Temporary Power Loss

[landon]

Took the 02 out to day for it's daily commute to work. Had an inspection this afternoon and proceeded on a 40 mile drive to the site. First 35 miles is freeway and we don't miss a beat at 4500 rpm with AC on. It is hot outside but the 02 is fine. Last 5 miles climbs 2-3000 ft elevation and we make it to the site at about 10,000 ft elevation without issue. The car is parked for about 45 minutes and I'm ready to go. Fires right up and I proceed around the block and start climbing a steep hill. The engine bucks a few times and we lose power. Clutch in and the motor revs up but as soon as the clutch is out the engine bogs down under load. I repeat this a few times and get a few hundred feet down the road before it dies. It will not restart. I backed the car down to a level turnoff and check under the hood. No loose wires, no missing vacuum caps... coil is not hot to the touch.... nothing unusual. I get back in the car and it fires right up. I proceed back to the office and we make it without issue.

 

Engine has about 225k miles. Pertronix is about 15+ years old. Red coil was new with the engine rebuild - so 225k and 23 years. I have a 38 DGAS carb with the Jeep filter on a return line. 

 

Coil? Pertronix? Vapor lock? 

 

Any ideas appreciated...

      

[slowbert]

Electric fuel pump or mechanical? Kind of sounds like vapor lock. Maybe a bubble of vapor in the line that prevented the bowl from filling but it has enough gas for idle. 
 

Sounds like the gremlin disappeared once you pulled over. 
 

Got to love the daily driver 02 in the high county. 

[landon]

2 minutes ago, slowbert said:

Electric fuel pump or mechanical? Kind of sounds like vapor lock. Maybe a bubble of vapor in the line that prevented the bowl from filling but it has enough gas for idle. 
 

Sounds like the gremlin disappeared once you pulled over. 
 

Got to love the daily driver 02 in the high county. 

Stock mechanical fuel pump. That one's a year old. I just had the car up on Independence pass a couple of weeks ago and its' always been solid reliable driver. I need to get over to Denver at the end of the month and now I'm spooked....   

[slowbert]

In every car I had a problem like that, I switched to an electric fuel pump. Dunno if it helped, but it made me feel like I was doing something productive. Also putting some insulation on the fuel lines has helped. 
 

I know what you mean about being spooked about driving when it might not feel reliable. Make sure you have your AAA membership up to date and you will be fine. 

[John76]

Just a few things to check.  Engine bogging down under load sounds like a fuel or advance problem.

 

How is your tank vented?

Do you have a vapor tank in the trunk and still use the charcoal canister?

Was your fuel tank almost empty?

Is your fuel filter before or after the stock mechanical fuel pump?

Using a 1-way check valve on the return line from the Jeep filter?

Are you using vacuum advance with the PerTronix?

Fuel lines in good shape?

John

[Mark92131]

Hot day, could be vapor lock but I would change the Jeep gas filter.  When I picked up my Cab from Port Hueneme and drove it home it would loose power on every hill,  Turned out the sediment in the fuel filter would float back and clog the fuel fuel flow starving the carb.  Changed the fuel filter, problem went away.

 

Mark92131

[landon]

1 hour ago, John76 said:

Just a few things to check.  Engine bogging down under load sounds like a fuel or advance problem.

 

How is your tank vented?

Do you have a vapor tank in the trunk and still use the charcoal canister?

Was your fuel tank almost empty?

Is your fuel filter before or after the stock mechanical fuel pump?

Using a 1-way check valve on the return line from the Jeep filter?

Are you using vacuum advance with the PerTronix?

Fuel lines in good shape?

John

I have the tank vented thru the stock vapor tank and the line routed into the air cleaner. I removed the old charcoal cannister a couple of years ago due to age...

The tank was half full. Regular fuel filter before the pump and Jeep filter after the pump with return line going to tank. No vacuum advance.  This is all the same setup that has been running for a long time under similar and more extreme conditions so not sure what changed today. 

I'll look closely at fuel lines, though I do always maintain them well.... i did change a hose clamp at the tank this Spring as i had a fuel smell in the trunk. The plastic adapter looked good.  I'll take a close look for any other air / fuel "leaks".   

