Help needed - no start condition (no power to fuel pump & fuel injectors)
March 11th, 2016, 2:39 AM
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Help needed - no start condition (no power to fuel pump & fuel injectors)
Dear forum members,
I am new to Chevy, new to US cars.
Bought a non-running 1996 Chevy Express Van which does not start.
Have checked for spark - it is there.
So, no fuel then.
The fuel pump does not come on when ignition key is turned to start/run position.
Pump is working when directly fed from +12V
But the engine would not start when pump is turning (from direct +12V) and the ignition key is turned to start/run.
Engine cranks over but does not start, not even catching.
Fuel pump relay is OK, checked that.
Fuses OK.
Power wires from relay to pump OK.
To me it seems that engine control computer does not give +12V to fuel relay and injectors when cranking the engine.
But Why?
Where to look?
Now there is also an issue with the fuel level sender. The needle on the instrument panel has maxed out and stays there all the time. The pump has been changed but I do not know if the no start condition started after changing the pump or later.
Is there any chance that the malfunctioning fuel level sender/gauge might be sending wrong signals to VMC and it does not provide further +12V to fuel pump and injectors because of that?
I don`t think this Van has a PassLock system since there is no SECURITY light ON and no contacts/senders on the ignition keys (original).
Where should I look now to identify no power to fuel pump and injectors condition?
I would really appreciate any hints on this.
Thank`s in advance!
I am new to Chevy, new to US cars.
Bought a non-running 1996 Chevy Express Van which does not start.
Have checked for spark - it is there.
So, no fuel then.
The fuel pump does not come on when ignition key is turned to start/run position.
Pump is working when directly fed from +12V
But the engine would not start when pump is turning (from direct +12V) and the ignition key is turned to start/run.
Engine cranks over but does not start, not even catching.
Fuel pump relay is OK, checked that.
Fuses OK.
Power wires from relay to pump OK.
To me it seems that engine control computer does not give +12V to fuel relay and injectors when cranking the engine.
But Why?
Where to look?
Now there is also an issue with the fuel level sender. The needle on the instrument panel has maxed out and stays there all the time. The pump has been changed but I do not know if the no start condition started after changing the pump or later.
Is there any chance that the malfunctioning fuel level sender/gauge might be sending wrong signals to VMC and it does not provide further +12V to fuel pump and injectors because of that?
I don`t think this Van has a PassLock system since there is no SECURITY light ON and no contacts/senders on the ignition keys (original).
Where should I look now to identify no power to fuel pump and injectors condition?
I would really appreciate any hints on this.
Thank`s in advance!
March 11th, 2016, 9:32 AM
#2
How are you confirming the fuel pump relay is ok?
Have you swapped it with the starter relay to see. They are the same part number. Give that a try. If it does not crank, but you hear the pump run with key on for a couple seconds....then it was the relay.
Have you swapped it with the starter relay to see. They are the same part number. Give that a try. If it does not crank, but you hear the pump run with key on for a couple seconds....then it was the relay.
March 17th, 2016, 10:28 AM
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March 19th, 2016, 12:58 PM
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uhh ...
still no luck.
Spark is there. After I had cleaned distributor cap contacts I think the distance between cap contacts and rotor arm was too big to throw spark. I soldered a piece of brass to get few mm more and spark returned.
fuel - I have signal to spider injector - all 8 are pulsing at injector plug. I have directly connected +12V to fuel pump so it is delivering fuel to fuel lines.
I took out one spark plug and it looked like it has been sitting long without spark and fuel. it was no wet which indicates to me that fuel is not thrown into the cylinders.
Fuel pump has been changed some time ago, so normally should be OK.
BUT ... the engine cranks but does not fire.
Van has been sitting since last summer.
What`s wrong? Where to look further?
Shall I change fuel filter? Change spark plugs?
What about all that insufficient fuel pressure thing?
Thank`s!
still no luck.
Spark is there. After I had cleaned distributor cap contacts I think the distance between cap contacts and rotor arm was too big to throw spark. I soldered a piece of brass to get few mm more and spark returned.
fuel - I have signal to spider injector - all 8 are pulsing at injector plug. I have directly connected +12V to fuel pump so it is delivering fuel to fuel lines.
I took out one spark plug and it looked like it has been sitting long without spark and fuel. it was no wet which indicates to me that fuel is not thrown into the cylinders.
Fuel pump has been changed some time ago, so normally should be OK.
BUT ... the engine cranks but does not fire.
Van has been sitting since last summer.
What`s wrong? Where to look further?
Shall I change fuel filter? Change spark plugs?
What about all that insufficient fuel pressure thing?
Thank`s!
