1988 F150 302 efi, no power to fuel pumps. I have replaced the eec relay and fuel pump relay. I can not hear the fuel pumps running. jumped the dlp fuel pump relay to return signal relay and pumps worked but still no fuel. Will start with starter fluid but dies when starter fluid burns out. took wires loose from collision swith and connected the 2 wires together and still no start or fuel. replaced fuel tank selector swith and still no start or fuel. rear tank went out about 3 weeks ago and now front tank. replaced fuel pump in front tank and still no start or fuel. please help. out of ideas.

 

Double-posting the thread doesn't help - it adds confusion.
https://www.f150online.com/forums/pr...ml#post4596603

 

Might be a stupid question, But have you checked your Battery voltage, not sure what the threshold for your engine management systems would be, but a voltage below the threshold will result in a "Shut Down" or "No Start" condition even with the pumps running. Have you verified that the pumps are not working and not just reaching the required pressure and shutting off, If the pumps are running you should be getting fuel,, unless there is a blockage or a shut down/no start condition, or maybe an EFI management problem. Have you checked the fuses/relays for the EFI system? The fuel system will reach the needed pressure very quickly and the pumps will cut out if there is no fuel pressure demands from the EFI system. "Hotwire powering" the pumps if the filter is plugged or the EFI system is all ready at maximum pressure may cause additional damage, I would be very careful when it comes to bypassing the stock electrical systems. have you checked/changed your fuel filters? Do you have a "check or service engine soon" light on? I'm not an automotive professional, So these are only suggestions, but these are the steps i would take to diagnose, and narrow down your problem.

Please read through all the steps before you start as you may have already done some of these checks,,
Ok, here we go!

You will need a few tools which i will try and list as you need them.

1: "Check Engine" or "Service Engine Soon" light. Even if your check engine light is NOT on, beg, borrow, or buy an OBD code reader for your model of truck, and check for any codes relating to the fuel or engine management systems.

1a: Deciphering OBD codes. **Some codes will cause a no start condition!!!** So this is an important step! If you don't have any codes, or get codes relating to fuel pressure, proceed to step 2. if you find any other codes, check them at this link and proceed accordingly, these are late model SVT lighting codes but almost all of them are the same. or try and find a list for your year/ model,,
If you find any that you can't find an explanation for, even after Google/fav search engine search,, ask in the proper forum subtopic, All the auto geniuses hang out here!!!

I would use the front tank for all the following tests, as we know it has a new pump.

2: Fuel Rail Pressures. You will need to check the pressure at the fuel rail, PLEASE, be careful with this step as there is very high pressure involved with this test. You will need to find the operating pressure for your engines fuel system, either in a manual or your local Ford dealer may be able to give it to you, or maybe someone on here may know it... you will need to find a pressure gauge that will read higher than the required pressure for your fuel system, and get a thread on style female shraeder valve end for your pressure gauge, if you can find one, and attach it to your pressure gauge.. If you can't find one, an old (or new if necessary) tire gauge, remove the part from the tire gauge that goes on the valve stem and attach it to the pressure gauge. Find the shraeder valve (looks the same as the inflation valve stem for your tires only steel) on the fuel injector rail tubing, I believe it is on the passenger side fuel rail, if you got a thread on style end attach it now, cycle the key to pressure up the fuel system, or if your using the press on gauge end. cycle the key first then quickly put the gauge on,, BUT BE CAREFUL!!
If you find no pressure go to step 2c. If your pressures are below what is required you can try starting with step 2b, or, if they are with in the spec pressures go to step 2a

2a: Fuel Volumes. Next we need to check volumes,,an easy way to check this is to release any residual pressure from the fuel system,,, simply press the center button of the shraeder valve with a small screw driver, just as you would the let the air out of a tire, do be careful though when you release it, as it could still be under very high pressure. next remove the center of the valve with a valve core remover, put a small piece of tube on the valve and have someone turn on the key for 2 or 3 seconds, make sure to time it as accurately as you can. Catch the fuel in a measuring container (remember it will be under high pressure), then reinstall the core, now locate the fuel filter (the factory one should be along the frame rail somewhere), disconnect it on the fuel tank side (you may require a disconnect tool to release the fuel line,, don't just cut them!!) and repeat the the above steps,, put the tube on, cycle the key for the same amount of time, now reinstall that line and remove the line from the engine side of the filter and repeat the test,,if these two are different replace the filter, if there the same, then compare the three amounts. If you are getting fuel but the volumes are different between the engine side of the filter and the fuel rail, go to 2b. If you aren't getting any fuel at this point, or if you are getting a very weak amount of fuel on any of these tests, and you have verified that all your fuses and relays are good, you already know that you fuel pump in the tank is good, as is your tank selector switch, then its time to start tracing wiring,, go to 2c.

