DirkSx1

My 951 has decided to become difficult to start. Everything was fine and then one morning the engine decided it would now take at least 3-4 tries to start when engine is cold. Even when starting to catch, it was decidedly uneven. Once it is hot, starts 1st time, every time. Other than that, car runs just fine and in fact just finished a track day where performance was perfect. Being old school this suggests that the choke is not working.

MY question: Is this a problem with the throttle valve switch not working properly or should I be looking elsewhere, E.g. the temperature sensor?

mahoney944

DME temp sensor. Easy and cheap to try. Also if you use a thick oil in a colder climate the oil can thicken adding strain to the crank.

gruhsy

Im gonna go with DME temp sensor for first pic

shortyboy

If you give it gas while cranking will it start properly? then die when you let off the gas?If so could be the Idle Stabilizer Valve ( ISV ). If not check the DME temp sensor on the block.

Baptizo

Mine has been doing this as of late too.....stupid question for the day....where is the DME temp sensor located on the block?

Sixline

It is right on the front of the block. Clark's Garage has a picture.

http://www.clarks-garage.com/shop-manual/elect-19.htm

Baptizo

Thank you!

blown 944

It may also be the fuel pump check valve.

Usually when the DME temp sensor fails, the car run horribly rich.

DirkSx1

Thanks guy for the inputs.

Can't be the fuel pump check valve, in my car as it has been eliminated to increase fuel flow> Removing it has never presented a problem over the last 2-3 years. Yes I use 20-50W oil but again it has never been a problem before. If I am not mistaken the 951 does not have Idle Stabilizer Valve ( ISV ), is this not correct?? Fuel / air ratio looks OK when it warms up, not running richer than usual.

Yes to one of the questions, if I give it some gas it seems to help getting it started but will die if to much gas is given. Its seems to require gas but only a very little bit but it is still hard to start. But requires a couple of tries before it start haltingly and then it seems to clear its throat and starts to run properly.

I will definitively check the DME temp sensor. If can anything else let me know.