chipsto

Hi folks,

I'm new here. I'm from Scotland but I'm living in Quebec for a while. I wanted to take the opportunity to own a proper truck because the pickups we get in the UK are tiny in comparison, so I got my hands on a '94 F150 5.0 4x4 auto. It has 177,000 kms on it, I got it for $3000 CAD.

Overall, it's in pretty good condition but it does have a few issues. I've searched around and come to a few conclusions about the things that might be wrong, but I have yet to pull the fault codes. I'm completely new to these trucks, engines and transmissions!

1. Speedo needle wobbles a bit, and sometimes dies completely - VSS?
2. When warm, it will reach much higher revs than it should before it will start moving forward. Changes into 2nd and 3rd gears are also quite violent - E4OD tranny, MLPS?
3. Also when warm and having sat for 30 minutes or so, it will crank a lot longer before the engine starts, along with a fuel smell - Vacuum leak?

Those are the main issues. It also pulls to the left a bit under braking but that's a pretty standard issue to deal with. There is also a slight leak from the transfer case.

I'm not sold on the colour but what swung me was the fact it has barely any rust which is a rare thing in these parts. Vehicles this age around here are usually on their last legs, if they haven't already died!

Here's some photos...

BLDTruth

Welcome to the forum - that's a nice clean looking truck, especially given where it has lived.

VSS would be the first thing I would look at - it might just solve your shifting/revving problems too but maybe not. The crank/no start problem at higher temps could be a few things - most important thing to figure out there is whether or not you have spark when it DOES NOT start so you can identify if it is fuel related or ignition related. Could be an ignition control module, could also be something like the engine coolant temp sensor.

I'd recommend doing the full tune-up and fluid change reginmen if you don't have any history on when the last stuff was done - motorcraft plugs, wires, cap, rotor, PCV valve. Go motorcraft for all of these parts including the VSS. If it were me I would consider testing and replacing the throttle position sensor too - also motorcraft only. Changing out all of the plastic vacuum lines with rubber or silicone based is a great idea as well.

Good luck!

Chris_1

iTrader: (1)

Speedo and shifting problems often go hand in hand. Could be the VSS but also could be an issue with the speedo itself (called a PSOM).
You can pull most of your codes without a code reader on a 94 - there's a thread at the top of this section that explains how.
A fuel pressure tester would be a good tool to lay your hands on - these trucks don't behave well at all without sufficient fuel pressure.
Also check the vacuum line on the fuel pressure regulator at the back (left) of the fuel rail for the presence of fuel or a fuel smell - could have a leaky diaphragm in there.

chipsto

Thanks guys. I'm going to go and get those codes just now.

chipsto

Here's what I got from a key on engine off test...

539 (O) System shows voltage at PCM pin 10 Is A/C on ?
1
181 (M) Fuel system was lean at part throttle Single, Right or Rear HO2S – Fuel control
334 (O,R,M) EVP sensor is/was high – EVR
452 (M) Vehicle Speed Sensor (VSS) problem
542 (O,M) Fuel pump open, bad ground or always on – – Power / Fuel Pump Circuits

So the VSS is there, as suspected. Also the EGR seems to have an issue. From what I've read both these things can lead to shifting issues.

Energized

Number 3 is your fuel injectors, trust me that's the exact same as my truck was, you are probably getting horrible mileage, well more horrible than the normal horrible... After it sits over night it starts instantaneously i'm sure. My 93 5.8l was the exact same.

Also if the speedometer PSOM is faulty it can cause the hard shifts and bouncing needle, so i'd say you need a new(er) speedometer, lots on Ebay if you trust that.

All in all i would swap out the speedometer and change the injectors and the oxygen sensor, oil change, air filter... see what it runs like then. Just my two cents.

In case you actually put any stock in my suggestion, here's the link to some decent rebuilt ones, you can do them yourself too if comfortable and they aren't rotten like a couple of mine were, it's just a whole lot easier this way, i'd say for 300'ish bucks you could have that running a whole lot better. Good luck anyways. My dad was a mechanic by trade, he was the one that said the injectors were shot in my case. He was right, obviously.

http://www.ebay.ca/itm/Bosch-Flow-Ma...767?rmvSB=true

chipsto

You are correct, it starts fine when it's cold. It also starts fine if it's warm and it's just been running. But if you wait 30 minutes to 2 hours and start it while it's still warm, it turns over for a good few seconds before it catches. I haven't run it enough yet to figure out what kind of mileage I'm getting. I'll get to the injectors but my priority at the moment is this shifting issue.

So first, I'm going to start with some cheap stuff and swap the VSS, replace all the vacuum lines and check for leaks and replace the fuel filter then see where I'm at.

Chris_1

iTrader: (1)

I wouldn't be diving into ripping off injectors either. That can get pretty major what with old bolts and other things. Kind of an only if absolutely necessary sort of thing. Some injector cleaner in the fuel tank would be a good idea.
You will want to check that regulator vacuum hose, that's a pretty common source of fuel pressure bleeddown which will flood the engine as it sits after running a bit. Injectors can do that too, but it's less common.
The regulator vacuum hose is wide open to the intake so if the rubber diaphragm inside leaks, it dumps fuel. It's probably original which makes it 20 years old so it's a good idea to check it.
Motorcraft only on that VSS - other ones are hit and miss.

Energized

I guess it seems scary at first, i live in Saskatchewan and the truck spent the entirety of it's life here, climate wise it doesn't get much more extreme in North America as far as harsh conditions for a vehicle, i had little to no problems and it was the first injectors i'd ever done. True i did them in my dads garage while he sat on the deck just in case i needed a hand but wasn't necessary.

Just pop the fuel pump fuse and crank it over a couple times then release the fuel pressure with the bleeder valve, pull apart the top of the engine and then pop off the rail from the injectors, don't even need to remove it. Anyways good luck with whatever you get up to.

east302

That'd be the first thing I'd look at since the part is cheap and pretty accessible. The diagnostic procedure is in a Haynes book or you could probably track it down online. Here's one link, you're just probing the sensor to see if the resistance is within spec at a given temperature range.

http://www.fullsizebronco.com/forum/...4491?_k=9afk38

If the sensor is faulty, it can cause hot start issues similar to what you're describing.

Also check the fuel pressure.