Looking for advice. Purchased my Maule MXT-7-180A back in February. Had no issues with starting or re-starting. Now that temps have gotten into the upper 90's - 100's in Texas, it starts fine on the initial start. However, when I try and restart after a flight or trip to the fuel pump, it is almost impossible to start. Even waiting an hour or so after the initial run it still won't start easily (if at all).

I've tried not priming, various mixture and throttle positions to no avail. The prop will turn over and cough but never catch. Again, this wasn't an issue until the temps really heated up here. I've had many different aircraft in the past (never a Lyc o-360) but never had this problem before.

Any suggestions?

I had an Aeronca 15AC with an O-360-A1A, and had trouble with hot starts after I started flying it. What ended up working was to set the throttle to full, mixture to full lean and hit the starter. Once it caught, which happened fairly quickly, I'd run the mixture to full rich and pull the throttle to idle.

It took trial and error to come up with this, but nothing else seemed to work, except letting it cool down.

Good luck with yours.

My Lycoming O-360-C1F starts more easily when it's hot than when it's cold. Fuel is easier to atomize in hot weather, which helps carbureted engines. Have you tried using your electric boost pump during hot starts to increase fuel pressure? What about pulling a plug and examining the electrodes for excessive carbon? Have you checked magneto timing? Does the engine backfire when it eventually starts? Carburetor adjustment?

Setting throttle to full and mixture lean as Newton mentioned will evaporate excess fuel quicker, if that's the problem.

If you eliminate all the other possibilities, a component may be malfunctioning due to high temperature, such as a magneto.

I think Andy might be on to something. The hot weather and hard starting might be a coincidence. How much time since overhaul on your slick mags, if its 500 or more it's time to send them out. I had an MXT 180A and almost like clockwork I would get hard starting at the 500hr point on my mags, once overhauled the problem went away.

I have the same plane and I'm thinking mags. Timing or something else. I don't know why it would be different hot but easy and important to check. Mine is always quicker to light when warm or hot.

Do you have an engine analyzer? If so you could compare EGTs on mag check.

When were the mags last overhauled. A good mag check when running does not necessarily mean that they will start well.

Thought I'd follow up with the cure. My A&P diagnosed it pretty quickly - gaps on half of the plugs were way too wide. Adjusted the gap and now no trouble starting.

My MX-7-180 just finished its annual and the A&P re-gapped the plugs with a slightly smaller gap. It starts much easier now. Over time the electrode material wears away so maybe that's why the gaps were too large.

I was having problems starting my o540. Replaced both slick mags with impulse mags. Best money I have spent starts every time one or two blades.