Crank no start 1988 Chevy C1500 5.7 350 tbi

Slade88

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It is still possible that you have a vacuum leak. Just because you can get it to fire and run for a few seconds does not mean there is not a vacuum leak. The fact that you can not keep it running at idle but it will run for a short time above idle is a perfect example of a possible vacuum leak. If the engine will not start and idle you cannot say that there is not a vacuum leak.
It runs roughly but still runs for as long as my foot is on the pedal so 900 rpm’s and onward. I replaced all my vacuum lines and made sure they were tight. Would a vacuum leak cause a truck to shut off as soon as I take my foot of the gas?
 

evilunclegrimace

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The vacuum lines are not the only place for a leak to occur. The TBI base gasket can leak, the intake gaskets can leak, the RTV seal on the China walls can leak and if your spark plugs are only finger tight the engine cannot pull a proper vacuum hence the engine will not idle.

This needs to be diagnosed with a proper scan tool like Schurkey said.

The 1988 light duty truck fuel and emissions/driveability manual lists the following possible causes.
Sticking TPS
improper ignition timing
ECM grounds
IAC circuit
Improper alternator output
Improperly adjusted/faulty park/neutral switch
faulty PCV valve
improper idle speed
faulty A.I.R. system
contaminated oxygen sensor due to silicon contamination from the fuel or the use of improper RTV sealant
faulty fuel pressure regulator
EGR stuck open at idle
improper idle air rate

With a proper scan tool you could look at the Block learn to see if the system is running lean (BL greater than 138) or rich (BL less than 118).
 

PlayingWithTBI

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Wow.. No one said to replace the spark control module inside the distributor cap. You guys are slipping.

Advanced Auto Parts#: D1943A (GM OEM)
well, personally I would go with the ACDELCO D1948A myself, but that's me, ha ha.

I asked about the ICM, pickup coil, etc in post #2 :33: Since the engine now starts and runs but doesn't idle, the ICM wouldn't be my 1st choice anymore.
 

thinger2

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By pulling the TBI. You had to disconnect the IAC (Idle air control) and the TPS (Throttle position sensor)
The IAC always needs to be reset.
There is a procudure for this.
On early tbi throttle bodies the TPS is adjustable.
The later TPS are not adjustable but thsy can be altered to make them adjustable.
Go back to step number one.
Pull the distributor.
Pull the plugs.
Set # one at tdc by verifying through the plug hole that it is actually at TDC on the compression stroke.
Dont trust the timing mark.
They are known to slip and especially on somdthing that old.
Set it at TDC with the piston at TDC.
No matter how you mark your distributor it will always be one tooth off when you re stab it.
Because the "TAB" on the end pulls out before the gear stops spinning.
That is the nature of how helical cut gears work.
a small block chevy will always be one tooth off if you pull it and restab unless you turn the oil pump back about ten degrees or so.
Always.
Everybody has a favorite way to do this.
Some people drop it in and push on it till it drops.
Some people crank it over untill it drops in.
I use a big monster standard screwdriver that is notched with small block chevy marks.
Pull the dist. Stick the screwdriver in the oil pump.
Back it off to whatever mark Im using that day.
Stab it.
Done deal.
Easy.
Rule number one on a Chevy is to make sure that you are not one tooth off.
And it is very likely that you are one toith off.
Rule number two is to make sure that you arent 180 degrees out.
But it wont fire at 180 out.
Not on a stock engine
But on a knucklehead engine
It might backfire at 180 out
Depending on the fuel and the aspiration it might chuck the blower across the street at 180 out.
Thats why you arent allowed to hang out in the staging area behind the lights on any decent track if you are not a crew member.
Though track safety is pretty much a joke these days.
Stand the **** back.
Buy a 12 dollar hot dog.
watch them run garbage cars.
**** if I was driving my mom to the grocery store and if we were starving to death I wouldnt take the time to steal their cheetos while they were staging at the light.
All jokes aside.
Car culture is alive and well.
It is just different.
I find it so odd that old farts with their perfectly preserved marmelade cars are such a pack of hypocrital *****.
We ran the same roads when we were young.
We did the same crazy ****.
But now that you got yer big fat ass on the couch eating pizza and fries and your second divorce.
Time to slam the car guys.
****** traitors .
******* old farts.
Dont hurt anyone.
That will ruin your life.
Dont get paralyised in a car wreck.
Dont flip your car upside down in a river and drown.
Dont loose it on I-5 in the rain and get run over by a semi.
Dont buy a car with plates from california and a title from alaska from a guy who has a big scar on his neck because his best friend murdered his parents and ran them through a blender and then ran him over with a car.
Even if Dad thinks he is kinda sorta maybe okay.
Sometimes you just need to take the hit and walk away.
Car culture can get really odd if you get involved with people who define their lives around cars.
It really can turn into an excluding and polititcal club that has the same weird bizzare characteristics as those crazy people who put their kids in talent shows and use their pets as props in facebook posts.
I just dont get it.
I dont understand that.
Why would you try to **** on the people who are doing the same things that you were doing when you were young?
Rotten old farts.
Your body will fail you.
You will get physically old.
You will have health problems.
You will wake up one day and feel like hammered ****.
Your friends and your family will die and that is just what happenes.
But with age you get a choice.
Who are you going to be and what are you going to be.
All kinds of things that you thought were important when you were young turn out to be nothing.
Vapors in the wind.
Just memories of a time long gone.
What really matters is what you have today.
This very moment right this minute today as we you read this .
This very moment.
Life can slap you right in the ******* head.
And it will.
My wife is 70 miles away from me right now.
Her Dad is in the ICU and it really doesnt look to good.
I cant be their for her because Im taking care of my 79 year old Mom.
But, we made a deal with each other almost twenty years ago that whatever happened we were going to do whatever it took to make sure that our parents never went into an old folks home.
We have an agreement that we will take care of our parents.
That is our deal. That is us. That is how we see life and that is what we are doing.
And it ******* sucks.
Mainly for her.
My Mom is as tough as nails.
A little old lady who will kick you right in the balksack if you piss her off.
Her Mom? nope just a whiny old princess who takes the ambulance to the hospital once a month to get attention.
Her Dad is in ICU and probably is done.
I dont think he is ever coming out but well see.
I think he has pretty much given up.
When you get older like me.
You can start to understand how that fire can dim.
But you need to keep that fire and that force for yourself.
That is the only thing you have that is really yours.
Dont give it away and for ***** sake dont let anyone steal it from you.
That is the one thing you own in this life and it isnt anyone elses property.
 

