Hi Gang,
Helping a friend figure out his 1994 GMC 5.7L TBI -spins but no start - no fuel or spark.
When did the General start using a crank position sensor?
thanks
hank
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Hi Gang,
Helping a friend figure out his 1994 GMC 5.7L TBI -spins but no start - no fuel or spark.
When did the General start using a crank position sensor?
thanks
hank
Gm started in the 90s. front timming cover lower bottom. front timming cover is plasic one time only deal to
thanx Pat
Time to start googling
didn't quite understand "front timming cover is plasic one time only deal to "
hank
the front timming cover is plastic that has a spot for the pick up . the cover are a one time only deal .that is if you have a seal leak or cover leak or look at it the wrong way you have to buy a new cover comes with front crank seal/ o ring gasket /with cover bolts. all as one kit ready to go on just to let you knowQuote:
Originally Posted by TOW'D
On that 1994, crank sensor and all is in the dist.The distributor controls spark and fuel until temp sensor tells the puter to take over.So no spark/fuel it has to be in distributor,(dist.not spinning, pickup,module or no power to dist.)
but there is a crank tigger on the crank .dist is fixed plastic body can not be moved . so timming is done threw crank????? ok looks like i was wrong i get them mixed up must be 95 or 96 up to 99 with the plastic front cover 5.7s ??? i think they started it sooner on the 4.3 .do not do many rebuild s on them only about two a year. i know you have to buy a new cover for them . customers do not like the price of front cover and gaskets set :)
I think I have only seen one of them here-----but I would be checking electrical issues first----how did you check for spark???how did you chech for fuel??????/
when you are missing 2 out of the three things needed to run, I question the methods---------
On the 4.3's the oil pressure switch acts as a low oil pressure switch shutdown where you would not have fuel or spark.If the switch is defective then......
No crank sensor that we can see
dist spins we checked for spark with #1 cyl wire to ground with leatherman in place of plug
no fuel spraying or dripping
We did a compression test and came up with 175psi all around
plugs white and lots of build up
cap and rotor corroded looks like they been there a long time
pulled the distributor and see the module pretty rusty
damn hard figuring the workings of that system without a book
thanks guys
the story continues
Soooooooooo--please explain how to check for spark with a leatherman---did you have him hold onto the wire?????????/
..........................coil wire ?
Probably similar to the 'tongue test'
So you didn't go to Ebay and order a factory service manual for what is usual 20 bucks??.Quote:
Originally Posted by TOW'D
"So you didn't go to Ebay and order a factory service manual for what is usual 20 bucks??."
that was the first thing I suggested to my pal
so explain who is this man made of leather and how he tests spark????????????????
something like what firebird77clone suggested only with naked body parts
he didn't always look like he was made of leather - too much spark testing
he said he was glad that the spark wasn't working ever since he got the used pacemaker
cheers
hank
Tow'd
somehow I'm thinking that you are maybe missing some basics---check the spark with a spark plug hooked to a wire-coil wire will bypass rotor/cap issues---
if you have spark, move on to fuel issues----spray some starting fluid into the intake and see it it will fire and run some----I've even done this with grandma's flamable hairspray----
I would almost bet on lack of fuel------------
we tested along side of the road where the truck died
I tried starting fluid first didn't even try to start
no spark
check grounds . check relays under the hood ? if like my old chevy ? then find a ECU to plug in
I'd like to test the coil --we got no signal from the dist. so figure that the ICM must be bad
i cleaned the grounds that I could find
there are two plugs going into the coil
one from the dist. one connection is 12v+ on with the key the other side must be the signal from the dist. or ground
I'm not sure where the other plug goes- the truck has a tach
I should be able to test the coil by powering it up and by touching the wire from the dist.to ground for a second it should spark when the ground connection is broken
(that is the way I've tested regular looking coils)
I haven't tried it yet to see what you guys say
I wouldn't be shorting out any ignition, sensor or injector wires on an engine with an ECU/Computer. That may have worked in the old days, but the days of 'arc & spark' testing are long gone. Get yourself a VOM (volt/ohm meter) and check for voltage on the positives. If you can't swing a VOM get a 12V test light, hook the lead to a good ground and probe for 12V.Quote:
Originally Posted by TOW'D
that's why I figured I'd ask
I've got a good VOM and a few different test lights
no doubt the factory book will be a big help when it gets here
thanks
I suppose that you have already checked out the fuses and relays????????? and the Ign/start switch?????????
plus---does that have one of those keys with the security chip/resistor????
You may have a bad ignition switch it could have moved as starter is not same contact as run.test light or vom meter realy should use a digital meter.
we get 12v on the red side of the push on connector with the key on- ignition switch is good then
how about in the start position??????
and are the fuses and relays good???? the ignition switch in modern vehicles only has enough amp cap to trigger relays--does not usually power something direct
check voltage to fuel pump at the tank
Turned out to be a bad distributor module
along with the module we installed a new dist cap & rotor and a good set of spark plugs and ign.wires
thanks
hank
I'm no good trying to work with these new-fangled pooters.Quote:
Originally Posted by TOW'D
It either goes...or it don't.
Glad it's all good for ya then mate!
:D :D
.