No ignition...fixed...what is wiring harness of back of dist? 4 wires...

[broncoman6524]

this is an 84 k5 350

ok tonight started out by me swappin on my old q-jet instead of my edelbrock...ran like crap i had to keep it ata bout 1500 to keep it idleing...

it dies once and we cant get it to fire again. pull a plug hold it agains header...no spark.

i check the power in all connections. its got power going into the dist but nothing coming out into the wires...

so far ive

check fuses (in box below dash anywhre else)
unhooked msd and rewired back to stock
changed coils (used but worked 2weeks ago...)


im thinkin gthis may be a bad ign module...but WHY would it just BAM all of a sudden go bad? for about a week now at first accel it would kinda stumble and almost die then gun it and it would pick up and run fine.

any other ideas? im goin to discount tomorrow and getting a NEW coil, and ign module anything else i should get?

 

[NewUser]

sounds like the ignition module to me...they will go out without any warning at all....i sell quite a few of them at work and always keep a spare in my glovebox

 

[broncoman6524]

gotcha thats what i was thinking too...i read somewhere that as it goes bad your initiall accel will flutter and stumble or some bs like that lol

 

[NewUser]

yep and eventually you'll have a no start situation....ive had them run fine, shut it off and run in the store for some smokes, come back out and BAM! nothing, nada, zip, no start at all....hence why i keep a spare in the glovebox

 

[diesel4me]

modules die when..

Excessively high voltage,voltage spikes,and poor grounds are what kill 90% of GM ignition modules..that and lack of the heat transfer compound under it,that will make it overheat and fail also..it's not a bad idea to keep at least a "good used" one with you,just in case!..I've had some fail suddenly for no apparent reason myself..GM AC-Delco's are the best,I've had several bargain brand ones fail all too soon..

 

[jones]

I just had this same problem a few weeks ago.my rotor had a pin hole in it and the plugs were shot from the Holley carb.Spend $5 on an inline spark tester before you spend the cash needlessly on other things.If you have spark ther,replace the plugs with new and it should be good to go.

Note:if the spark tester looks like it's laying on the manifold,resist the urge to touch it while it's be turned over.WOW!

 

[broncoman6524]

ya i know itll bite the **** outa you...ok

like i said i had NO spark, replaced module no go...check it and old one with tester...both good. replace coil with brand new one no go. only thing left is pickup coil...**** that. lol. so i grab my spare dist and throw it in now it runs

lol, only thing is im quite disapointed in the q-jet the edelbrock felt like it had more balls...kinda dissapointing. lol.

the 5 pin dist that was in had a harness on the back of it with 4 wires. the new dist dont have that...what did these go to? the truck runs and drives fine id just like to know what is now unhooked...

idk if anybody knows but you can hook up a msd box to a 4 pin dist same as a 5pin correct? i cant find my manual or id look...

 

[dyeager535]

Was that originally a 305 truck?

In any case, the harness you are talking about sounds like ESC. The one you pulled, did it even have vacuum advance?

I know with some of the ESC setups, it's failure can cause all sorts of problems.

Although the Q-jet is considered a "bolt on and run" carb, that is not true. There is a WHOLE bunch of tuning you can do to them, (secondary rods/hangars, primary rods/jets, power piston spring, needle seat, secondary tension spring, and so on) and done right, there is no reason it won't run as good or better than with any aftermarket carb out there.

 

[broncoman6524]

yes it was an orig 305...and yes it did have vaccum advance. what is this exc you speak of? lol


i plan on changin out the secondayry jets for bigger ones. as well as doin that thing where you get hte 2ndaries to open alot faster once i figure out exactly what that involves nad how to do it lol

 

[dyeager535]

ESC is electronic spark control, also known as EST, electronic spark timing. Some setups had vac/mech advance and used a knock sensor SOLELY to retard timing if "knock" was detected, some setups had no vac/mech advance, and the setup controlled ALL aspects of timing.

Without a dyno, O2 sensor, or exhaust gas analyzer, your going to need to measure your time from a stop over a given distance to see if you are hurting or helping your motor with carb mods. Too much or too fast on the secondaries and you'll do nothing but waste gas and annoy yourself.

 

[broncoman6524]

gotcha....i gotta tell you either this carb runs like poo or msd makes a HUGE difference in power/get up...lol