Why vapor lock now?!

[dblclutchr]

Have had my 64 IIa 2.25 petrol up and running great for two seasons now. All of a sudden, vapor lock. I've done all the routine (near daily) maintenance including fuel filter. Mech pump seems to be working. No changes at all to my set up. Why am I experiencing vapor lock now and what is best fix? New pump? Switch to electric pump?

[darbsclt]

After trying just about everything to combat VL symptoms... I found the best solution was also the easiest. I simply sought out and filled up with pure (non-ethanol) gasoline. Adding Ethanol to gas significantly lowers the temperature at which fuel turns to vapor.

If you're not already a Pure Gas convert... try it. I haven't looked back. There's a nice little app (free) that maps out gas stations selling pure gas - all based off of your GPS. Just look up "Pure Gas" in your app store of choice.

[Andrew IIA]

Interesting.

[slowmo]

I thought I had the vapor lock beast conquered but it reared its ugly head last night on the way home.

I was blasting up the Mt Rose highway (3rd gear - 35 mph - line of honking cars behind me) when it went chuga-chuga-dead.
Disconnected the fuel line at the carb, pumped lever on the fuel pump furiously (1st degree burn blister covering my left index finder tip) and no fuel coming out. Poured some fuel into the fuel line, pumped some more. Nope. Started it up and it ran for 30 seconds or so and died again. Repeated this several times. Then I did the Hokey-Pokey (thinking that's what it's all about). Nadda. This is a new fuel pump. I said something like "fiddle-sticks".

After about the fifth iteration it started and stayed running and I made it home.

That is it. I'm getting an electric fuel pump and I will mount it low on the frame near the fuel tank optimizing the siphon for the fuel pump intake. I'm getting stainless braided fuel line which I will run as far away from the engine heat as possible. I will then remove the mechanical fuel pump (I have evil plans for its demise) and I will fashion a plate to cover the hole it leaves behind.

I will report the results.

[lumpydog]

I've been dealing with this too. I rerouted the fuel line without any added benefit.

Basically - after being parked on a hot day for longer than 15 minutes, it fires right up, gets me about 30 yards and shuts down.

My solution is to pull the fuel line off the carb, put a rag to the end of it, use the manual lever on the fuel pump until fuel flows into the rag, reattach the fuel line to the carb, Vroom... I've gotten good at it and it takes 2-3 minutes.

I figure the vapor lock must be taking place in the fuel pump or in the fuel line because I can run the engine for a bit and drive before it cuts out. It's a pain in the ass because having it cut out while under way is almost worse than having it not start at all,

I wonder if there is anything we can add to the fuel to increase the temperature at which it vaporizes.

[LaneRover]

An old 'anti-vapour lock' trick is to take a potato cut it in two (or drill through it) attach it to the fuel line and presto you're done. From what I have heard it lasts for a bit too as it takes awhile for the potato to dry out.

[slowmo]

Installed electric fuel pump on the rigid bracket rising from the frame to hold the right fender...er...wing on and ran the new lines away from direct heat transfer. So far, all signs of vapor lock have disappeared and it has been hot. To review, every time I have had a vapor lock situation, when I removed the fuel line at the carb and pumped the mechanical fuel pump lever (furiously) no fuel came out. After a bit, when things cooled down, it again functioned (this is a new fuel pump).

I am pretty dang sure my problem was that the temperature of the block on the fuel pump resulted in a vapor lock in the suction chamber = crappy design. If this problem occurs again with the new fuel pump and setup, I'll certainly hang my head in shame and report the results, but I'm 99% sure it is solved.

[siiirhd88]

I run electric fuel pumps on our Series trucks for this same reason. One concern with an electric fuel pump is they will continue to pump with the power on. I install a low oil pressure safety switch in the power circuit to the pump, so at low oil pressure (such as the engine stopped after a wreck....) the fuel pump shuts off. VDO makes a switch, part # 230-504 that shuts off at 4 psig oil pressure, but there are several other makes available. For starting, the switch is bypassed during engine cranking.

I have also had issues with heat soak after shutdown, causing the fuel in the carb bowl to boil over into the intake. Using a fuel filter with a return port (back to the tank) usually keeps the boil off vented to the tank, and lets the electric fuel pump push a constant cool flow of fuel thru the supply line and back to the tank.

It can get more complicated if you use more than one fuel tank.....

Bob

[keneiler]

Attach about 6 wooden clothespins to the fuel line

[slowmo]

...I install a low oil pressure safety switch in the power circuit to the pump...

Great idea. Thanks.

[lumpydog]

I install a low oil pressure safety switch in the power circuit to the pump, so at low oil pressure (such as the engine stopped after a wreck....) the fuel pump shuts off.

Ok, but then it won't start pumping until the engine starts and builds oil pressure… but the engine needs fuel to start… so how does that work? Does then engine start via what's in the fuel line?

[slowmo]

I suspect (which means I'm not sure) that since the oil pump is mechanical it generates more than 4 psig when the starter is cranking. The switch closes, and voila, the fuel pump pumps and the deafening noise begins.

[slowmo]

Attach about 6 wooden clothespins to the fuel line

Between the potato, the clothes pins, and the family of raccoons living in my engine compartment I'm about out of space. Dang thing is the raccoons are used to eating the potatoes which makes it hard to get them out. Also when I hang my laundry on the clothes pins, my whites come out gray and sometimes the pockets are filled with raccoon poop. However, they make adorable pets. Bitey is my favorite one of all.

j/k

[siiirhd88]

For starting, the switch is bypassed during engine cranking.

For starting, the open low oil pressure switch contacts are bypassed while the engine is cranking. This would be only work for the trucks with a starter solenoid, as the power used for the starter solenoid coil is used to bypass the low oil pressure switch contacts. On trucks with a mechanical solenoid or pushbutton starter, you would need to run a small jumper from the big starter cable terminal to the switch bypass terminal.

Bob

[slowmo]

Thanks!