unique fuel problem
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Elder User
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unique fuel problem
Need a little help with this one. Truck is a 97 Ranger with 3.0L, auto trans. I am having a problem with all my fuel returning back to the tank. When I cycle the ignition, my pump primes the system with fuel as usual. Odd thing is, as soon as I get fuel pressure, it instantly drops. I unhooked the return line at the tank and as soon as the pump activates, every ounce of fuel that was just pumped to the engine is returning to the tank. What could be allowing this to happen?
Originally thought it could be the fuel pressure reg. But I just replaced that and same issue. Max I can get the fuel pressure to rise is 42psi. At that point the fuel returning to the tank is matching that of the pump. Applying vacuum, no vacuum, and plugged vacuum line at the regulator makes no difference.
Anyone know what's going on? Thanks
Originally thought it could be the fuel pressure reg. But I just replaced that and same issue. Max I can get the fuel pressure to rise is 42psi. At that point the fuel returning to the tank is matching that of the pump. Applying vacuum, no vacuum, and plugged vacuum line at the regulator makes no difference.
Anyone know what's going on? Thanks
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Elder User
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No it won't start. I know the fuel returns to the tank when running but not all of it. The excess, after the rails have reached operating psi, is what is returned. When my pump kicks on ALL the fuel is returning to the tank. None is being held up in the fuel rails. That's the problem.
No real problems that I can remember effecting the truck. Only thing I do recall, is on a few occasions I would start the truck, first thing in the morning, and it would cut off after a few seconds. Just cranked it again and it would start without a problem. There was never any hesitation, stumbling, or cutting out at any time once running like is usualy associated with a fuel problem.
No real problems that I can remember effecting the truck. Only thing I do recall, is on a few occasions I would start the truck, first thing in the morning, and it would cut off after a few seconds. Just cranked it again and it would start without a problem. There was never any hesitation, stumbling, or cutting out at any time once running like is usualy associated with a fuel problem.
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Alright that helped some. Took some vice grips and gradually increased the tightness. Was able to get it running but I had to almost completely close the line. With the line pinched and truck running, fuel pressure at the rails was only 32 psi. If I removed the vise grips if would instantly stumble and die
Posting Guru
Joined: Feb 2010
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From: CASA GRANDE AZ
that sounds like a bad fuel pump and regulator to me ! when it was running did it sound like it was running on all cylinders or was there one not firing ! did you check the oil for gas in the oil , may be one injector is leaking gas in the engine !
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Elder User
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I believe you are right about the pump. When I pinched the line yesterday the pump sounded like it was struggling. I know its putting out enough volume but aparently not enough psi. Thanks for the help
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Fleet Mechanic
Joined: Feb 2007
Posts: 1,716
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From: Boston, MA
Need a little help with this one. Truck is a 97 Ranger with 3.0L, auto trans. I am having a problem with all my fuel returning back to the tank. When I cycle the ignition, my pump primes the system with fuel as usual. Odd thing is, as soon as I get fuel pressure, it instantly drops. I unhooked the return line at the tank and as soon as the pump activates, every ounce of fuel that was just pumped to the engine is returning to the tank. What could be allowing this to happen?
Originally thought it could be the fuel pressure reg. But I just replaced that and same issue. Max I can get the fuel pressure to rise is 42psi. At that point the fuel returning to the tank is matching that of the pump. Applying vacuum, no vacuum, and plugged vacuum line at the regulator makes no difference.
Anyone know what's going on? Thanks
Originally thought it could be the fuel pressure reg. But I just replaced that and same issue. Max I can get the fuel pressure to rise is 42psi. At that point the fuel returning to the tank is matching that of the pump. Applying vacuum, no vacuum, and plugged vacuum line at the regulator makes no difference.
Anyone know what's going on? Thanks
Fleet Mechanic
Joined: Feb 2007
Posts: 1,716
Likes: 0
From: Boston, MA
Alright that helped some. Took some vice grips and gradually increased the tightness. Was able to get it running but I had to almost completely close the line. With the line pinched and truck running, fuel pressure at the rails was only 32 psi. If I removed the vise grips if would instantly stumble and die
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Elder User
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I didn't think to apply a vacuum to the regulator when it was running. Don't know why because I had a vacuum gauge there hooked into the FPR line and my vacuum tool to apply vacuum to the regulator. Guess I got a little excited when it fired up. Will see what I can get done this evening
Fleet Mechanic
Joined: Feb 2007
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From: Boston, MA
I didn't think to apply a vacuum to the regulator when it was running. Don't know why because I had a vacuum gauge there hooked into the FPR line and my vacuum tool to apply vacuum to the regulator. Guess I got a little excited when it fired up. Will see what I can get done this evening
koeo 35-45
at idle
koer 25-35
koer with vacuum line removed 35-45
IMHO I think the pump is fine!
