89 ranger Fuel pump will not quit priming

[reef93]

OK got a long one here so here it goes......89 ranger 2.3 auto. Was driving my truck to work one day and noticed the check engine light illuminate, next thing I know the truck stumbled and smoothed right out. I get to work pop the hood look under and notice the little connector that hooks up to the capacitor on the coil pack had gotten against the heater hose and looked as if it got hot. I zip tie it away and truck runs fine for a few weeks. Problem starts up again only this time its getting hard to crank like its really sluggish a few turns so i stop and try again then it eventually cranks right up. SO....I "assume" crank sensor. So I purchase a new crank sensor from Ford and decide its a good time to do water pump, timing belt, and tensioner. I get truck put back together it cranks up runs fine so I drive it around to see how it does. Get home and starts doing the hard crank again. So at this point I think it could be the Ignition Control Module. So I drive the truck back to the shop. I have a 93 mustang 2.3 that had an issue but I havent figured it out and just let it set. So I steal the ICM from it.....same part number. So I swap the modules. The truck cranks right up and shuts off. Every time. That was the problem the car was having. SO I assume I have figured out the problem with the car and think the module was bad. I swap them back and now the truck will not crank and the fuel pump constantly runs with the key on engine off. Had both modules tested and both tested good........SO ive changed crank sensor, swapped out coil packs, and had ignition control modules checked and both tested good.....So im at a loss at what direction to try now. Any help would be greatly appreciated!

 

[RonD]

"Cranks slow", this means battery, battery cables or starter motor issue

"Cranks long", this means either fuel or spark is lacking, sometimes compression.

Not sure which you are dealing with?


Fuel pump relay might be grounded if fuel pump comes on and stays on with key on.
Fuel pump relay gets 12volts with key on
Computer Grounds relay for 2 seconds then ungrounds it unless engine starts, or key is cycled off and on again.

Find your OBD connector in engine bay
Looks like this drawing: http://www.therangerstation.com/tech_library/OBD_I.shtml

In the drawing Fuel Pump slot is labelled.
That slot is the GROUND for fuel pump relay

12volt(key on)--------------FP Relay--------------OBD port------------------pin 22 on computer----Computer Ground

Check if that slot is always grounded, it shouldn't be.

 

[tomw]

If you remove the EEC-IV computer from its spot in the passenger side kick panel, and inspect, (open the case), you may find one or two capacitors that have failed, and have bulging tops. If that's the case, you can replace them for a buck, and likely will have no more problem. There's a youtube of replacement, along with symptoms, for EEC-IV computer used in a Mustang of about the same vintage.
In most cases, where the fuel pump continues to run, it is the computer or the relay being sticky. The relay has power, and 'control' power to close the relay, but gets its ground from the computer, which energizes the relay and closes the contacts, sending power to the pump through the 'rollover' switch. Older systems were a lot simpler.
Check the two electrolytic capacitors in the computer as their failure gives pump run symptom.
tom

 

[RonD]

Picture of computer with top off here: http://www.auto-diagnostics.info/ford_eec_iv

Blue capacitors are the ones that leak

 

[reef93]

Ok thanks for the replies, I went to check it over this am and tried a new relay. Nothing happened switched back to old relay pump ran continually. Took a relay out of dads ranger nothing happened. Put old relay on dads truck. Fires right up. So now i put old relay in and turn key and nothing happens. Turn off and on a few times and eventually truck primes like it supposed to and fires right up and runs smooth as silk. Works fine for a few cranks then back to doing same thing. Either pump either continually running or not at all with a working correct sprinkled in lol. So I'm gonna check computer out, or could it be the switch?

 

[RonD]

Could be Ground wire between computer and relay, i.e. a short to metal on this wire causes relay to close and pump to run when key is on.

So just vibrations of starting could cause it to short to ground, would be intermittent as described

 

[reef93]

Ok so I removed the computer today and popped it open and it looks as if one of the capacitors popped. It has a white residue on it and the others are clean.
https://photos.app.goo.gl/DsXYIwmOBkbvfMLc2
https://photos.app.goo.gl/FVaERV85yQ0oynm42

Any idea on what to replace it with. I feel confident I can swap it as long as I know what exact part I need LOL

 

[RonD]

There are two caps with 47uF 16volts, one with 10uF 63volt

Look on the side of the Capacitor: http://support.moates.net/wp-content/uploads/2014/01/original-cap-1-414x450.jpg

You can use any voltage above 16v usually you will find 35v easier
10uF 63v is just more common so Ford used it

You do want 102deg capacitors, usually blue color, Black are lower temp so can "boil away" at a lower temp, 102 cost more, but not that much more, lol.

Pay attention to the Negative side of capacitor when you remove it, new cap must go back in the same way.
These types of capacitors have a + and - polarity, it must be put in correctly

 

[reef93]

Ok just an update. Got the capacitors swapped out in the computer and reinstalled. Still was having the same problem. So I figured something else may be up in the computer so I get another computer. Installed it and same thing. Lol. So I started searching online and found a link where someone was having almost identical issues and it was the brown relay beside the fuel pump relay. So I Rob the relay off my dad's truck and it runs perfect. So I go to parts store tell them what I need and they order it. Relay comes back 4 prong just like that was in there. I install it and nothing happens. So I assume bad relay. I get another on the way and guess what. Same thing when it arrives. So today I take the actual ford part number in and it comes up as a completely different part. It was a 5 prong relay. Napa part number ar242. I put it in and have been driving ever since! All of this over a freaking relay.

 

[RonD]

Yes, that would be odd

Brown base relay is EEC relay(PCM relay), when it is Closed, it powers EEC(computer), fuel injectors, a few sensors, spark system and the fuel pump relay

 

[tomw]

Relays that have 4 pins are (I think) all SPST, NO relays. Single Pole Single Throw, Normally Open. Add a 5th pin, and you have a SPDT throw. It will have one NO connection and one NC (normally closed) connection. The pictograph on the top of most should show that. I did not know FoMoCo used a SPDT relay... but I am not a pro.
tom

Add: If you replaced the capacitors, you likely dodged a bullet. They cook over time, and could leave you by the side of the road when they decide they have 'had enough'.
tom