[rkm1003]

To begin, here is my setup-MOTOR- '69 Pontiac 400 YA, .060 over, stock crank, SpeedPro L2262F pistons, CAT H-beam rods, HS 1.65 rockers, Crane cam kit # 283802, Edelbrock 72cc heads, Performer RPM Intake, Q-jet, 12 bolt 4.10 posi, 200-4R with Transgo HD shift kit, 2200 stall, 2" MadDog Headers, Holley 12-837 fuel pump.

Problem--Couple months ago, cruised up to Houston(apprx 200 miles). Little over half way, car started losing power, like it was running outta gas. Pulled over, saw tranny fluid coming out between pan/gasket. Checked fluid, looked high, so I drained out some fluid, started up and made trip to H-town. BUddy has lift, checked pan bolts, tightned, did some cruisin that night, no problem. Next day on way home, started doing it again. Did this 5-6 times. Each time, I'd pull over, wait 1-3 minutes, start car, and go 10-20 miles before it would do it again. Got home, next day, installed external tranny cooler, this Saturday, took trip of about 100 miles, started again. Does not feel like a miss(spark), more of power loss(like outta gas). Not much to go on, ideas where to start troubleshooting? Thanx, Kel

[dave s]

try looking at fuel system,filter,pressure,volume,fuel tank vent. weak ign coil? good luck

[rkm1003]

All new Teflon fuel lines with 6AN fittings, new vented gas cap, and new MSD coil..........I know, just because parts are new, doesn't mean theybare good though...

[Half-Inch Stud]

Smells like a fuel supply problem. HOwever:

Them early birds have an ingniton wire funny. some white wire from the Starter Solenoid. Maybe the Ignition is presently reliant on that white wire.

I assume you gots an HEI (not points): How about a copper wire from Switched-12V (wiper motor Black/yellow ) for awhile to see if the drop goes away.

[boater bill]

This sounds similar to a problem I just had on a roadtrip a couple of weeks ago. I think the oxygenated fuel was plugging up the lines or filter. It would start acting very poorly and really down on power about 50 miles after fill up in a station along the highway. I topped of the tank with Texaco 93 octane and it ran fine, until the next fillup with oxygenated fuel.

This was in a late model M*****G but sounds similar to your problems.

hope that helps.

[dave s]

one thing I forgot to mention .If your car has the the orig. sending unit it may have a filter on the pick up tube.when you drive it plugs,shut it off for 10 min. The rust ,dirt fall off .on and on. Take a blow gun a blow air back in to the fuel tank till you here it bubble, this should help if it has the filter.

[rkm1003]

one thing I forgot to mention .If your car has the the orig. sending unit it may have a filter on the pick up tube.when you drive it plugs,shut it off for 10 min. The rust ,dirt fall off .on and on. Take a blow gun a blow air back in to the fuel tank till you here it bubble, this should help if it has the filter.

I put new sending unit in about 4 years ago, had sock on it........

[shaker455]

Sounds like your fuel is boiling in the line and carb.

Any lines in direct contact with the hot engine?

[screamingchief]

With a mechanical pump and "smallish" lines on the suction side look for ANY restrictions that are adjacent to ANY heat source.

Restrictions cause a pressure drop (vacuum = extremely low pressure) this low pressure reduces (lowers) the boiling point of the fuel in the suction side of a fuel system,same deal as coolant in a cooling system,pressure raises the boiling point,so rarely is the problem on the pressure side.

Fuel already has an extremely low boiling point (it can start "boiling" to a small degree at room temperature & amospheric pressures,this is why it evaporates easily),and putting it in a system with a vacuum that lowers the pressure just makes the situation worse,add some unwanted heat load (heat increases the chance of boiling,,,right...) and pretty soon the fuel is boiling and the suction is unable to overcome the boiling fuels positive pressure lock in the line.

On mechanical pump fuel systems it's often the use of the forged 90 degree elbows on the inlet (suction) side that create serious restrictions,that or a restrictive filter(s) on the suction side.

Give the system between the tank and the pump a real close exam with an eye open for anything that resembles a restriction,especially if it's close to a heat source.

I myself would have used -8AN for the lines between the tank and the pump,and absolutely no "forged" 90 degree fittings that are'nt the large radius/gradual "bent tube" style elbows,filter for the suction side needs to be 80-100 micro "zero pressure drop/high flow" style filters with a GPH rating to match the pump,JMO.

[lust4speed]

Agree that it is vapor lock. Probably still runs fine on a cool night. Get back to daytime and hot pavement along with engine heat and it's cooking the gas in the line. It's also a good idea to reroute the fuel line as far away from the exhaust as you can get it. Then see if you can shield the fuel line for more heat prevention.

[screamingchief]

While going thru some other posts I ran across a pic of you engine,I'll point out what I'm talking about in that pic.

I also include some pics of the proper "style" of fittings to use.

Do note the large gradual radius of these fittings,this helps avoid cavitation/aeration/vapor lock better than "sharp" 90 degree fittings which offer significant resistance to flow.

Always avoid sharp 90 degree or greater bend fittings on the suction side of a fuel system!

The larger the radius,the less resistance it will offer.

In some cases you may be forced to bend your own from hard line for good results.

[rkm1003]

While going thru some other posts I ran across a pic of you engine,I'll point out what I'm talking about in that pic.

Nice catch Bret........last week, I decided to hook up an electric fuel pump in back, to boost mechanical pump(am having a power issue when launching hard, will post on another thread), so I deleted all existing fuel lines and made up some braided Teflon lines. All fittings are as you suggested(and they were somewhat a PITA to do), but looks better now. The line coming from the tank to pump is running on drivers side now, routed away from heat sources, better than stock setup. I am gonna rig up pressure gauge to see what it is doing when it starts to fall off, stay tuned........

[rkm1003]

Had a guy tell me today to put several wood clothes pins on fuel lines for cooling......he is pulling my leg?

[James408]

no, I've heard of that too. Thats on old trick hot rodders used to use. Kel, maybe buy some of that insulation tape from summit and rap your lines. Its supposed to reflect heat. I have some on my fuel line. It seems to work.