Alright fellow Maulers,

97' MX-7-180C
LYC O-360-C1F (carbureted)


I just bought the aircraft in July so its been warm out every time I've started it the first engine start of the day. Here within we'll refer to this as "cold start". Never had a starting problem. The last 2 times I've flown it have been in the early morning with ambient temperature around 45 degrees. I know this is not "cold" by any means and I believe the engine should start normally at this temperature. When the outside temperature is warm(er) it starts beautifully within 3-5 seconds of spinning the starter. (it will at least begin to fire a cylinder or 2 and then the remaining cylinders catch up very quickly) with this starting sequence

Ambient temp: WARM Engine: cold start

mixture: full rich
throttle: cracked 1/4"
prime: 3 "shots" (I do not count the 1st shot of prime until I can feel the primer is completely full of fuel and I'm actually injecting fuel)
Boost pump: Not used at all in the sequence
starter in left hand, throttle in right. hold throttle 1/4" until engine fires within 3-5 seconds
*voila* .... engine is happy!
every start after that on the same day, I start without prime and it comes to life quickly

NOW.....

With the colder ambient temps: I believe I need more fuel (colder air=more dense=more fuel for rich mixture required on startup so I add more prime)

Mixture: Full rich
Throttle: 1/4"
Prime 5-6 shots (again I don't count until I feel fuel pressure in the primer)
Boost pump: No
Starter in left hand, Throttle in right
Starter: engage for 10-12 seconds *no fire, hiccup, burp, nothing*

Prime: 5-10 more shots
Starter: engage 10-15 seconds *nothing again*

fuel slightly running/dripping out overflow
(I think - may be flooded)

Mixture: full lean
Throttle: full open
Starter: engage 10-15 seconds to clear in case of flooded cylinders *still no fire, hiccup, burp,nothing*

Mixture: full rich
Throttle: pump 3-10 times then 1/4" to 3/4"
Starter: engage 10-15 seconds
Throttle: pumping then full then pumping
Mixture: various
Pilot: cussing
get out, check around engine, move airplane because of leaked fuel under cowling and let starter cool for 5-10 minutes.

Mixture: full rich
Starter: engage 10-15 seconds
Throttle: pump the ever living $#!T out of it
Mixture: in and out
Throttle: pump more then open, then close, the pumping
Boost pump: on, watch fuel pressure rise, then off
Engine: spinning, no fire
Pilot: cussing more
Starter: engage 10-15 more secs
Throttle: pumping
Fuel pressure falling while pumping throttle
Engine: cough, hiccup, blip, blip, pip, pop, (still spinning starter) cough, cough, cough, cough.......coaxing mixture and throttle and finally boom boom boom, we're running and happy!!!
Every start of the day afterwards (even if its been sitting for a few hours) is no problem at all. May require 1-2 shots of prime if any at all.

What I've considered:
- Battery level: I've tried it with and without a jumper pack - it spins over strong with and without the jumper pack.
- Mixture adjustment: I have plenty of mixture travel - lean to rich - and mixture cutoff works well ( I get 3-4 seconds of engine run, after pulling mixture to shut down engine, then it dead cuts - No dieseling)
- Not enough prime (but it starts running out the overflow shortly after starting the 1st or 2nd try)
- Too much prime (the last time I tried to start it the 1st attempt, I started off with no prime at all - No avail)
- Prime not getting to the engine; I haven't checked the lines from the primer but It seems to be working on warm days/cold start and fuel runs out of the carb overflow after a bit of starting on cold days/cold starts. I don't see fuel leaking anywhere else
- Flooded engine: I have cleared it several times via the LYCOMING manual suggested method
- Fouled plugs; I haven't pulled them out yet but my mag drops are impeccable and I have no rough running issues
- Engine preheater; I don't have one and I don't have electricity at my hanger
- Every engine has a "starting combination" that it likes and maybe I haven't found this one's yet
- I'm used to a injected Lyc AEIO-320 and I don't know if I should be using the electric boost fuel pump in the starting sequence anywhere ( I know injected engines cold start better than carb'd ones but this is boarder line crazy
- I can't keep doing this without having a sponsor to buy be new starters all winter long

What am I doing wrong?????

Any help or advice or suggestions or voodoo or séance would be greatly appreciated

That’s a familiar story. I have a fixed pitch with similar problems when it’s cold. Pretty sure I’ve used the same technique (complete with the requisite amount of swearing). I’ve not yet found the sweet spot when she’s cold iron. Previous owner thought I was crazy for using six shots of prime when it’s cold. I may try one more for good measure next time. It’s getting cold here, so the opportunity is upon me.

Cold day first starts - full rich, three “fully engagedâ€￾ primes followed by two full throttle pumps back to 1/2â€￾ before turning engine over usually works for me. Pre-heat is your friend but I understand your limitations. Two throttle pumps for all starts after that on same day.
Warm day first starts - no prime just two throttle pumps.

First we should define "priming". If you mean by priming you're using the primer located on the IP by the pilot's yoke; OK. If priming is done with the accelerator pump via the throttle; NO.

The danger in using the throttle as a primer is that the fuel can leak back and cause a fire. ONLY use this when the engine is spinning if you absolutely must.

The primer, on the other hand, squirts fuel directly into the intake ports of two cylinders. This is a much safer means of priming. And if you are overzealous with priming, you have only flooded two cylinders instead of all of them.

Try using the primer only as the engine is cranking; remember that you starved the engine for fuel at shut down ergo the induction system is void of fuel. Once you get a kick from one or both primed cylinders, stop priming and lock the primer. The engine should have fired with enough momentum to allow induction currents to draw fuel to the remaining unprimed cylinders and they will catch up quickly.

