98 blazer intermittent fuel related starting
missmopar
04-29-2009, 09:05 PM
Sometimes start, most times no start. When it pumps it makes good pressure it starts up and stays started, no leak down. Then a hot start a little later while holding about 40 poundsw it may not come back.
Trying to tell if the pump has good ground or not or is comming on every time. Suspect ground or connection on the pump. If the switch is working fine for everything else could it be the switch.
Trying to tell if the pump has good ground or not or is comming on every time. Suspect ground or connection on the pump. If the switch is working fine for everything else could it be the switch.
MT-2500
04-30-2009, 08:10 AM
Sometimes start, most times no start. When it pumps it makes good pressure it starts up and stays started, no leak down. Then a hot start a little later while holding about 40 poundsw it may not come back.
Trying to tell if the pump has good ground or not or is comming on every time. Suspect ground or connection on the pump. If the switch is working fine for everything else could it be the switch.
Welcome to AF.
Does it do it more on a cold start or hot start?
What engine?
What are you fuel pressure readings cold start an hot start and after 30 minutes on road running?
Have you checked for good ground and power to fuel pump at all time?
Make sure the pump has good pressure cold an hot.
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.
Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.
Trying to tell if the pump has good ground or not or is comming on every time. Suspect ground or connection on the pump. If the switch is working fine for everything else could it be the switch.
Welcome to AF.
Does it do it more on a cold start or hot start?
What engine?
What are you fuel pressure readings cold start an hot start and after 30 minutes on road running?
Have you checked for good ground and power to fuel pump at all time?
Make sure the pump has good pressure cold an hot.
The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.
Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.
missmopar
04-30-2009, 11:02 AM
4.3 w blazer with spider injection it is a vortec cpi. Pressures look fine but I will run it down the road and run it hot. It looks more like electrical problem... turn key this morning, no pump. Wind the motor up and after oil pressure gets up it kicks in pressure and running. Bleed it down, turn the key, then get the 2 second run, everything is ok. I will heat it up but I am mostly looking at further grownd or relayor computer swith intermittent activity I think. I realy appreciate your posts.
Where is the relay for the 2 second startup or the oil pressure relay.
I am checking a relay in the box on the driver fender for the fuel pump. I could not locate a test wire for this vehicle like is said for others , but found the grey to the pump under the fender and pulled it through to stick it for test runs. What color is the ground on the pump, I think I will have to lower the tank when I get back there. Considering direct wiring the pump and beefing up the ground it I dont locate something, to rule out bad conections or just an intermittent bad pump which is new for one month. Are there any pump pressure switches or tank switches that could knock out the pump intermittently.
Thanks again, I will not give up!
Where is the relay for the 2 second startup or the oil pressure relay.
I am checking a relay in the box on the driver fender for the fuel pump. I could not locate a test wire for this vehicle like is said for others , but found the grey to the pump under the fender and pulled it through to stick it for test runs. What color is the ground on the pump, I think I will have to lower the tank when I get back there. Considering direct wiring the pump and beefing up the ground it I dont locate something, to rule out bad conections or just an intermittent bad pump which is new for one month. Are there any pump pressure switches or tank switches that could knock out the pump intermittently.
Thanks again, I will not give up!
MT-2500
04-30-2009, 11:53 AM
4.3 w blazer with spider injection it is a vortec cpi. Pressures look fine but I will run it down the road and run it hot. It looks more like electrical problem... turn key this morning, no pump. Wind the motor up and after oil pressure gets up it kicks in pressure and running. Bleed it down, turn the key, then get the 2 second run, everything is ok. I will heat it up but I am mostly looking at further grownd or relayor computer swith intermittent activity I think. I realy appreciate your posts.
Where is the relay for the 2 second startup or the oil pressure relay.
I am checking a relay in the box on the driver fender for the fuel pump. I could not locate a test wire for this vehicle like is said for others , but found the grey to the pump under the fender and pulled it through to stick it for test runs. What color is the ground on the pump, I think I will have to lower the tank when I get back there. Considering direct wiring the pump and beefing up the ground it I dont locate something, to rule out bad conections or just an intermittent bad pump which is new for one month. Are there any pump pressure switches or tank switches that could knock out the pump intermittently.
Thanks again, I will not give up!
The 2 second prime up is built in the VCM/PCM.
But the ign system spark/rpm signal has to trigger.
The fuel pump relay should turn on pump key on or engine crank.
Oil pressure switch does not switch any thing ubtill you have oil pressure and is only there if relay fails.
Check for power to fuel pump orange wire and out of relay on gray fuel pump wire.
What brand of fuel fump did you install?
Did it have a rewire plugin kit with it?
One black on it is ground for fuel pump and the other black should be gauge ground.
When pump does not turn on check for good spark to plugs.
Let us know what you find.
Where is the relay for the 2 second startup or the oil pressure relay.
