Need help with carb and HEI...can't get the truck to start.
Jon R. Pickens
I posted something similar a few days ago on
alt.autos.4x4.chevy-trucks, but under a more generic subject line...so
I figured I'd repost here where there's more traffic.
Basically, here's the details: Months ago, I came home from work and
immediately went about changing the jets in my Edelbrock carb to lean
it out. The engine was hot, and when I had it (almost) back together I
tried to start it. Well, the fuel line hadn't been reconnected to the
carb (oops), so cranking the motor just shot gas all over the hot
engine and started a fire. Months (and a replacement wiring harness)
later, I really need to get the truck started THIS week. I'm moving in
2 weeks, and will no longer be within walking distance to work.
Truck is a 1986 K5 Blazer, 4x4, 350ci with an Edelbrock 600cfm (elec.
choke, vac. secondaries). I installed the new harness and I believe I
have everything necessary connected. I don't have the AC compressor's
power wires connected...
The HEI distributor took quite a hit in the fire, and most of it was
replaced. It uses/used the 5-pin ignition module that connected to a
very basic ECM of sorts--the ESC (elec. spark control) module, which
retards spark based on input from a knock sensor. Being that the
harness that connected the module to the ESC was shot after the fire, I
made a new one. I installed a new ignition module and new condensor.
Truck won't start. I *think* I'm getting fire to the plugs. I
installed an aftermarket tach that I'd bought, and connected it to the
"tach" connection on the HEI. When I turned the engine over, it does
its thing and jumps up to about 1000rpm.
When that didn't work, I questioned the integrity of my home-made
harness to connect the ESC to the ignition module. I had a spare
(brand new) 4-pin module on hand, so I eliminated the ESC althogether.
I removed the plastic shell of the pass-thru connector that ran between
the 3-pin side of the module and the ESC connector, and serves as the
connection to the pickup coil. With the metal connections exposed, I
pushed them onto the 4-pin module, and essential converted the HEI to
the earlier style, 4-pin module (sans ESC).
Following me so far?
There was no difference when I tried to start it. I will add that I
had accidentally forgot to connect the condensor to the ignition coil
the first time around. After replacing some parts and connecting it
properly, it SOUNDS different, like it's trying to start, whereas
before the coil was in the circuit, it just turned over, with a
consistent sound.
While trying to start it, heavy fumes are coming out the tailpipe, so I
know it's getting gas.
Also...the fire was on the back of the engine and firewall (ironically
enough). The HEI's cap was melted, among other things. That's mainly
due to the fact that the fuel line was laid aside and pointed back
toward the firewall when I tried to crank it.
Could the fire have damaged the carb in some way? Granted, the last
time it ran, I turned it off and swapped the jets in the carb, so maybe
I should try putting them back to stock first.
Can someone please advise me on testing the HEI? I can't imagine that
the pickup coil was damaged. There weren't any blackened parts
underneath the rotor when I pulled the distributor--so I don't think it
necessarily saw any more heat than it would during normal use. I
cleaned it out with a non-conductive cleaner used for alternators and
electric motors. The ignition coil and pickup coil are the only two
pieces that were not replaced.
I feel confident that I properly aligned the HEI when I reinstalled it.
I had marked the pickup coil's inner and outer pieces with bright nail
polish before removing it. I didn't see anythign weird about the
distributor gear that would indicate that it had to be connected to the
cam in a specific way (I've heard of distributor having to be aligned
exactly or else they wouldn't seat). It seats well and it obviously
turning, as I've had the cap off several times and it's always pointed
in a different direction.
Please help!
Thanks,
~jp
wayne c
will have advanced or retarded ignition depending on which way its off. If
you have access to a Clymer or Motor manual, check the correct procedure for
your model and set the distributor accordingly. If you don't, I'm sure
someone here can help with that. Wayne
"Jon R. Pickens" <jonr...@gmail.com> wrote in message
news:1147700708....@j55g2000cwa.googlegroups.com...
ShoeSalesman
plugs, well, find out for *sure* first.
Jon R. Pickens
> plugs, well, find out for *sure* first.
What is the quickest way to check?
~jp
ShoeSalesman
a 3/8" from something thats grounded and crank the engine. You should
see blue sparks jumpin. pop-pop-pop-pop-pop-pop...like that
Jon R. Pickens
small enough to fit. My main Craftsman driver uses interchangable bits
and doesn't fit into the boot. I'll pick up a cheapo for this purpose
today.
I thought maybe there was maybe a different way.
