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88 K5 will not start...need help.

THEMCGUIRE said:
I have 12v at B2 for 2 sec during starting. So ordered a new ecm.
Click to expand...
I forgot one more check, during crank check to see if C3 gets a signal? It should as the truck is cranking and signal comes from other side of fusible link.

Could also tap on ECM while cranking and see if it starts? Yes tapping on ECM is a GM tech diagnostic procedure. I have known good ECMs for when I run into weird crap like this... for some reason A1 is sending signal to prime fuel when key on, but does not when in Crank!

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I am ready to start tapping. With a 10 pound sledge. 6 days on this, I am just so tired of it.

I ordered the ECM, my Napa does not take returns on electronic parts so I am stuck with it now.
 
Still not starting...

New ECM - no start - fuel pump not running.

To reiterate new parts:

Spark Plugs / Wires
Oil Pressure Switch
Fuel Pump Relay
ECM
Fuel Pump - Entire Assembly
Battery

I have power for 2 sec while cranking at the following places:

ECM port B2,
Fuel Pump in ,
Out side of fuel Pump Relay.

Following copied from earlier post so people don't have to scroll back - all result in NO START:

1. Tested voltage at relay. With key on I have 12v at power IN connection i.e. "A".

2. When turning the key I have 12v for about 2 sec at the output side of the relay. "E"

3. I tested the other end of "E" at the fuel pump assembly and have 12v for 2 sec.

To me the means that the existing wire is OK!

4. When turning key and holding the relay in hand can feel the click and 2 sec later another click.

5. Connected 12v to red wire at relay. I have 12v at the fuel pump assembly.

6. Connected new 14 gauge wire (temporary splice) from "E" to the fuel pump assembly. I have 12v at the fuel pump assembly.

7. I have tested the ground from fuel pump assembly to frame using continuity. Result is .000 on the meter.


Have not tried the noid light because if the fuel pump does not run then the injectors will not release fuel.

Since the engine runs when I apply 12v directly to the fuel pump does that CONFIRM that my Coil, Pickup coil, Spark plugs and wires, distributor cap, rotor, TCM are all ok ?
 
If it's running with power to fuel pump bypassing fuel pump relay then yes, they are fine...

On B2 there should be a 2 second on with key on even if you don't go to crank, as soon as you turn to crank it should again have power. Mine does I just checked! Yours does not? Why?

Then if there is a crank signal to C9 when key is cranked the fuel pump trigger at A1 turns relay back on and looks for the signal again at B2.

Do you have power at Orange wire B1 and C16 Batt Power? Key off, key on, key Crank? Should be hot always.

Do you have power at Pink wire A6 Ignition, should be hot key on and key crank? Should be hot key on and key crank.

I'm wondering if your ignition switch at bottom of column is faulty? This will prove ECM has all Batt power and Ign power needed for operation. Something is not triggering fuel pump relay in Crank! But it does Key On?
 
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Thanks eagle mark for confirming that my coil, pickup coil, plugs and wires, cap, rotor and ICM are all ok. That helps.

I am very tired, physically, mentally and emotionally. It's like 7 days now ?

Decided to just throw the money at it. Bought a new ignition switch and key.

Came back from the store and my son cleaned up everything. Guess I am done for the day. (He sure gets a lot done when I am not around and it's near clean up time, and it's going to be his damn truck.)

Will install on Monday.

Thanks to all!
 
Don't bother, it's not the key switch, it may be the ignition switch on bottom of column...

Your trying hard and this is not an easy find, I've never seen it before. But go through this before you go and just replace another part, I'm trying to figure out what is wrong?

On B2 there should be a 2 second on with key on even if you don't go to crank, as soon as you turn to crank it should again have power. Mine does I just checked! Yours does not? Why?

Then if there is a crank signal to C9 when key is cranked the fuel pump trigger at A1 turns relay back on and looks for the signal again at B2.

