85' 720 Possible vapor lock and other issues

[Tanken]

As of recently my truck has been having a lot of issues starting when the vehicle is warm. i'll go into the store and come back and i have to put my foot to the floor on the gas and hold it until it starts and after it does start it runs horribly for a while. I took off the air filter and I could see fuel boiling. I don't see how this could be happening since my weber is hooked up to the factory fuel hard line with the return line. It seems to be getting worse to the point that my truck barely even runs now. Do i just need to rebuild my carb or could this be fuel pump or something? I was going to buy a fuel pressure guage tomorrow and see if anything is being weird. any advice would be much appreciated 

[datzenmike]

Vapor lock at this time of year??? unlikely. On a warm engine it's normal to see misty fuel vapors inside the carburetor.

 

Next time before starting when warm take the air filter off and see if the choke is still on. You have electric choke???

 

If choke is off perhaps the carburetor is flooding.

[Tanken]

2 minutes ago, datzenmike said:

Vapor lock at this time of year??? unlikely. On a warm engine it's normal to see misty fuel vapors inside the carburetor.

 

Next time before starting when warm take the air filter off and see if the choke is still on. You have electric choke???

 

If choke is off perhaps the carburetor is flooding.

Yes i do have the electric choke. What's the best way to see if the choke is on? Sorry I don't have much carburetor experience. 

[datzenmike]

Choke closed...

 

 

Choke open...

 

 

This isn't a Weber but the principal is the same. Closed when starting cold and opens in about 10 minutes during warm up.

[DwayneOxford]

Electric fuel pumps at/in tank, pressuring the gas to carb, eliminated vapor lock, caused by mechanical pumps on engines pulling fuel from tank, lowering gas boiling point.

You may have float and/or needle seat leaking residual pressure. 

[Tanken]

17 hours ago, datzenmike said:

Choke closed...

 

 

Choke open...

 

 

This isn't a Weber but the principal is the same. Closed when starting cold and opens in about 10 minutes during warm up.

 

here it is after going on a drive to get it to operating temperature. waited about 15 minutes. wouldn't start still. It's to the point i can't even drive it. the first initial start of the day is fine but it just dies when it's in neutral for too long after being driven for a bit.

[datzenmike]

Not fully open is it. The choke flaps should be straight up and down so it is off.

 

Check that you have 12v on the electric choke heater. If there is 12v, adjust the choke so the flaps are fully open when engine is hot.

[Tanken]

30 minutes ago, datzenmike said:

Not fully open is it. The choke flaps should be straight up and down so it is off.

 

Check that you have 12v on the electric choke heater. If there is 12v, adjust the choke so the flaps are fully open when engine is hot.

Okay I will double check for 12v. Any tips on adjusting the choke? you do it when it's completely cold right?

[DwayneOxford]

Is it flooding/black smoking after warmup? I set mine so's it's just barely/lightly closed cold. May need to tweak in summer and winter. Heater should be warm a little after it starts. Need to just crank up and watch carb. Depress accelerator, check how tight choke is closed. Crank up and watch how choke opens. Pull off should open choke just enough to run smooth, then heater should be warming and slowly moving choke to full open when warmed up. Look in top and see if you see drops going in. If so the float/needle are not right. Same if drops/seeps after shut down.

Edited December 23, 2023 by DwayneOxford
Add.

[None_zero]

Also check fuel filter. $15 bucks is a pretty easy hit to weather