I am checking a relay in the box on the driver fender for the fuel pump. I could not locate a test wire for this vehicle like is said for others , but found the grey to the pump under the fender and pulled it through to stick it for test runs. What color is the ground on the pump, I think I will have to lower the tank when I get back there. Considering direct wiring the pump and beefing up the ground it I dont locate something, to rule out bad conections or just an intermittent bad pump which is new for one month. Are there any pump pressure switches or tank switches that could knock out the pump intermittently.
Thanks again, I will not give up!
The 2 second prime up is built in the VCM/PCM.
But the ign system spark/rpm signal has to trigger.
The fuel pump relay should turn on pump key on or engine crank.
Oil pressure switch does not switch any thing ubtill you have oil pressure and is only there if relay fails.
Check for power to fuel pump orange wire and out of relay on gray fuel pump wire.
What brand of fuel fump did you install?
Did it have a rewire plugin kit with it?
One black on it is ground for fuel pump and the other black should be gauge ground.
When pump does not turn on check for good spark to plugs.
Let us know what you find.
missmopar
04-30-2009, 04:43 PM
An Airtech pump from Orielly, has one year waranty. When the pressure is there the blazer hits good. The pump had a wire kit and I used it.
When I hot wire the pump it works sometimes. Foing back to tapping the tank when I try to fire it up and work the connections. It is narrowing in on the pump being a bad starter. I will recheck the fuel filter although It was new too, Pressure is fine when it works so I think its a poor starting pump. Continuety works on ground and hots to the pump.
Thanks a Heap still workin on it
When I hot wire the pump it works sometimes. Foing back to tapping the tank when I try to fire it up and work the connections. It is narrowing in on the pump being a bad starter. I will recheck the fuel filter although It was new too, Pressure is fine when it works so I think its a poor starting pump. Continuety works on ground and hots to the pump.
Thanks a Heap still workin on it
MT-2500
04-30-2009, 06:16 PM
An Airtech pump from Orielly, has one year waranty. When the pressure is there the blazer hits good. The pump had a wire kit and I used it.
When I hot wire the pump it works sometimes. Foing back to tapping the tank when I try to fire it up and work the connections. It is narrowing in on the pump being a bad starter. I will recheck the fuel filter although It was new too, Pressure is fine when it works so I think its a poor starting pump. Continuety works on ground and hots to the pump.
Thanks a Heap still workin on it
Airtex pump is bad news. :nono:
Most are pure junk.
I have never saw one pass the pressure test.
And very few last very long.
Check for power and ground and wiring plug to it and if it still gives problems have O'rielly replace it with a delphi oem pump.
Also on the wiring kit pitch the crimp on wire terminals and solder the wires and seal with sealer and heat shrink
May cost you 25$ more for delphi over airtex but I would hit them with a labor claim if pump checks bad.
They should know better than sell anyone a Airtex pump.
Pin them down on how many airtex pumps gets returned.:rofl:
Let us know how it goes.
When I hot wire the pump it works sometimes. Foing back to tapping the tank when I try to fire it up and work the connections. It is narrowing in on the pump being a bad starter. I will recheck the fuel filter although It was new too, Pressure is fine when it works so I think its a poor starting pump. Continuety works on ground and hots to the pump.
Thanks a Heap still workin on it
Airtex pump is bad news. :nono:
Most are pure junk.
I have never saw one pass the pressure test.
And very few last very long.
Check for power and ground and wiring plug to it and if it still gives problems have O'rielly replace it with a delphi oem pump.
Also on the wiring kit pitch the crimp on wire terminals and solder the wires and seal with sealer and heat shrink
May cost you 25$ more for delphi over airtex but I would hit them with a labor claim if pump checks bad.
They should know better than sell anyone a Airtex pump.
Pin them down on how many airtex pumps gets returned.:rofl:
Let us know how it goes.
missmopar
05-04-2009, 10:18 PM
Delphi pump in and I am road testing it soon, its working fine now. Cost me 100 dollars to upgrade I think its about 300 total and an expta pump change. I appreciate the help and discussions, this is a great idea for auto fixers and anyone who can avoid being slaves to the coorprate shops.
Thanks again you guys,,,Realy;
Thanks again you guys,,,Realy;
MT-2500
05-05-2009, 08:20 AM
Delphi pump in and I am road testing it soon, its working fine now. Cost me 100 dollars to upgrade I think its about 300 total and an expta pump change. I appreciate the help and discussions, this is a great idea for auto fixers and anyone who can avoid being slaves to the coorprate shops.
Thanks again you guys,,,Realy;
You are welcome.
And thanks for posting back how it went.
If they charged you a 100 $ to switch over you got robbed a second time by the parts place.:lol2:
First time when they sold you a junk aftermarket pump and second time on the 100$ for switch over.
Plus they should have paid a labor claim for the first bad pump they sold you.
But live and learn.
Good Luck
Thanks again you guys,,,Realy;
You are welcome.
And thanks for posting back how it went.
If they charged you a 100 $ to switch over you got robbed a second time by the parts place.:lol2:
First time when they sold you a junk aftermarket pump and second time on the 100$ for switch over.
Plus they should have paid a labor claim for the first bad pump they sold you.
But live and learn.
Good Luck
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