Another AFP vs. Precision Question

stickandrudder1 · #1 10-08-2009, 05:42 PM

I like the idea of the AFP FI system because of the purge valve, an option that is designed to facilitate hot starts. However, I've been told by someone who I would consider to be knowledgable on the subject, who said that hotstarts with the Precision are not really an issue, due to the state of the art, and the quality of the entire system. Also that the Precision system is much more common and would be more familiar to your average A&P. I'm interested in what the real world experience has been. Are hot starts a problem with the Precision FI system? If you've put in a Precision, would you go with the AFP if you had it to do over again? Finally, any comments good or bad on each company's customer service?

Thanks

Jamie · #2 10-08-2009, 05:59 PM

I have the Precision FI and have no problems at all with hot starting here in Georgia in three summers of flying. I would not let the existence of a purge valve be a deciding factor in your decision.

My Superior manual contained the following hot start procedure that works like a charm.

1) NO prime.
2) Throttle full open.
3) Mixture full rich.
4) Throttle closed.
5) Mixture ICO
6) Throttle cracked 1/4 of an inch.
7) Engage starter.
8) When engine fires, bring in mixture.

I never sweat having to hot start my RV. I have yet to see a need for a purge valve. I understand the concept and the theory but for me it's just another potential failure point the fuel system.

No regrets at all with my decision. I would install a PA FI system on my next RV.

Hope that helps,
Jamie

airguy · #3 10-08-2009, 06:13 PM

Not to sway your decision - but in the (granted, relatively unlikely, but extremely ugly) chance of a vapor lock scenario on approach, you have the additional tool of the purge valve to flush fuel through the pump, delivery lines, and injector body for a few seconds to purge the vapor bubble and regain power.

I'll be using wing-root electric pumps so that won't be an issue. Just sayin'...

Bubblehead · #4 10-08-2009, 10:14 PM

I don't have the purge system and once I learned the right procedure I've not had any trouble in almost 200 hours of flying.

I DO prime the engine a little when hot, then move the mixture control to idle cut-off and leave the throttle wide open. Crank it over and when it fires move the throttle back to about 1/3 throttle and then slowly move the mixture control back to rich.

DanH · #5 10-09-2009, 06:39 AM

If I had a Bendix or Precision system and it needed service, I'd send it to Airflow.

As for the purge valve, Don just announced the availability of a new no-purge AFP system.

Don at Airflow · #6 10-09-2009, 08:34 AM

Yea, I bet Precision won't flow test your air box designs for free

BTW Dan, 2nd design A OK. Report on the way.

Don

DanH · #7 10-09-2009, 08:55 AM

Quote:

Originally Posted by Don at Airflow

Yea, I bet Precision won't flow test your air box designs for free

That's for sure, but I was thinking more about the new Precision carb I pulled apart for leaking at the body joint. Significant machining error; it went back to them and came back uncorrected. 'Nuff said.

Dogtail2 · #8 10-21-2009, 06:10 AM

Until someone from Precision Airmotive finds this site and logs on, the outcome of any debate re AFP versus Precision, will inevitably be somewhat biased in favour of AFP.

hydroguy2 · #9 10-21-2009, 08:01 AM

Quote:

Originally Posted by Dogtail2

Until someone from Precision Airmotive finds this site and logs on, the outcome of any debate re AFP versus Precision, will inevitably be somewhat biased in favour of AFP.

Both good products, but yes the balance will tilt in favor for the company that has better customer service.

Bubblehead · #10 10-21-2009, 08:26 AM

Don at Airflow has always been helpful by phone and email and always quick to provide information. I'm very satisfied with their product too. I have not dealt with the other guys so cannot comment, but I don't see how they could be any better than Airflow.