944 hard start-no start
 

Ok so this is my story..
I have an 86 944 NA that refuses to start right more then 3 days a week.. Engine gets warm,shut the car off,won't start.. If it sits for more then 2 minutes after warming up it won't start 80% of the time,if it sits in the sun all day but engine is warm or cold 75% it won't start.. I want to check my DME and coolant sensors but don't know how,I have looked at clark's garage but doesn't make any sence to me.. Can't I just check the sensors with an ohm meter?? It talks about some Variable Resistance Potentiometer to test with and I have no idea what that is,where to get one or how to use it,can't I just use an ohm meter to test the dme and coolant sensors??? Can someone please dummy this down some so it can be understood?? This has been an ongoing issue for 11 years and counting,getting a little tired:confused: The more I try to troubleshoot and try to understand,the more I get confused and don't have a clue what to do with this car.. I have been working on cars for more then 20 years fixing my own stuff and this car has me to the piont I feel as if I at square one starting over....... Anyone could give some pointers as to what and how to check the sensors would be great..

so what is it doing when it won't start - cranking? If not, what kind of noise you get? more info would be helpful
dave

Yeah sorry about the details..
The car always cranks,tach bounces when cranking,I'm getting power to the coil keyed up-start mode and running on both + and - when it does start so I know I'm good at least to the coil.. I carry four extra DME relays with me and if one works they all work,if none works then none work.. New plugs,wires,cap and rotor are in good shape.. The car seems to really have an issue anything above 60 degrees outside or more,the hotter it is outside the harder it is to start,5% of the time it is hard to start engine cold,50% it is hard to start after running until warm or sitting in the sun all day.. It also has a bad miss when (engine cold) until it warms up it misses if it's 10 below 0 or 100 outside until warms up some.. I did find out my check valve to keep pressure on the gas line was sticking so got that freed up and the very next morning was hard to start.. I did check my ohms on my DME sensor it was between 2500-3400 ohms cold and 280-340 hot,not sure if that's within reason or not.. Didn't check my temp sensor yet as I just want to eliminate one thing at a time before moving on.. Basically it seems to be temperature related I just can't figure out if it's engine temp or outside temp.. It hasn't been much above 65 degrees since fixing the check valve but it does hold pressure now,it didn't before but still has the issue of cold starts and misses when cold..... I'm sure there is more details but my mind is pretty much blank right now.....