Fuel pump issues 1998 5.0

[5.0limited]

In the past two years I’ve put 4 fuel pumps in think my current one is starting to get weak could it be low voltage problem anyway to trouble shoot what could be causing me to burn up pumps

also I have a donor 1999 moutanieer I’m gonna use for a 5.0 ranger swap it has the non return fuel system thinking I want to swap mine over to that anyone familiar with what all I need to take off the mountaneer ive has some fuel connector issues had to put in a splice rather have it all stock with no fuel return

thanks for any help

 

[C420sailor]

What make pump are you using? That’s a lot of pumps. I put a Motorcraft in at 215,000 and I’m at 340 with no problems now. Buy once, cry once.

I’d definitely test the harness. You may have high resistance in there somewhere.

Also, fuel up at 1/4 tank so the pump stays cool. I assume the tank is clean, along with the strainer? New fuel filter?

 

[J_C]

If you had a bad pump due to a voltage problem, then you swap in another pump, the voltage problem doesn't go away, at least the odds are against it being something like a wire shorting out, but your moving it fixes that, but then it starts shorting out again, and stays that way till another pump goes in.

For that reason, the odds seem to be against low voltage, but you can check that with a multimeter while the engine is running, at the fuel sender connector.

What brand of pumps? IIRC, Motorcraft or Bosch are the top two choices, then in a pinch I might go with Denso or Delphi.

You stated that it's starting to get weak, is there an engine performance issue or you are measuring low pressure? Have you changed the fuel filter? Have you been buying fuel from a dodgy gas station and it could be worthwhile to try a different major brand?

I'm not 100% certain on the engine swap but I think you will need from the '99, the fuel rail, with the pressure dampener on it (and a vac hose from that to *somewhere*, fuel injectors, PCM, wiring harness, and the sending unit with the pump and pressure regulator. Connectors, I don't know.

 

[410Fortune]

You can run the return fuel system or the returnless system the 5.0 pcm does not care or know, it is simply a matter of plumbing and using the correct injectors

If your pumps are failing this often then

1. You are using cheaper quality pumps like airtex or duralast when you should be using Bosch

2. You are not changing the filter w each pump

3. You run the truck with low fuel, should keep 1/4 tank or more at all times. The fuel on top of the pump is what cools the pump. Pumps run often with low fuel burn up much quicker. Not exactly easy to do when fuel is $4-5 a gallon! Sucks! But i tell my wife all the time (she think the e in the fuel gauge stands for “enough”) it’s still cheaper the. Dropping tanks and replacing pumps

4 after the other 3 then I would start to suspect possible power /‘corrosion/ resistance issues. The system is pretty simple. The key is turned the pcm comes on the pcm energizes the fuel pump relay. The fuel pump relay sends fuses power through intertia switch and to pump. Only a few wires and connections to check

 

[5.0limited]

You can run the return fuel system or the returnless system the 5.0 pcm does not care or know, it is simply a matter of plumbing and using the correct injectors

If your pumps are failing this often then

1. You are using cheaper quality pumps like airtex or duralast when you should be using Bosch

2. You are not changing the filter w each pump

3. You run the truck with low fuel, should keep 1/4 tank or more at all times. The fuel on top of the pump is what cools the pump. Pumps run often with low fuel burn up much quicker. Not exactly easy to do when fuel is $4-5 a gallon! Sucks! But i tell my wife all the time (she think the e in the fuel gauge stands for “enough”) it’s still cheaper the. Dropping tanks and replacing pumps

4 after the other 3 then I would start to suspect possible power /‘corrosion/ resistance issues. The system is pretty simple. The key is turned the pcm comes on the pcm energizes the fuel pump relay. The fuel pump relay sends fuses power through intertia switch and to pump. Only a few wires and connections to check

I believe I used the denso last time it’s all they had I’ve searched rock auto O’Reilly AutoZone advanced I can’t find the motor craft or Bosch looks like the best one I can get is Delphi I remember seeing the motor craft one on rock auto but I appears they aren’t available anymore

 

[5.0limited]

You can run the return fuel system or the returnless system the 5.0 pcm does not care or know, it is simply a matter of plumbing and using the correct injectors