March 19th, 2016, 2:37 PM
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The distance between the rotor and cap contacts is a calibrated distance. If you don't get any spark unless you close that small gap a little bit your spark is too weak. Get a new rotor and cap so you can mark this off the list as a factor. They are fairly cheap and good insurance against problems down the road. How are you checking to see if you have good spark? Just because it merely sparks doesn't mean it will spark under compression. If you don't have one, I would get a real tester like this one: The HEI Spark Tester (The Best Spark Tester On the Market) Good article too.
Cheap. GearWrench 2756 - HEI Ignition Tester | O'Reilly Auto Parts
As far as fuel pressure, there is a minimum pressure the fuel injectors need to be able to work. I don't know specifically what it is on your make and model but it should be at least 40 PSI. The way to test this is fairly easy with a tester. Most of the auto parts places will let you borrow one with a deposit. It looks like a tire pressure gauge with an extra hose and seals made to tolerate fuel. Equus 3640 Innova Professional Fuel Injection Pressure Tester - Walmart.com At the front of the fuel rail is a Schrader (tire) valve. You will probably have to remove the intake tube between the air filter box and the throttle body to get to it. Connect the fuel tester to it and turn the key to the on position - DO NOT TRY TO CRANK. You will hear the pump turn on then off. See what the pressure is and make sure it doesn't drop more than a couple PSI. It is OK to turn the key off, wait, then on again if you need to.
Let us know the results of these 2 tests.
Cheap. GearWrench 2756 - HEI Ignition Tester | O'Reilly Auto Parts
As far as fuel pressure, there is a minimum pressure the fuel injectors need to be able to work. I don't know specifically what it is on your make and model but it should be at least 40 PSI. The way to test this is fairly easy with a tester. Most of the auto parts places will let you borrow one with a deposit. It looks like a tire pressure gauge with an extra hose and seals made to tolerate fuel. Equus 3640 Innova Professional Fuel Injection Pressure Tester - Walmart.com At the front of the fuel rail is a Schrader (tire) valve. You will probably have to remove the intake tube between the air filter box and the throttle body to get to it. Connect the fuel tester to it and turn the key to the on position - DO NOT TRY TO CRANK. You will hear the pump turn on then off. See what the pressure is and make sure it doesn't drop more than a couple PSI. It is OK to turn the key off, wait, then on again if you need to.
Let us know the results of these 2 tests.
Last edited by cropduster; March 19th, 2016 at 2:41 PM.
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March 19th, 2016, 3:03 PM
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Thank`s!
The spark on spark plug (attached to ignition lead and grounded to van chassie) does throw spark but rather small/weak to my eye.
Will get new distributor cap on monday. New rotor already sourced.
In case of weak spark - is it ignition coil problem or anything else? Central ignition lead is throwing 5x stronger spark than 1-8 ignition leads.
The spark on spark plug (attached to ignition lead and grounded to van chassie) does throw spark but rather small/weak to my eye.
Will get new distributor cap on monday. New rotor already sourced.
In case of weak spark - is it ignition coil problem or anything else? Central ignition lead is throwing 5x stronger spark than 1-8 ignition leads.
March 20th, 2016, 1:17 PM
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So got to test my fuel pressure and the results are following:
At key on ON - 60 psi
Key on START (cranking) - 45 psi
After releasing key pressure stays at 50-55 psi forever.
What does this mean - do I need 50+ psi at CRANKING?
If pressure stays after releasing key it means pressure regulator is good?
What is wrong?
Is the fuel pressure too low.
Will put new distributor cap and new rotor just to rule those out. I got spark but quite week to my eye.
But one plug I pulled was dry which to me says it does not see fuel as I have been trying to start this engine and cranking for several weeks.
What about fuel filter. Can that be stealing any psi from my fuel pressure? The pump has been changed some time ago ...
The engine is completely dead. It does not even catch a bit, just cranking without any hope if starting. Obviously either spark or fuel is not present ... But I have this 60-45 psi pressure, have pulse on spider injector plug and have some spark.
What am I missing there.
So annoying ...
Thanks
At key on ON - 60 psi
Key on START (cranking) - 45 psi
After releasing key pressure stays at 50-55 psi forever.
What does this mean - do I need 50+ psi at CRANKING?
If pressure stays after releasing key it means pressure regulator is good?
What is wrong?
Is the fuel pressure too low.
Will put new distributor cap and new rotor just to rule those out. I got spark but quite week to my eye.
But one plug I pulled was dry which to me says it does not see fuel as I have been trying to start this engine and cranking for several weeks.
What about fuel filter. Can that be stealing any psi from my fuel pressure? The pump has been changed some time ago ...
The engine is completely dead. It does not even catch a bit, just cranking without any hope if starting. Obviously either spark or fuel is not present ... But I have this 60-45 psi pressure, have pulse on spider injector plug and have some spark.
What am I missing there.
So annoying ...
Thanks
Last edited by KurBads; March 20th, 2016 at 1:55 PM.
