The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-10-2015, 12:40 AM   #1
rich weyand
Registered User
 
rich weyand's Avatar
 
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
Re: 3rd gear bogging

Quote:
Originally Posted by SkinnyG View Post
Going out on a limb - try a run with the gas cap off. Perhaps (long shot), that the tank isn't venting enough to keep up with the fuel needed, creating a partial vacuum. A cheap test anyway, on your way to buy a timing light (grin).
Hey, SkinnyG: Nice catch! Sounds like you got it. Forgot all about that. It's been five years since I vented my caps.
__________________
Rich Weyand

1978 K10 RCSB DD.
rich weyand is offline   Reply With Quote
Old 10-10-2015, 12:31 AM   #2
Zach079xxx
Registered User
 
Zach079xxx's Avatar
 
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
Re: 3rd gear bogging

Now that you say that, about the gas cap... The man I bought the truck from painted the entire truck and while doing so painted the gas cap, when I would have a full tank of gas it would leak out the back side like pyshically inside the wheel well, but coming from the cap. I bought a new acdelco cap and when I get gas at a gas station, I'll loosen the cap and psshhhhhhh for 4-5 seconds the pressure is released. Dang.... If it weren't after midnight I'd go run it with the cap off and see if that changes it. It's so weird thigh because I've had the gas cap for months & the truck ran amazing after the rebuild then surprise the unknown happens. Hey thanks guys, I appreciate all the help. Going to update tomorrow

Should I have a vented cap?
__________________
85' GMC Sierra Classic
Built 350; Weiand intake, Holley 600, Thumpr Cam
Built 350 turbo with shift kit & 2500 Stall
Thumpin' away
Zach079xxx is offline   Reply With Quote
Old 10-10-2015, 12:36 AM   #3
rich weyand
Registered User
 
rich weyand's Avatar
 
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
Re: 3rd gear bogging

It got cold enough for the gas to shrink enough to create enough vacuum....

Like I said, just run a 1/16th-inch drill through the center of the cap. That's all I did. On both caps. Five years ago now. No problems.
__________________
Rich Weyand

1978 K10 RCSB DD.
rich weyand is offline   Reply With Quote
Old 10-10-2015, 12:41 AM   #4
Zach079xxx
Registered User
 
Zach079xxx's Avatar
 
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
Re: 3rd gear bogging

I'm going to test this tomorrow. Glad you guys pointed this out. Wish I had the joy of 2 tanks. My engine sure sucks the gas, sometimes I swear I can see the needle moving down. BUT I enjoy my square more than my 08 Cadillac SRX. Love them both but there's something about a square!

Still can't wrap my head around why it only acts up once third gear hits
__________________
85' GMC Sierra Classic
Built 350; Weiand intake, Holley 600, Thumpr Cam
Built 350 turbo with shift kit & 2500 Stall
Thumpin' away
Zach079xxx is offline   Reply With Quote
Old 10-10-2015, 01:13 AM   #5
rich weyand
Registered User
 
rich weyand's Avatar
 
Join Date: Apr 2014
Location: Bloomington Indiana
Posts: 1,041
Re: 3rd gear bogging

Quote:
Originally Posted by Zach079xxx View Post
I'm going to test this tomorrow. Glad you guys pointed this out. Wish I had the joy of 2 tanks. My engine sure sucks the gas, sometimes I swear I can see the needle moving down. BUT I enjoy my square more than my 08 Cadillac SRX. Love them both but there's something about a square!

Still can't wrap my head around why it only acts up once third gear hits
Because 1) you are using more gas and 2) the rpms went down, which reduces the amount of strokes per minute the mechanical fuel pump takes.

And I agree with you: Ain't nothin' like a squarebody.
__________________
Rich Weyand

1978 K10 RCSB DD.
rich weyand is offline   Reply With Quote
Old 10-10-2015, 01:18 AM   #6
Zach079xxx
Registered User
 
Zach079xxx's Avatar
 
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
Re: 3rd gear bogging

Will update in the morning good sir, thanks for the tips.
__________________
85' GMC Sierra Classic
Built 350; Weiand intake, Holley 600, Thumpr Cam
Built 350 turbo with shift kit & 2500 Stall
Thumpin' away
Zach079xxx is offline   Reply With Quote
Old 10-10-2015, 11:25 AM   #7
Zach079xxx
Registered User
 
Zach079xxx's Avatar
 
Join Date: Apr 2015
Location: Shenandoah Valley, Virginia
Posts: 332
Re: 3rd gear bogging

Thank you BOTH for mentioning the gas cap! It was acting up with 3/4 tank of gas, took the cap off and drove and it ran fine! I put a vent hole in the cap so we'll see how it goes. I can't thank you guys enough for the help. Finally I can enjoy my truck as much as I'd like to! Hope this fixes it permanently. Again, kudos guys.
__________________
85' GMC Sierra Classic
Built 350; Weiand intake, Holley 600, Thumpr Cam
Built 350 turbo with shift kit & 2500 Stall
Thumpin' away
Zach079xxx is offline   Reply With Quote
Old 10-10-2015, 12:00 PM   #8
SkinnyG
Registered User
 
SkinnyG's Avatar
 
Join Date: Feb 2012
Location: Beautiful BC, Canada, eh?!
Posts: 2,267
Re: 3rd gear bogging

__________________
1961 Apache: "Grabber Orange" Shortboxed, pancake, step-notch, air-ride, turbo, LS
1977 Silverado: Shortboxed & dropped, potato-potato
V8 Pontiac Firefly (Chevy Sprint): The ultimate engine swap: 5.7L in a 1.0L bag
Lotus Super 7 Replica: Scratch-built street-legal rollerskate
SkinnyG is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 09:56 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com