Summer Heat Issues? (12 Viewers)

[faalkinaey]

Now that it’s finally summer my 60 here in Colorado has been experiencing some problems, generally around fuel, after about two hours of highway driving in 90° weather the car begins to “stumble” or buck, and progressively gets worse until you let the car stop and cool down, it only happens under load so you could sit there revving it at a standstill and no issues. this used to be a frequent and HARSH problem before I switched the charcoal canister hoses around venting the tank, now it only seems to buck after extended period of driving during warm weather. The truck is completely stock besides having the EGR bypassed, new OEM pump, new OEM filter, rebuilt carb (allegedly from P.O). This issue is driving me nuts to pinpoint, it also important to note that the fuel in the sight glass is below half, it’s not completely absent but I would say sits at a 1/4 way up the sight glass and the fuel filter fills up about 3/4 of the way. Could I just have a low float that needs adjustment? Maybe dirt in the jets? Or could this be a heat soak / vapor locking issue since it seems to definitely correlate with higher temps. I’ve thought about replacing the pump again but how common would a Toyota pump go bad with less than 1k miles on it?! My 62 series seems to perform flawlessly in the hot GCC climate that sees 120-130 degree weather and I daily it with just a stock setup (albeit we didn’t get a smog pump or fuel injection over there) I’ve verified timing to be exactly on the dot, new plugs, HEI dizzy, and no vacuum leaks from what I can find. My next step is going to be to wrap all fuel lines under the hood with some insulation to see if that does it, but I’d love for somebody to chime in

 

[MDH33]

Are you running ethanol fuel? I just passed through last week when temps were hot and had same issue because i could only get ethanol at most stations. Ran horrible and had constant fuel boil.

 

[OSS]

hook the EGR system back up

 

[POTATO LAUNCHER]

Most likely vapor lock caused by ethenol in the craptastic summer blend fuels found in Colorado. Find pure fuel and see if it helps. Put some heat shielding on the fuel lines and route away from heat sources. An inline electric fuel pump rated for carburators, IE. 6-9#, can help also.
It all Boils down to the boiling point of the fuel. The higher the Ethenol / Alchohol the lower the boiling point.

 

[DrRock]

Most likely vapor lock caused by ethenol in the craptastic summer blend fuels found in Colorado. Find pure fuel and see if it helps. Put some heat shielding on the fuel lines and route away from heat sources. An inline electric fuel pump rated for carburators, IE. 6-9#, can help also.
It all Boils down to the boiling point of the fuel. The higher the Ethenol / Alchohol the lower the boiling point.

This was one of the reasons I went with a pressure regulator on my EFI that resides back by the tank. Now I don’t have fuel that has been heated in the engine bay returning to the fuel tank.

OP: I’d also check your ignition wires, coil wire and igniter connections. Connectors can have issues when exposed to heat.

 

[CruiserTrash]

I agree with Casey - it was really hot here last week. Mine doesn't experience any fuel-type bucking issues very often, but it happened once last week when it was 105 out.

You should also test your fuel cut solenoid per the Emissions manual.

 

[OSS]

I experienced similar fuel starvation problems over 1000 miles away from home - in Mexico. Bucking.
I couldn't figure out what was happening but managed to limp all the way home.

When I eventually got the carburetor removed and inspected stuff, I found a piece of debris inside the float bowl that was intermittently blocking the jet. I don't know how it got in there.

 

[DrRock]

I experienced similar fuel starvation problems over 1000 miles away from home - in Mexico. Bucking.
I couldn't figure out what was happening but managed to limp all the way home.

When I eventually got the carburetor removed and inspected stuff, I found a piece of debris inside the float bowl that was intermittently blocking the jet. I don't know how it got in there.

You answered your own question. Mexico. I’ve had to purchase fuel in all kinds of conditions out of all kinds of vessels in Baja. My favourite was a rancher who used a 1 gallon milk jug as a way of “measuring “ how much fuel he was selling me as he dipped the jug into an open 55 gal drum of petrol and put it in my tank. Amazing how much help and support one gets down there.

 

[Sethro60]

Try taking off your gas cap when it happens and see if your cruiser gets happy.

 

[faalkinaey]

Are you running ethanol fuel? I just passed through last week when temps were hot and had same issue because i could only get ethanol at most stations. Ran horrible and had constant fuel boil.

Yes…. Maybe ethanol free gas is the way to go

 

[Michael Hanson]

Compression numbers?

 

[zeeklafreek]

When driving around town yesterday BB, after about 45 minutes BB heated up to near overheating and she 'bucked' a couple of times and felt like near vapor locking to me. I've tried adding a bit of extra coolant but after stopping the motor, she burps out what I've added.

 

[DrRock]

When driving around town yesterday BB, after about 45 minutes BB heated up to near overheating and she 'bucked' a couple of times and felt like near vapor locking to me. I've tried adding a bit of extra coolant but after stopping the motor, she burps out what I've added.

Sounds to me like you still have air in the coolant system then. I went through a similar scenario post engine rebuild. First thing to check is your coolant overflow bottle. If it’s got a wide range of fluctuation between a hot engine and a cold engine, this is an indication there is still air in the system. My engine took close to a month to purge all the air and now my overflow bottle only fluctuates from 10mm above the low mark when cool to just below the full mark when hot. Post rebuild and fresh fill, it would go all the way to the bottom of the tank when cool to overflowing when hot.

On the temp needle topic, what you are seeing is completely normal. These trucks provide more feedback in the gauges combined with not as mature thermal management versus newer cars yield more dynamic readings on the temp gauge. Personally, now that I am accustomed to this, the additional feedback is welcome as it let’s me know when I should go a little easier on my driving habits.

Hope this helps.