Do you have power at Orange wire B1 and C16 Batt Power? Key off, key on, key Crank? Should be hot always.

Do you have power at Pink wire A6 Ignition, should be hot key on and key crank? Should be hot key on and key crank.

I'm wondering if your ignition switch at bottom of column is faulty? This will prove ECM has all Batt power and Ign power needed for operation. Something is not triggering fuel pump relay in Crank! But it does Key On?
 
what he said... the key switch will have nothing to do with it, other than a bunch of work pulling the column apart.. :doah:

check the output of the rod-activated switch on top of the column down at the base.. iirc, it's 2 3/8's screws hold it in place... you can use a small screwdriver to manually activate it once off the column...

it's possible one of the contacts is burned out, allowing to crank only.. never seen it, but certainly possible..
 
ok

Ok will avoid the key change.

I need a day off. I will replace the ign switch Monday and if it does not start then will perform the tests the eagle mark suggests.

Thanks guys.
 
I appreciate the PM, but honestly, until you stop throwing parts at the problem, and ignoring troubleshooting advice (from all, not just me), I feel I'm wasting time here.

You said you didn't have money for a test light, so you went out and bought an ECM, a key switch, and now an ignition switch?

I'm not trying to hurt your feelings, but I obviously don't have the patience or tolerance these other guys do.
 
THEMCGUIRE said:
Ok will avoid the key change.

I need a day off. I will replace the ign switch Monday and if it does not start then will perform the tests the eagle mark suggests.

Thanks guys.
Click to expand...
Test's first will show if you need an ignition switcth!

Don't forget the Crank signal!
 
You Said it.

dyeager535 said:
I appreciate the PM, but honestly, until you stop throwing parts at the problem, and ignoring troubleshooting advice (from all, not just me), I feel I'm wasting time here.

You said you didn't have money for a test light, so you went out and bought an ECM, a key switch, and now an ignition switch?

I'm not trying to hurt your feelings, but I obviously don't have the patience or tolerance these other guys do.
Click to expand...

You are right. I have lost my patience. It should be noted that I am 62 years old, big bellied, disabled, bad vision, and out of shape. I am only doing this because money is tight with all I have been spending on the body rebuild. (referring to my "WTF Do I do now - 1988 K5" thread.)

I did not want to spend $25 buck on a test lite that I figure I will only use this one time and if the fuel pump is not running why bother testing the injectors.

I bought the ECM because eagle mark said that if I have power at ECM port B2 during cranking that it is likely that the ECM is bad. When the new ECM failed to solve the problem someone else suggested the Ignition switch and / or Key.

I would rewire the entire circuit if I could understand that diagram. The circuit from "E" on the relay connects to B2 on the ECM and the oil pressure switch and to "A" on the fuel module and to the fuel pump.

AND, "C" on the fuel module also connects to the IGN across a "20A Gage" ???????

It would make more sense if the diagram showed that only the fuel module connects to the fuel pump.
 
THEMCGUIRE said:
I bought the ECM because eagle mark said that if I have power at ECM port B2 during cranking that it is likely that the ECM is bad. When the new ECM failed to solve the problem someone else suggested the Ignition switch and / or Key.
Click to expand...
I was following the GM Diagnostic flow chart and that is what is suggested. But you do not have power at B2 in crank, only 2 seconds key on, so replacing ECM is not called for.

It may be Ignition Switch but that is not the same as a key cylinder/switch.

If you follow the last instructions I left we can see if it is an Ignition switch issue or the Crank Signal to C9

THEMCGUIRE said:
You are right. I have lost my patience. It should be noted that I am 62 years old, big bellied, disabled, bad vision, and out of shape. I am only doing this because money is tight with all I have been spending on the body rebuild. (referring to my "WTF Do I do now - 1988 K5" thread.)
.
Click to expand...
Well your just like me but a few years older and can afford a body rebuild! Calm down, look at other tests! We'll find it.

