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

 

does the truck run ? if not , what where the problems leading up to it ? cause the fuel will return back to tank !

 

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.

 

have you tried to pinch off the return line and see if it starts ? if it would start with it pinched off then it sounds like the regulator is defective !

 

No I didn't even think of that. Will try that in a min. I already replaced the regulatorand it didn't fix the issue.

 

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

 

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 !

 

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

 

it sounds to me like the regulater is not working. it might be fine but not be working because you have a bad vacuum leak and you don't have enough vacuum to pull the regulator. look around for a big vacuum leak. I also would pull codes and see if you have any "pending one"........also does the pump ever shut off....maybe the relay is bad?

 

do this again and get it running then pull the vacuum line of the FPR and see if there is a vacuum on the hose.......

 

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

 

fuel pressure

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

 

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.

 

-did you swap out the fuel pump relay?($5 or switch with blower motor etc)

-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!!

 

Whats the procedure to check codes with this truck