[landon]

18 minutes ago, Mark92131 said:

Hot day, could be vapor lock but I would change the Jeep gas filter.  When I picked up my Cab from Port Hueneme and drove it home it would loose power on every hill,  Turned out the sediment in the fuel filter would float back and clog the fuel fuel flow starving the carb.  Changed the fuel filter, problem went away.

 

Mark92131

I replace my filters every Spring and these have about 6000 miles on them. Not real old but you can't see if they are clogged so I may just replace those. I climb a 10% grade most everyday on my driveway, usually in the heat of the day and at low rpm in 1st gear but never experienced this.  

[Son of Marty]

It really sounds like the fuel boiled out of the carb and fuel lines with enough left in the float bowl to start the car and get to the bottom of the steep hill that the fuel not quite full and the hill just added to the struggle to fill the float bowl. I would ditch the filter before the pump as it serves no real function. And yes change the filter and inspect the fuel hoses.

Edited September 9, 2022 by Son of Marty

[7502]

Do you have the phenolic  carb spacer?

Edited September 9, 2022 by 7502

[Mike Self]

Sure sounds like you were sucking air vs fuel at some point...mechanical pumps will pull the least dense fluid in favor of denser stuff, so air over gas every time.  Old (cloth covered) hoses?  loose hose clamp(s)?

 

Does the run of fuel line from the firewall to the pump run right alongside the cylinder head--and even touch it?  A sure receipe for vapor lock, especially if there's a loose or porous fuel line involved...

 

mike

[resra]

I bought a new mechanical fuel pump that lasted 6 months. Don’t be surprised with built quality of things. I took it off and put a low pressure electric fuel pump and going over three years no problem so far.

['76mintgrün'02]

My vote is for vapor lock due to chitty gasoline.  I buy ethanol free typically, but settled for e10 recently and had it boil off when I pulled over to the side of the road on a hot day.  The car died and would not restart, so I popped the hood and heard this hissing sound.

 

 

 

It fired right up after cooling down.  I took the top off of the carb and found 3/8" of an inch of fuel still in the bowl, so that must have been the stuff with a higher boiling point in the "distillation curve."  This is an interesting little article on the topic.

 

Mixing New Fuel for Old Cars

WWW.MOTORTREND.COM

---

There are plenty of ways to be mixing new fuel for old cars, but we give you some tips on how to do it properly.

 

They sell ethanol free gas at a CENEX near my house, so I stopped at one while on the road, but they only sold e10.  Ironically, that was the gas that boiled off.  I've since learned that Sinclair stations carry e-free gas and am shopping there when I can find them.  It really does run better with real gasoline.  (I suspect gas quality might be going down along with the prices).

 

When you say "new stock pump" are you referring to a long neck pump, or the stubby one that pushes down on the coolant line?  I bought one of those thinking they look cool, but went back to the original tall one thinking it's more apt to stay cool. 

Although, when mine overheated, almost everything on the engine was too hot to touch, including the pump.

 

I've been using the same Jeep filter for maybe ten years.  The clear filter before the pump keeps it clean and that filter's been in place for several years and still looks fine.

 

I doubt you need to fix anything, but I'd try to buy pure-gas when you can find it.

 

Tom

[landon]

11 hours ago, 7502 said:

Do you have the phenolic  carb spacer?

Yes. I'm a bit stumped because the engine was cooler after the 45 minute rest and it was hotter at the end the 40 mile drive while I was climbing. No where close to overheating but hotter in the sense of boiling off gas.

[landon]

1 hour ago, '76mintgrün'02 said:

My vote is for vapor lock due to chitty gasoline.  I buy ethanol free typically, but settled for e10 recently and had it boil off when I pulled over to the side of the road on a hot day.  The car died and would not restart, so I popped the hood and heard this hissing sound.

 

 

 

It fired right up after cooling down.  I took the top off of the carb and found 3/8" of an inch of fuel still in the bowl, so that must have been the stuff with a higher boiling point in the "distillation curve."  This is an interesting little article on the topic.

 

Mixing New Fuel for Old Cars

WWW.MOTORTREND.COM

---

There are plenty of ways to be mixing new fuel for old cars, but we give you some tips on how to do it properly.

 

 

 

I doubt you need to fix anything, but I'd try to buy pure-gas when you can find it.

 

Tom

 Hard to find around here. Especially when I'm on the road alot and you just get what you can get. Wonder if anyone has additives to counteract the E10 issue? I looked around a bit last night and could not find anything to fix.... yet.