New guy with questions.. 462 fuel issues. - Pontiac GTO Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 8 (permalink) Old 03-31-2018, 08:55 PM Thread Starter
 
Join Date: Mar 2018
Location: Pgh Pa.
Posts: 5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
New guy with questions.. 462 fuel issues.

Hi, I'm new here, I think I may have registered in the past but could not find my login. Anyhow, my good friend and neighbor has a 1969 Pontiac GTO. He wanted one his entire life and finally bought one. He got a little screwed. The "dealer" told him the car was restored with an original GTO engine, not numbers matching and not the original motor. Well it wasn't, it was a smog era 400 from 1975 (IIRC) that made like 185 hp. Well he loves the car so a few years ago he bought a pro built 462 with Kaufmann aluminum heads from a guy named Jeff in Michigan (I think). The dyno info he got with the 462 says it makes 605 HP. I helped him put it in. We got it running, but it was never quite right, hard starting and stalling issues, it never idled very well. This past weekend I went to help him get her woke up for spring and she was really running rough. He put a 750 Holley on it last year with a Earls fuel line kit with a filter and pressure gauge. Well, as we were trying to get it to idle I noticed he only had about 3 lbs. of fuel pressure. It was like spitting raw fuel out of the tailpipes. He told me he had replaced the pump with a reproduction Ram Air pump from one of the restoration companies that specialize in GTO's. He had a Holley he had bought new (12-398-11?) and still had it new in the box. We went down to the parts store and bought the barb fittings and hooked it up. I immediately saw the FP jump up to 6 1/2 lbs. and it began running much better, really good actually. Holley recommends 6 to 7 lbs. of pressure for this particular carb. Well that was all fine until it started leaking like a sieve from the new barb fitting where it hooked into the Earls AN type hose. I ordered a better fitting from MSC that fit the ID of the Earls hose better, leak was fixed. Fired it up and now it is back to running at 3 lbs! I was dumbfounded. I did some searches and found this place. I have read a bunch of posts to try to figure this out. The only thing I can come up with is we need a 1/2 inch supply line to the fuel pump (Thanks BearGFR). My question now is, if I have a 1/2 inch supply line from the tank will I need a 1/2 inch fuel pickup tube on the sending unit? I doesn't seem like just making the line bigger would do anything if the fuel pickup tube is still only 3/8 of an inch. Any thoughts are appreciated. Thanks in advance.
Eagle223usa is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old 04-02-2018, 11:09 AM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
What are the details of the whole fuel system - line sizes all the way from the tank to the carb, what filter(s) if any are present, does it have a pressure regulator, etc.

I'm not sure I understood everything in your post, is that Holley pump an electric pump? If so, then be aware that running an electric pump is a whole different animal than running a mechanical pump. It'll require a fuel pressure regulator near the carb and also a fuel pressure return line from that regulator back to the tank that's the same size as the fuel line to the carburetor.

If it's a mechanical pump or if he wants to run mechanical, there aren't a lot of pumps out there that will be able to keep up with that much demand. Personally, I'm running a mechanical pump from RobbMc that's more than capable.

I'm not a big fan of barb fittings on fuel lines, or of rubber lines anywhere in the system. A little 'engine fire' from a leak can really ruin your day. 100% of my fuel system is either hard line or stainless belted hose with AN fittings - even the vapor return.

Also, 750 is going to be a little small for that engine.

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
post #3 of 8 (permalink) Old 04-02-2018, 11:58 AM Thread Starter
 
Join Date: Mar 2018
Location: Pgh Pa.
Posts: 5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks for the response Bear, His car has a mechanical Holley fuel pump, His entire system is Holley. (Holley recommended the system and the carb to him) 3/8's hard line from the rear, 6 AN to the carb, Earls inline fuel filter and Holley fuel pressure gauge. I like hard lines too. At least he is running Fuel injection rated rubber at the nipple connections on the fuel pump. If he gets a new line made that will take care of the rubber and barbs. Thanks again for the response. Is it possible to get a half inch sending unit made? Thanks again.
Eagle223usa is offline  
 
post #4 of 8 (permalink) Old 04-02-2018, 02:44 PM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
Yes, I know RobbMc has them available for certain and InLine Tube might. I have no experience with the Holley pumps so I can't offer advice there.

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
post #5 of 8 (permalink) Old 04-02-2018, 03:32 PM Thread Starter
 
Join Date: Mar 2018
Location: Pgh Pa.
Posts: 5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Does RobbMc have a website? Do you think the 3/8's fuel line is the problem? Thanks.
Eagle223usa is offline  
post #6 of 8 (permalink) Old 04-02-2018, 04:28 PM
Super Moderator
 
BearGFR's Avatar
 
Join Date: Aug 2008
Location: Springtown, TX
Posts: 5,730
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 122 Post(s)
Garage
I think it's possible that the 3/8 line will cause problems under high load, wide open throttle conditions but I wouldn't think that it would account for low fuel pressure at idle. His web site is at Welcome to RobbMc Performance Products. I'm using his starter, big fuel pump, regulator, and two of his filters. I've been very happy with all of it.

If the pressure is low at idle, I'd suspect an obstruction in the path somewhere, the pump itself, perhaps even an incorrect gauge.

I chased a fuel problem on my 69 for a long time. Under WOT it would sometimes just shut off and die, usually about 2/3 of the way through second gear, but would always restart. I sent the pump back to Robb for checking, even rebuilt it - but it was fine and showed no evidence of problems. All the filters were clear. Eventually, I found it. A piece of welding slag was in the tank from when I welded on the rear sump. Every so often, it would get lodged "just right" into the fuel pickup fitting and block it off.

Bear

BearGFR
Springtown, TEXAS
BearGFR is offline  
post #7 of 8 (permalink) Old 04-02-2018, 05:11 PM Thread Starter
 
Join Date: Mar 2018
Location: Pgh Pa.
Posts: 5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Me and Frank will be dropping the tank on his car to check the sock and sending unit. His "restored" car seems to be an interior kit and a paint job. I can't wait to see what the inside of the tank looks like.
Eagle223usa is offline  
post #8 of 8 (permalink) Old 04-03-2018, 09:32 AM Thread Starter
 
Join Date: Mar 2018
Location: Pgh Pa.
Posts: 5
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Well, Frank texted me this morning, The sending unit and 1/2 line are on the way. I need to figure out how to post pic's of his car, it is gorgeous. Frank is really in love with her too, and he even gave her a girl's name! I need to get him registered on here so he can do his own posting! We are dropping the fuel tank tomorrow morning, I'll let you know if we find anything interesting. Thanks.
Eagle223usa is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
462 Dyno Wendt69 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance 9 12-31-2017 01:15 PM
69 fuel tank issues REDMAN 1964-1974 Tempest, Lemans & GTO Exhaust, Suspension, Alignment, Fuel Tank and Brakes. 4 09-15-2016 07:49 AM
Fuel gauge issues jjenkins 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 11 10-19-2014 12:55 PM
Pump-to-Carb fuel line issues Orion88 1964-1974 Tempest, LeMans & GTO Technical and Electrical Wiring 4 04-01-2014 01:47 PM
clutch issues and questions! Johnson_05goat Drive train, suspension, alignment and brakes. 4 10-17-2011 01:52 PM

Posting Rules  
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome