Hey everyone,

First post! I've been reading the forums trying to troubleshoot this truck I just bought... it's a 98 F150 with a 5.4 litre (out of a 2000 truck though, roughly 160k)

This truck has a SEVERE engine vibration/misfire. Starts fine everytime, idles about 6-800rpm... so what it's doing... let's assume the truck is idling in park and I hit the gas the engine hesitates and spudders as if it's not getting enough fuel almost or timing issue? It is road driveable but has no power really.

Symptoms:

1) Truck is puffing white smoke, smells VERY strongly of rich gasoline that is not getting burned possibly?? From a cold start the smoke takes about 5 minutes before it starts exiting the tailpipe.

2) Severe hesitation / stumbling / misfire?? - shudders a bit if you're easy on the gas, put your foot into it though and the whole dash almost rattles off.

When I bought it I drove it about 100km back home and so far for troubleshooting:

1) Replaced spark plugs
2) Pulled COP's and OHM tested, all are within specs.
3) Pulled Fuel Injectors and bench tested (I made a setup to do this, hooked up a hose filled with gas, fitted to the fuel injector and applied 35 PSI compressed air and used a 9v battery on each injector to verify they were functioning and not leaking - all were good.
4) Checked Coolant and Oil. Coolant is old, could probably use a flush but there is no oil or any oil sheen to it really. Oil looks a bit old but there is definitely no water in it.

Although I have bench tested COP's and injectors... am have not used a NOID light on the injectors to ensure the PCM is firing them correctly. Same with COP's I have not used a spark tester on them yet (I may buy one tomorrow) to ensure they are firing from the computer properly.

That's pretty much as far as I've gotten so far. Now the guy that I bought this truck off of (from craigslist) didn't seem to know too much of what he was talking about, but for 600 bucks I figured worst case scenario I can throw another engine in it, if this one is no good.

He said the truck was running fine for him, for 2 months since he had bought and he went up a logging road over some washboards and all of a sudden it started hesitating and stumbling etc... he tried diagnosing it and couldn't figure it out and just wanted to get rid of the truck.

I am going to tear it apart tonight so I can do a compression test on it tomorrow to find out if it's the headgasket or not.

Any and all help would be greatly appreciated!






So this yellow hose in this pic... on the right side it connects to the valve cover... I have a diagram from another post that I saw down below and it looks like to me this hose is connected in the wrong spot?? If anyone can clarify it would be much appreciated.





You can see this hose in the other picture that's blocked off with a nut and hoseclamp. Obviously this is suppose to connect somewhere...if anyone can tell me where so I can get this fixed up again, much appreciated.





In this picture there are 2 vacuum lines... you can see them disconnected next to the power steering reservoir, they almost look like fuel return lines of some sort but I don't think they are, and no idea where they connect to.

Any and all help again, would be greatly appreciated really looking forward to getting this truck roadworthy again.

I'll keep this thread alive if anyone else is facing similar issues.

 

Fuel pressure good?

 

I don't have a guage to check properly... but I just started the truck... killed the engine jumped out and used a key on the fuel rail test port and there was hardly any pressure there (it didnt really pop, fuel just kind of fizzled out). I'll try and borrow a guage to get an actual reading today or tomorrow. Is it possible the fuel pressure is crap because of any of those missing hoses that aren't connected?

I also checked the fuel pressure regulator... seems to be okay no fuel in vacuum line... will know for sure when I get a guage on the fuel rail though.

 

Just completed the compression test...not so good..


Cylinders ---- Compression

5 ---- 175 psi
6 ---- 160 psi
7 ---- 160 psi
8 ---- 173 psi

1 ---- 150 psi
2 ---- 160 psi
3 ---- 160 psi
4 ---- 30 psi

Any ideas guys? Could this be a semi easy fix, intake gasket or most likely head gasket?

 

I just did a wet compression test on cylinder 4... inconclusive results... when I did the dry test I did it twice to make sure (removed the compression adapter and rethreaded it into the cylinder to make sure I didnt have it loose or anything) and I got 30PSI both shots.

I did a wet compression test, added about 2-3 tablespoons of oil and redid the test... on the first turnover on the cylinder the guage jumped up to 50 PSI... I reset the guage and did another crank and now I'm getting about 0-10PSI... any ideas?

EDIT: also when I pulled the #4 spark plug, it was drenched in fuel.

 

I'll give it a shot....The yellow hose is actually ok, just a crank vent. The two smaller vacuum hoses you were questioning belong to the DPFE sensor which in turn controls vacuum to the EGR valve. This sensor is located next to that yellow hose about 6 inches to the right of the red throttle body spacer you have ....it has an arrow with the word "up" on it. Those hoses absolutely need to be connected. The black hose connected to the intake directly above the yellow hose connects to the IAC valve around the back of the intake. The hose that has a screw in it and is clamped on top of the intake should be connected to the canister vent solenoid which is on the firewall to the right with the white and green cap. It should be connected to the green cap. Will need more photos to figure out the rest. Hope this helps.

 

White smoke is usually water. You might have a head gasket problem on #4. Pull the valve cover and check the valve operation. If that looks good, probably have to pull the head.

 

Another update.... First of all thanks ParnAZ that was a great description, I got the 2 small vacuum lines figured out... however the canister vent solenoid has a hose connected to the green port already as seen here:





Is that correct or should it be connected to the blocked off hose above where it is currently connected to?<br/><br/>In this next picture I found another hose that runs down behind the engine that is also blocked off with a bolt and hose clamp. I'm thinking maybe it connects to the top of the intake where the other bolt/clamp are?





In the left of this pic, is the new hose/bolt/clamp that I discovered today.

Good news hopefully!!

So I just pulled the passenger side valve cover off (what a pain the a$$) If anyone ever has to pull that passenger valve cover, the last bottom bolt near the firewall I found easiest to get to from the wheel well, and believe me I spent an hour and a half trying to get that last bolt from top and underneath. Discovered the wheel well and bam, had it out in 2 minutes.

Anyways I got the cover off, and what do I see just laying there at the back near the firewall? a rocker arm. I'm hoping this would explain the compression on #4 cylinder? The rocker arm missing was the second last near the firewall - intake or exhaust??

Do I just kind of use a screwdriver and try to place the rocker arm back where it should be? I've never done this before any advice would be greatly appreciated.

 

If it wasn't popping back through the intake, the broken rocker is off the intake.