Anyone removed the Fuel Pump Inertia Switch out of circuit because it's faulty (and expensive)?

[cobrajocky]

Update:

I jumpered the plug - Green to Pink and nothing, still won't start.
I measured 6.8VDC across those two connectors in the plug with the ignition on, 5.4VDC with the ignition off. Shouldn't there be no voltage with the key off?

Now I am stumped. Last time it wouldn't start up, I tracked it to the Inertia Switch, which I found tripped. I reset it and the truck started immediately.

I crawled under the truck as close as possible to the gas tank and had my wife turn the ignition to on a few times. I can barely hear the fuel pump come on each time for just a couple seconds. Sounds like a very quiet low F Flat "groan" motor noise. ( what can I say, I'm a musician) You can't hear it in the cab at all, not with that damn loud "Ding Ding Ding" key warning blasting away. But it still won't start.

 

[19Walt93]

I'm not sure what the voltage at the inertia switch should be but I have some suggestions and opinions(as always). I've heard some noisy fuel pumps and some exceptionally quiet ones, if the pump gets noisier it's headed for failure. Unfortunately quiet ones can also fail. Please reconnect or replace the inertia switch when you're done with diag, if you could predict an accident it wouldn't be an accident. They can be reset with no problems, 84 LTD wagons started coming in as no starts on Monday mornings during the summer. After a poor round of golf, the bag would get tossed in the back and the tailgate slammed hard enough to trip the inertia switch. We fixed them by showing the owners how to reset them and suggested they not slam the gate. Foreign cars and GM's at the time didn't have inertia switches and there were fires.

 

[SonOfBob77]

Update:

I jumpered the plug - Green to Pink and nothing, still won't start.
I measured 6.8VDC across those two connectors in the plug with the ignition on, 5.4VDC with the ignition off. Shouldn't there be no voltage with the key off?

Now I am stumped. Last time it wouldn't start up, I tracked it to the Inertia Switch, which I found tripped. I reset it and the truck started immediately.

I crawled under the truck as close as possible to the gas tank and had my wife turn the ignition to on a few times. I can barely hear the fuel pump come on each time for just a couple seconds. Sounds like a very quiet low F Flat "groan" motor noise. ( what can I say, I'm a musician) You can't hear it in the cab at all, not with that damn loud "Ding Ding Ding" key warning blasting away. But it still won't start.

Well, there’s your problem. Nobody knows what the hell to do with an F flat… approach the truck from the low-side and look for an E natural “groan”, much easier to diagnose. Just keep an ear out for the elusive B sharp, that means bearings are cooked

 

[RonD]

The green wire at inertia switch should have 12volt for 2 seconds with key on, that 12v would go to pink wire(fuel pump) to power it up for 2 seconds, which generates about 10psi fuel pressure

You can run a jumper wire from battery positive to the pink wire to turn on fuel pump full time, to hear it, but also you can, at that time, test for fuel pressure at the test port on the engine's fuel rail, that will tell you if pump is working like it should

The tan wire, computer monitor, can have 5-8volts, no amps just volts, and yes that voltage can stay after key off until capacitors are drained

 

[cobrajocky]

I'm not sure what the voltage at the inertia switch should be but I have some suggestions and opinions(as always). I've heard some noisy fuel pumps and some exceptionally quiet ones, if the pump gets noisier it's headed for failure. Unfortunately quiet ones can also fail. Please reconnect or replace the inertia switch when you're done with diag, if you could predict an accident it wouldn't be an accident. They can be reset with no problems, 84 LTD wagons started coming in as no starts on Monday mornings during the summer. After a poor round of golf, the bag would get tossed in the back and the tailgate slammed hard enough to trip the inertia switch. We fixed them by showing the owners how to reset them and suggested they not slam the gate. Foreign cars and GM's at the time didn't have inertia switches and there were fires.

All I've got is a Haynes manual for 1993 to 2000 Ford Rangers and Mazda B Series trucks, and I can't find any reference to voltages to that Inertia Switch with key off, or on. Nothing in the manual about testing that switch either. I did find a YouTube video about generically testing an Inertia Switch (using a DMM), but I can't get to the male blade terminals and I can't get the switch off the firewall because Ford used what looks like a metric bolt that is smaller than 6mm and I don't have sockets or wrenches smaller than 6mm. Go figure.

