Vapor Lock Hot starting problems - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 05-25-2011, 10:40 PM
Registered User
 
Last photo:
Join Date: Jan 2011
Location: Pittsburgh, PA
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Vapor Lock Hot starting problems

Ok,

I have read lots of posts here, but figured I would post my problem.

I have an almost completely rebuilt 355 sbc, edelbrock performer intake, eddy 600 cfm electric choke carb, mechanical fuel pump with return line. I have a breather in the gas cap. I am running hard line from the pump up the block and then running rubber line to a clear plastic filter, then more rubber line to a fuel gauge then to the carb. It all sets off the intake, but is close to it and the heater hoses. Also ran 87 and 89 octane, seems to be same issue, and lastly running a 10" air cleaner.

Cold it starts up great, truck idles fine at 1k, drives fines, has pretty good response, loves going up hills. doesn't ever seem to miss, engine keeps cool at about 185 consistently. When I stop and try and start it it doesn't want to go. I have to pump the pedal like crazy and eventually it will go.

It is definitely not a starter issue, it has plenty of juice. My fuel pressure has been around 5-7 and sometimes more. so I changed the fuel pump and now it is even higher, sometimes up to 9psi. So I ordered a regulator and also an air/fuel ratio kit that I will be installing.

So could this be vapor lock? I have also noticed my fuel filter is sometimes full an sometimes not so full and sometimes empty. That is partially why I changed my pump. I am told also when you shut the engine off the pressure gauge should hold pressure for several minutes.

I don't know my under hood temp, but I assume it is hot because it is a 51' chevy with lots of metal and an e fan pulling hot air. My manifold seems extremely hot as well. My dist is brand new and I don't recall the mfg off hand but it is a 50 or 65 volt something like that, I have to look.

I was going to try this regulator and I was also told to ditch the hardline and run all rubber line from the pump. I have new carb gaskets from edelbrock, two of them, can I put two gaskets in instead of one? I am thinking maybe the fuel is getting too hot?

I don't know if it is too lean or rich at this point, I know there is not black smoke. I also looked down the carb and squirted the throttle and gas was coming out but still took a little longer to start. So I was thinking either too much gas or not enough air. I have tried it with the air cleaner off but still it will need some pedal pumping.

My gas mileage hasn't seemed to be what I expected, so far I am between 12-15 mpg with 3.42 rear end and a 5 speed. I would assume I would get a little better than that. I do feel like I have some more tuning I can do, but I just want to get past this hard starting after running. My cam is an isky .465 220/220 I believe. So nothing too radical there. Stock heads 60 cc

I constantly check my oil for any signs of gas, so far no signs, but inside my carb when I take off the air cleaner after it was running seems offly smelly of gas. I checked my floats a while back when this was on another engine and they were fine. I to my knowledge and running factory everything in the carb. I think the lack of gas in the filter is telling me something, I just don't know if the gas is running into the carb or down the line and if it is too hot thus disturbing air/fuel ratio.

Lastly the choke stays open when warm.

any thoughts would be great, sorry for the long write up and if I got off track, I tried explaining everything the best I could. I don't feel like it is a timing, starter or choke problem at this point.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-26-2011, 07:16 AM
delawarebill's Avatar
Registered User
 
Last photo:
Join Date: Mar 2009
Location: delaware
Posts: 1,272
Wiki Edits: 0

Thanks: 16
Thanked 68 Times in 68 Posts
extra heat

last wk i was in ocean city md and there was a guy selling just what your looking for... needless to say my bucket don't have those problems so i passed.. but it was cermanic compressed with alum to make an insulator.. maybe try to google carb insulator or something...
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 05-26-2011, 12:28 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,827
Wiki Edits: 0

Thanks: 4
Thanked 451 Times in 386 Posts
Quote:
Originally Posted by 99 to Life
Ok,

I have read lots of posts here, but figured I would post my problem.

I have an almost completely rebuilt 355 sbc, edelbrock performer intake, eddy 600 cfm electric choke carb, mechanical fuel pump with return line. I have a breather in the gas cap. I am running hard line from the pump up the block and then running rubber line to a clear plastic filter, then more rubber line to a fuel gauge then to the carb. It all sets off the intake, but is close to it and the heater hoses. Also ran 87 and 89 octane, seems to be same issue, and lastly running a 10" air cleaner.

Cold it starts up great, truck idles fine at 1k, drives fines, has pretty good response, loves going up hills. doesn't ever seem to miss, engine keeps cool at about 185 consistently. When I stop and try and start it it doesn't want to go. I have to pump the pedal like crazy and eventually it will go.

It is definitely not a starter issue, it has plenty of juice. My fuel pressure has been around 5-7 and sometimes more. so I changed the fuel pump and now it is even higher, sometimes up to 9psi. So I ordered a regulator and also an air/fuel ratio kit that I will be installing.

So could this be vapor lock? I have also noticed my fuel filter is sometimes full an sometimes not so full and sometimes empty. That is partially why I changed my pump. I am told also when you shut the engine off the pressure gauge should hold pressure for several minutes.

I don't know my under hood temp, but I assume it is hot because it is a 51' chevy with lots of metal and an e fan pulling hot air. My manifold seems extremely hot as well. My dist is brand new and I don't recall the mfg off hand but it is a 50 or 65 volt something like that, I have to look.