~jp
aarcuda69062
<1147811135.8...@j33g2000cwa.googlegroups.com>,
It doesn't -have- to be a screwdriver, a piece of coat hanger
wire or a straightened out paper clip will work also.
wayne c
"aarcuda69062" <none...@sbcglobal.net> wrote in message
news:nonelson-373CA5...@newsclstr02.news.prodigy.com...
Jon R. Pickens
Screwdriver was tested against a known good ground. I tested it right
before attempting this with a multi-meter. The spark was so small,
that I practically had to touch the ground to get it to arc. I've done
this in the past, and normally you can hear the "tick...tick...tick..."
of the arcing--I could not.
The timing light did not flash at all while the truck was cranked.
I swapped in another ignition coil...nothing.
Ideas?
~jp
Jon R. Pickens
are the chances of that being the problem?
Isn't it a relatively low-voltage device? It's just acting as a
trigger to left the module know when to fire the plugs right? Seems
it'd either work or it wouldn't, with no middle ground.
I put the old 5-pin module back in, and the results got worse. Doesn't
seem to be firing at all, although that time I didn't have a "helper"
to crank the engine while I tested for spark. But it sounds different.
When I put it in, I did the ESC bypass, where the green and black
wires are jumpered together and the harness is unplugged from the ESC.
I'm running out of options here.
Like I said earlier, there is 12vdc present on the ignition circuit
when the key is in the "on' position, and the aftermarket tach I
connected to the HEI does jump up to about 1000rpm while I try cranking
it, so I think the output is at least getting to the coil.
I have never removed or installed a distributor until this all
happened, nor have I replaced all the plug wires, except by doing it
one at a time. I followed the diagram in the Haynes manual for the
firing order, and double-checked each one time.
Should the spark test with the screwdriver have made a big spark or a
small one...? It was awful small to me.
~jp
ShoeSalesman
sure you didn't forget the ground strap that goes on the coil (under one
of the screws) to the elect plug. Yes, it should be a big spark, move
the screw driver slowly away from the ground while cranking and see if
it will jump about a half inch or more. I would say 3/8 at least. The
spark should also be blue not just yellow. It wouldn't hurt to
disconnect your tach and try it, it could be screwing it up. Also, on
HEIs the rotor likes to burn through right to the dist shaft and grounds
out the spark. If it has an external coil check the coil wire for burnt
ends (very common)As for the pick-up, your description is correct but it
could half-ass work but not likely. Are you sure of your wiring? If you
got something wrong you could easily cook a good module. Man its been a
while since I worked on a HEI but I don't remember jumping anything to
by-pass esc. Did you read this in a manual? It seams like you disconnect
something near the dist/module. But like I said, its been a LONG time.
Jon R. Pickens
Concerning the ground wire... The coil has 3 wires, a red one for the
12vdc input, a yellow one that connects to the tach (both yellow and
red also terminate to a connector for the condensor) and then a black
wire with a metal eyelet connection. That metal eyelet goes under one
of the 4 screws holding the coil in place on the top of the cap. Thing
is, the screw is just going into the plastic cap, not a metal grounded
connection.
Shouldn't the old-style (4-pin) HEI require only 1 wire?? (12vdc+) I
have seen "grounding straps" for sale in the LMC and Pace Performance
catalogs. Where do they go?
The spark will NOT jump a 1/2" gap. It was sorta blue, but very small.
BTW, the HEI includes the following NEW parts: coil, cap, rotor,
carbon button, condensor, ignition module, and plug wires.
Could a missing ground strap be causing this?
The bypass you mentioned...this particular HEI used a 5-pin module
connected to an ESC (elec. spark control) module--sort of a early, very
simply ECM. It was also connected to a knock sensor. The whole
purpose is to retard spark if knock is detected. It's known to be a
performance killer, as it retards spark in fixed increments, like 5 or
10 degrees at a time, depending on the programming of the ESC. It was
apparently problematic enough for Chevy to release a service bulletin
on disabling it; basically jumpering 2 of the wires going back to the
ESC together.
Those 2 wires formed an electronic loop, that went in and out of the
ESC. The ESC could interupt and delay spark as needed. By jumpering
the two wires together, you remove the ESC from the loop, and the HEI
should function as a 4-pin, pre-ESC distributor. If the connection is
made before the connector going back to the ESC, the ESC doesn't even
have to be connected. That was the latest scenario, and it seems as if
it's getting even LESS spark now. At least before it kind of sounded
like it was trying to kick over. Now it doesn't. The engine just
turns over and over, with no change in sound.