I am beginning to believe the Sporadic "No Start" issue is not that Inertia Switch. While this is my old seldom used "truck", nothing heavy is ever hauled in it in recent years, no golf clubs, etc and I think I've had the tailgate down only 4 times all year. Haven't hit anyone, nor my being hit. Previously when I suspected the Inertia Switch is when I had some grocery bags on the passenger floor and MAYBE a bag with 1 Litre soda bottle might have fallen over theoretically bumping the firewall, but I really doubt it. No sudden stops, this has happened before after driving it for hours on errands AFTER coming back home and it sits there overnight in the driveway.

This sporadic No Start issue has happened maybe 4 or 5 times in the last 18 months. A diagnostic nightmare.

Here's a brief chronology of this problem's history, keep in mind this 97 B-4000SE 2WD 4.0L V6, Auto Trans (same as a Ranger XLT) with only 100k Miles oddly exactly, never been in an accident-

1) This "No Start" the next day, or more, after driving it fine with many errand stops has happened 4 or 5 times before.

2) Other than the last occurrence 2-1/2 weeks ago, the truck would just decide to start with very little cranking to immediately! (WTF?) I was thinking a Vapor Lock issue. Again, on my B-4000, you can't hear the Fuel Pump from inside the cab, never could, too much sound insulation on the upper "SE" models.

3) The Last time 2-1/2 weeks ago, which I believe the Inertia Switch was tripped, though the button was NOT all the way up and I reset it and it started right up. Coincidence?

4) I have had a long-standing issue with the Crankshaft Position Sensor, located on the bottom front of the engine where street crap (water, grime, dirt and dust) easily gets thrown up at it fouling the connector, maybe (I don't know) damaging or prematurely aging that sensor. If, or can, that sensor become intermittently Flaky and inhibit the starting as I'm experiencing?

5) This truck has had an occasional problem with stalling from stops at stop lights, signs or turning at a corner from a stop. Started a few years after having the head gaskets done from an over-heating episode. I guess this stalling issue is possibly due to a vacuum leak somewhere causing a delay on the timing advance? I have no idea where to look for this leak, but with 23 year old hosing all over the place (I had to replace all the AC and Smog related hoses last year), the leaks could be anywhere. SO ..... could this vacuum leak cause the No Starting issue Sporadically?

I did replace the Fuel Filter 2 years ago. When the truck runs, the engine is very strong, no hesitations and this 4.0L V6 in such a light Pup is damn fast. Every mechanic I've ever talked to says these Ford 4.0L V6 engines may be one of the best Engines Ford every design in the recent era. ( I wish I did have the later SOHC version though).

Again, I think the key clue here is it's been Sporadic.

Appreciate ALL the sound advice guys.

 

[19Walt93]

Speaking of the crank sensor, look closely at the harmonic balancer, I've seen the outer ring slide back and rub on the sensor. If that's what is happening the problem won't stay intermittent, it'll die and stay dead.

 

[cobrajocky]

Speaking of the crank sensor, look closely at the harmonic balancer, I've seen the outer ring slide back and rub on the sensor. If that's what is happening the problem won't stay intermittent, it'll die and stay dead.

First thing this morning, before touching anything else on the truck, I decided to get a closer look at that Crank Sensor, which I've had problems with on and off for years (see #4 on my list of "history" on the above post.). Not necessarily the sensor as far as I know, but the connector has gotten fouled from road crap and it was loose a couple of times. My driveway is a 8 degree slope, so can't use jacks and I don't have a lift, so it's a matter of squeezing under the front of the truck which doesn't have any lift kits. The connector wasn't loose, but I "jiggled" it anyways and pushed down to seat it to the sensor as far as it would go.

Jumped into the cab and the truck started right up. Well damn! No movement on the harmonic dampener, I think the truck is too mileage young for that, get this, it stopped running EXACTLY at 100,000 on the Odo! (look below)

So, is this conclusive, could it only be the crank sensor or just a fouled connector that is the Troublemaker for the no start the day after it ran fine? Or do i keep looking elsewhere for a co-villian? Anyone know if this is a common problem on the 4.0L V6? Or am I just jinxed.

If it could be just the sensor, I think I'll order a new sensor and have a service shop I've gone to before and trust and will install my parts at a fair price install the Sensor and clean up the connector good and make sure it stays on tight, the truck needs a pressure radiator flush and fresh plugs anyways, also need to have caster / camber adjustment bushings installed on the front A arms. It's got a serious camber problem on both side and there's no more play in the factory arms.

I am still concerned that the voltage to the Inertia Switch with the key on is not 12v, I read only 6.8vdc. That supply is from the fuel Pump relay only. Need to figure that out.

Thanks for your good input "19Walt93".

