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91 Taurus sat 3 yrs, little fuel flow to engine.


kenny'sid

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Hi, I have a 91 Taurus that sat for 3 or so yrs due to it immediately burning up fuel pumps when replaced. I recently put a cheap after market pump in the fuel line and ran another power source to it, it pumps fine.

The car starts but runs for a second and I let the fuel pump run a few seconds and it will do the same thing, as if the pump is having to push past an obstruction to get a tiny bit of fuel to the engine and as soon as it starts, it uses that fuel up. It runs awhile longer if I put cas in the intake so should run if I can get a constant flow of gas.

I've traced the fuel flow beyond the filter,but knowing nothing about fuel injection, not sure what to test next..Fuel injectors? Is there something else that could obstruct between the filter and the engine? Am also now thinking the original pump pumps more pressure than this cheap one but never heard of that being a problem, and that these cheap pumps work pretty well for their whopping $8 price tag. Can someone here tell me where the fuel line enters the intake so I can check for flow there at least? I can't seem to find it, but haven't done an extensive trace yet.

Thanks for any help.

Edited by kenny'sid
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Is it a 3.0 or 3.8? The fuel lines run to a fuel rail. It's silver and feeds each injector. This system has a return line and a fuel pressure regulator. Ideally you would have a pressure Gage to check fuel pressure. There is a schreader valve that is used to attach a Gage on the rail.

You can also disconnect the fuel lines, which are quick connect fittings and turn the pump on and see how much flows into a catch container.

Edited by fordtech1
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Thank you for the fast reply. I found one of the aftermarket pumps on the floor and recalled I had one that still worked, and that was it. I replaced the $8 one with it, dropped it in a jar of gas, and it sucked up the fuel much much more then the cheap in line one. Once I tightened up a few lines that kept popping off the test rig due to much more pressure, it started and ran, not long because I shut it down, but pretty sure that'll do it once I figure out how to make this work.

 

Though I know nothing about fuel injection, I'm thinking the fuel pressure is much higher than normal...the reason these cheap pumps may work on non fuel injection systems, but not for me?

 

Problem is, the in tank pump, there is only an exit line, no place to put an intake, just a little hole in the bottom of the pump, so no inline hookup. I could solve that by mounting it back in the tank but I'd much rather keep it out (in line) in case of problems. I do have the hole cut in the floor to reach it, but I also hate the idea of anything electrical in my fuel tank, especially if it's a rig. Aside from looking for a high pressure in line, universal pump which I will do, any advice on that?

 

Question, is the automatic pump shut off regulated within the pump?

 

See, I need to rewire this because evidently there was some kind of problem with the original power source as it burned out as least 2 new pumps. I hope that was all it was, if this one burns, I'll be at a complete loss as to the problem. Anyway I want to be sure all I need is the positive and negative to the pump or is there a connection to some type of stand alone switch hooked to the pump that turns it off when the shut down pressure is reached?

 

Other that that, I can't think of anything else...yet. And thanks again.

Edited by kenny'sid
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To my understanding you are trying to put an inline pump instead of an in tank pump. But you can't do an inline because you can't pull fuel through the existing in tank pump. Is that correct? Three things went wrong with the fuel pumps. One was the pump it's self, another is the CCRM constant control relay module and or the inertia switch which is in the trunk. Personally, I would replace the in tank pump, put it back to stock since it's a fuel issue. That way no worries about fire risk.

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I ordered an aftermarket in tank high pressure pump as a back up a few hrs ago, and decided to put the working in tank pump I have back in the tank. But I still have the problem that caused two or three other pumps to burn out almost immediately, that problem is in the original wiring. For that reason I cannot use my original wiring, and this is why I was asking if the auto shutdown is within the pump or is it external? if external, I have a problem because I'm afraid my original wiring that would operate the external shut down, would burn my pump up again...see what I'm saying?

 

At the moment, I'm running power straight form the battery and it's not burning up the pumps. Also I didn't wan to stick a jury rig in that tank but hot wires in a gas tank are there originally so, at this point I've decided to go that route.

 

If I remember correctly, the inertia switch shuts the fuel system down after a crash, or even less, whatever. I have power in the original wiring, but the original wiring, as mentioned keeps burning out pumps, so if I have power to the pump, not understanding how it can be the I.S.?

 

Sorry, this is a little complicated to explain, and my fault, but maybe that did it.

 

Main question now, even if all else is not understandable...Is the fuel pump shut down within the fuel pump itself, or external. IOW will the fuel pump shut down by itself once enough pressure is built or is there some type of external relay wired to it that tells it to shut down?

Edited by kenny'sid
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All controls are external to the pump. I can't think of any reason the pumps can be burned up so fast. It's a two wire set up. Pink/black is hot and black is ground. Have you verified power and ground? When the key is turned to the run position the pump gets 2 seconds of power to prime. Then when the pcm detects engine cranking the check engine light goes out and pump gets constant power. I highly recommend putting a load in line like a light between power and ground of the pump circuit. It should illuminate just like I stated during key cycle and cranking.

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If, when you say is it getting power you mean the original wiring, yes. It would start the car then the next time I go to start it...dead pump. I found the pumps today..killed 3 of them,. I've never seen anything like it, one of the reasons I give up on the original wiring, as if I use it, the other pumps will burn up. It's just beyond my abilities to do testing and much easier just to run a new hot/ground. Time is a factor to, unfortunately I need to get it running as quickly as I can.

 

Problem is, it appears you are saying the pump does not shut itself down when pressure is built, meaning just any hot wire won't do. IOW the hot wire needs to come from whatever sending unit shuts the pump on and off in order to keep the pressure correct? Right? and if I am correct and understand correctly, where is that unit that regulates the pressure by turning the pump on and off?

 

thanks again and hopefully we are almost there

Edited by kenny'sid
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The pressure retention helps prevent hot starting concerns. This pump is capable of supplying 60 liters (15.8 gal) of fuel per hour at 269 kPa (39 psi). The fuel pump has an internal pressure relief valve to provide overpressure protection in the event the fuel flow becomes restricted (damaged lines, clogged, filter, etc.). Overpressure is restricted to 850 kPa (123 psi) and reduced fuel flow will result. The system pressure is controlled by a pressure regulator mounted on the engine.

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I finally woke up, googled it, and not sure why I assumed the pump shutdown, but between that and your post mentioning "pressure relief" now I get it, and understand all should be well with what I'm doing.

 

One more quick question, do you know where I can find a connection that comes on when the key is turned on that would most likely work for this? I hate to use a manual switch that inevitably, I will forget to turn off.

 

Thanks so much for taking the time to help me.

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Probably your best bet would be to connect it at the electrical part of the ignition switch. Use a test light and determine which are hot all the time and which are key on power only. Make sure to use an inline fuse. Use one of the large wires. That should work fine. Ideally, you would use a relay and use ignition switch to control relay and get power from positive battery. But since you got a rig going on this would be the easiest.

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