Again, it's getting gas...there's all kinds of nasty fumes coming out
the tailpipe.
Thanks,
~jp
aarcuda69062
<1147873454.4...@g10g2000cwb.googlegroups.com>,
"Jon R. Pickens" <jonr...@gmail.com> wrote:
> Yeah...coil in cap.
>
> Concerning the ground wire... The coil has 3 wires, a red one for the
> 12vdc input, a yellow one that connects to the tach (both yellow and
> red also terminate to a connector for the condensor) and then a black
> wire with a metal eyelet connection. That metal eyelet goes under one
> of the 4 screws holding the coil in place on the top of the cap. Thing
> is, the screw is just going into the plastic cap, not a metal grounded
> connection.
There should also be a stamped steel ground strap that fits under
the coils steel frame, it sort of loops up and into the multi
plug where all of the externals plug into the CAP.
Viewed from the top, the electrical connections in the CAP are
arranged like this:
I I I
- -
Left to right they are;
coil negative / ground / B+
Tach / 12 volt feed
The ground strap fits in the center of the group of three.
The NAPA part number is:
RR204SB
Picture at this link:
http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&Li
neCode=MPE&PartNumber=RR204SB&Description=Ignition+Coil+Strap
Any major brand parts store should be able to cross reference
this part number.
> Shouldn't the old-style (4-pin) HEI require only 1 wire?? (12vdc+) I
> have seen "grounding straps" for sale in the LMC and Pace Performance
> catalogs. Where do they go?
Externally, only one wire is required (12 volts), but internally,
the three that come up from the distributor base into the cap are
also needed, one of these three goes to a ground screw inside the
distributor base.
> The spark will NOT jump a 1/2" gap. It was sorta blue, but very small.
> BTW, the HEI includes the following NEW parts: coil, cap, rotor,
> carbon button, condensor, ignition module, and plug wires.
>
> Could a missing ground strap be causing this?
Absolutely, very important. The ground strap IS the ground path
for the coil secondary. Without it, there is only one side of
the coil secondary (the carbon brush in the center of the cap) as
part of the secondary circuit.
Usually when someone forgets to install the ground strap, it
smokes the ignition module, so, installing the ground strap is
not a guarantee that you'll have spark, may require another known
good module.
> The bypass you mentioned...this particular HEI used a 5-pin module
> connected to an ESC (elec. spark control) module--sort of a early, very
> simply ECM. It was also connected to a knock sensor. The whole
> purpose is to retard spark if knock is detected. It's known to be a
> performance killer, as it retards spark in fixed increments, like 5 or
> 10 degrees at a time, depending on the programming of the ESC. It was
> apparently problematic enough for Chevy to release a service bulletin
> on disabling it; basically jumpering 2 of the wires going back to the
> ESC together.
>
> Those 2 wires formed an electronic loop, that went in and out of the
> ESC. The ESC could interupt and delay spark as needed. By jumpering
> the two wires together, you remove the ESC from the loop, and the HEI
> should function as a 4-pin, pre-ESC distributor. If the connection is
> made before the connector going back to the ESC, the ESC doesn't even
> have to be connected. That was the latest scenario, and it seems as if
> it's getting even LESS spark now. At least before it kind of sounded
> like it was trying to kick over. Now it doesn't. The engine just
> turns over and over, with no change in sound.
You've got the ESC down pat...
>
> Again, it's getting gas...there's all kinds of nasty fumes coming out
> the tailpipe.
Given your time constraints with the move and all, you might be
better off getting a pre ESC distributor from a junk yard...
Good luck, I gotta go do a timing belt and water pump on a 300M
Jon R. Pickens
> There should also be a stamped steel ground strap that fits under
> the coils steel frame, it sort of loops up and into the multi
> plug where all of the externals plug into the CAP.
> Viewed from the top, the electrical connections in the CAP are
> arranged like this:
Ha! I just did a bunch of Googling and reading... it DID come with
that piece...has an eyelet on the other end. I assume to stack the
eyelets together on the same screw, which makes contact with the
ignition coil's frame.
Now that I think about it, it makes sense. I only have TWO blade
connections in the cap, but the connector coming up from the
condensor/module is indeed a THREE wire connection.
Smack me now.
> Left to right they are;
> coil negative / ground / B+
> Tach / 12 volt feed
>
> The ground strap fits in the center of the group of three.
Gotcha...
> Externally, only one wire is required (12 volts), but internally,
> the three that come up from the distributor base into the cap are
> also needed, one of these three goes to a ground screw inside the
> distributor base.
