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Old 06-07-2010, 01:24 PM
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350 TBI Starting when i pour gas from glass to carb

Hello guys !
I have a '88 Chevy G20 Van with 350 TBI.
When i turn key to ON position i can hear fuel pump for 2 seconds.
When i try to crank, engine not start (fuel injectors pour some gas drop) but when i pour some gas into carb engine starts and running excellent for about 3-7 seconds, and then runs badly and i is idling i must kicking gas pedal to make engine runs, but when i pour again some gas to carb runs excellent. And one more thing - my oil pressure gauge is not moving (bad oil pressure sensor ??)
Thanks
Michael Paczka
POLAND

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Old 06-07-2010, 01:35 PM
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I'd have to pull up some old diagrams, but many of the older GMs use oil pressure to power up the fuel pump. Get in a wreck, engine dies, no oil pressure, no fuel pump, no fire, no lawsuits.

Secondly, if the pump is continuing to run while it dies, 9 PSI and lower fuel pressure will cause similar symptoms to yours. 6-9 PSI is just enough to tease you into thinking "it just may run", but it'll die or hardly move.
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Old 06-07-2010, 01:45 PM
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Quote:
Originally Posted by custom_rider
Hello guys !
I have a '88 Chevy G20 Van with 350 TBI.
When i turn key to ON position i can hear fuel pump for 2 seconds.
When i try to crank, engine not start (fuel injectors pour some gas drop) but when i pour some gas into carb engine starts and running excellent for about 3-7 seconds, and then runs badly and i is idling i must kicking gas pedal to make engine runs, but when i pour again some gas to carb runs excellent. And one more thing - my oil pressure gauge is not moving (bad oil pressure sensor ??)
Thanks
Michael Paczka
POLAND
For your own sake- Do NOT pour gas into the carb to keep the engine running. Priming it before starting it is one thing, but the engine will often spit back through the intake-and if you're holding a glass of gasoline in your hand when that happens...

Get a can of starting fluid- the kind w/some lubrication in it. Much better on the engine than raw gas, and safer to boot.
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Old 06-07-2010, 01:56 PM
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OK you need to go here! there are lots of good info on tbi there is also a tbi fourm so start out here! www.fullsizechevy.com

Craig
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Old 06-07-2010, 01:56 PM
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Quote:
Originally Posted by cobalt327
For your own sake- Do NOT pour gas into the carb to keep the engine running. Priming it before starting it is one thing, but the engine will often spit back through the intake-and if you're holding a glass of gasoline in your hand when that happens...

Get a can of starting fluid- the kind w/some lubrication in it. Much better on the engine than raw gas, and safer to boot.
yeaaa, you are right
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Old 06-07-2010, 02:06 PM
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Quote:
Originally Posted by KMatch
I'd have to pull up some old diagrams, but many of the older GMs use oil pressure to power up the fuel pump. Get in a wreck, engine dies, no oil pressure, no fuel pump, no fire, no lawsuits.

Secondly, if the pump is continuing to run while it dies, 9 PSI and lower fuel pressure will cause similar symptoms to yours. 6-9 PSI is just enough to tease you into thinking "it just may run", but it'll die or hardly move.
Can i baypass oil pressure switch to check problem ?
Michael
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Old 06-07-2010, 06:18 PM
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Quote:
Originally Posted by custom_rider
Can i baypass oil pressure switch to check problem ?
Michael
There are a couple of easier things to do. If you can find it, there is a prime connector under the hood. It's a red wire with a female spade terminal on it. It's usually in the area under the master cylinder on trucks, or behind the plastic cover on the passenger side of trucks. On vans? I'd look at the harness for tape that appears to serve no real purpose. Many times the prime connector is taped under a main harness out of sight. If you find it, put 12 volts to it. Of course, if the relay is working right, the prime connector goes open when you turn the key on, so:

Another option is to find the fuel pump relay, also under the hood. It's a relay with dark green/white, black/white, orange, red, and tan/white wires. Find that one and jump to orange to tan/white. This will run the fuel pump full time to test it. Make sure the orange is hot, first.

