89 302 efi mpi really hard to start/ will not idle

[Krafty]

89 302, new gas tank( hasn't run since putting in the new tank, only tried one time), new pumps,(both turning on) FPR is good,

will never start on its own, I have spray gas in the throttle body to get it to run. once it runs and dies it usually doesn't want to start again extra fuel or not. when it does run it will only run with the throttle open a bit otherwise it just sputters and dies.

im pretty much a carb guy, so I need to learn quickly

im hoping with the idle thing figured out it should help the starting to.

what do you guys think?

 

[BroncoJoe19]

First thing I'd suspect is a dirty IAC

What does the IAC do? How does it work?

http://www.fordfuelinjection.com/?p=39

Check and clean your IAC

http://www.ford-trucks.com/article/idx/8/1...er_IAC_Fix.html

Then pull diagnostic trouble codes.

How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway

Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more

 

[Krafty]

okay here is my problem. I checked the IAC and there were no electrical issues, and I cleaned it out and put it back together.

I decided I was going to swap out my plugs and wires, and when I tested the wire to my coil from the distributor, and found it had alot of resistance, so a new wire was in order.

tried starting the truck, no luck.

pulled a wire off a spark plug and ran one to a plug that was grounded on the engine.

No Spark I then pulled the wires off the front of the coil and tested the positive wire. with the key turned on it gets like 2 volts, I haven't had a chance to check it when the engine it turning over yet.

is that normal?

 

[Krafty]

hey sorry looks like I was testing the wrong wire going to the coil. here is my new predicament. the coil is getting juice, the coil is giving juice to the distributor, but the distributor is not sending any juice to the spark plugs.

what are the causes of that?

 

[Krafty]

cap and rotor?

 

[BroncoJoe19]

I think he means the the coil wire will spark, but that the plugs don't.

YEs could be cap and or rotor, OR the rotor may not be turning. Pull the cap, and crank it, see if the rotor turns.

 

[Krafty]

okay here is what i've got. new cap new rotor, new plugs new wires, new coil, power getting to the coil. but still no spark

***???

any other ideas?

 

[Krafty]

I've been checking over the manuals and I did a couple of the ground tests. According to the book and my results either the ground or TACH wire that goes to the ICM is faulty, or I need a new ICM.

how are those things to change? they are on the side of the distributor right?

 

[Krafty]

the ground wire goes to both the EEC and the ICM, but only the ICM completes the circuit by grounding on the distributor.

just so you know for later

 

[Krafty]

okay so I need some diagnostic help, i've been going through the haynes manual ignition system check. now I think I found my problem.

but first I need someone with a good running truck or bronco with the same setup as me, 87 to 89 302 with the TFI-IV ignition system, that utilizes the distributor mounter ICM.

please do this check with a multimeter, or volt meter for me and give me the number you get.

take the plug off the ICM on the distributor. with the key turned to the ON position check the voltage from pin 2 ( second from the bottom ) should be the green and yellow wire same that comes from the EEC and the coil.

and tell me what your voltage reading is.

thanks guys, and gals

 

[Krafty]

I have done all the tests in sequence and the only discrepancy is the voltage check to pin 2 ( tach ) that connects to the ignition control module, that gets its power from the EEC. I followed the wire all the way to the EEC and the discrepancy is still the same.

 

[Krafty]

the tests say that the voltage reading with the key on should be 90% of battery voltage so like 11.5 volts, I am getting 4 volts from the EEC

I am prepared to get my hands on one form a scrap yard provided that someone else is getting the 90% total voltage from that wire

 

[Krafty]

well its getting power from the eec like I said, and when I tested the wire I got a low reading, it was dim/ low voltage. it stayed on / did not flash

I am away for a couple of days so when I get back i'll recheck it again.

but I got a low voltage issue no matter where you look at it. after my coil it should have 120 000 volts + but its not making the voltage to create the spark.

its got a brand new coil on it, so something either going to or coming from the coil is messed up. the + wire going to the coil passed the tests.

the negative or TACH wire is not. and when I go through the checks the problem is between the ICM connector and the EEC.

now something that threw me for a loop was when I was looking at the resistor in the wire from the EEC, there is another wire (red with blue dashes on it) that go into the resistor but I can't find it on the wiring schematics, it goes into a plug on the drivers side wheelwell. despite it going into the resistor along with the tach wire from the EEC, there is no conectivity between it and any of the wires?

and Ideas whats going on here?

 

[Krafty]

if I have time today im going to redo the tests again, I stopped when I did the voltage test that goes to the ICM when I got the low number, im going to make sure I do it right this time, and then carry on through the tests if I get a different reading.

Im sure I had something setup wrong. but we'll see.

I had it highlighted which steps I had to jump around to so if I get boggled again I'll post my tests and the results.

 

[Krafty]

so here is what I did. looked over the tests, I realized I had a wire unplugged when I was doing the voltage check for the ICM. looked throught the rest of the tests, the only ones left were PIP sensor and PCM, but they said that if there were no engine codes for those circuits then the tests were not needed. so I bought a new ICM and the tool I needed, swapped it out. turned the key and took the truck through my mud hole.

VICTORIOUS

I win damn it !

thanks for all your help guys.

as for the idling, the vacuum canister was rotten right out. I don't have a/c or anything that needs alot of vacuum so I plugged the two hoses with screws and gasket maker before I swapped the ICM, now the truck runs and idles, until I run it out of gas. lol