I really hope someone has a new lead for me on this frustrating 3 yrs old intermittent starting problem on my 1994 Ford Ranger. Truck is old, 220K miles, but still runs great (when it starts clean). Started when I had a ball joint replaced, I took it back to shop, they diagnosed and replaced EGR valve, but that didn't solve issue. CEL goes on, sometimes it won't start at all (like no gas), sometimes it will start w/rough idle and no power (can't drive forward, or you can very, very slowly). Never happens on first start of day, I used to think it was heat related, but no longer. Replaced fuel pump, o2 sensor, crank sensor, ignition control. Have always had problems w/fuel pump relay (since truck was new) so I carry spares (but when relay goes bad it won't start at all). I tried running a new ground wire to the relay after watching a youtube fix, but that didn't help either. Sometimes when I press hard on relay it will start up, but not always. What's troubling is that it's not just a "no start" - it will start but run very rough, CEL on, and can't drive until CEL off. NOT THROWING ANY CODES (everyone & his mother has checked this). Sometimes when rough start w/CEL light, I can drive around the parking lot really, really slowly - engine will jerk, lurch, and sometimes die, but sometimes CEL light will blink, engine revs, and then CEL goes off and off I go like nothing was ever wrong!
I live in Hawaii, salt air - one mech thinks PCM is bad. Headlights also cut out (rarely) but scary, they've always come back on after shutting on/off. Is there a way to test for a wiring issue before replacing PCM? it's not the inertia switch either (that is a no start, mine will turn over, but not run right until CEL off or I get a good, new clean start). When it does start up, idles great, runs great, no problem, it never dies after a clean start, even when idling. Gets great gas mileage. Could it be catalytic converter? Thanks for any help, sure would like to nail this down.

 

Might be helpful to know which engine your 94 Ranger has. With the CEL lit, you should have a trouble code stored, or at least a pending code stored, even if the CEL turns off.

It takes air, fuel, spark & compression to make em run, so whats missing when yours won't start???? Have you performed fuel pressure & spark delivery tests when it won't start????

From the clues you've given about the fuel pump power relay, right now it kinda sounds like you may a socket corrosion, or contact problem where the relay plugs in. If you can see corrosion, but the contacts look ok, not physically damaged, try a good contact cleaner like CRC QD, to try & tidy things up & see how it goes.

Also check your battery to engine & body grounds for voltage drop with your multi-meter. If your not familiar with doing voltage drop testing, look at the last post in the Battery Tutorial thread atop this forums thread index page for a link on how to do it & let us know how it goes.

 

Thanks Paw-paw, you tried to help me back in 2012. Still struggling with the same issue. I will check out the thread you provided, as I am suspicious - sometimes when the battery connections are tweaked, it starts great for a few months, but the issue always returns. I thought about replacing the battery cables, and I do see the neg terminal ground to body. Visual inspection looks ok.

Could need a tuneup, but it idles so smooth, and this is only a starting problem. I'm suspicious of the fuel pump relay too - from what I've read, 2 prongs run the fuel pump, 2 prongs send signal to the PCM (these are the 2 I'm suspicous of). I got a light meter, and tested ground side - when I turn key the light comes on when in the ground side. (See youtube "1995 Ford Ranger Intermittent Starting Problem Fixed!") - I tried this, worked great for 2 days, then started up again. The ground wire I used made it hard to press in the relay firmly, so I got concerned and took it off. I do hear fuel pump priming when I turn key. As I mentioned, I replaced the fuel pump (wasted $).

I don't see any corrosion in the relay housing, but the outlet plugs are really small. There's a small yellow plastic part that looks like I might be able to pry this off to check the wiring underneath, but I'd hate to tear it up.

 

The battery cables can look ok, but the connections to the cable ends can be corrupt underneath out of sight & only a voltage drop test or a low resistance parallel bypass/jumper lead would be able to spot the problem. I once had a random no start problem on my 85 Renault that turned out to be just such a problem with the B+ cable between the battery & starter motor. Cable & end connections looked like new, but were corroded where the wire strands were molded into the cable end lug & battery clamp. It failed the under load voltage drop test, a New B+ cable put things right. If the connection is suspect, it'll be warm or hot when under load, if resistance & current demand are high, so touching a hot suspect connection can be our first clue to perform the voltage drop test.
Our electrical connections must be clean, bright & tight!!!!
More thoughts for consideration, keep us posted on your troubleshoot.

 

Wish I had a nickel for every time some connector looked fine but was wonky.

 

Yup, we only have 12 volts to work with, so it doesn't take much resistance from corroded, loose, or dirty connections to corrupt electrical connections & cause mischief. As clm2012 lives in Hawaii where he is surrounded by salt water, drives a vintage Ranger, his battery to engine & body electrical connections belong high up on his corrosion suspect list. All electrical connections must be clean, bright & tight, for things to operate as designed!!!!

So he needs to perform some voltage drop & wiggle tests, to see if he can find his intermittent electrical mischief. Seeing as how our battery cable connections on both ends are exposed, they belong high up on the suspect list, with the battery posts to clamp, grounds to engine & body & the cable molded on end connectors to the wire strands, belong at the top of his suspect list. Under load voltage drop & wiggle tests will quickly & easily confirm the soundness of those connections, so we've just gotta encourage him to bite the bullet & do it!!!!!!!