95 F150 dies when engaging clutch

[Mk42gunner]

My 95 F150 has an intermittent problem. 300 six cylinder with a 5 speed, 2WD. It dies when engaging the clutch, but not every time. If I rev it up and slip the clutch to get rolling, even a little bit, it runs okay.

It will do it hot or cold, and makes it a real pain to pull up a boat ramp (not knowing if this is the time the truck goes swimming or not).

The only codes it had were the fuel pump relay (didn't make sense to me, but I replaced it anyway) and the O2 sensor, also replaced. I have replaced several of the vacuum lines.

It is also getting pretty bad mileage; after replacing the O2 sensor, I got 15.2 yesterday on a 170 trip on the highway. This truck used to get (20K miles ago) 18 mpg regularly. Sparkplugs have about 15K on them, air filter is good. Good fuel flow, but I haven't checked the pressure.

I don't want to just throw money at it, that is a quick trip to the poor house.

I have asked most of the mechanics around here, one "ford guy" said on the 94 and 95's that if it isn't showing a code, the only chance is to find someone that had seen this problem.

Any ideas? A new to me truck really isn't in the budget right now.

Robert

Almost forgot. When it is acting up, the electronic speedometer bounces around, about 5-10 mph. When the truck runs right, it is steady.

R

[starnbar]

I have had a few that drove me crazy like that too. Start with the wiring and check all of your ground points including the battery it might be a bad ground or a loose/corroded wire. Double check all the wiring harness connect points including the bulkhead connection on the firewall. I hope this helps you out.

[pmer]

I wonder about timing and what it has uses to advance the timing as RPMs pickup. Do you think it could be stuck in the "advanced" mode during the times it dies when you're trying to get the truck moving

[Dark Helmet]

Grounds, your battery is dying and or your alternator is dying.

[dmize]

First off not just being a"Ford Guy" but a Ford technician,I would say take it to a Ford dealer.
It is common where I work in Jefferson City Mo,to have vehicles that have several hundred dollars worth of stuff thrown at them and we end up fixing them for a lot less.
There are a bunch of thing that if the happen at the correct time that can cause these issues.
vacume leaks are usually temp related,fuel problems can happen at any time but usually are not that intrmittant. But those rules arent written in stone.
Only thing that comes to my mind,check your negative battery cable clamp,there should be 2 wires coming out of it,check the small one to make sure it is solid to clamp with NO wire strands broken,also if has had a replacement clamp put on it,make sure it has a solid clean connection. ANY problem with this will seriously screw up the EEC system.

[Blammer]

I would suspect the vehicle speed sensor, since you report that " When it is acting up, the electronic speedometer bounces around, about 5-10 mph. When the truck runs right, it is steady"

•When not replaced, vehicle may experience CEL/MIL illumination, high fuel consumption, loss of power and/or inaccurate transmission shift points.

basically it's a $20 part that has a lifetime warrenty from Autozone.

I work at autozone and have had a few Ford owners come in with the same symptoms.

[geargnasher]

How the output speed sensor on the diff (which runs the RABS and speedo, + sends a speed signal to the ECM for speed control functions) is affecting fuel trim/spark advance on a 5-speed manual is confusing to me, but I don't have the wiring diagram in front of me, either. Maybe this one has a tranny-mounted sensor also.

My very first inclination is to pop the hood, scrutinize the battery terminals, and then start pulling on wires and harnesses. The intermittent driveability issues and speedo dropping out is a dead-ringer for a bad ground like the other wrenchheads mentioned. I think it's safe to say that if you've been an automotive technician for any length of time these days that you've had your butt kicked more than once by intermittent high resistance at a ground somewhere.

The VSS is a high-failure component, probably needs to be cleaned anyway, and it wouldn't hurt to change the gear oil either and get all the metal finings out of it. If the tip of the sensor looks like it needs a shave, pull the cover and change the oil. I don't, however, think this has much to do with your speedo dropping out or the loss of fuel economy. A bad battery connection can do that, and the extra fuel you're burning is due to increased resistance in the serpentine belt because the generator is working overtime.

Gear

[Lloyd Smale]

first thing id check is the fuel pressure

[Mk42gunner]

I will check the battery cables, terminals and grounds; along with any other connections and grounding points that I can find. And check the battery; it isn't that old, I seem to remember replacing it shortly after I got the truck two years ago.

I hadn't connected the VSS to this problem, (it has been doing it for about a year) but the speedometer just started doing the jitterbug. I don't quite see how it could cause the engine to stop when the clutch plate just starts to get squeezed by the pressure plate and flywheel; the vehicle doesn't even move an inch when it dies.