This makes sure the pump runs. If it still runs like crap, it's time to tap into the line and check the pressure. 12 PSI is to be expected. 11-13, good. 6-9, no bueno.
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Old 06-07-2010, 06:21 PM
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Easier yet, pull the fuel filter. Classic plugged filter syptoms.
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Old 06-07-2010, 06:33 PM
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yes these things are really picky about fuel volume pressure. they will start and run but usually when the pump is dying they wont drive for chit. no power and sputtering and bogging out but wont die.

fuel pressure has to be good or they do funny things. just because the pump runs doesnt means its pumping enough on the TBI versions anyways.

seen lots of them do this, and have replaced lots due to this.

some will plain die completely and not run at all. others still run but dont pump enough. usually they start and idle fine though. but wont do anything else very well.

check spark make sure its white also.

if cap and rotor are very old then pull and check center button on the tbi engines they burn out pretty quick and you dont evne know it and cause all kinds of running issues. if you pull the cap and theres a bunch of black powder in the center of the rotor then its time for a cap and rotor. commonly are burnt on all the tbi engines.... mines done on my awesome strong running 202k miles '91 s-10 4.3 daily driver right now as i type this and its only a year old., its burnt into the plastic of the cap, totally gone. they burn out pretty quick i dont know why....


so....
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Old 06-28-2010, 12:23 PM
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Hello guys
Hello
I don't find the problem, but i'm one step forward. I change the fuel filter, and my G20 starts for about 5-10 sec. when i crank , but i have other trouble ;
Engine is hot, i ride about 30-40 minutes on straight road, and there is a turn (left or right) i break a little, turn and my engine is working poorly - like out of gas, but tank is full, i must kick a gas pedal and then it's ok - sometimes it's dead, then i must crank it very hard.... so i don't know what i should do (i read on forums that ; it can be a ignition module, ignition coil, fuel pump , fuel pressure regulator, oil pressure switch ...) i have all this things in my garage - what shoul i check first ???

Michael Paczka from POLAND
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Old 06-28-2010, 01:07 PM
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I would check Fuel Pressure-
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Old 06-28-2010, 01:16 PM
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I plugged fuel filter will often times hurt the pump as well.
You need to check the pressure to be sure of what is going on
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Old 06-28-2010, 01:22 PM
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yeah, i know this, but i don't have a gauge (but i have a new fuel pump...) Now i'm thinking : " remove a fuel tank and change a pump, or try everything else ; coil etc.)
Michael
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Old 06-28-2010, 04:48 PM
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Quote:
Originally Posted by custom_rider
Hello guys !
I have a '88 Chevy G20 Van with 350 TBI.
When i turn key to ON position i can hear fuel pump for 2 seconds.
When i try to crank, engine not start (fuel injectors pour some gas drop) but when i pour some gas into carb engine starts and running excellent for about 3-7 seconds, and then runs badly and i is idling i must kicking gas pedal to make engine runs, but when i pour again some gas to carb runs excellent. And one more thing - my oil pressure gauge is not moving (bad oil pressure sensor ??)
Thanks
Michael Paczka
POLAND
The starting system is that when the key is initiated the starter turns the engine, the ignition comes on and a time out relay is engaged which runs for about 8 seconds to start the fuel pump. If the engine fires the initiating relay is replaced by a run relay as the former drops out. If you can hear the pump the relays are probably OK but the pump has to deliver fuel to the TBI. there's lots of reasons why it might not.

1) Inlet filter plugged ahead of the pump, being a 1988 one can imagine what it looks like.

2) Pump worn out or rotor not turning with the motor.

3) Regulator dysfunctional bypass all fuel back to the tank.


The fact the engine will fire on a prime of fuel but not keep going is proof positive that it isn't getting fuel. If you have the equipment, a pressure test at the TBI would be proof-positive for fuel being delivered there. Oil pressure may or may not be an issue, some looked for oil pressure, others don't they look for RPMS and use a gravity roll over switch to kill the engine in the event of an upset. They all look for a tach signal from the computer.

Bogie
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Old 07-28-2010, 12:28 PM
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Problem Solved Thanks Guys !!!!

Hello !
I solved the problem :

- i totally removed fuel tank (full of mess and water)
- changed fuel pump
- changed fuel filter
- and PRESSURE REGULATOR !

My chevy runs like new !

/RIDE NOW, WORK LATER/
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