Truck just goes dead while going down the road

cgrey8 · Post by **cgrey8** » Sun Jun 10, 2007 6:13 pm

Today my truck started acting up something fierce. I thought I was going to have to get a tow about 3 different times on the way home. I'm hoping somebody here can help give me ideas as to what to look for to diagnose what's going on.

The symptoms are when it runs, it runs great. However sporadically and for no apparent reason (i.e. not necessarily hitting bumps or taking turns) it just decides to dump to zero power. It's like the fuel pump just quits pumping, but I'm confident it isn't the fuel pump for 1 reason. The tach drops to zero even when I KNOW the engine is spinning (it's a manual). As soon as the engine comes back to life, the tach jumps to RPM as well. So here are my thoughts:

the EEC is loosing power
the TFI module is no longer reporting the PIPs to the EEC which results in the injectors no longer firing AND no report of spark to the tach
the hall sensor pickup in the distributor is not reporting spark to the TFI module

At one time during it's misbehavings, I turned the ignition on and off while I had it in gear just to see if that'd make any difference. I saw the tach move up and down, but no more than I'd normally see when turning the ignition on.

Is this one possible behavior of a TFI module going bad? My previous experience with them has been that once they go, they are gone and never work again. But perhaps they don't always fail in this way.

Thoughts/opinions?

87ranger · Post by **87ranger** » Sun Jun 10, 2007 6:49 pm

check the 10$ ignition relay inside of the steering column, mine did the exact same thing and that was the issue, it will drop poer to everything

cgrey8 · Post by **cgrey8** » Sun Jun 10, 2007 7:21 pm

I've never taken the column apart before. Can you give me some heads-ups on anything that may not be straight forward in getting it apart? Also what's the relay called? I'm sure it's original if my truck has one of them. So it's worth replacing just to be sure even if it isn't the problem.

Another tidbit that I "think" I remember is that my datalogging software was working and datalogging through the dead period. If the EEC wasn't powered, the datalogging software wouldn't datalog. However I can't swear on this. As a result of this issue the 1st time it happened, the engine momentarily ran really lean while idling. It backfired up the intake when it died and created such a high pressure wave that it blew the rubber cap off one of the vacuum taps. The rubber cap was oily because it was blocking an unused vacuum tap that is opposite of the PCV valve's tap. Being oily, it was probably easy for a few PSI of a backfire to blow it off. So even when the engine was trying to run, it wasn't running very good until I discovered that this had happened. Once I discovered this, I blocked it with a piece of hose that'd fit the tap with a bolt in the hose. It's not very professional looking, but I had to get home and it's what I had. Point being, when the engine was misbehaving and the datalogging software was datalogging through the misbehaving, it was probably not running because it was running so lean due to the unblocked vacuum tap (and it was a big tap, not one of the smaller ones). I don't think I got a datalog of it when I KNOW it wasn't a vacuum problem. While I'm messing around later this week trying to get it to reproduce, that's one of the things on the list to do.

87ranger · Post by **87ranger** » Mon Jun 11, 2007 9:36 am

use a screw driver and get ride of that annoying key lock while your at it, just use a vise gripes and rip it out, and if the relay is only 10$ or so, youd be an idiot to not replace it

cgrey8 · Post by **cgrey8** » Mon Jun 11, 2007 10:19 am

By key lock, do you mean the ignition switch? I should rip it out and replace it with a new one or rip it out and hot-wire it to work? I'm not following you on this one.

And I agree, if the relay isn't that expensive, it's worth replacing even if it isn't bad...just as good preventative maintenance.

Another thing I was thinking that strengthens the possibility of this being the TFI module is it has never happened until the truck sat for a good 10 minutes idling on what was a fairly hot day yesterday (upper 80s). Had I known I was going to be that long, I probably would've turned the engine off, but I expected to be in and out. The pushers were running and the engine temp was being maintained (datalogged 198-206 from the EEC). I suspect that as well as it was cooling the engine, it still may not have been pushing enough air into the engine bay and caused the TFI to overheat. Had I not had an MSD box, it's possible that the additional load a coil puts on the TFI module would've done it in completely. However since I have an MSD box, it's possible the load just wasn't enough to make it complete give up the ghost. Is that possible or just rambling nonsense?

plowboy34 · Post by **plowboy34** » Mon Jun 11, 2007 6:06 pm

I'm guessing by key lock he means the button you push in so you can turn key back to remove. Just a guess but that's my thought. Personally I like the key stop being there, saved my butt big time once. It's just a personal thing, if you don't like it he is right, now would be the time to get rid of it.

I also believe he is talking about replacing the ignition switch, not the key cylinder. The key cylinder actually is not the ignition switch. There is a steel rod that connects the key cylinder to the switch which is farther down the column. If you would remove the plastic covers from around the column which should be just two phillips screws from the bottom. It will come apart in half, top and bottom. Once the cover is off you will see the two nuts that hold the column up to the dash, take them out and the column will come down. You will see the ignition switch on top of the column, it is obvious. You will see the rod that goes from the cylinder to the switch. If i remember right there is two bolts that hold the switch on, except for they are not headed bolts. They almost look like rivets but they are bolts. Use whatever you can to get them started turning, usually not that hard. New bolts should come with new switch. I believe that should be enough info to get you there, it is not that hard Chris. If you need any other info or if maybe something isn't as I described let me know and we'll go from there.

