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84 Corvette starting problem

 
mickmoto
I love my Chevy Chevette!
Posts: 5
Joined: 04/11
Posted: 04/03/11 08:26 PM

my 1984 corvette was having heating problems, and after cooling it down twice on the way home on the interstate it cut out, like it wasnt getting any spark. towed to the house it still won't start but it will crank. replaced ignition module (est), coolant sensor, ecm also swapped prom,new battery, new starter., checked timing chain, ok., reset dist timing. still won't start. has fire, has fuel, HELP!  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/03/11 10:39 PM

wow.. you have done a lot...  

lets go back to basics...

i am taking that you have a timing pointer on the timing cover...
and that your balancer has a mark..    line up the balancer mark.. with the timing pointer at 6 before by turning the crank in the proper direction of rotation.. if you go past.. back up an inch or two...  bring it back to the 6 before top dead center....

now.. pull the cap...    which way is the rotor pointing...??? toward the number one wire or the number 6... either is OK at this point in testing..  pull the rotor..  see if the reluctor teeth and the pick up coil teeth are lined up perfectly.. ><  

why line up the pickup coil and reluctor with the damper set to base timing .... thats where the module fires the spark when cranking..  once it gets up above 400 rpms.. it switches to the computer control..

now... take out the number one spark plug or the number six...  which ever is easier for you.....

stick  a folded tissue into the hole...  or use your finger over the open spark plug hole...   have somebody crank the engine around... till you get compression from that cylinder...  is the rotor pointing at the number one or the number 6 spark plug wire????/

there have just been so many times the distributer is installed 180 out after a timing chain replacement..    why.. when the timing gear marks are close together..  the distributer rotor should be pointing at the number 6 wire in the cap..   when the cam sprocket dot is straight up.. the engine is ready to fire the number one cylinder..


have you checked the compression..   if you don't have  tester.. some chain autoparts stores keep decent versions behind the counter.. in the loan a tool section..


i have seen overheated engines that blew the head gaskets and had NO compression to start the engine...

are the spark plugs clean????  

is the rotor in the distributer new.. not burned through...

when you changed the distributer cap... did you swap over the ground strap under the coil.. that is hard to see....  

HEI Largecapgroundstrap

Heibigcap

how is the coil...  have you changed it????   have you checked it for signs of external leakage...

Coilhighvoltageleakareas


is this the shape of the coolant temp sensor that sticks out the front of the intake below the thermostat housing...  

the left head has the temp sending unit for the dash gauge...

the right head has the radiator cooling fan switch...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/03/11 10:42 PM

the radiator fan switch is in the right head between the rear two spark plugs

Radiatorfanswtichtopview

Radiatorfranswitch S500sideview

this is the proper connector for the radiator fan switch in the right head.. it comes out of the harness down by the starter usually...

Radiatorcoolingfanconnector231

if  you ground this connector.. then turn on the key.. the radiator fan should start spinning at full speed...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/03/11 10:49 PM

this is the proper engine coolant temp sensor replacement... this goes into the front of the intake manifold...

Su102

this is an duralast SU102 at autozone or wells... ask for it by part number.. its only a buck or two more than either the sensor  or the connector individually..

this sensor replaces the sensor that looks like the fan switch.. but this one works better..  the original coolant temp sensor have 2 wires to them.. black and yellow...   the connectors fail.. the sensors fail...

the su102 is under 20 bucks as a kit... at AZ...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/03/11 10:57 PM

this is the aldl connector under the drivers side dash board..

Aldl

jump the A and B with a short piece of wire.. or a fork terminal...

turn on the key...  count the check engine light flashes...

the first code will be a code 12...

0________0____0______________0________0____0______________0________0____0____________  notice the pattern...   it will flash each code 3 times...  before going on to the next code...

post if you get any....


if you look in the active posts... probably about 30 or 40 posts back.. i put up a post about what scan tools for early C4 cars with OBD1 systems.. from craigs list..  

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mickmoto
I love my Chevy Chevette!
Posts: 5
Joined: 04/11
Posted: 04/04/11 06:33 AM

thanks for the help i will go from there  and see what happens, i have checked the compression and it was low in all but the #8 cyl ? what do you think; cleaned and re-gaped plugs they were wet but looked ok  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/04/11 08:18 AM

how low is the compression...

top off the radiator... pinch the overflow hose... with the radiator cap off...

crank the engine...   when you crank the engine..  if the coolant level rises..  you have probably blown a head gasket or cracked a head...   there should be no movement from the coolant when just cranking the engine.... any overflow while cranking would be the compression leaking into the cooling system...

you can also stick a timing light on the number one spark plug wire.. have somebody crank the engine.. see if the timing marks line up??  if they do.. then your timing chain and gears may not be bad...  

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mickmoto
I love my Chevy Chevette!
Posts: 5
Joined: 04/11
Posted: 04/11/11 05:59 PM

compression was 30psi in all cyls x-cept #8cyl which was 60 psi, don't see any gray matter on oil stick, replaced cap & rotor, still no start, timed dist accord to shop manual, acts like it wants to start but won't
what next ?  

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mickmoto
I love my Chevy Chevette!
Posts: 5
Joined: 04/11
Posted: 04/11/11 06:21 PM

thanks for all your advice; grounded the aldl ab terminals, dash doesnt work, but, center info ck engine flashes once, then twice, but doesnt give me any codes ? i'm stumped !  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 04/11/11 09:42 PM

NO engine will start with ONLY 30 or even 60 pounds of cranking compression...

you need to pull the distributer cap....  rock the crank back and forth.. watching how much it moves before the distributer rotor responds...

if the damper outer diameter.. moves more than about 5/8 of an inch.. your timing chain has slipped...


or you have completely blown the head gaskets...

or you have a really really clogged exhaust system....

remove the oxygen sensor from the exhaust..   see if your compression comes back... when the exhaust is totally blocked..  the air cannot escape..

do you have compressed air in your shop????    do you have a remote starter switch////  

take your compression tester hose.. see if you can use various quick connects so you can hook the compression tester hose to the shop air supply..   take the valve core out..  don't loose it...

stick the hose into one of the spark plug holes.. use the remote starter to bump the engine around till you get that cylinder to TDC...  charge the hose with the shop air...   oh...  you should have the radiator cap off and the system totally filled...   does the radiator level stay steady... if it rises.. you have a combustion chamber or head gasket leak..   yep.. the engine is probably going to spin ... but try to reset it... i use this a LOT.. instant easy proof that a head gasket or combustion chamber is leaking..    add compressed air..  if the coolant level rises.. instant proof..


you can also move the timing marks up to TDC... pull the cap.. does the rotor point at the number one or the number six wire....   it should..  

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