Vapor lock

[INflyboy]

I fly a 9A with an io360. This engine has a very bad habit of vapor lock after shut down. It's been recommended to me that I invert the "spider" fuel valve. 1) has anyone done this? 2) where you successful with reducing the problem? 3) did you purchase the kit from Lycoming or is there an after market kit available? Thanks to anyone that could give direction.

[eddieseve]

Have you thought of trying the purge valve from airflow performance?

Easy retrofit.

This will allow you to run cool fuel through your whole system before attempting a hot start, works quite well for me.

Cheers

[Walt]

"Vapor lock" occurs ahead of the engine driven pump do to the low pressure there, everything after the pump is not subject to vapor lock as its pressurized so I can't imagine how flipping the fuel distrubution manifold (spyder) will help anything.

[RV10inOz]

That is what your electric pump is for, or one of the three reasons.

[erich weaver]

It has been my experience on this forum that the term 'vapor lock' is often incorrectly used to refer to vaporization of hot fuel in the fuel injection distribution lines from the spider. This vaporization can cause rough idle after landing or a tough restart if no purge is done to circulate cooler fuel. Perhaps the OP is referring to this instead of a true vapor lock, which as previously pointed out , occurs at the mechanical fuel pump.

erich

[mike newall]

Some variables here that need establishing.

We have an IO-360 parallel valve motor with Silverhawk injection. It doesn't have a return line, therefore after landing when everything is warm, you need to pay attention if you start - say - after fuelling.

Throttle 1/4" open, mixture lean, no pumps - crank until it fires then smoothly advance the mixture and it should pick up fine.

It may run like a rough old jalopy though because there is vapor around and it just needs ingesting. A blip with the pump may help, but it isn't recirculating anything, it is just pumping into the motor.

It is normal for the motor to run rough - surging and dying for a couple of minutes, particularly on a hot day. Once you open up to significant fuel flow on take off, it will be fine.

If you Airflow Performance, then there are differences and you need to refer to their operating instructions.

Hope that helps.

[INflyboy]

Thanks everyone for the comments and advice.

[boomer]

When it was new, I had quite a bit of trouble with hot starting my stock IO-360-M1B. Turned out it was all my technique (or lack thereof). I finally called Lycoming tech support and talked to the guy that did the engine run in's. He said that he had started many hot IO's with no problem, using the following technique:

Before you start open the throttle and mixture for a few minutes, generally long enough to do your walk around. The do a normal start (throttle 1/4, mixture idle cutoff) with no priming. Slowly advance the mixture when it the engine fires. Takes a few extra turns than a cold start but works for me.

-John

Originally Posted by mike newall

Some variables here that need establishing.

We have an IO-360 parallel valve motor with Silverhawk injection. It doesn't have a return line, therefore after landing when everything is warm, you need to pay attention if you start - say - after fuelling.

Throttle 1/4" open, mixture lean, no pumps - crank until it fires then smoothly advance the mixture and it should pick up fine.

It may run like a rough old jalopy though because there is vapor around and it just needs ingesting. A blip with the pump may help, but it isn't recirculating anything, it is just pumping into the motor.

It is normal for the motor to run rough - surging and dying for a couple of minutes, particularly on a hot day. Once you open up to significant fuel flow on take off, it will be fine.

If you Airflow Performance, then there are differences and you need to refer to their operating instructions.

Hope that helps.

[skylor]

Originally Posted by boomer

When it was new, I had quite a bit of trouble with hot starting my stock IO-360-M1B. Turned out it was all my technique (or lack thereof). I finally called Lycoming tech support and talked to the guy that did the engine run in's. He said that he had started many hot IO's with no problem, using the following technique:

Before you start open the throttle and mixture for a few minutes, generally long enough to do your walk around. The do a normal start (throttle 1/4, mixture idle cutoff) with no priming. Slowly advance the mixture when it the engine fires. Takes a few extra turns than a cold start but works for me.

-John

PLEASE, PLEASE, PLEASE be darn careful about doing your walk around with the throttle and mixture set to full!!

Skylor
RV-8

[Glas467]

Interesting comment about talking to a Lycoming rep ... I did the same thing at Oshkosh many years ago and got another (safer, IMHO) technique that works perfect for me every time with my IO-360B1E:

1. Before shutdown, run engine at 1500 RPM for 1 minute with mixture leaned for max RPM.
2. Next, reduce throttle to 1000 RPM for about 10 seconds.
3. Pull mixture to idle cutoff to shutdown engine. Leave throtttle in the position from step 2.
4. For hot start, do not move the throttle or mixture from the positions in step 3 and do not prime the engine or use boost pump.
5. Turn over the engine with starter as normal, when the engine first fires move mixture to rich and turn on boost pump.

With this technique my hot start IO-360 fires on the 3rd or 4th blade every time.

Reggie