Unpredictable Stalling
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New User
Joined: Aug 2004
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From: Near Portland Oregon
Unpredictable Stalling
1990 7.3L Non Powerstroke
I have replaced the Fuel Transfer Pump and the Fuel Filter.
I am considering a fault in the Injector pump.
Some have suggested a possible fault in the fuel shutoff selonoid area.
It goes like stink when it runs. It developes irregular power just before it stalls. It may run 3 weeks before it stalls and then it may stall 3 times in one day too. Currently it will no longer start and I suspect it is not getting any fuel at all.
I am going to try starting it with the Fuel Shutoff/Cold Timing advance cover detached. I am told that it will run if the selonoid is the cause.(of course this is messy)
I do not have any special gages or fuel pressure measuring tools at my desposal.
Any one have any other ideas that I have not mentioned here ? I would like to be sure before I replace the expensive Injector Pump.
I have replaced the Fuel Transfer Pump and the Fuel Filter.
I am considering a fault in the Injector pump.
Some have suggested a possible fault in the fuel shutoff selonoid area.
It goes like stink when it runs. It developes irregular power just before it stalls. It may run 3 weeks before it stalls and then it may stall 3 times in one day too. Currently it will no longer start and I suspect it is not getting any fuel at all.
I am going to try starting it with the Fuel Shutoff/Cold Timing advance cover detached. I am told that it will run if the selonoid is the cause.(of course this is messy)
I do not have any special gages or fuel pressure measuring tools at my desposal.
Any one have any other ideas that I have not mentioned here ? I would like to be sure before I replace the expensive Injector Pump.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
Do you know it you are losing power to the fuel shut off?
Are you getting fuel from the transfer pump to the injector pump?
Loosen fuel line from transfer pump to fuel filter and crank it over, shoud be 6 or 7 pounds pressure if you install a guage on it.
If you pass that test, check the fuel filter outlet line to see if it is going through the filter.
If you pass that test, loosen an injector line and crank it over to see if you are getting fuel there.
Do not crank the engine for more than about 20 seconds with a long wait between cranks or you will fry the starter.
Opening the pump would be my last resort. I would probably tow it to an injection pump service place for that. You do not want to break more than is already broke.
Are you getting fuel from the transfer pump to the injector pump?
Loosen fuel line from transfer pump to fuel filter and crank it over, shoud be 6 or 7 pounds pressure if you install a guage on it.
If you pass that test, check the fuel filter outlet line to see if it is going through the filter.
If you pass that test, loosen an injector line and crank it over to see if you are getting fuel there.
Do not crank the engine for more than about 20 seconds with a long wait between cranks or you will fry the starter.
Opening the pump would be my last resort. I would probably tow it to an injection pump service place for that. You do not want to break more than is already broke.
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Joined: Aug 2004
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From: Near Portland Oregon
Unpredictable Stalling Update #1
Additional information.
After cleaning and examining the check ball in the fuel return fitting atop the Injector pump I found that it could possibly be sticking. I am told that th is can cause my Injector pump to stop functioning.
I then took it for a ride after a succesfull start and idle to charge the batteries.
I made it about 1200 yards and it stalled again. It would not start till after much trying and releaving of the air from the schrader valve.
The schrader valve affixed to the fuel filter fixture reveals bubbles and sometimes nothing at all while there should be only fuel comming out when the valve stem is pushed in.
I have an important question now !!! Could this "Check Ball" as mentioned above be causing a vapor or air lock to be present in the top of the fuel filter fixture ?
As most of us know air in the injector lines will cause difficulty getting it started again. The question is ---- How is this air getting in ?
The transfer pump is brand new as is the fuel filter. I would like to test the fuel presure but I see little value in it since the pump and filter are new.
I still await more suggestions.
After cleaning and examining the check ball in the fuel return fitting atop the Injector pump I found that it could possibly be sticking. I am told that th is can cause my Injector pump to stop functioning.
I then took it for a ride after a succesfull start and idle to charge the batteries.
I made it about 1200 yards and it stalled again. It would not start till after much trying and releaving of the air from the schrader valve.
The schrader valve affixed to the fuel filter fixture reveals bubbles and sometimes nothing at all while there should be only fuel comming out when the valve stem is pushed in.
I have an important question now !!! Could this "Check Ball" as mentioned above be causing a vapor or air lock to be present in the top of the fuel filter fixture ?
As most of us know air in the injector lines will cause difficulty getting it started again. The question is ---- How is this air getting in ?
The transfer pump is brand new as is the fuel filter. I would like to test the fuel presure but I see little value in it since the pump and filter are new.
I still await more suggestions.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
That check valve is more likely to cause you problems after it is setting and not running.
I have bought more than one part that was new and was no good.