If your pumps are failing this often then

1. You are using cheaper quality pumps like airtex or duralast when you should be using Bosch

2. You are not changing the filter w each pump

3. You run the truck with low fuel, should keep 1/4 tank or more at all times. The fuel on top of the pump is what cools the pump. Pumps run often with low fuel burn up much quicker. Not exactly easy to do when fuel is $4-5 a gallon! Sucks! But i tell my wife all the time (she think the e in the fuel gauge stands for “enough”) it’s still cheaper the. Dropping tanks and replacing pumps

4 after the other 3 then I would start to suspect possible power /‘corrosion/ resistance issues. The system is pretty simple. The key is turned the pcm comes on the pcm energizes the fuel pump relay. The fuel pump relay sends fuses power through intertia switch and to pump. Only a few wires and connections to check

I did change the filter and sock each time I replaced the fuel pump rely and cleaned all the connections any idea why voltage I should see once I turn the key on at the pump connector also searched every retailer can’t find the Bosch or motor craft anywhere seems like the Delphi is the best one available

 

[5.0limited]

If you had a bad pump due to a voltage problem, then you swap in another pump, the voltage problem doesn't go away, at least the odds are against it being something like a wire shorting out, but your moving it fixes that, but then it starts shorting out again, and stays that way till another pump goes in.

For that reason, the odds seem to be against low voltage, but you can check that with a multimeter while the engine is running, at the fuel sender connector.

What brand of pumps? IIRC, Motorcraft or Bosch are the top two choices, then in a pinch I might go with Denso or Delphi.

You stated that it's starting to get weak, is there an engine performance issue or you are measuring low pressure? Have you changed the fuel filter? Have you been buying fuel from a dodgy gas station and it could be worthwhile to try a different major brand?

I'm not 100% certain on the engine swap but I think you will need from the '99, the fuel rail, with the pressure dampener on it (and a vac hose from that to *somewhere*, fuel injectors, PCM, wiring harness, and the sending unit with the pump and pressure regulator. Connectors, I don't know.

It starts to miss as soon as I put it under a load especially when getting on the interstate in the past it gets worse and worse changed The pump got about 6 months before it starts happening again I changed the sock and filter each time cleaned out the tank as well I never run it below a 1/4 tank generally get gas at good gas stations any idea what volts I should be reading at the pump connecter when I run the key on

 

[Turdle]

Spark plugs? How old are they?

Fuel pressure check? You can tape a fuel pressure gauge to windshield for fuel pressure check while driving.

Also, you might check the fuel pump and pcm relay sockets for heat damage- discoloration.

 

[5.0limited]

Spark plugs?

Fuel pressure check?

I replaced the plug about 15,000 miles ago I can already tell the fuel pressure is low by the way it misses under a load this now my 5th rodeo with the same issue I’m gonna replace the pump tomorrow just need to figure out why they don’t last very long

 

[J_C]

It starts to miss as soon as I put it under a load especially when getting on the interstate in the past it gets worse and worse changed The pump got about 6 months before it starts happening again I changed the sock and filter each time cleaned out the tank as well I never run it below a 1/4 tank generally get gas at good gas stations any idea what volts I should be reading at the pump connecter when I run the key on

Get a fuel pressure reading. That is more difficult driving but if you can get it revving in park, that might show it low... if it is.

Voltage at the pump connector should be very near the current battery voltage. It's a load, across a wire (resistance) so it may be a little lower but not much. Consider that the pump should provide the full PSI at the nominal 12.6V battery voltage but that once the engine is running the pump should be pumping better still at the electrical system charge voltage of 14.(n)V.

 

[410Fortune]

Hmmm denso should be a decent pump
5 times? Something is fishy! For sure give the system a good once over and check power (should be same voltage as battery) and pressure

 

[C420sailor]

98 is return, right

It’s rare as ****, but FPR maybe?

Gotta rig up a pressure gauge and monitor it while driving

 

[5.0limited]

i have an update check engine light came on bank1 sensor 1 was slow response changed it (the most difficult one) ran better but started missing again having to work all the time couldnt get to the auto parts store to rent on so my next step is to check fuel pressure i believe mine should be at 40psi at idle my fuel system has a return want to make sure thats correct i have a scanner now aswell any one know what my short term fuel trims should read

thanks again for all the help