Engine problems in hot weather M20K 252

[N252CG]

I have an 1986 M20K 252 and pretty proud of it.

 

But I do have a problem with the engine that I can by now almost predict on hot days.

 

After the plane has sat all day in the sun it will start up very nicely but when applying take-off power the engine will quit.

If I put on the low boost pump it will not quit and continue running.

 

Mostly in the flight levels above 100 and some cooling it will operate with the low boost pump off but I have had one flight lately where it would start to run rough and stop if not re-engaging the low boost pump (maybe not enough cooling time). Next morning and with cooler temperatures normal operation. This happens with outside temperatures above 90°F (33°C). This is clearly temperature related.

 

First I suspected vapor lock but now I am not so sure about this since vapor locking should terminate once it has been pushed out of the system once.

The fuel pump has recently been revised but I still suspect some problem with fuel pressure or maybe an air leak somewhere in the system (there is no fuel leak noticeable though). The maintenance shop believes it might have something to do with the fuel selector valve.

 

Any ideas on how to proceed with troubleshooting?

[jackn]

Just guessing, but you mentioned the Fuel pump was repaired. The symptoms you report  would be consistant with a loose/leaking MP connection to the fuel pump.

[Earl]

I also have an 86 252 and have never had that problem but it would bother me no end and I probably wouldn't fly the plane until it was fixed.  To me it sounds like a problem with the fuel pump but what do I know.  My mechanical expertise is limited to watching them work and writing checks.......although I do sometimes use a credit card........just to keep it interesting.  

[Earl]

Just guessing, but you mentioned the Fuel pump was repaired. The symptoms you report  would be consistant with a loose/leaking MP connection to the fuel pump.

Jack:  How do you like your Encore conversion?  I exchanged emails with Parker when he had his done and I have been considering it and then something comes up that takes away the disposable income I would use for the conversion.  Who did yours, when and do you know about how much it cost?  Sorry to hijack the thread.......

[jackn]

Earl,

I'm very happy with my plane. There is really nothing out there that fits my mission better. From April - November, my flights are local or generally within 200 nm. So I throttle back, train & just enjoy. Dec - March I fly out to CO and fly the Rockies. I bought mine already coverted. I would not spend the time and money to convert the MB to an SB engine unless the MB was shot. If you do, I would(and did) install a certified JPI 930(or similar), since you need new MP and RPM anyway. I added TKS anti-ice as well. The added 10hp seems to balance out the performance lost on this. I also have extended tanks. I feel these upgrades (TKS, Extended tanks, and 930) should come first, although the extra 10hp helps.

[FlyDave]

N252CG - did you get this resolved?