 

[19Walt93]

You may be able to get a new connector through a Ford dealer, it's worth checking.
I'm glad it helped. We had a customer driving her 120k Explorer through Massachusetts a few years ago when it quit. The cop called a tow service and they towed it to their shop, saying they could fix it. They found the outer ring on the balancer had slid back and ground into the sensor, shorting it out. They replaced both pieces, charged her more than double the time it should have taken an something like 50% over retail for the parts. Before they handed her the inflated invoice, they gave her the old balancer in a box and told her to see the dealer when she got home for a refund because that part should "never fail". Never mind that the warranty was 3 years/36,000 miles. That directed her attention away from the bill and she paid it. I was the bad guy when I explained that Ford wouldn't reimburse her for a part failure on a 10 year old, 120.000 mile vehicle. I also looked up the job in our estimating system and told her what it would have cost at our dealer price, but she didn't believe it. I was the bad guy and the guy who drastically overcharged her was the hero. If I had a nickel for every time an independent threw us under the bus to distract the customer's attention away from what they charged I'd have to borrow an F350 to get them home.

 

[pjtoledo]

the connector with short wires is available aftermarket. did my 2005 last summer.

 

[RonD]

You should read 5 to 8 volts at inertia switch, no AMPs, its just volts from computer monitor circuit
You would only see 12volts(battery volts) for 2 seconds just after key was turned on, then just the 5-8volts after that
When computer "sees" RPMs above 400 it will send 12volts full time to inertia switch/fuel pump, its a safety thing

Engine would not have started if there was no 12volts at inertia switch

 

[cobrajocky]

You should read 5 to 8 volts at inertia switch, no AMPs, its just volts from computer monitor circuit
You would only see 12volts(battery volts) for 2 seconds just after key was turned on, then just the 5-8volts after that
When computer "sees" RPMs above 400 it will send 12volts full time to inertia switch/fuel pump, its a safety thing

Engine would not have started if there was no 12volts at inertia switch

Ron - I'll recheck that voltage today and look for the 12v just as the Ign key is turned on and then the 5 to 8v after. Thanks for that clarification.

Hey do you think it's normal that I can barely hear the Fuel Pump in this late 90's (97) B-4000/Ranger XLT equiv? I've never heard it from inside the cab since it was new . It's one of those things, don't hear it don't think about it.

The Fuel Pump in my '88 Ford F-150 you could easily hear standing next to the truck if there wasn't any traffic noise. Loved that truck, wish I still had it.

 

[cobrajocky]

the connector with short wires is available aftermarket. did my 2005 last summer.

Thanks for that input. You don't happen to remember where you got it and the part number?

 

[RonD]

I hear it more when tank is below 1/4, but can hear it if I listen for it, it only runs for 2 seconds

 

[cobrajocky]

You may be able to get a new connector through a Ford dealer, it's worth checking.
I'm glad it helped. We had a customer driving her 120k Explorer through Massachusetts a few years ago ......

I'm gonna search for a replacement connector and probably a sensor since it's had a bad "history" with this truck in recent years. The Mechanic I use will install it for a few extra bucks with the other work I have for him to do to get it in shape for WInter. Since it's not going to be an expensive Fuel Pump replacement job I may have the extra cash to get this poor looking "outside parked" babe repainted over at Maaco. Paint is badly "sun burned" and all the matching paint color has pealed off the Lear Bed Shell. Used to be a great looking truck.

I know what you mean about the dealer catching the "down hill roll" of BS some independent shop give customers. My father owned 4 Ford / Lincoln - Mercury dealership in the 3-state area of Illinois, Indiana and Wisconsin after he left Ford Dearborne as VP of Truck Engineering in the 50's after leaving the USAAF. He had a great mind for marketing, but being an Engineer by education, he put customer service first at the dealerships. Customers came back to buy again even when they had a factory lemon because the dealership took care of them. But a bad independent like you explained still makes it hard on the dealer's shop when the customer been given a load of crap and a bloated repair bill. I never had an engineering class in my life, I was in the sciences, but I learned to rebuild a motor the right way from the great mechanics we had at the dealerships. Wish I had spent more time on the electrical system though. Now you have to be a rocket and computer scientist to work on anything after the mid 90's though.

Thanks Walt

 

[pjtoledo]

should be available at most parts stores, NAPA is my favorite.

https://www.napaonline.com/en/search?q=Nty%3D1%26N%3D2500011%2B2601109%2B2800152%2B10200500%2B5002800%2B200280440%26Score%3D0.78&referer=plp&partTypeName=Fuel%20Pump%20Switch%20Connector&keywordInput=fuel%20inertia%20switch&scene=partTypesScene1&fullyQualified=true