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. 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.

 

This is the PRE-'97 forum; if you have a '98, you'll get better answers if you post in the '97-04 forum. But the 5.0L wasn't offered in '98; was it swapped in? Take a little more time to proofread your post, and make it easy to understand.

 

sorry, 1988. please help

 

First: stop buying/changing parts.

Second: find out if ANY of the fuel pumps is getting power. Read the first part of this caption & install a jumper wire in the DLC:



Then turn the key to RUN and crawl under the truck to listen/feel the frame pump & the selected tank. If they're running, it'll be obvious by the whine & vibration. If not, use a 12V test light to check the circuit between the FP relay & the frame pump.

If you hear the frame pump running, unplug it to check the tank pump. If it's not running, check for power.

 

have tried all that. grounded the dlc(test port far right connection) to the starter reay ground and no fuel pump movement. just a thought but what about the ignition control module. it seems i read somewhere that it has a hot off of it that goes to the fuel pump. also, are the pumps powered thru the tank selector valve or tank selector switch. the fuel gauges read tank amount

 

The ICM is the logical input to the EEC that causes it to turn on the FP relay, but you're bypassing all that with the jumper wire.

Apparently you didn't try ALL that because you didn't check for voltage at any of the pumps. Power flow is:
battery
Br fusible link
EEC PWR relay
FP relay
inertia switch
frame pump AND tank switch
tank pump
ground

 

ok, thanks. I grounded the fuel pump relay to starter relay before. Just tried your diagram and grounded fuel pump relay ground to the return signal ground and heard pumps come on. I am pretty sure I heard the inline high pressure com on also but did notice for sure that the tank selector valve was on. would not start without starting fluid though and shuts down when starting fluid vapor burns out. Whabt next?

 

please help

 

With the fuel pumps on what is your fuel pressure?

 

I dont have a pressure gauge. What are your thoughts about the fuel pressure?

 

Have you checked and tested you FPR? Pressure testers aren't that expensive, maybe you should consider purchasing?

 

Finish the tests I listed in post #4.

BTW
Quadruple-posting the thread doesn't help - it adds confusion.
https://www.f150online.com/forums/el...uel-pumps.html

 

so, after i grounded the fpr on the dlp and pumps come on then what next? i unplugged the interia switch and tries it unplugged and jumped. i guess i dont understand what is next

 

Find out if all the fuel pumps get power. Get a gauge & find out how much fuel pressure you have. If the pumps make good pressure with the DLC jumpered, but the engine still won't run without spraying something into the intake, then the injectors aren't opening, which indicates an ignition system or EEC problem. But if there's no pressure, the diagnosis will be different.

Also:
Put your truck's details in your profile & a signature so they're visible with every post. Most of us read & reply to MANY threads, and we can't necessarily remember what you're working on if it's not right there.

 

Wish I'd noticed/followed Steve83 link before I went through the process of writing this.... oh well its there if you want to try it Trex

Steve83 is absolutely right multiple posting a question is a good way NOT to get helped FYI