Engine runs fine but hard to start

[thistle3585]

Just rebuilt my MC2100. It idles fine, accelerates fine and really haven't any performance issues but I'm having trouble getting it started. Fuel pressure is 5-6 psi. Electrical is fine. It acts as if it isn't getting any gas. If I pump the pedal once it might fire and die. I have to pump it a couple times to get it going, rev it up then its fine. It seems a little worse after I have driven it, shut it off then try to restart it. I have been messing with the mixture screws as I felt like it was running lean, but have tuned it like the instructions. As I said, once its going it runs great. It did not do this before the rebuild. Also, trying to be a descriptive as possible, it seems to start after I let off the key but wont start while cranking. I'm not sure if I'm imaging something since I'm trying to diagnosis it.

Did a little bit of research on vapor lock. I recently replaced my air cleaner with a new one that did not have a snorkel on it. I also reran my fuel lines in the engine compartment because they were close to the exhaust. Since it is doing this with the engine cold would that eliminate vapor lock as the problem?

 

[Torxhead]

Do your starting problems occur after sitting overnite or so? I'm thinking either the accelerator pump has a leak or the fuel is evaporating out of the float bowl. Check for the squirt from manually operating the pump prior to a startup.

 

[harleydragon]

Do your starting problems occur after sitting overnite or so? I'm thinking either the accelerator pump has a leak or the fuel is evaporating out of the float bowl. Check for the squirt from manually operating the pump prior to a startup.

agreed..if you have fuel in the bowl then usually hard starting can be attributed to bad accelerator pump,choke not working,timing off or vacuum leak..since yours idles fine,that probably rules out the vacuum leak..take the breather off and see if the choke is working and if by working the throttle by hand,with the engine off,the accelerator pump is shooting good streams of gas

 

[priceg]

Which choke does it have?

 

[thistle3585]

It happens cold or hot and worse hot which led me to think it was vapor lock. I just put a manual choke on but it was doing it before I hooked it up. I was hoping that would solve the problem. It is also worse when the choke is on. Would a new air cleaner cause it? I'll check the accelerator pump.

 

[mtnwhlr]

You might what to check that the float is at the right height and not sticking.

 

[hdgapeach]

I was first thinking choke problems, and really, it still may be. The choke can cause problems with the engine hot or cold.

Then I caught the "...it seems to start after I let off the key but wont start while cranking." and that makes me wonder about the ignition. I had the same happen to me once and I can't remember if it ended up being the ignition switch or something else.

Sounds like you ought to start at the carb, troubleshoot from A-Z and verify settings, check vacuum problems and then, when you're sure you've eliminated those possibilities, if you still have the same issue, might want to move to the ignition. This is one of those problems that would be a bunch easier to figure out by getting hands on rather than commenting on the board.

Good luck!