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IH Vapor Lock - How To Stop

A

Anonymous-0

Well-known Member
I have a 1967 IH 1600 Loadstar with a 304 and a Holley two barrel. Starts and runs like a champ. However, once it's been out on the road, gets warmed up, and I shut it down, it is really really hard to start.

I guessing this is due to vapor lock, but I'm open to any other ideas. It has a rebuilt carb and a new Carter fuel pump. The line running from the pump to the carb is steel.

I'm thinking of wrapping the fuel line in rubber hose and trying a new fuel filter. Any other suggestions?
 
Running an electric fuel pump (Facet makes a very good easy to mount small reliable pump for modest cost) and bypassing all the existing fuel pump and lines. Use fuel injection rated hose (it is lined and much tougher), and put pipe insulation over that. If it still causes issues, I would use a 4psi pressure regulator right at the carb as a bypass, and the Facit pump to supply it. The pressure regulator output should go to (best) the tank with a return line. Or at least through a fluid to air cooler, then back into the intake of the Facit pump. This circulation keeps the fuel being delivered in liquid form. JimN
 
It might be vapor lock.

But, I had a Dodge pickup a long time ago that had a Holley 2 bbl carburator on it that did the same thing. It would start cold just fine. Get it warmed up and try to start it and it was no-go. Was fouled up from brand new. It was a brand new 1978 Dodge D-150 with a 318 engine. The so-called service manager promised to fix it at least 6 times. He never did. I finally found it myself and fixed it. Started just fine after that.

What I finally found was that the float was set wrong from the factory. It didn't close the needle valve and was dumping raw gas down the throat of the carburator into the intake manifold. Until the gas evaporated away, it was too flooded to start.

I'd pull the carb apart and check the float setting.
 
Hey Buddy,

Can't figure out how you made the jump from hard starting hot to vapor lock? Especially so, since you've already replaced the fuel pump?

Think about it. The truck was running just fine before you shut it off. Now, it won't start.

Lotta things can cause that, but it darned sure isn't vapor lock. :>)

Allan
 
That 304 has the fuel line in close proximity to the exhaust manifold. this causes the gas to boil before getting through the pump "Vapor Lock" AS mentioned below if you put an add on electric pump on frame before routing line past a heat source, the fuel pressure will stay constant at the carburetor. I have heard of some people insulating the line like you said with a hose. But those old Loadstars run pretty hot when working them.

The clothes pin's wooden [spring style] I've seen on automobile engines and they did help.
 
Yep,

It might be caused by percolation, flooding, an electrical issue, engine dwell/timing or maybe even bad compression, but it 'taint vapor lock. :>)

I'm with you. Take a flashlight, yank the air cleaner and watch for fuel coming over the top when hot.

Allan
 
If it has a holley carb it may be the float but myself i am leaning more to the power valve . As it more then likely has gone bad and is is dumping the gas out of the float bowl down into the manifold and draining the float bowl , So when ya try and start first off the float bowl is darn near empty so the fuel pump has to refill it along with the raw gas in the manifold causeing a flooding cond. making it even harder to start.
 
Well, "Buddy," since you are so quick to criticize, but yet offer no help, maybe you should take up your position with Holley.

Holley only engineered the fuel system so maybe they might know a thing or two about possible root causes. You, on the other hand, only have demonstrated that you know, well, nothing.
Hmmmmmmmmm, Look Here
 
Just a thought, are you sure that its a fuel issue? a little squirt of gas down would confirm or not.. Ive had the same problem when a ballast resistor went out, wait a few mins til it cooled an it cranked right up, jumper from bat to coil and it cranked right up. If you find it definitely is fuel you might try the hose over the line method or like a buddy did with my old motor home that vapor locked every time you stopped stopped to pay a toll he packed fiberglass hood insulation out of a junk car between the fuel line (also steel) and the engine between the pump and the carb, took him all of about 3 minutes and it never starved for gas again...just a thought....OCG
 
We used to use a glass bowl filter Turned upside down up close to carb back in the good old days when cars had Carbs.
 
Ran a 1600 as a fuel truck in the oilfield, it's vapor lock problem was solved by wrapping an alum foil heat shield around the gas line from the carb down past the manifold
 
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