D_jet trouble shooting question - car is home, journey continues, June, update- no more problem-- the fix was simple.... Options

[DRPHIL914]

OK. car has been in shop for the past week, and today Bob spent several hours on it but what he found was when the MPS is disconnected from the vac hose it will idle and run, but when it gets connected it goes immediately lean and dies, and will not run with that hose on there- the MPS holds Vac no loss of pressure, but that doesnt mean that its not bad.
1- i thought that if an MPS went bad it defaulted rich? but when this is getting vac it goes lean right away and dies. but it will run and idle with out the vac , the AF meter then shows 9.8-10.2 or so which is of course rich but not flooding out.

so the question is why is it going lean when hooked up? when this issue started about 2 weeks ago, it had been running just fine and all of a sudden it quit running.

2. could there be another issue we dont see that would be making it way to lean other than the MPS?

might need to test another MPS, my 2nd one i just bought from someone here and it has never been opened but will not hold vac (slowly looses vac pressure) so it probably need to be opened and re-sealed. not a good candidate to trouble shoot with. ------

FYI- 1975 d-jet 2.0. newer wiring harness , CHT is newish(replaced 2 months before this issue started and was running perfect at that time)

[DRPHIL914]

started this morning- so i drove it to work!(25 miles each way), as long as the rain stays away im going to driv it to work aleast 3x a week until it decides not to start or gives me fits. going to keep fiddling around until i figure out what the issue is.
so far since installing the tuna can and the nwe oil temp sensor and taco plate no leaks - but the VDO sender and the nitrous gauge seem to work fine together,- temp gauge reads almost exactly waht the dips stick thermometer reads.
seems like this car still runs a bit hot. The air guides for under the car are not there. timing and advance are right on, not running lean. Does not go into dangerous levels but seems like at 50 degrees it would not go over 210 and after running for 30 minutes , under more load that temp will go up to the 230 - 235 range. (IMG:style_emoticons/default/confused24.gif)