Hi, yesterday my truck died on me. was getting no power to the fuel pump so I bought a new relay after testing showed that was the problem, but now the fuel pump is running constantly, even with no key in the ignition. what the heck could be causing this to happen?

 

Welcome to FTE

Are we talking about your 87 Ranger????

Seeing as how it was apparently running ok before the old relay laid down & now acts up after the new relay was installed, are you sure you were given the correct replacement relay????

Do you think maybe you have a short in your relay wiring????

if you are uncertain the replacement relay is the right one, I suppose you could try swapping a like relay, say the A/C relay, if it's the same part as the fuel pump relay on your 87 & see what happens.

If it still runs, I'd maybe suspect something is up with the ignition switch & it's not killing power to everything when switched off.

Maybe someone with a wiring schenmatic for the 87, will chime in.

Just a couple of thoughts to ponder.

 

You may bave plugged it in wrong, or got the wrong relay. Or it may be stuck closed internally. Try giving it a knock with something solid to shake the plunger loose. Also make sure there isnt a short some where some how. I know for the most part automotive relays are the same, but there are variences.

Here's my fuel pump relay in my 94.



On a relay there are 5 total plugs. As mine shows plug #'s 85 and 86 are an external +12V low amperage trigger to contact the plunger. With one the +12 and the other a ground.

Then #30 is your +12V 30 Amp input from the battery. The 87's are both the +12 30A output, the truck only uses one of these outputs(or at least mine only uses one from looking into its socket).

The exact same relay powers on the EEC as well, so you could try putting that in its place to try it.

This is probly a little too much information for your problem. I just thought I would share since relays are a fairly common problem on our Rangers and they are quite handy for powering on things such as lights and you want to stop burning up switches from 30A running thru them.

By the way, Welcome to FTE!

 

You beat me to it pawpaw! lol I ran to grab a pic of my relay.

 

But a picture is worth a thousand words!!!! lol

 

well the weirdest thing happened. I was taking the truck to a friends to check it out and the new relay blew, along with something in the dash (big puff of smoke) so I ran a jumper to get to my friends house and once i got there we put the old relay on and it worked fine.

 

Ummm the part about the dash bothers me. Almost makes me think that the ignition switch went or something. You might try crossing your starter solenoid on your wheel well with a wrench while key is off to make sure that the ignition switch isnt staying engaged or partially engaged. Something to do with that may have went up if your truck seems to run funny now.