THEMCGUIRE said:
I did not want to spend $25 buck on a test lite that I figure I will only use this one time and if the fuel pump is not running why bother testing the injectors.
Click to expand...
You don't need a noid light. But trying to do this without a test light and DVM is near impossable.

THEMCGUIRE said:
I would rewire the entire circuit if I could understand that diagram. The circuit from "E" on the relay connects to B2 on the ECM and the oil pressure switch and to "A" on the fuel module and to the fuel pump.

AND, "C" on the fuel module also connects to the IGN across a "20A Gage" ???????

It would make more sense if the diagram showed that only the fuel module connects to the fuel pump.
Click to expand...
Your Blazer should not have a Fuel Module! That is only available on HD trucks. It's a timer to run fuel pump 20 seconds after shut down to cool TBI fuel.

If you look at wiring left the Oil Pressure Switch is redundant/second circuit, and provide power when oil pressure is reached closing connection, either one will provide power to fuel pump.

Your trying hard and this is not an easy find, I've never seen it before. But go through this before you go and just replace another part, I'm trying to figure out what is wrong?

On B2 there should be a 2 second on with key on even if you don't go to crank, as soon as you turn to crank it should again have power. Mine does I just checked! Yours does not? Why?

Then if there is a crank signal to C9 when key is cranked the fuel pump trigger at A1 turns relay back on and looks for the signal again at B2.

Do you have power at Orange wire B1 and C16 Batt Power? Key off, key on, key Crank? Should be hot always.

Do you have power at Pink wire A6 Ignition, should be hot key on and key crank? Should be hot key on and key crank.

I'm wondering if your ignition switch at bottom of column is faulty? This will prove ECM has all Batt power and Ign power needed for operation. Something is not triggering fuel pump relay in Crank! But it does Key On?
Click to expand...
 
It stopped raining. I will replace the ignition switch since I bought it already and if that does not work will do your other tests and get back to you.

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Ok after a few trys I found that I was putting the switch in upside down . What a dumb ass I can be.

It's in but does not start. Actually even connected to another running car battery it is not turning over like it did. sluggish sounding.

It has started raining again. will go back and to other tests when it stops.
 
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test results

Bought a $5.00 test light

On B2 there should be a 2 second on with key on even if you don't go to crank, as soon as you turn to crank it should again have power.

I have power at B2 when turning on key that lasts for 2 seconds. On cranking I have power again.

Then if there is a crank signal to C9 when key is cranked the fuel pump trigger at A1 turns relay back on and looks for the signal again at B2.

I have a light when cranking to C9

Do you have power at Orange wire B1 and C16 Batt Power? Key off, key on, key Crank? Should be hot always.



Yes I have power to B1 and C16 under all 3 conditions.

Do you have power at Pink wire A6 Ignition, should be hot key on and key crank? Should be hot key on and key crank.

I have power at A6 both conditions.

I have replaced the ignition switch.

Using Bypass wire on relay I have power at purple wire at fuel pump assembly. I then attached the test light to positive power and tested the ground wire at the fuel pump relay and at the bolt where the ground meets the frame. Test light lights up.

Again put 12 volt from battery to fuel pump. THis is a brand new fuel pump. No WIRRING. Could I have burned out the fuel pump with all this testing ?

Can the fuel pump be tested OFF the truck ? Put in a bucket of water and apply 12v ? will water hurt the pump ?

Also went back and tested C3. It lights with key on but does not light during cranking.

btw - engine is connected via jumpers to a running car but rotation rate is now sluggish. So i sprayed 1 shot of starter fluid in and it started and ran until the started fluid was gone.
 
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THEMCGUIRE said:
Bought a $5.00 test light

On B2 there should be a 2 second on with key on even if you don't go to crank, as soon as you turn to crank it should again have power.

I have power at B2 when turning on key that lasts for 2 seconds. On cranking I have power again.Check!

Then if there is a crank signal to C9 when key is cranked the fuel pump trigger at A1 turns relay back on and looks for the signal again at B2.