Way back when my V8 Pinto did the samething. I would be cruising down the road 60mph and it would just shut off. Just like you turned the key off. The switch had gone bad and would lose contact, took me a long time to figure that one out.

cjcnomor4 · Post by **cjcnomor4** » Mon Jun 11, 2007 6:57 pm

the tfi and stator were new when you got that dist. if you want to try new ones let me know, i'll send you one of each. just remember to change the stator the gear has to be pressed off. if you can get it to happen long enough to check for fuel pressure or spark you can pin it down. in my opinion it doesnt sound like a fuel problem. too sudden. i had an ignition switch (not lock cylinder) go bad on a 87 mazda pick up i drove in college. it would just cut out, some times backfiring through the exhaust. it got so bad i had to pull the switch and start it with a screwdriver to get the contacts to connect. they were just badly worn. new switch and it was good to go.

87ranger · Post by **87ranger** » Mon Jun 11, 2007 7:13 pm

thank you for spelling it out plowdude, thats exactly what i meant

plowboy34 · Post by **plowboy34** » Mon Jun 11, 2007 9:10 pm

No prob 87ranger(dude)....LOL. reminds me of my california day's.

cgrey8 · Post by **cgrey8** » Tue Jun 12, 2007 5:53 am

Plowboy34, that's the detail I was looking for. Now I should be able to dig into that column, and know exactly what I'm going to see before I see it, which makes me much happier. I'll stop by the auto parts store today at lunch and pick up an ignition switch to replace my factory one. Even if that's not what it is, it'll be worth replacing just because I know what's there is original. Although my gut feeling is it isn't the switch just because I'd think turning the ignition on and off would cause it to intermittently run. There was a period going down a hill that I played with the switch turning it on and off a few different times and it never gave a blip. I had to pull off to the side of the road at that point. I looked under the hood. Didn't seen anything odd, but lifting the hood I'm sure did let out some heat. After about 3 minutes, it crunk back up and stayed cranked. It blipped once or twice getting back onto the road but after that, it ran perfect all the way home and didn't give another blip. But that doesn't mean it isn't the switch, so I'll still be replacing it.

Cjcnomor4, thanks for the offer, but I have a 2nd 302 distributor with supposedly working TFI module and pickup. I found a 302 distributor off eBay for $30 (inc shipping). It was sold in working, used condition. I just wanted a 2nd distributor for parts to build the 331 with so the 302 I have now would be a complete engine once it was pulled. However now, it's going to serve as a parts donor. If I knew what to do to get it to readily reproduce, you are right, I could start diagnosing and pinpoint the problem. But I can't even get it to readily reproduce on the side of the road long enough to figure it out although I am glad it did crank back up and get me home. The only hints as to what's wrong is:

The tach drops to 0 with the loss of engine power even when I know the engine is spinning
Messing with the key didn't have any particular affect on things
Lifting the hood everytime this happened seemed to result in the engine coming back to life

At this point, I only have theories as to what it is. Everybody seems to agree it's most likely one of 3 components...so, I'm happy to replace the TFI, pickup, and ignition switch all at once just to get the problem fixed and get my daily driver back even if I'm left not really knowing which is to blame. I'm puttin' around in the 97 Ranger, and it SUX. Don't get me wrong, I'm thankful I have a 2nd vehicle I can drive. But that doesn't mean I have to like driving it. I'm so spoiled to the torque of the V8 it's not even funny.

BTW, do they make TFI relocation kits for the distributor I have to get the TFI module off the engine and onto the fender? If so, I'd be interested in doing that upgrade.

cgrey8 · Post by **cgrey8** » Tue Jun 12, 2007 1:10 pm

I got the switch.

Yall were right on with the price too. From AutoZone, it was less than $9 including tax for a Wells (GP Sorensen pictured).

I got back into the truck trying to figure out how it worked since I didn't see any handles or obvious moving parts. But then it clicked...the center behind all the connectors moves and I guess the rod from the lock yall were referring to goes into that slot. It didn't come with new bolts, just a new clip that I assume is what holds the rod in that slot.

I probably won't get a chance to mess with it tonight, but hopefully I'll have tomorrow afternoon to get this and the TFI module replaced. I don't know how big of a PITA replacing the pickup will be or if I even need to do that at this point.

plowboy34 · Post by **plowboy34** » Tue Jun 12, 2007 9:06 pm

No clip on rod, switch actually sets down on rod and bolts holding switch down keeps rod in place. You'll see when you get there, as I said it is not that bad of a job.

Just for the record I believe your problem is electrical since the tach quits. I have also seen coils go bad and quit when they get hot. It is rare but I have seen it. I hate to add another possibility into the mix but it is possible.

87ranger · Post by **87ranger** » Wed Jun 13, 2007 4:20 am

you managed to put a v8 in a ranger, i think you can put in an ignition switch

cgrey8 · Post by **cgrey8** » Wed Jun 13, 2007 8:04 am

87ranger wrote:you managed to put a v8 in a ranger, i think you can put in an ignition switch

I guess you are right. I just assumed the factory would've put some trick to it in the name of anti-theft. But if it's just a matter of pulling 2 screws, a plastic piece, and 2 bolts, then that doesn't sound too bad.

cgrey8 · Post by **cgrey8** » Wed Jun 13, 2007 5:21 pm

I see what the anti-theft strategy is. It's mounted on top of the column.

6 bolts and a few scrapes on my hand, the switch is replaced. However I'm probably going to have to pull the column again because I'm not sure I like the key position where the switch ended up.

I let it idle for a good 20 minutes and it didn't die. But it's also fairly cool this afternoon and the fans were having no trouble maintaining temp. They were actually turning off as opposed to Sunday.

I would've replaced the TFI module but I forgot that I'd need thermal grease to put one of those on. I'll pick some of that up tomorrow. I don't want to ruin my other module by not putting grease on it.