2b: high pressure lift pump (sorry, I don't remember if that series of engines use this arrangement). ok testing this unit can be a bit tricky, if you have a service manual, it should give you a fluid schematic for the fuel system. as well as input and output volumes, if you don't have one your local library should have one in the reference section.. Ok, if your pressures are low from test 2, or there is a marked difference in volume between the rail and filter from test 2a, you should check and see if there is a high pressure lift pump on the engine or on the frame somewhere close to the engine, and repeat the steps from 2a on the lift pump, again first on the tank side of the lift pump. then on the engine side, and now that we have the line off of the high pressure side of this pump we can also check the pressures here too. remember this is a high pressure pump. the pressure on the engine side here should be the same as what is called for on your fuel rail. If their not, and you haven't done so yet, you will need to do step 2a. If there is a marked drop in volumes from the tank side of the pump and/or you have already done the tests in 2a, replace this pump. then reassemble and try starting, if it still doesn't start and assuming everything else tested so far is functioning correctly and your volumes and pressures are fairly close, we will need to move on to step 3,

2c:Primary fuel system wiring. You will need a multimeter/ohm meter, with a set of test leads with alligator clips, and a small screw driver for coaxing the plugs apart in this step,, most manufactures plugs use a small lock mechanism on one side of their plugs, try not to break the locks as this can cause plug separation or moisture intrusion problems in the future,,, ok, start by cleaning an easily assessable spot on your frame as a good ground can make or break these tests!!! Now start with the plug closest to your fuel pump and work your way toward your power source, as you unplug each plug verify that it is getting the proper voltage on the pins that are suppose to have power, using the 12v power setting on your multimeter, and that the ground is actually grounded, do this using the ohm meter setting on your multimeter between the ground pin of each plug and frame this will verify the ground (Should be little or no resistance). if you find an open circuit you have a bad ground situation, if these all check out, start testing for resistance between each of the plugs, make sure you disconnect the power from the circuit before you test the power wires, these should be fairly close to 0 ohms, if you find anything over a couple of Milli-ohms or an open circuit between the plugs you will need to repair the wire if you can locate the problem or replace it if you can't, if you find a problem, reassemble everything and try starting it. If you don't find anything, on to step 3

3: EFI system. You can check the basics of the EFI system, fuses, relays, plugs, voltages at the ECM and EFI management connector plugs, and such. *WARNING* Some EFI systems use VERY HIGH VOLTAGES!!! OK if you haven't scraped your truck yet, or (gakk!!) taken it to the dealer,.. you will again need to have a multimeter/ohm meter, test leads, and a small preferably flat bladed screw driver for coaxing the plugs apart, and you will DEFINITELY need to refer to wiring schematic and voltages in a service manual, this is not only to locate the right wire circuits and plugs, but also have the proper voltages and any built in resistances for each circuit. Use the same basic steps as 2c, start at the back of the circuit (the fuel injectors in this case), BE VERY CAREFUL with the injector harnesses as fuel injector circuits often use VERY HIGH Voltages, (make sure your multimeter is rated for the required voltages!!!) and work your way towards the initial power source, checking for proper voltages and resistances, If there is a Control Unit problem it should be showing up with the OBD reader. But even if it isn't showing up, the above steps should help isolate which unit is faulty if that's the case...

If you locate and repair your problem at any point, make sure you clear any codes and reset all the control units with your OBD tester, or the poor mans way, is to simply disconnect the battery for aprox. a minute.

I Hope this helps! and I haven't discouraged you!
I'm sure if I missed anything, some of these other fellows here will correct my mistakes or make better suggestions..
If I have missed any steps I apologize in advance, it has been many years since I have worked on Gas fuel systems.

Good Luck!