Fuel Starvation / Mechanical Fuel Pump

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redfastback said:
Run the car without a fuel cap, or with it loose. If it is not venting, that could be an issue.
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I tried that last summer with mixed results. I'll try again this week. If that doesn't work, I'm going to make those fuel lines look like a mummy.
 
I couldn't wait any longer. Kids in bed and wife busy on the phone. Time to test the car without the gas cap. I know it's not sunny and 90 degrees. It's 78 degrees and 81% humidity. I drove the car 30+ miles without an issue. Mixed driving, but mostly highway, and no stalls.

Popped the hood immediately, upon arriving home, to see how hot the area is where the fuel line runs by the header primaries.

Here are the results.



I could keep my hand on the fuel line/inner fender area for 10 seconds without crying.



Am I right to think it's strictly a venting issue?
 
Got some days in the 80s this week. Just waiting for a day when it's not raining for hours on end.
 
In my opinion... the factory mounted a metal filter vertically behind the lower rad hose and alternator at the same time the unleaded fuel came along. I took that as clue and did the same for current 67 273. Thickest carb spacer under my 2 brl was listed for 75 model 318.
I'll install the metal filter with port for return line in next build. It's not needed today. I do drive farther and pay more to get premium ethanol free fuel though.
 
I have absolutely NO fuel delivery problems. I run a 205*F stat,naked TTIs , dual 3"pipes,no hood scoop,no isolator between the AG and the Holley carb, and no fuel-line insulators.Granted our hottest days of summer rarely exceed 95 to 97 and rarely hover there for more than a week.Typically the summer temps hover between 80 to 90.I never worry about the outside temps. I drive it exactly the same way. I beat on it,race it,cruise it,idle it,and get stuck in traffic in the concrete city. Sometimes from mourning til night. No, not stuck. Driving.
This is how I beat it;
I ran my home-bent 3/8 fuel line inside the frame from the outboard rear-end of the front sub-frame, to come out of a hole within about 6 inches of the pump,then continued to about 3 to 4 inches from the pump. Then a short piece of hose to the pump. Then from the oem 340/Carter, a hard line all the way to the dual-feed splitter for the Holley. There I put another very short piece of hose.I have no filter at the front. I put an EFI large-canister hose-barbed filter way at the back,at the lowest point of the line. In 15 years/125,000miles, I have yet to change that filter. The hose that connects the in-tank line to the hardline right at the tank I have changed somewhat regularly. That hose is double gear-clamped at each end, with the screws offset 180*. All the hoses are EFI-type.All the hose connections are straight or nearly so.The in-tank sender is an oem one, that I converted to 3/8 pick-up,complete with sock.I fabbed my own copper-wire ground strap for the gauge.
This has worked flawlessly for me.
Oh yeah, I run 87E10. Never anything else.
 
with this new Gas we have to use, I have fought this issue more then one time, and have found the only sure way to fix it is intank pump. MT
 
I had vapor lock problems on a vehicle with similar bolt together Carter pump. It happened a short time after purchasing a new pump. I took it apart, and found the check valve disks were loose in the housing. The valves should have been press fit, but they fell out when I flipped the housing over. It looked like an adhesive was used in manufacturing. Very few adhesives work with modern fuel. I returned to store, the replacement worked fine.

It would get enough fuel to carb when cool, but not when hot.
 
Update:

I drove the car yesterday afternoon for about an hour, with the gas cap off. Equal mixed driving this time around (50% city/50% highway). The temperature was between 85 and 88 degrees w/ 70% humidity. The car didn't stall once. It did sputter one time, but I'm pretty sure it was due to my funky 700r4 shifting into OD prematurely and bottoming out the rpms.

The clear fuel filter didn't have much fuel in it, but apparently enough to keep it from stalling. I still intend to wrap the entire fuel line from where it's parallel with the header collector all the way to the carb. Extra insurance.

I'm concluding my tank isn't venting properly and I might have a moderate vapor lock issue that can be solved by further fuel line insulation. Hopefully I'm right or it's going to be a long 3,000 mile trip.
 
KitCarlson said:
I had vapor lock problems on a vehicle with similar bolt together Carter pump. It happened a short time after purchasing a new pump. I took it apart, and found the check valve disks were loose in the housing. The valves should have been press fit, but they fell out when I flipped the housing over. It looked like an adhesive was used in manufacturing. Very few adhesives work with modern fuel. I returned to store, the replacement worked fine.

It would get enough fuel to carb when cool, but not when hot.
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I bought/used the same pump years ago, lasted a week or two, replaced it with a cheap oem autozone pump. No problems for well over a decade now. Allot of wasted money on that carter pump. They look cool and all but sheesh:protest:
 
mopar head said:
I bought/used the same pump years ago, lasted a week or two, replaced it with a cheap oem autozone pump. No problems for well over a decade now. Allot of wasted money on that carter pump. They look cool and all but sheesh:protest:
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Same here, and what I got was the one rated for 50 or so gallons an hour.
Sometimes the actual cheap stuff works better than the expensive cheap stuff. :D
 
plumkrazee70,

Thanks for asking.

I vented the cap when I got to Iowa, but still had some stumbling with a full tank. After a few miles of driving, the stumbling subsided. Half way through the trip I also downsized the fuel filter and covered it in a head shield. I think the larger diameter fuel filter required too much fuel to fill effectively. I made the entire 4,000 mile trip w/ relative ease.

Long term, I'm going to switch over to an electric pump and braided lines.
 
Never had a problem with mechanical fuel pumps even with the California gas we have here. We have lots of older pre 73 cars in the family.

Just last month our car club went on a 100 mile cruise. It was a 100+ degrees out. Lots of old car with mechanical pumps. Not one problem with vapor lock.
 
What is your vacuum reading in park and in gear? What power valve is in there?

Check to see if your holley has screens at the fuel inlets. One of mine did, one didnt. If your needle and seat are old, they may be sticking.
 
Find the vent for you gas tank(NOT the vented cap) and blow the vent out. i had a problem after i replace the rubber part of the vent line. Line was full of bug and plugged completely off. when i replace the cracked rubber line the tank was no longer vented.

Took me a long time to figure out why i had to keep my gas cap off to keep it running when i mashed the go peddle.

I also ran a split down the middle 1/2 fuel hose over the fuel line next to the headers, hooked a small fan that blue air on the pump, spacer for the carb. all this i did, before i fix the fuel tank vent and cured my vapor lock.

In the heat of the summer, drag racing i could still get it to vapor lock, run out of fuel about the 60' mark. wouldn't die just mess up a et real bad. Put a small elect pusher pump and problems when a way.
 
I haven't the foggiest idea. It was bought new and the only thing I did was change the jets.

The car is currently buried in boxes until it cools down and I can fix a few other issues. I've received a couple of other tips and will apply when I yank her back out of the garage in October.

redfastback said:
What is your vacuum reading in park and in gear? What power valve is in there?

Check to see if your holley has screens at the fuel inlets. One of mine did, one didnt. If your needle and seat are old, they may be sticking.
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