I was going to try this regulator and I was also told to ditch the hardline and run all rubber line from the pump. I have new carb gaskets from edelbrock, two of them, can I put two gaskets in instead of one? I am thinking maybe the fuel is getting too hot?

I don't know if it is too lean or rich at this point, I know there is not black smoke. I also looked down the carb and squirted the throttle and gas was coming out but still took a little longer to start. So I was thinking either too much gas or not enough air. I have tried it with the air cleaner off but still it will need some pedal pumping.

My gas mileage hasn't seemed to be what I expected, so far I am between 12-15 mpg with 3.42 rear end and a 5 speed. I would assume I would get a little better than that. I do feel like I have some more tuning I can do, but I just want to get past this hard starting after running. My cam is an isky .465 220/220 I believe. So nothing too radical there. Stock heads 60 cc

I constantly check my oil for any signs of gas, so far no signs, but inside my carb when I take off the air cleaner after it was running seems offly smelly of gas. I checked my floats a while back when this was on another engine and they were fine. I to my knowledge and running factory everything in the carb. I think the lack of gas in the filter is telling me something, I just don't know if the gas is running into the carb or down the line and if it is too hot thus disturbing air/fuel ratio.

Lastly the choke stays open when warm.

any thoughts would be great, sorry for the long write up and if I got off track, I tried explaining everything the best I could. I don't feel like it is a timing, starter or choke problem at this point.
Vapor lock occurs between the tank and pump. This is the suction side of the pump, when the fuel is close to the vaporization point because its temperature is raised by the surrounding environment, the pressure reduction caused by the pump trying to pull it forward allows the fuel in the supply line to flash into a vapor which the pump cannot pull forward. A bypassing pump would not make a difference. The placement of an electric pump into or immediately outside the tank results in the long line to the engine compartment being pressurized which gets around this problem.

The other issue and one that sounds likely in your case is the fuel being boiled out of the carb during shut down. The engine's heat soaks through the carb and boils the fuel from the bowls. I suspect at restart that fuel has been leaked into the engine flooding it to which you add some more from what was left in the accelerating pump system making the engine hard to light off till the excess is purged from the cylinders and while that's happening the carb refills. I'd recommend putting a heat barrier type spacer made of plastic between the intake and the carb, perhaps even one with a shield that fits between the intake and the float bowls, although the Edlebrock carbs whether the Q-jet or the Carter designs aren't as sensitive to this as the Holley is with those overhung bowels, so thr shield may not be useful.

9 psi pressure is too much, you need a regulator, 4 to 5 psi is plenty.

Bogie
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 05-26-2011, 01:20 PM
Registered User
 
Last photo:
Join Date: Jan 2011
Location: Pittsburgh, PA
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
thanks guys,

Yeah I have a regulator I am going to put on asap.

Can I run two gaskets under the carb for now or would that just do
too little? I just ordered from summitt yesterday and I don't know if
I can get one of those spacers at the parts store.

do you maybe know of any off hand or is this definitely a specialty item?

So any ideas on why the fuel filter isn't staying full?

I'll check my plugs now too, perhaps they are getting fouled out with all this
extra fuel.

Lastly if the fuel in the carb is getting too hot and thus the air being hot, obviously this is effecting my air/fuel ratio and gas mileage? I will be hooking
up my o2 sensor this weekend most likely as well.

thanks
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 05-31-2011, 05:22 PM
Registered User
 
Last photo:
Join Date: Jan 2011
Location: Pittsburgh, PA
Posts: 99
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
hey guys here is a link to my fuel filter while running (rpms are a little high I know, also the filter that I have at the tank and also the filter when the truck is off. 600 cfm edelbrock

It will start right up cold, when hot I have a real hard time starting it and when it does start I can smell gas, as if it was flooded out.

I been playing with my timing to see if that would help any but it is not. I was also going to get a spacer for the carb to help with the heat.

I just installed an o2 sensor and a fuel regulator. I am running a mechanical pump with a return line (also I am running a 3/8 in and 3/8 return line, not sure if that is making a difference or not). My gauge is reading rich pretty much either way I set the timing. When I am driving my lights go out at WOT but as soon as I let off a little the lights are about 13.5-14. So I think it is running rich at idle and cruise and way too lean at WOT. I am just wondering if this carb is causing the problems. I planned on tearing into it with a rebuild kit to eliminate some variables, maybe step down the jets. any thoughts would be great, also I don't think the fuel filter should bubble after it is off and sometimes it is full and sometimes it is not. That is why I changed the fuel pump but that didn't seem to be the problem.

http://www.youtube.com/watch?v=mC4O0DHJ4m0
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Vapor Lock? number_1cropped Engine 9 04-03-2007 05:29 PM
vapor lock ford59 Hotrodding Basics 3 12-20-2005 08:38 PM
Vapor Lock Problems cherry55 Engine 5 05-22-2005 07:04 PM
Vapor lock scottgto Engine 11 10-01-2003 08:13 AM
Vapor lock? miltoncobra Engine 3 04-02-2003 07:26 PM


All times are GMT -6. The time now is 01:14 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.