PY Online Forums - Bringing the Pontiac Hobby Together

PY Online Forums - Bringing the Pontiac Hobby Together (https://forums.maxperformanceinc.com/forums/index.php)
-   68-69 GTO Tempest & LeMans TECH (https://forums.maxperformanceinc.com/forums/forumdisplay.php?f=433)
-   -   lack of power (https://forums.maxperformanceinc.com/forums/showthread.php?t=743831)

Darth Menace 12-20-2013 05:40 PM

lack of power
 
Hey, the short little time that I drove my car (about 1.5 hours after driving, we felt it was not the safest thing driving with such little brake power as well as super cracked wheels:)) the car seemed to have little pep and stalled while stopped at a light. My friend then towed the car home where I parked it.

I am hopeing to work towards this problem. Barring any internal mechanical issues, what would you guys suggest.

What I am doing at the moment is spark plugs, wires, air cleaner (the idle really picked up if the air cleaner was removed, but it wasn't driven with it off). Out of these I am thinking the new cleaner will make the significant difference.

Afterwards, I am thinking to check the timing, and adjust the carb screw, replace cap/rotor, coil.

Could there be a vacuum leak causing this issue too?

Ben M. 12-21-2013 12:25 AM

A new air cleaner isn't going to drastically improve performance. A new air filter would if the old one is gummed up and plugged. A basic place to start with any unknown engine is get the timing determined (initial and advance curve), spark plugs gapped properly (wires, plugs, points too if need be), verify idle speed, and check for any vacuum leaks.

Cap\rotor only need doing if they are in bad shape, coils usually don't go bad at all so no reason to focus there unless you're having serious ignition issues.

Simple Man 12-21-2013 06:02 AM

Are you running fresh gas in it?

It could also be a vacuum leak.

Txbobcat 12-21-2013 09:07 AM

I was thinking vacuum leak myself

Darth Menace 12-21-2013 10:15 AM

Quote:

Originally Posted by Simple Man (Post 5090452)
Are you running fresh gas in it?

It could also be a vacuum leak.

There was fresh gas in it. It was empty when I got it (nice fuel leak) so gas was put in

So is this a pain to track down/assess a vacuum leak? This could be very likely considering when I got it there was also a break line, fuel and antifreeze leak, so add this to the list of leaks and it would make sense.

Darth Menace 12-21-2013 10:41 AM

I guess this is a loaded thread due to the fact of it could be a million and 1 possibilities, but could it also be the fuel pump?

paint guy 12-21-2013 12:20 PM

If you were able to drive the car for 1.5 hours, I would'nt start with the fuel pump, I would also look for un-metered air (vacuum leak). Get enough vacuum hose at the auto store to replumb all the lines, it's not expensive. You'll need various sizes. When you replace the hoses, look for any lines that are split or disconnected, and also any vacuum ports that may be open. If you find any, plug them with a little rubber cap. Then if you still have symptoms of a leak, start the car and spray some carb cleaner or starting fluid around the base of the carb and observe idle. If it speeds up temporarily while spraying, you have a base gasket leak. If you are going to change a bunch of things, (plugs, rotor, cap etc) briefly start the car after you change only one or two items. That way you'll know if you installed something defective out of the box or incorrectly.

Darth Menace 12-21-2013 01:03 PM

Quote:

Originally Posted by paint guy (Post 5090641)
If you were able to drive the car for 1.5 hours, I would'nt start with the fuel pump, I would also look for un-metered air (vacuum leak). Get enough vacuum hose at the auto store to replumb all the lines, it's not expensive. You'll need various sizes. When you replace the hoses, look for any lines that are split or disconnected, and also any vacuum ports that may be open. If you find any, plug them with a little rubber cap. Then if you still have symptoms of a leak, start the car and spray some carb cleaner or starting fluid around the base of the carb and observe idle. If it speeds up temporarily while spraying, you have a base gasket leak. If you are going to change a bunch of things, (plugs, rotor, cap etc) briefly start the car after you change only one or two items. That way you'll know if you installed something defective out of the box or incorrectly.

I would gladly replumb all lines, I just redid all the rad hoses/heater hoses and it's great to start fresh.

Only problem is that I have NO IDEA about the vacuum system. If I just replaced every hose in the engine bay area, would that suffice? Like I said before the pontiac repair manual is just not very useful to me.

paint guy 12-21-2013 01:29 PM

Yes that would be a great start. There may also be a vacuum line to your heater control and another to your transmission. If you just replace all of the rubber lines present, one at a time with an equally sized replacement, you'll have your bases covered.

Darth Menace 12-21-2013 01:43 PM

Great, I had might as well replace them all and be done with it. I guess I won't know if I'm successful until I can do a street drive, but might as well do what I can.

I'm assuming a leaky fuel line didn't help the situation. :)

Greg Reid 12-21-2013 03:19 PM

I'd be curious to see an under hood shot of your car Darth.