HawkDsl

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well, personally I would go with the ACDELCO D1948A myself, but that's me, ha ha.

I asked about the ICM, pickup coil, etc in post #2 :33: Since the engine now starts and runs but doesn't idle, the ICM wouldn't be my 1st choice anymore.
It still could be the problem.. But the first order is to make sure your timing is correct in the first place. Thinger2 is right. Make sure you are TDC, all the plug wires routed right.
 

Slade88

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Hi everyone, I appreciate all the advice, so here’s where I’m at now, I can’t afford a scan tool but I’m gonna check and fix everything you all told me too. I replaced my TBI base gasket, it was pretty old and crusty so I figured why not since it could cause the vacuum leak, and I’m pulling my headers so I can have comfortable access to my plugs with a ratchet. This whole issue started after I toyed with the timing messed with the fuel and changed my spark plugs, when I replaced them I put them in finger tight. I’m guessing that’s not tight enough from what everyone’s said, so I’m gonna go ahead and make sure they are all in snug, replace all my plug wires, then reset my IAC valve and see what happens when I try to start it up after that. I have a good feeling after I do all this stuff my truck will idle. Life’s gotten in the way recently and I needed some time to think about the next corse of action for my vehicle. Hell maybe I will have my truck on the road in time for prom after all? I will update you all on my findings after I do the aforementioned work.
 

Aem72717

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Scan tool is not as important as all that you can jump the ALDL to get your codes all the other stuff can be checked with a Digital volt meter way more useful in this particular situation the advice is good on making sure you have the distributor dropped correctly and it is in time with the wires ran correctly the procedure to set your IAC valve is fairly strait forward and easy jump the ALDL connector just like your pulling codes turn your key on wait at least 15 seconds and then unplug the IAC shut the key off pull your jumper out of ALDL and disconnect the timing bypass just like when you time the engine now you got to have the steel cap over the idle screw out of the TBI easiest way for me is with it removed from the motor use a hack saw or a Dremel or whatever you have to cut an 1/8th inch or so top and bottom of the cap and knock the cap out with a chisel now you can access the torx head screw that sets your idle and set the idle to the recommended setting from the label under the hood or a manual after you get it set shut it off hook up the IAC and the timing bypass and you are good to go
 

evilunclegrimace

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Scan tool is not as important as all that you can jump the ALDL to get your codes all the other stuff can be checked with a Digital volt meter way more useful in this particular situation the advice is good on making sure you have the distributor dropped correctly and it is in time with the wires ran correctly the procedure to set your IAC valve is fairly strait forward and easy jump the ALDL connector just like your pulling codes turn your key on wait at least 15 seconds and then unplug the IAC shut the key off pull your jumper out of ALDL and disconnect the timing bypass just like when you time the engine now you got to have the steel cap over the idle screw out of the TBI easiest way for me is with it removed from the motor use a hack saw or a Dremel or whatever you have to cut an 1/8th inch or so top and bottom of the cap and knock the cap out with a chisel now you can access the torx head screw that sets your idle and set the idle to the recommended setting from the label under the hood or a manual after you get it set shut it off hook up the IAC and the timing bypass and you are good to go
Jumping the ALDL will only show codes. A scanner will allow you to see what is happening with inputs from things like the O2 sensor, fuel trims, coolant temp sensor, TPS voltage, MAP voltage, P/N switch position, etc. While it is possible to check SOME of the sensor inputs with a DVOM it is not nearly as easy.
 

DerekTheGreat

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If it ran fine before you touched it, revisit the things you touched and ensure they are correct!
 
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