I have a light when cranking to C9Check!

Do you have power at Orange wire B1 and C16 Batt Power? Key off, key on, key Crank? Should be hot always.


Yes I have power to B1 and C16 under all 3 conditions.Check!

Do you have power at Pink wire A6 Ignition, should be hot key on and key crank? Should be hot key on and key crank.

I have power at A6 both conditions.

I have replaced the ignition switch.
Check!
Using Bypass wire on relay I have power at purple wire at fuel pump assembly. I then attached the test light to positive power and tested the ground wire at the fuel pump relay and at the bolt where the ground meets the frame. Test light lights up.

Again put 12 volt from battery to fuel pump. THis is a brand new fuel pump. No WIRRING. No Good! Bad Fuel Pump if you had power and ground hooked up? Could I have burned out the fuel pump with all this testing ? Doubt it, I ran one on the wall off my test bench for years till I put in a light bulb...

Can the fuel pump be tested OFF the truck ? Put in a bucket of water and apply 12v ? will water hurt the pump ? Why? It does not run?

Also went back and tested C3. It lights with key on but does not light during cranking. C3 is a typo from wiring disagram copy, it's an IAC wire, disregard.

btw - engine is connected via jumpers to a running car but rotation rate is now sluggish. So i sprayed 1 shot of starter fluid in and it started and ran until the started fluid was gone. Clean Batt terminals, charge batt, load test, should not need a jump start and still ne low power/slow crank. If something is drawing all this power there will not be enough left to turn on fuel pump relay!
Click to expand...
Reply in RED!
 
Thanks again Eagle!

Was asking about running the fuel pump outside the truck because I still have the one i removed last week and was wondering if that was bad after all.

So the slow crank is a condition due to insufficient power from the battery ? This is a new battery and the positive connection is also new. Starter is also new.

Could all these temporary wires be pulling the power away from the starter ?

I will remove all the temporary wiring and try again.
 
Could be a bad connection anywhere or just a low batt? Just because it's a new part does not mean it's a good part?
 
sort of update

Despite moving to Vegas in the fall the wife insisted that I get our pool up and running for the next 2 months. Aaargh.

So not a lot of time today to work on the truck but I did get to test the OLD fuel pump.

I put 12v and ground to it's connections, immersed it into a plastic jar full of Marvel with a fuel line up out of the pump and back into the jar.

Go a wirring noise but no fluid was pumping.

pulled pump out of the marvel and something was making noise but the lower impeller was not spinning.

hopefully back to the truck tomorrow.
 
She lives !!!!!!!!!!!!

OMFG... All along I was using the purple wire to the fuel pump assembly. It was the gray.

We took the pump out. Immersed it into marvel mystery oil, applied 12v and it ran fine.

Tested all the wires from both sides of the fuel assembly and found that the purple is for the gauge and the grey was for the pump.

Ran a wire from the exit on the relay to the grey wire going to the pump and bang zoom she started right up.

Please feel free to diss me for my stupidity in buying all those parts that I did not actually need.

Oh well, you live and you learn.

Thanks for all your help, advise and other comments.


(On the negative side, the fuel coming out of the injectors is a stream, not a mist. I ordered the noid light. When it arrives I will test for injector pulse.)

I found these injectors on another post: http://marine-performance-parts.com/57gmtbiinjectorspair.aspx.

Does anyone have any comments about them.

They cost $170.00 for the pair and they say that

"each pair is flow matched within 1% of each other. These are not new but are serviced and cleaned. "

Looking for comments if these are good and if the noid light reports the the pluse is correct.
 
I hate when that happens. There's not a single person here who has not made a dumb mistake they feel embarressed for, so no diss-ing... :waytogo:


Well old injectors then sitting six years they just need a service!
http://www.mrinjector.us/

You should have the tank cleaned out by now along with fresh fuel and new filter. You'll be good to go.
 
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