Darth Menace 12-21-2013 04:12 PM

Quote:

Originally Posted by Greg Reid (Post 5090832)
I'd be curious to see an under hood shot of your car Darth.

Consider it done. Take a look in my album. Those are the pictures from the ebay ad. Nothing has really changed since then

Greg Reid 12-21-2013 04:42 PM

Vacuum and fuel lines don't appear to be running in the standard configuration. What kind of carb are you running?
After the tuneup and replacing vac hoses, that's what I'd be looking at to improve idle and drive quality.
You might want to get rid of the 'fire hose' (aka- rubber fuel line to carb) when you get to that as well.

http://forums.maxperformanceinc.com/...ictureid=10366

Darth Menace 12-21-2013 04:49 PM

The carb is an edelbrock carb. Is this fire hose you speak of the hose with the fuel filter? Either way looking to replace them all. The overspray itself makes it annoying beyond belief. Does proper routing change the idle/drive quality that much?. If so this somewhat easy project could turn to a headache having to look up some sort of diagrams. wow

paint guy 12-21-2013 06:28 PM

Personally, I would not drive that car nor any other that does not have metal fuel lines all the way from the pump to the carb i.e. no rubber lines above the exhaust manifolds. My reasoning also eliminates using a plastic fuel filter in that location. At the very least until you can change the fuel line, keep a good fire extinguisher handy.

JVM225 12-21-2013 07:22 PM

Basically the motor needs three things to run right.
Fuel, air, and good spark. Anything that interferes with the proper delivery of any one of those three things will cause the problems you describe in a motor with good compression.
Have you done a compression check? If so, and that checks out:
Start with a good tune up including spark plug wires and filters, then replace the vacuum hoses even if they look good because they are cheap and looks can be deceiving.
Make sure you set the timing properly. Next move on to that fuel line. You'll probably have to wind up with some part of it being rubber because of the aftermarket carb, but at least make sure it's new, good, and tightly clamped.
These are basic things you want to do to a car that is new to you anyway.
If you still have a problem after the compression check, tune-up, and changing the vacuum and fuel lines, then you can start to narrow it down from there.

Greg Reid 12-21-2013 07:46 PM

Quote:

Originally Posted by Darth Menace (Post 5090893)
The carb is an edelbrock carb. Is this fire hose you speak of the hose with the fuel filter? Either way looking to replace them all. The overspray itself makes it annoying beyond belief. Does proper routing change the idle/drive quality that much?. If so this somewhat easy project could turn to a headache having to look up some sort of diagrams. wow

Fire hose is the rubber fuel line. Rerouting in and of itself will change nothing. I was just pointing out that it must be an aftermarket carb based on where I saw the power brake hose, fuel line, etc.
Some of the earlier models (389) did have rubber for a short distance but I too prefer all metal for fuel lines. I lost my first GTO to a fuel leak and rubber is more likely to leak than metal.

Darth Menace 12-22-2013 10:54 AM

Quote:

Originally Posted by Greg Reid (Post 5091025)
Fire hose is the rubber fuel line. Rerouting in and of itself will change nothing. I was just pointing out that it must be an aftermarket carb based on where I saw the power brake hose, fuel line, etc.
Some of the earlier models (389) did have rubber for a short distance but I too prefer all metal for fuel lines. I lost my first GTO to a fuel leak and rubber is more likely to leak than metal.

Shows what I know. My old Yamaha bike was a rubber line, etc...that would make for a hot crotch.

I'd gladly switch to a metal fuel line. I dont know if they are custom jobbies or like a brake line that can be bought and bent, but I will add this to my to do list for this car (I made it yesterday and it looks annoyingly long)

charles bledsoe 12-22-2013 01:26 PM

I would take a good look at your fuel pump. If it looks to be the original pump or 10 years or older replace it. You can get one at your local auto parts house. There is a diaphragm inside the pump which deteriorates due to the ethanol in the gas. I have a few stations where I live that have ethanol free gas. If you google ethanol free gas you will find a web site that list the stations that have it by state.

Greg Reid 12-22-2013 01:50 PM

Quote:

Originally Posted by Darth Menace (Post 5091353)
Shows what I know. My old Yamaha bike was a rubber line, etc...that would make for a hot crotch.

I'd gladly switch to a metal fuel line. I dont know if they are custom jobbies or like a brake line that can be bought and bent, but I will add this to my to do list for this car (I made it yesterday and it looks annoyingly long)

Well, to be honest, the one I lost had nothing to do with a rubber line. It was the stripped inlet threads on the stock Quadrajet with metal line. What it did for me though, was to make me very careful about fuel delivery in the engine compartment...and rubber is an unnecessary risk.
If you ever change to the stock carb, you can get the exact metal fuel line from PY. If you keep the carb you have, it can be made just as you mentioned.


All times are GMT -4. The time now is 10:10 AM.