Fuel pump doesn't work when engine is hot

[Unoman]

Is this possilble? I have a 75' with the stock F and mechanical fuel pump. Yesterday the engine died while accelerating and wouldn't start back up until the engine had cooled. I have a clear fuel filter before the carb and can see the pump is only pumping minimal fuel if not any when the engine is hot. When the engine is cold, the pump will pump enough fuel to fill the filter up completely and run as normal. I took it on a few short errands today without problem, but anything more than that, the engine dies. Is my fuel pump going out?

 

[nuclearlemon]

sounds like standard vapor lock. the pump probably works fine, your fuel just isn't liquid at that point. look for areas where the fuel runs by anything hot (like exhaust) and put a heat shield there, or wrap the fuel lines in a thermal material to help keep it cool. you can also run it through a small cooler.

 

[F-junker]

x2 this is not uncommon

 

[In2cruisers]

Then again.........it might just be the pump... I have replaced 5 so far on different rigs... cheap enough to know that is not a problem now....or in the future

 

[Unoman]

Thanks guys. The fuel line does pass farily, but not extemely close to the header. What kind of insulation wrap do you recommend? Where can I pick it up?

 

[nuclearlemon]

Thanks guys. The fuel line does pass farily, but not extemely close to the header. What kind of insulation wrap do you recommend? Where can I pick it up?

check summit racing. thermotec makes an insulating sleeve. should be listed with fuel hoses. for a poor mans fix, or until you get the sleeving, wrap tinfoil around the line.

 

[Pin_Head]

I doubt that this is classic vapor lock due to the fuel line is over heating. This just doesn't happen that often in cruisers, especially with the stock fuel return line from the carb to the tank. Make sure that the fuel tank and lines upstream of the pump are not clogged or kinked first.

 

[Unoman]

Still confused why the pump will dump gas into the fliter when cold, but nothing when hot. The more research I do, one of the more logical answers seems to be vapor lock. I guess I should clarify my set up first. I have a Weber carb. Do Weber carbs have return lines to the tank because right now, I don't see one. There are two lines that run along the inside of the frame. One of them is capped off and the other runs directy into the fuel pump. The factory fuel filter is still mounted to the frame, but obviously has been bypassed. I'm assuming one line was at one point a return line and the other is a feed line. The new filter is between the carb and the hard line after the pump.

I've only had this 40 for about 3 weeks.....still trying to find the gremlins