try to catch a pending code
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Alright, with the truck running, at idle, it pulled a steady 13.5" inches of vacuum hooked directly to the FPR line. Snapping the throttle wide open and it went to 0 as it should. I wasn't able to get fuel pressure readings this time, busted o-ring in my tester. I assume it would be the same as yesterdays reading of 32 psi. Changing the amount of vacuum to the regulator made no noticable change. I gradually increased and quickly increased the rpm's with 0 and 15 lbs of vacuum and there was no lack of fuel. Truck acted like normal.
If a remove or loosen the vise grips, it will die. Too tight and it won't start. With it running good like it was I decided to unhook the guages and take it for a spin in the back yard. That's when things went bad. Made around the house into the back yard and it started to act like it had no fuel. Had to feather the throttle to get it back out front. As soon as I got back in the front of the house, the motor started to shake like it was running off 2 cylinders on the same side of the motor. Never seen a block move that much side to side. No matter what I did I could not get it back to running smooth. So I shut her down before something broke.
If a remove or loosen the vise grips, it will die. Too tight and it won't start. With it running good like it was I decided to unhook the guages and take it for a spin in the back yard. That's when things went bad. Made around the house into the back yard and it started to act like it had no fuel. Had to feather the throttle to get it back out front. As soon as I got back in the front of the house, the motor started to shake like it was running off 2 cylinders on the same side of the motor. Never seen a block move that much side to side. No matter what I did I could not get it back to running smooth. So I shut her down before something broke.
Fleet Mechanic
Joined: Feb 2007
Posts: 1,716
Likes: 0
From: Boston, MA
Alright, with the truck running, at idle, it pulled a steady 13.5" inches of vacuum hooked directly to the FPR line. Snapping the throttle wide open and it went to 0 as it should. I wasn't able to get fuel pressure readings this time, busted o-ring in my tester. I assume it would be the same as yesterdays reading of 32 psi. Changing the amount of vacuum to the regulator made no noticable change. I gradually increased and quickly increased the rpm's with 0 and 15 lbs of vacuum and there was no lack of fuel. Truck acted like normal.
If a remove or loosen the vise grips, it will die. Too tight and it won't start. With it running good like it was I decided to unhook the guages and take it for a spin in the back yard. That's when things went bad. Made around the house into the back yard and it started to act like it had no fuel. Had to feather the throttle to get it back out front. As soon as I got back in the front of the house, the motor started to shake like it was running off 2 cylinders on the same side of the motor. Never seen a block move that much side to side. No matter what I did I could not get it back to running smooth. So I shut her down before something broke.
If a remove or loosen the vise grips, it will die. Too tight and it won't start. With it running good like it was I decided to unhook the guages and take it for a spin in the back yard. That's when things went bad. Made around the house into the back yard and it started to act like it had no fuel. Had to feather the throttle to get it back out front. As soon as I got back in the front of the house, the motor started to shake like it was running off 2 cylinders on the same side of the motor. Never seen a block move that much side to side. No matter what I did I could not get it back to running smooth. So I shut her down before something broke.
-you have to have pending codes check for them?
- I think you want to get the fuel pressure all around......definitely a strange issue
- any chance the coilpack etc is acting up!!
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Elder User
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-did you swap out the fuel pump relay?($5 or switch with blower motor etc)
I didn,t swap the relay because the pump does not run constantly. It cuts on for about 3-5 seconds when I turn the key and when the truck is running. Just like normal.
-you have to have pending codes check for them?
I have not tried to pull any codes. Didn't know it was possible to do at home with OBD2 systems. I know you can with OBD1. I will have to look into how that is be done
- I think you want to get the fuel pressure all around......definitely a strange issue
Yeah, I am struggling with this. It has got me stumped
- any chance the coilpack etc is acting up!!
I don't think so. Truck didn't even have a slight miss. Plugs and wires bout 6 months old.
I didn,t swap the relay because the pump does not run constantly. It cuts on for about 3-5 seconds when I turn the key and when the truck is running. Just like normal.
-you have to have pending codes check for them?
I have not tried to pull any codes. Didn't know it was possible to do at home with OBD2 systems. I know you can with OBD1. I will have to look into how that is be done
- I think you want to get the fuel pressure all around......definitely a strange issue
Yeah, I am struggling with this. It has got me stumped
- any chance the coilpack etc is acting up!!
I don't think so. Truck didn't even have a slight miss. Plugs and wires bout 6 months old.