diagnostic help!!!

[bmxr152]

Some updates...
I was letting it idle in the garage and it died with no fuel pump prime and no start, then let it sit and restarted. Then it died and wouldnt start with no fuel again. so then i unpluged and used a paperclip to test the inertia switch. It primed up and started. Then i pluged the harness back into the inertia sensor and it would not start. So i guess it went bad, and causes my truck to die randomly?

 

[MrShorty]

It's not very common, but I've heard of a few cases where something goes wrong with the magnet and/or the ball inside the inertia switch that causes the inertia switch not to stay closed. The best write-up I recall seeing on this issue was over at therangerstation.com, if they are still around.

 

[Tony H]

Thanks for the update. Something to keep in the back of my head.

I sure hope that's your probelm

 

[bmxr152]

yeah, its been stressful. Always getting stranded places and having to call AAA to tow me to my house just to wait until it will start again. I wonder why the inertia switch would go out. I dont know if it has anything to do with it but earlier that day i was Pre running a course and slide off the top of a jump sideways and almost rolled it, bending my shackles. It wasn't maybe 4 hours after that it started acting up. So maybe all the hard driving and bumps messes it up? Also if i tap it with a screwdriver i can hear that ball in there move around and then it dies.

 

[Tony H]

I dont know if it has anything to do with it but earlier that day i was Pre running a course and slide off the top of a jump sideways and almost rolled it, bending my shackles.

A jump? with the 'X' save that for the BMX Bike not the stock Explorer. These toy trucks were not made for hard Wheeling.

 

[bmxr152]

Its not stock, just the motor and interior.

 

[cosual]

I have a 94 explorer, and when driving you have to let off the pedal and push it again,
cuz it looses speed I have changed the fuel filter, fuel pump & sending unit, tps sensor,
and it still acts like this any help?

 

[bmxr152]

So has anyone broke their inertia sensor before?

 

[cogs]

I have a 94 explorer, and when driving you have to let off the pedal and push it again,
cuz it looses speed I have changed the fuel filter, fuel pump & sending unit, tps sensor,
and it still acts like this any help?

you're hijacking a thread here, but have you checked your accelerator line?

 

[cosual]

sorry

 

[MrShorty]

So has anyone broke their inertia sensor before?

Here's a link to the TRS article I mentioned before. http://www.therangerstation.com/tech_library/InertiaSwitch.html

 

[bmxr152]

well after reading that, i tested my inertia sensor. Now i know its not the inertia sensor like i thought it was before. It must be the jimmy rigged setup as pictured above with the 5 prong relay. I just cant figure out the wiring. Im so lost and need some help.

 

[bmxr152]

i just pulled some new codes code 95, 96, 10

 

[MrShorty]

KOEO 95 and 96 both point to a problem in the fuel pump circuit. The 10 is how some of the more expensive code readers represent the separator pulse that comes between the KOEO codes and the CM codes (see my "notes on pulling EEC-IV codes" thread for an explanation of what KOEO and CM codes are).

Can you describe what you can't figure out about the wiring? Do you have a wiring diagram? The picture isn't great, but I can see a red wire, a pink? wire, and a black or brown wire coming out of the wiring harness going to the relay. With a wiring diagram, we should be able to figure out what those three are supposed to do.

 

[bmxr152]

Well it looks like there is a pink, red, and black/yellow wire going into the harness but there are two green/orange wires cut. The thing that gets me is, well it could be the wiring but i have had the truck for a year before noticing that the fuel pump relay is rigged up that way. All the wiring diagrams ive seen dont have the same color wires. What are the color wires for a 91 that go to the fuel pump relay?

 

[MrShorty]

I don't have a wiring diagram specific to a '91.

Ford was consistent in using the red wire as the EEC power supply wire. The red wire is coming from the EEC relay, powers the coil side of the FP relay, and should have power whenever the key is on.

On my '92, the blk/yel wire is the main FP power supply. If your '91 is the same, it comes from the FP fuse, should go to the switched side of the relay, and should have power at all times (key on or off).

The only other two wires going to the relay are the "control ground" which goes from the coil side to the PCM, and the power out to the fuel pump (which is usually the same color as the wire going into the inertia switch). It appears from your picture that the relay has a little diagram on it. If we've properly identified the 1st two wires, you should be able to tell what the other wires attached to the relay are based on the relay's pins.

I understand your frustration in finding a good wiring diagram. Haynes tends to use a representative wiring diagram, which means they don't always show all the variations used over several years. Chiltons includes year/engine specific diagrams, and I've found them adequate for many projects I've undertaken, so I tend to prefer Chiltons manuals for wiring diagrams. I haven't checked in a long time, but autozone used to provide a free online version of Chiltons -- you might look there for a wiring diagram. Libraries also often have good manuals you can look at. Some libraries are even providing subscriptions to online auto repair info where you can get good wiring diagrams. I find that it is important to have a wiring diagram I can trust. If you are having trouble getting one, you might check with your public library to see what resources they have.

 

[bmxr152]

well i just unplugged all the wires to the relay and turned the key and heard the fuel pump, so i started it, it ran for about 10 seconds and died. Turned the key again no fuel pump prime. i waited 10 mins and tried again same thing happened. It seems that the relay i thought was the pump relay might be for something else. But the problem is still there. One minute the pump works and the next it doesn't. I used my haynes manual to try to figure out the wiring but the colors were wrong to that relay so maybe that relay is for something else. What should be my next test?

 

[bmxr152]

Did some testing today with the multimeter. I decided to test to see how much power the fuel pump relay fuse and ecc fuse were getting. I got 10V to the EEC fuse, 12V to ign fuse, 8v to fuel pump relay fuse. Then i tested the inertia plug, i got 7 volts. all was tested with key on.

 

[MrShorty]

Do you trust your voltmeter (what does it read across the battery KOEO)?

10 V at the EEC fuse seems low.
8V to the fuel pump fuse is low
7V at the inertia switch is low. There's a 6-8 V "ghost" voltage on the fuel pump circuit KOEO (which means the relay will be open) that comes from the PCM.

Assuming whoever did the wiring wired it the same way Ford did, it looks like there's a break between the fuel pump fuse and the battery. It also looks like there might be something wrong between the EEC fuse and the battery.

 

[bmxr152]

Its a snap on multimeter i got from UTI. BTW this is using a jumper battery because mine died and i cant get it to run long enough to charge it again. Anyways so maybie i have corroded or some pulled out wires or something. It almost is like it will start when you let it sit for a while, but once it turns off the pump i needs a bream before it will start again. So is there any chance it could be the wiring at the fuel pump end of the circuit? I dont understand why all of a sudden now it starts to act up.

Im going to check the wiring out again tomorrow and see what i find out.