running rough? lean?, suggestions or answers? Options

[mipstien]

ok so i get my haynes manual soon and i have been searching but don't have all the information in the same place and i also don't know all of the shorthands yet. AAR CHTS etc etc. which brings me to my question

tomorrow i will have a fuel pressure tester and need to know what all the different pressure's need to be at all the spots.

basically if we give it extra fuel at the intake it idles fine and as soon as you stop and the fuel runs out from there it goes back to really rough again. we have a handful of other things to check also so any suggestions?

one other thing that makes me think its running lean is when i rev the car and hold the peddle in one place it begins to drop revs unless we add our own fuel into the intake. once we add fuel the car runs very smooth.

so any ideas and fuel pressure numbers and where to check it?
thanks
ryan

PS- its a 75 2.0l

[realred914]

ok it is a D-jet 2.0 liter he says it runs lean, could be several things


lets check.

fuel pressure should be about 28-29 psi measure it at one of the two fuel rails, there should be a test port on one rail.


head temperature sendor (very likely culprit) this is near cylnder #3 it changes ohms when it heats up, and command the computer (brain) to give more fuel when cold, less when hot. if you remove the wire to it, you may then ohm test it to ground (ohm test the pig tail wire to the sendor, NOT the wire that goes back to the brain!!!!!) cold, the head temp sendor should be a couple thousand ohms, when fully warmed up, it should be less than 100 ohms. also wiggle the wire vigrusly when you do the test, often the wire breaks, or the insulation tears and you get intermittant opens or shorts. if you got an open, the system will give too much fuel and flood, if you got a short, the system will not give enough fuel to keep her running while cold.

Trigger points, these are under the distributor and are a pair of points, they trigger the injection pulses. there is a three wire connector that goes to them on the dizzie base, make sure the wires is good. the points are hard to test, pull the dizzie and by rotating and with an ohm meter you should be able to tell if they make contact of not. they can fail by being dirty and not making contact (no fuel then) or they can have a worn lifter and that will cuase them to not open far enought and hence bouncem, thus givving multible trigger pulses and hence too much fuel (rich running)

the pressure sendor n make sure it is wired intact (inspect the plug carfully for torn wires) make sure the vacuum hose to the sendor is leak free, and suck on the hose to make sure the sendor does not leak.


good luck my bet is ont he head temp sendor simply cuase I have found them to fail most often, so test that first it is also the eaisist to test of the bunch.


good luck!!! (IMG:style_emoticons/default/driving.gif) (IMG:style_emoticons/default/driving-girl.gif) (IMG:style_emoticons/default/chowtime.gif) (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/beer3.gif) (IMG:style_emoticons/default/beerchug.gif) (IMG:style_emoticons/default/beer.gif) (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/screwy.gif) (IMG:style_emoticons/default/smash.gif) (IMG:style_emoticons/default/sawzall-smiley.gif) (IMG:style_emoticons/default/santa_smiley.gif) (IMG:style_emoticons/default/icon8.gif)