suppose.


Had a real weird one last week, though. My son called me early in the morning. On the way to work, he had braked hard at a traffic light, then killed the engine and was unable to restart it.

We pushed it to a gas station and I loaned him a car to get to work. I figured out that the truck was getting zero fuel pressure. I swapped the fuel pump relay with another relay with the same markings, no change. Then I swapped the fuel pump fuse with the headlight fuse and it fired up. AND the headlights worked. Then I swapped the fuses back and everything still works. Pretty baffling.

I'm thinking either: the inertia switch was tripped by my son's hard braking, but it somehow (??) reset itself while I was fiddling with the fuses. Or there was a bad connection around the fuse box and fiddling with the fuses fixed it. I think the inertia switch is more likely, but still not a great explanation. Has run fine ever since.