Cold fuel doesn't atomize well and so extra fuel is needed to provide a combustible mixture. But the caveat is it is also an environment where you can quickly flood it as the fuel just wets things down. That threshold is a very thin line, so be conservative and give it only what it takes to fire.

I have never used more than about 3 squirts from the primer while cranking (I never prime with a still engine) and have operated down to 18ºF. Try this and see if it helps.

I had the same problem with my MX7-160. After having the 500 hour inspection completed on the mags and properly setting the idle RPM and mixture the engine now easily starts. The Slick mags have a weak spark at best. If not properly maintained and internally timed they will not produce a hot enough spark for good starting.

DeltaRomeo wrote:Try using the primer only as the engine is cranking; remember that you starved the engine for fuel at shut down ergo the induction system is void of fuel. Once you get a kick from one or both primed cylinders, stop priming and lock the primer. The engine should have fired with enough momentum to allow induction currents to draw fuel to the remaining unprimed cylinders and they will catch up quickly as you continue to crank. Once the engine has fired with enough speed to disengage the starter drive, release the key and it should sputter along until stable.

Cold fuel doesn't atomize well and so extra fuel is needed to provide a combustible mixture. But the caveat is it is also an environment where you can quickly flood it as the fuel just wets things down. That threshold is a very thin line, so be conservative and give it only what it takes to fire.

There's a good rub your belly and pat your head operation. It works well, though. On the C-140 I flew before buying the Maule, I was able to turn the engine over with the mags off. So give it the prime it needed, then pull the starter handle with the mags off for a few blades to get things flowing through the system. Then I'd turn on the mags and pull the starter handle and it would start right up. I'd love to be able to do the same on my Maule.

BamaMaule wrote:Cold day first starts - full rich, three “fully engagedâ€￾ primes followed by two full throttle pumps back to 1/2â€￾ before turning engine over usually works for me. Pre-heat is your friend but I understand your limitations. Two throttle pumps for all starts after that on same day.
Warm day first starts - no prime just two throttle pumps.

Thanks Greg, I'll give that a try. I'll try just about anything at this point to keep from burning up a starter. You guys that have been through several years with your Maules have some good "tried and true" methods that I haven't learned just yet.

DeltaRomeo wrote:First we should define "priming". If you mean by priming you're using the primer located on the IP by the pilot's yoke; OK. If priming is done with the accelerator pump via the throttle; NO..

When I say prime, I'm referring to the actual primer on the IP left of the pilots yoke. Pumping the throttle comes purely out of desperation after a few unsuccessful starting attempts.

DeltaRomeo wrote:Try using the primer only as the engine is cranking; remember that you starved the engine for fuel at shut down ergo the induction system is void of fuel. Once you get a kick from one or both primed cylinders, stop priming and lock the primer.

Thank you DR. I haven't thought to try to use the primer while starting. Mostly because the starter is in my left hand already but I'm going to switch that and give that a try next time.

CaseyM wrote:Thank you DR. I haven't thought to try to use the primer while starting. Mostly because the starter is in my left hand already but I'm going to switch that and give that a try next time.

That's what I'm thinking about, too. I usually have my left hand on the key and right hand on the throttle so I can catch it if it starts up at higher RPM than I thought it would. Sure would help to be an octopus during this event.

montana maule wrote:I had the same problem with my MX7-160. After having the 500 hour inspection completed on the mags and properly setting the idle RPM and mixture the engine now easily starts. The Slick mags have a weak spark at best. If not properly maintained and internally timed they will not produce a hot enough spark for good starting.

Thanks for the advice. I try to always run slightly ROP so I'm sure my plugs are not squeaky clean an could use a cleaning/replacement but I'm just boggled because it starts so well with warmer ambient temperatures. I had the idle and mixture adjusted 2 weeks after I bought it for dieseling on shutdown and super low idle but its been flawless ever since. I will have the mags checked and tested soon, especially if I can't get this figured out on technique alone.

Chris in Milwaukee wrote:That's what I'm thinking about, too. I usually have my left hand on the key and right hand on the throttle so I can catch it if it starts up at higher RPM than I thought it would. Sure would help to be an octopus during this event.

Haha, It would, wouldn't it! I may have to have someone else hold the starter switch while l attempt to be a pianist playing the instruments of my starting sequence... I now have more respect for Harry Houdini's diligent hands during "crunch time"

I give my O-360-C1F three good primes and set throttle almost full idle. No throttle pumping. For warm or hot starts, I give one prime. Hot or cold, it sually fires after the second or third compression stroke.

But each engine is different, so this may be something you just have to experiment with.

I had a lot of trouble with cold starts until (in desperation) I changed the lower plugs to fine wire. After that, no problem, but it could also be coincidence or that I suddenly found the right technique.

Thanks for the input Njacko, I want mine to start that well in the cooler weather and believe it will once I get it right.

I had to start mine up on Friday morning from cold iron at 22F (because I didn't get over to plug it in the night before). Dave's primer technique actually worked pretty well. I had to finesse it a bit, because I wasn't sure how it was going to react. But I did get it started in fewer evolutions than I had in past days when trying to start it cold.

The 180 bucks like a frikkin' bronco until it gets fuel flowing (and igniting) in all cylinders. Must have been running on two cylinders for a bit until things finally caught up.

Definitely going to keep this technique in mind for future adventures.

I did not have the time to read this whole thread but I had my primer system changed so that all 4 cylinders get primed. Cold starts (Preheated below 40*) are OK now. For some reason these engines never light as fast as a fuel injected motor when cold.

+1 on the mag suggestions. Confounded barbaric things.