Engine won't start

1993 GMC VAN

ALBEE9

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My problem started when I started getting black smoke from the exhaust so i thought change the spark plugs which were very fowled just to get it home .

but still black smoke so i changed the fuel injectors still hard to start so to make a long story short .

I have replaced : the spark plugs,the wires distributor,rotor, the ignition coil,EGR solenoid ,and fuel injectors and it still won't start .

So I'm thinking it maybe it's the Fuel Injector Pressure Regulator because i get a stream of gas not a mist like it should be .

I'd like to know if I'm right .

AS OF 3/3/09

well i blew out the return line for fuel and it started rough but it was running .

Now it won't start at all .
i get it to turn over but it just won't start i have checked everything i can think of .

I checked or replaced the list below.

(REPLACED) spark plugs,the wires distributor,rotor, the ignition coil,EGR solenoid ,and fuel injectors .
(CHECKED)all the connections ,Battery,starter,fuel pressure, blew out the fuel line

Please help

thank you for your time

Mar 15, 2009 at 9:00 AM

RACEFAN966

CERTIFIED EXPERT
5,029 POSTS

Two things come to mind first the MAP sensor sounds like it has fallen out or is not working causing the engine to think you are under full throttle all the time fouling the plugs or the fuel pump is weak causing the fuel not to atomize. Here are some guides to help us find the problem.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

and

https://www.2carpros.com/articles/car-cranks-but-wont-start

Please let us know what you find.

Cheers

Mar 15, 2009 at 9:48 AM

ALBEE9

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11 POSTS

yes I'm getting good spark , compression,fuel .

I have all the tools i need

Mar 15, 2009 at 12:49 PM

RACEFAN966

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Ok what is the fuel pressure? Have you checked the coolant temp sensor? If not unplug the sensor and check ohms of resistance across the terms on the sensor (not the wire harness) and give me that reading and what the temp is at the time, if you test it cold air temp will be fine.

Mar 16, 2009 at 1:19 PM

ALBEE9

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11 POSTS

ok fuel pressure is at 10 psi ,ohms of resistance across the terms on the sensor are inconclusive getting a new sensor However I have been getting a code 15 for that sensor.

Mar 16, 2009 at 2:25 PM

RACEFAN966

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Ok the fuel pressure is a on the lower end of ok it should be 9 to 13 psi so not bad yet. With the coolant temp sensor once you replace it let me know how it goes.

Mar 17, 2009 at 10:46 AM

ALBEE9

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11 POSTS

well replaced the temp sensor , still not starting .

I'm going to pull the converter and recheck all the sensors that I have not replaced yet see where that gets me.

I'm also thinking about the timing

Mar 18, 2009 at 7:33 AM

RACEFAN966

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Ok does this thing spit or sputter or even try to start? I am thinking that we should look into the timing control module it is different and seperate from the ignition module. I can walk you through the test if you like. Here is pic of how it connected and such. So if you like I will walk you through the test. Get back to me

Mar 18, 2009 at 10:33 AM

ALBEE9

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Yes it does try to start Ok I tested that and all other sensors that have to do with the starting system .

All seem to be good .

P.S I did record the sound it makes when i try to start it

Mar 18, 2009 at 3:06 PM

RACEFAN966

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Ok lets test a couple of things ok. First I would like to test the TPS (throttle position sensor). What I need you to do is back probe the wires one at a time first the gray wire should have 5 volts with key on engine off. Then the Dk blue wire this one is the reference wire it tells the computer how wide the throttle is open ok. So with the key on engine off throttle closed should be .8 to 1 volt, now slowly raise the throttle it should slowly and steadly increase to 4.5 to 5 volts when you get to wide open. Now while lifting and lowering the throttle watch for any glitches or drops or increases that are not normal. Meaning it should slowly and steadly increase as you lift the throttle and decrease as you lower it. Just for kicks check the firing order of the engine ok I know that this sounds redundent but hey this will happen to the best of us where we were one wire off or something so please just check 1-8-4-3-6-5-7-2.

Mar 19, 2009 at 10:14 AM

ALBEE9

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I'm not getting any voltage at all I did hook up my sensor tester to the tps it's self and every thing was good, and the firing order is good

Mar 19, 2009 at 1:53 PM

RACEFAN966

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If I understand right you are getting no voltage to the tps at all. The gray wire doesn't have 5 volts with key on engine off? If you would unplug the tps and check the gray wire for 5 volts, check the other wire just to make sure that the wiring diagram I am looking at it correct. If you have no voltage to the tps then it won't start and we need to check the gray wire for any breaks first and if there is no breaks then we need to look at the PCM and do some test there. Get back to me and we will go from there.

Mar 20, 2009 at 10:06 AM

ALBEE9

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I found the problem with the voltage then I did the test you asked me to do and everything is good there.

I notice that when I try cranking it I was not getting as much gas from the injectors as i was before.

so I checked the pressure and it went up to 10 psi then down to 3 psi .

what happen ???

Mar 20, 2009 at 1:04 PM

RACEFAN966

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Ok this may be the problem. Now what we need to do is spray carb clean down the throttle body does it start? I am thinking that maybe the fuel pump is bad. Get back to me.

Mar 21, 2009 at 9:26 AM

ALBEE9

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No It does not start that's what i thought.

If it was something like no fuel ,spark, compression or even if it was a sensor that was bad I would like to think that I would have gotten it running after a year ?

I'm trying to think outside the box what else would cause a no start

Mar 21, 2009 at 9:43 AM

RACEFAN966

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With the low fuel pressure there really is nothing else that could be the problem and with out the proper fuel pressure the rest is irrelivent at this point as any other tests we could do as the injector pulse and stuff would give false readings. So if the fuel pressure is low it is either the fuel pump or the fuel pressure regulator at this point. Get back to me and we will go from there.

Mar 21, 2009 at 7:47 PM

ALBEE9

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11 POSTS

Ok I changed the fuel pressure regulator , and still won't start, and the pressure still at 3 psi it won't go to 10 now as soon as it warms up I'm going to change the pump .

I also was playing with the timing,and now when I spray
starter fluid in it backfires where before it did nothing, so I am thinking that's the next step after the pump replacement.

Am I Right ??

Mar 24, 2009 at 6:48 AM

RACEFAN966

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If the pressure won't come up and there is power to the pump then yes that is correct I would replace the pump. This is the only thing that makes sense at this point with having fuel pressure but it being so low as it should be 9-13 psi.

Mar 24, 2009 at 10:10 AM

ALBEE9

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That did it I replaced the pump, and the engine fired right up ya! thanks for you help

Mar 25, 2009 at 7:10 AM

RACEFAN966

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Nice work, we are here to help, please use 2CarPros anytime.

Cheers

Mar 25, 2009 at 9:17 AM