Fuel Starvation on my 69 Z?

[sixt9rsx33]

My Z is losing power at 5K rpms. Acts like a fuel starvation problem. Previously this same situation was present at 4500 rpms. I installed a new fuel pump and now it runs hard up to 5K rpms. The stock rubber fuel lines were installed in 2009. I am thinking that the ethanol laced fuel may have done them in? The other thing I was thinking is the fuel screen in the tank is clogged. Anyone every shot air in the fuel line towards the tank to try an blow debris out of the screen?
I have rebuilt the carb, and changed the filter in the carb.
Thanks

Lawrence

[earntaz]

Lawrence -- I had an old 69 Buick Estate Wagon with a big, big, big engine and I went thru the same drill ... fuel pump, fuel filter, etc. etc. Finally blew out the line back to the tank and that would cure the problem for about 1K miles. She was a battle wagon and sold it later to a dude who dropped the tank and found rust and more rust. So yes -- blow out the line back to the tank ... suggest pretty low pressure as to not shred the sock. I would assume you've already pulled a pump pressure test and checked the inline filter. Also, some Holley carbs came with a sinthered metal filter at the inlet(s) -- make sure they are not plugged. TAZ

[sixt9rsx33]

I installed a new tank, no inline filter, just the filter(s) in the carb. I need to check the rear sinthered filter now that you mention that. I don't think I changed that one <<GRAEMLIN_URL>>/shocked.gif

[PeteLeathersac]

'
Couple more thoughts...
- Float adjustment
- Fuel Pump cam lobe
<<GRAEMLIN_URL>>/beers.gif
~ Pete

[sixt9rsx33]

Checked the float adjustment. Man I hope it's not the fuel pump cam lobe..... <<GRAEMLIN_URL>>/cry.gif

[Salvatore]

spark plugs look real lean? any vacuum leaks do you think? valve spring issues?

[PeteLeathersac]

'

Good thoughts too Sam!
I hope it's not cam lobe wear too...try a gravity feed supply from above the carb or road test w/ temporary elec' pump installed?
When/how did the problem first begin...slowly worsened or all good one day/not the next?
Any chance the T'chain is off a tooth, loose and jumped or installed new and lined up w/ keyway slot not timing mark?
How's the dizzy itself, advance weights not seized and vacuum advance pot working plus points also plug gaps checked and Ok?
Unlikely w/ your year/model but exhaust obstructions can hold back revs too, sometimes clogged Cat' Converters etc on newer vehicles.
Best of luck!
<<GRAEMLIN_URL>>/beers.gif
~ Pete

[Mr.Nickey Nova]

Do you have Hi perf points installed?? Points should have a heavy spring so they don't bounce at high R's.

[earntaz]

AND while you're in there -- check the dist shaft for excessive side to side movement ...

[sixt9rsx33]

High Perf points installed, distributor weights nice and free not sticky. I need to map this distributor and see if I get any spark scatter at high rpms. Have not looked at the plugs yet. Will start with the filter and go from there. Easy first then go more difficult. Thanks for the suggestions.

Lawrence

[Salvatore]

did you run it with the air cleaner off? I had an early corvette that had an air filter that was to thin from top to bottom and at higher RPM's the carb was trying to suck the lid in. Poor air flow.

[sixt9rsx33]

Replaced the fuel pump, blew air in the fuel line back to the tank still have the same problem. My guess is that the dizzy is giving the problem.
No I have not tried running the car without the air filter but will give it a shot. Nothing to lose.
I will swap out the carb from the silver car to see if I can isolate the issue to the carb.

[Salvatore]

process of elimination.

[livettes]

If you are running the reproduction date coded original type plug wires they could be your problem.
My Deuce would nose over at 6000. Felt like it was running out of fuel. I chased the whole fuel system and could not find any problems. A friend suggested the plug wires were breaking down because of the higher cylinder pressure at high RPM. I swapped the original style for a set of MSD and problem solved.
Pulls hard to 7000.
Jamie

[PeteLeathersac]

'

Have you confirmed yet whether you do/don't have a fuel delivery problem?
Reviewing all again, the plug wires are possible but I'm starting to suspect the coil itself?
<<GRAEMLIN_URL>>/hmmm.gif
~ Pete

[sixt9rsx33]

I think I have located an issue. The coil wire had corrosion on the lead that connects to the coil. I cleaned it up and now the car will tach up clean to 5K before breaking down. I started thinking about the cheap Packard wires on the car, and they have been on there for at least 11 years. I bought the car November 2005, and were on the car then. I think I will replace.

Lawrence

[Alss]

my copo did the same thing...bad coil!

[bigsixman]

I had a similar problem and it was the coil wire. The coil wire receives all the voltage and the individual wires only see voltage when that cylinder fires.

The condition of the repo style wires would raise a question being 10+ years old.

Are the plugs fresh?

[Zman1969]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Alss</div><div class="ubbcode-body">my copo did the same thing...bad coil! </div></div>

X2 try another coil

[sixt9rsx33]

I have....same problem. I have another coil wire but have not put it on yet. Work is getting in the way with playing with old cars <<GRAEMLIN_URL>>/mad.gif

[sixt9rsx33]

Yea plugs are good.

[sixt9rsx33]

Changed the coil wire with a used one and the problem was worse. I will try another coil that I have and see what happens. If I have the same problem pull the distributor?

[sixt9rsx33]

I think I finally sorted this out. My problem was a combination of things. I had a bad corroded coil wire, and a weak coil. Cleaned up the coil wire really good, and installed a known good coil, and all is good right now!

Need to find a good 293 coil.

Thanks for the help,

Lawrence

[VintageMusclecar]

As the old saying goes--

&quot;99% of all carburetor problems are in the ignition system.&quot; <<GRAEMLIN_URL>>/smile.gif

[sixt9rsx33]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: VintageMusclecar</div><div class="ubbcode-body">As the old saying goes--

&quot;99% of all carburetor problems are in the ignition system.&quot; <<GRAEMLIN_URL>>/smile.gif </div></div>

Totally agree Eric!!!

[x77-69z28]

I think Pacecarjeff has some 293 coils on eBay right now.
Buddy

[earntaz]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: VintageMusclecar</div><div class="ubbcode-body">As the old saying goes--

&quot;99% of all carburetor problems are in the ignition system.&quot; <<GRAEMLIN_URL>>/smile.gif </div></div>

Haaaa!! Isn't that the damn truth ... <<GRAEMLIN_URL>>/haha.gif

[mockingbird812]

<<GRAEMLIN_URL>>/biggthumpup.gif

[Salvatore]

I have some good 293 coils Lawrence. Give me your address and I will send you one.

Sam

[sixt9rsx33]

Thanks Sam!! Just sent you a PM

Lawrence