After I get done with these ideas, if I can't find the fault, the next step is to take it to the dealer. I just hate to admit failure on what is probaly a simple problem.

--------

The bad part is that I have had a few carburated six cylinder and small V-8's with three speeds, that got better mileage than this truck.

Robert

[geargnasher]

You might check for vacuum leaks at the intake manifold if that has a separate intake, some of the 300s are famous for losing the gaskets and warping manifolds. Not related to the stalling problem but might be affecting fuel economy since un-metered air leaks mess with the fuel trim.

Gear

[starmac]

check out this site, anything that can happen to a ford pickup has been dealt with at some time or other.

http://www.ford-trucks.com/forums/index.php

[Mk42gunner]

Update.

When I checked the battery voltage today, the first volt meter I put across the terminals read 30 volts. I got a little bit excited at that, then realized that I had the junky multimeter in my hands. I checked the battery in my tractor and it also read 30. I went and got the newer meter and things read more normal ~14 volts.

The Negative cable insulation was cracked so I replaced it, no real change in the stalling problem.

While playing with the wiring harness, I mean moving it in a systematic manner, there wasn't any noticeable change in rpm; but when I drove it it acted a teensy bit more civilized. tomorrow I will take the covering off and check for broken or frayed wiring in the engine harness.

I will also check for vacuum leaks around the intake. And the fuel pressure if I can find my guage kit.

Thanks for the help, sometimes it makes a difference just getting another point of view.

Robert

I also removed the VSS, no metal whiskers, but the oil stain wiped off with a paper towel. I forgot to check if it was magnetized; a Hall effect proximity switch has to have a magnet somewhere close.

[Dark Helmet]

Maybe you improved your circuit path a teensy bit, keep lookin! Also try breaking and reconnecting circuits, to include alternator bolts, body grounds, coil bolts, relay attaching bolts, etc.

[400short]

On 2 different mid 80's fords with the 300 six and singlebarrel carter, the carb mounting nuts worked loose, so air was being sucked into the manifold but not going thru the carb. I don't know how similar the 95 is to the eightys, but the symptons are similar. Idled like **** and had poor fuel economy.

[jimbower58@hotmail.com]

On 2 different mid 80's fords with the 300 six and singlebarrel carter, the carb mounting nuts worked loose, so air was being sucked into the manifold but not going thru the carb. I don't know how similar the 95 is to the eightys, but the symptons are similar. Idled like **** and had poor fuel economy.

Has there been any update to this problem? I know it was originally posted 8 years ago, but I'm having the same issue now.

[Mk42gunner]

Yeah, I forgot to update this thread when I got it fixed.

Turns out it wasn't the VSS, but the PSOM (speedometer to normal folks). I got a replacement from a junk yard, put it in and everything ran right. The bad was the junkyard speedometer had about 50K more miles than the truck. Oh well.

The best way I found to check was to pull the fuse for the PSOM, I can't remember now if it was #8 or #18. This will kill the speedometer, but the truck didn't die on take off anymore.

After verifying that was it, then it just came down to tearing apart a couple of dash panels to fix it.

If you are asking about the loose carb bolts, I would invest in a few nylock nuts for the studs. Can't remember if they're ¼-20 or ¼-28 thread.

Robert

[jimbower58@hotmail.com]

Yeah, I forgot to update this thread when I got it fixed.

Turns out it wasn't the VSS, but the PSOM (speedometer to normal folks). I got a replacement from a junk yard, put it in and everything ran right. The bad was the junkyard speedometer had about 50K more miles than the truck. Oh well.

The best way I found to check was to pull the fuse for the PSOM, I can't remember now if it was #8 or #18. This will kill the speedometer, but the truck didn't die on take off anymore.

After verifying that was it, then it just came down to tearing apart a couple of dash panels to fix it.

If you are asking about the loose carb bolts, I would invest in a few nylock nuts for the studs. Can't remember if they're ¼-20 or ¼-28 thread.

Robert

Hey Thanks Robert. I have spent a lot of money I didn't have to on this problem. I was told it was the clutch but I thought all a long it was electrical. I had a new clutch put in and still doing the same, stalling unless I ride the clutch. And my speedometer doing the same as you mentioned. So let me see if I got this straight, if I pull the fuse for the speedometer, that should fix it until I can replace speedometer?.

[Mk42gunner]

It did on mine.

IIRC the computer gets a signal from the PSOM somehow, and if it doesn't bad things happen. There was quite a discussion on this on the Ford truck forum at the time. That is where I got the idea to pull the fuses to check.

A Haynes manual isn't a whole lot of good in this particular instance, from my memory.

Robert