Again, it's all making sense now.
> > The spark will NOT jump a 1/2" gap. It was sorta blue, but very small.
> > BTW, the HEI includes the following NEW parts: coil, cap, rotor,
> > carbon button, condensor, ignition module, and plug wires.
> >
> > Could a missing ground strap be causing this?
>
> Absolutely, very important. The ground strap IS the ground path
> for the coil secondary. Without it, there is only one side of
> the coil secondary (the carbon brush in the center of the cap) as
> part of the secondary circuit.
> Usually when someone forgets to install the ground strap, it
> smokes the ignition module, so, installing the ground strap is
> not a guarantee that you'll have spark, may require another known
> good module.
We'll see... I have a few.
> > The bypass you mentioned...this particular HEI used a 5-pin module
> > connected to an ESC (elec. spark control) module--sort of a early, very
> > simply ECM. It was also connected to a knock sensor. The whole
> > purpose is to retard spark if knock is detected. It's known to be a
> > performance killer, as it retards spark in fixed increments, like 5 or
> > 10 degrees at a time, depending on the programming of the ESC. It was
> > apparently problematic enough for Chevy to release a service bulletin
> > on disabling it; basically jumpering 2 of the wires going back to the
> > ESC together.
> >
> > Those 2 wires formed an electronic loop, that went in and out of the
> > ESC. The ESC could interupt and delay spark as needed. By jumpering
> > the two wires together, you remove the ESC from the loop, and the HEI
> > should function as a 4-pin, pre-ESC distributor. If the connection is
> > made before the connector going back to the ESC, the ESC doesn't even
> > have to be connected. That was the latest scenario, and it seems as if
> > it's getting even LESS spark now. At least before it kind of sounded
> > like it was trying to kick over. Now it doesn't. The engine just
> > turns over and over, with no change in sound.
>
> You've got the ESC down pat...
Heh...well, desperate times call for much research.
> > Again, it's getting gas...there's all kinds of nasty fumes coming out
> > the tailpipe.
>
> Given your time constraints with the move and all, you might be
> better off getting a pre ESC distributor from a junk yard...
I think I have the conversion procedure down. Like I said, the only
difference between the pickup coil on the pre-ESC HEI, and the
ESC-controlled HEI is the physical connection to the module, which I
modified. The pickup coil WAS "picking up". The very small spark was
occuring every 2 revolutions of the motor--as it should, indicating
that the pickup was doing its job.
I may as well run without the ESC. It's just one more thing to go
wrong and complicate matters at a time when I can't afford any
complications.
> Good luck, I gotta go do a timing belt and water pump on a 300M
Have fun! Thanks very much for helping put this in perspective.
Hopefully I can get it running today and have it towed to the tranny
shop Monday.
~jp
fill_eh
over without the distibutor in?...maybe roll the engine over and
position the # cylinder at top dead centre and reinstall the distibutor
or at least check it...your getting gas and spark, maybe the timming is
off...happened to me once, i replaced the timing chain and installed
the distibutor 180 degrees out...doh!
Jon R. Pickens
Thanks for the reply, but I think I have it figured out... It'll have
to wait till after I get off work, although I'm considering making the
change during lunch. I just can't wait to find out if it works.
The timing chain was not disturbed during any of this. I attempted to
start the hot engine with the fuel line (accidentally) disconnected,
which caused the fire. The damaged components were most electrical. I
only pulled the distributor to get it cleaned out and the damaged parts
replaced more easily.
I had very carefully marked the distributor before removing it and it
went back in without a hitch. As far as I could tell, there's no
specific indexing to get it to mesh properly with the cam.
I think we've narrowed it down to a missing grounding strap inside the
distributor.
Thanks again for the reply.
~jp
ShoeSalesman
does this help?
http://members.aol.com/pullingtractor/images/hei.gif
HEI Coil Ground Strap can be seen here:
http://www.kendrick-auto.com/ignition.htm
it is a little piece of metal that goes from the body of the coil to the
electrical plug on the dist cap. Yes, you NEED this strap.
look here too: http://www.no-bling.com/techdocs/7PIN_SCH.GIF
Jon R. Pickens
case, it's an extra piece of wiring, with an eyelet connector on one
end, and the flat pins on the other end to fill the center space for
the 3-pin connector coming from the condensor/module.
>From what I can tell, the eyelet, as well as the eyelet (black wire)
coming from the coil, join together under one of the 4 screws holding
the coil in place.
Thanks for the pics...they really do tell 1000 words.
~jp