I just replaced a clutch master cylinder that was leaking, had to refill the reservoir every other week.
The new replacement leaks worse, I have to refill it every other day.
I have bought more than one part that was new and was no good.
I just replaced a clutch master cylinder that was leaking, had to refill the reservoir every other week.
The new replacement leaks worse, I have to refill it every other day.
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From: Near Portland Oregon
Stalling Fixed now Hard Starting Only
I found the problem with the Stalling symptom to be a cracked rubber hose at the fuel line coming from under the engine to the lift pump.
Now the problem is after it sits a few hours it will start right up and then die with the system full of air. I crank three or four times with a pause to let the air out of the schrader valve and it will eventually start and be just fine untill it sets again for a few hours.
I would like to know if I have to replace all the 'O' rings at the fuel return rail tees or is the problem just the check valve located at the top of the Injector pump ?
Some experienced advice would be appreciated !!
Now the problem is after it sits a few hours it will start right up and then die with the system full of air. I crank three or four times with a pause to let the air out of the schrader valve and it will eventually start and be just fine untill it sets again for a few hours.
I would like to know if I have to replace all the 'O' rings at the fuel return rail tees or is the problem just the check valve located at the top of the Injector pump ?
Some experienced advice would be appreciated !!
Senior User
Joined: Apr 2003
Posts: 198
Likes: 1
From: Kansas
You're like a detective who "knows" someone is guilty. He quits looking and focuses on the one thing! That check valve is not going to be your solution. If you are going to replace that valve it'll probably cost you 4 times what the fuel return line hose, clamps, "t's", O-rings (kit) cost.
You're getting air into the fuel system and it takes a step by step procedure to catch it. Follow Dave's coaching and you'll be amazed at how well you'll understand your fuel system by the time you catch the problem.
I went back and reread your original post. Since you replaced the lift pump double check the connections there. It there a steel line going up to the fuel heater and into the filter housing? Then a hose from the steel line coming from the water separator to the intake side of the pump? That's the way my '84 is. Check the connections you had lose.
You're getting air into the fuel system and it takes a step by step procedure to catch it. Follow Dave's coaching and you'll be amazed at how well you'll understand your fuel system by the time you catch the problem.
I went back and reread your original post. Since you replaced the lift pump double check the connections there. It there a steel line going up to the fuel heater and into the filter housing? Then a hose from the steel line coming from the water separator to the intake side of the pump? That's the way my '84 is. Check the connections you had lose.
Last edited by ditch witch; Aug 28, 2004 at 05:14 AM.
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I also have a friend that has a 86 F-250 that dies intermitenly while driving. She'll be going down the roed and bang the engine dies. It has a new fuel filter, batters and cables and a fresh oil change with filter. I need some Ideas to check for the problem. She works out of this truck and so it needs to be reliable.
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Senior User
Joined: Apr 2003
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From: Kansas
700hp,
Your friends truck is either running out of air or fuel. Once the engine is running it needs no electricity to keep running unless it has an elec. fuel pump. So how difficult is it to start after it dies? What symptoms do you notice? Is it running smooth and just quits? Give us all the clues!
Your friends truck is either running out of air or fuel. Once the engine is running it needs no electricity to keep running unless it has an elec. fuel pump. So how difficult is it to start after it dies? What symptoms do you notice? Is it running smooth and just quits? Give us all the clues!
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
TekJim, now you are looking at the check valve, or a cracked pickup tube in the fuel tank.
If you see fuel by the injectors it could be the o rings in the bleed off tees or the lines connecting them.
How you get air in the fuel system is the hardest thing to find on these trucks.
700HP, if the connector is loose or not making good contact on the fuel shut off solenoid it could be her problem. That almost sounds like it could be electrical to me.
But it could be anywhere between the IP and the battery by way of the ignition switch.
If you see fuel by the injectors it could be the o rings in the bleed off tees or the lines connecting them.
How you get air in the fuel system is the hardest thing to find on these trucks.
700HP, if the connector is loose or not making good contact on the fuel shut off solenoid it could be her problem. That almost sounds like it could be electrical to me.
But it could be anywhere between the IP and the battery by way of the ignition switch.
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Joined: Jul 2004
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After getting more info, she says that the whole truck dies, raido, fan, every thing. The truck will not start or even turnover, this has happen several times. The truck will sit for a while or so and then it starts and runs fine.
I'am thinking the key switch at the base of the steering collum or may a main relay of some kind. I have not seen a wiring diagram for it yet, so I'am hoping for some ideas to start with. Thank you
I'am thinking the key switch at the base of the steering collum or may a main relay of some kind. I have not seen a wiring diagram for it yet, so I'am hoping for some ideas to start with. Thank you