M20 cranking too long!

Fri Jun 29, 2012 10:52 pm

My M20 used to start like a dream and now it's awful, almost twice a day when engine is cold it cranks for about 4-5 seconds.
I need something to start with since I don't know what can be the problem?
Sometimes during the cranking if I let the hand of the key it starts by itself, but pretty roughly

Sat Jun 30, 2012 2:09 am

Reads like lack of fuel or fuel pressure to me,so you are looking for a possible poor seal to an injector,or a failing FPR or seal. Injectortune in the UK repair and service injectors,I expect that the postage cost for you is a little high,but I expect that you will be able to find a local guy who can sort the injectors for you.

Sat Jun 30, 2012 7:32 am

daimlerman wrote:Reads like lack of fuel or fuel pressure to me,so you are looking for a possible poor seal to an injector,or a failing FPR or seal. Injectortune in the UK repair and service injectors,I expect that the postage cost for you is a little high,but I expect that you will be able to find a local guy who can sort the injectors for you.

already done that. Injectors are fine

Sat Jun 30, 2012 7:59 am

As daimlerman says, fuel pressure is the most likely cause, but you really need to get a pressure meter on the system to make sure the supply is alright. A failing pump, a broken FPR, a blocked fuel filter, holes in the pipework (even micro-splits at the end of the rubber lines) can cause the fuel pressure to drop over time, meaning the system has to charge up when cold.

Sat Jun 30, 2012 8:19 am

Could also be fuel leaking form the injectors into the cylinder and wetting the plugs. Worn stem seals or worn rings. Small airleak around the inlet side can also cause this.

Get searching all simple tests.

Sat Jun 30, 2012 9:48 am

I hunted and sorted all vacuum leaks, tested with carb cleaner..seems fine now but I can't guarantee it still leaks a little somewhere.
Fuel pressure will be checked, and rubber hoses are replaced last year, also fuel filter last summer

But weird thing is if I let the key during cranking it will fire, it cranks fine from first and then starts choking
like in this vid

Sat Jun 30, 2012 6:40 pm

Have you checked to see if your plugs are getting wet?

Get a cylinder leak test done.

Sat Jun 30, 2012 8:19 pm

Worn ignition/barrel mechanism possibly ?

Sat Jun 30, 2012 10:28 pm

Check that 12 power is maintained at the + terminal of the coil while cranking. A faulty ignition switch can sometimes disconnect the ignition feed when turned to the start position.