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Engine Keeps Wanting To Die

jmbrwn

jmbrwn

Well Known Member
I have a buddy with an RV6A with O320 carbed 160hp. For about the last year, every time he lands, after touchdown the engine keeps wanting to die. He has to pump the throttle to above 1200rpm to keep the motor running....not good on our 2200' grass strip. He runs 100LL and this happens with the engine hot or cold. Both hard surface and grass strips. The engine idles at 700rpm. Other than that, the engine runs great. Today though, he said he couldn't get the engine shut off with the mixture...had to cut ignition off to shut down engine??? Any ideas???
 
Try landing with the electric (aux) fuel pump off and see if it still wants to die on touchdown. It sounds like the engine is getting too much fuel. I have had the same problem and it turned out to be a faulty engine driven fuel pump. It did not keep a steady pressure from the engine driven pump to the carb with the electric fuel pump on. Result was an overfilled carb killing the engine..
Mine ran fine with the elctric pump turned OFF but died with the pump ON which had me puzzled and dazzeled since one expects the opposite....

Do you have a fuel pressure gauge ?
 
Sounds like the float level is too high, sinking float syndrome, or leaking float needle valve.

Roberta
 
Thanks for the replies, guys. We've looked at his idle mixture and it idles at 700rpm. I suggested he lean the mixure on final to see if it helped, but yesterday it did the same thing. We'll try turning off the electric fuel pump on landing next. Thanks for the suggestions.
 
Just a idle thought here on trying a landing with the electric pump off with his issues. Perhaps do it at altitude first in landing configuration/speed/descent etc just to make sure that the engine does not die at low altitude.

PS. Considering the runway length, do it over an airport with a longer runway in case a deadstick landing is required. Know the in air restart method before trying it.
 
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I had this happen with my carbed O-320 recently... But it was before takeoff. Wanted to quit at idle, and bounced around from 1000-1400 when I tried to set it at 1200. Oddly enough, turning the fuel pump on seemed to clear it enough to fly the 10 minutes back to my home airport where I pulled the lower cowl and plugs... Where I found nice big lumps of lead between the ceramic and the shell on 3/4 plugs.

After cleaning the lead out with a dental pick, the problem has gone away. I'll be checking those at each oil change now instead of just at annual.
 
If it has a hand primer system on it I would check and make sure its locked closed. If it has elec primer I'd check for broken lines or drawing fuel. Just an idea if everything else fails.
Shine'r
 
Rob, consider substantive leaning while on the ground. Reset proper mixture setting during the runup.
 
Ron Lee said:
Just a idle thought here on trying a landing with the electric pump off with his issues. Perhaps do it at altitude first in landing configuration/speed/descent etc just to make sure that the engine does not die at low altitude.
Click to expand...

Oh yes, never switch off common sense and sound judgment.. :):)
 
May seem strange but

Check the carb mounting gasket.
Had an engine a few years ago that did the same thing and a leak was found in the gasket. Every time the engine was set to idle after running it died. Found it by spraying a little DW-40 around the gasket while it was running and the engine speeded up when the leak was hit by the spray.
This may seem a little strange but I couldn't figure out the problem till an old hanger bum told me to try it and by gosh he was right.;)
 
A thought

This may be the key to the issue,

jmbrwn said:
Today though, he said he couldn't get the engine shut off with the mixture...had to cut ignition off to shut down engine??? Any ideas???
Click to expand...

As Roberta said, a float or needle valve issue. A little shot of really rich mixture, in a hot engine, at idle, will most certainly cause it to quit. The question I would ask is what happens on the restart? Does it fire right up or does it crank some on restart? Is there any sign of black smoke when started after quiting?

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
He told me yesterday that on the times that the engine died after landing, he had a hard time restarting it. Thanks for all the good brain-crunching, guys. I'll write all this down and pass it along to him.
 
Eratic engine

Had the same problem, in my case caused by two things. Carburetter butterfly bush was worn, needed new kit to fix. Also checked jet & seats to ensure not worn. Other problem was some leaking/bypass of primer. Repaired carburetter and replaced primer gakets. All works well now.
 
After reading more posts, instead of checking to see if the engine dies under certain approach to landing conditions, it is probably better to ground it and find the problem.
 
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