Engine/Transmission (1994 - 1998) No Black Smoke???

[NKenny]

I have been driving my '94 regularly for the first time starting this week. I bought it for an employee's (Brother-in-Law) seasonal job this summer, but am now driving it primarily because I blew up the transfercase on my 2001. In order to get this truck to run, I replaced the fuel filter and the lift pump, eliminated the pre-heater, and replaced numerous fuel lines that had been worn.



When warm or after being plugged in, the truck fires immediately, as in the truck is running before the key is even fully turned. It is like a 1st gen. However, I noticed today that the truck will not reach more than 85mph and will never even puff black smoke, even when the pedal is floored and the converter locks-up. In it's current mode it feels very low on power.



This morning, I got under the hood after a 25 mile trip to do some inspections. The throttle seemed to have full travel and I didn't see any leaks nor have I noticed any fuel since replacing the pump, filter, and lines. I did a no-load test on the motor and it began blowing significant white smoke and would only rev up to ~2700 rpms and seemed to miss at those rpms. It really feels like the truck is not fueling sufficiently throughout the RPM range (I know it defuels on the top-end but it should be able to reach redline before puking white smoke)



Cold, not plugged in, starting is very difficult and includes a huge cloud of grey smoke. Idle smoke smells funny at any temp.



These symptoms are listed all over search, but I likely didn't search deep enough to find any conclusive answer to what my next step should be. Does this sound like a timing issue, thermostat as mentioned recently, injector pump, AFC? These symptoms on my '01 mean VP44 without question.



This is a great truck and I always have wanted a world-beater P7100 12-valve, but I don't know where to begin on this one. Thanks in advance.

 

[Fordiesel69]

Taking fuel pressure reading will tell you if the fuel is getting to the pump. Unless the engine surges like it is starving, I would place my bet on the timing.

 

[BTanzini]

Check your overflow valve it affects power. Could you have bad head gasket? Check your oil for water, check radiator for foamy white substance around radiator cap after removing.

 

[GDMRTN]

If it's high miles, it could be worn injectors. Would place my bet on timing or injectors.

 

[JAmos]

My issue like this was fixed with timing. Tried injectors first, its took 3 times to get the timing right, but it worked and it was a great runner. You should put a gsk in while you're at it. It'll be worth the money.



Jordan

 

[NKenny]

Truck has 250,000 miles on it, so really pretty low on mileage for a '94.



I will study up on the timing process and for sure on the GSK. I have been eyeing that upgrade for a while and the price is very reasonable.



JAmos, what did you finally set the timing at to get it right? There are a few numbers floating around here like 15* advanced.

 

[JAmos]

I'm not sure where the timing is. I had a guy set it for me and he set it twice before with no improvement, but he had me come back one more time and he kept playing with it till it ran good. The first two times he set it the same way as the other trucks he had done. For some reason my pump seemed to need a more advanced timing setting to get the feel of 15*. He pops the gear lose on the pump and backs the engine up 3/8 inch by measureing the dampner.



Jordan

 

[NKenny]

The trial and error method!!! I like it as it seems like the easiest one for me to perform.



Thanks.

 

[Forrest Nearing]

If it's high miles, it could be worn injectors. Would place my bet on timing or injectors.

worn injectors would smoke more than fresh ones

 

[okayred]

I'm having the same problem with my '95 right now. I changed out the fuel lift pump and now I'm not getting solid fueling throught the mid to upper rpm range.

 

[Calebh9806]

What is the GSK upgrade and the overflow valve where is it located... . can i get a diaghram of the 12valve engine ?

 

[JAmos]

A gsk is a governor spring kit. It broadens th power band of the engine greatly. My 95 would fall on its face at a little over 2000 rpms, but after I put in a 4000rpm kit, it pulled good to 2500. With a better fuel supply system or more timing, it would have revved even higher.



I would add a governor spring kit. Remove the air horn from the manifold. Remove the fuel shutoff solenoid assembly. Clip the wire that goes over a plug that threads into the governor assembly towards the rear of the pump and unscrew the plug(some oil will drain out). Rotate the engine using the nut on the alternator pulley till you see a spring with a keeper(looks like a valve spring). There is a threaded stud in the center and 2 slots on either side(like a flat tip screw with a hole in the center). Use 2 smaller flat screw drivers or take a large one and grind/file the center out to clear the stud, and push and turn to remove the nut. The spring kit will tell ya what pieces to reuse and what to store away. There are technical ways to set the tension on these springs, but I have had good results by tightening the nut till the first time it "clicks" then 2 more clicks. Now turn the engine while watching for the other spring to come into view(there are 2 spring sets 180 degrees apart) and repeat the same steps that apply. Keep the number of clicks the same for both spring sets. The springs can be tightened further though the idle will rise and have to be lowered. I left my idle high(trying to get the rpms I wanted from my former trucks 160 pump with a mysterious history), but set my dads down(he has stock springs, just tightened them some to give him a little extra)-only down side is he has to press the gas to start the truck every time.



The overflow valve is located on the side of the pump, close to the front, between the head and side of the pump. You might need to file the head a little to get it out.



Jordan

 

[Calebh9806]

THanks alot jordan I appricate the advice I've just had my truck for about a year and was looking for advice for it i love the truck but i haven't gotten much info on everything yet thanks a bunch



Caleb

 

[Vaughn MacKenzie]

When warm or after being plugged in, the truck fires immediately, as in the truck is running before the key is even fully turned. It is like a 1st gen. However, I noticed today that the truck will not reach more than 85mph and will never even puff black smoke, even when the pedal is floored and the converter locks-up. In it's current mode it feels very low on power.

A stock truck or one with minimal mods that's tuned up right won't make much more than a light haze at WOT.

 

[NKenny]

As a bit of a recap to further the investigation process:



-Advanced the timing slightly by pulling the timing gear and rotating the engine backwards ever so slightly.



-Ground the fueling plate to mimic the #10 plate



-Replaced the rubber portions of the line from the Turbo to AFC



-Turned the star wheel forward a bunch of clicks (I'm looking for any sign of fueling here)



-Removed the fuel preheater



-Adjusted the throttle cable



-New lift pump and filter less than 2,000 miles ago



-Removed, cleaned and stretched spring on overflow valve.



Truck still won't smoke at all and the turbo shows no signs of spooling, although it did seem to drive better following the overflow valve work. (I haven't looked at fuel or boost pressure, so I am kind of going at this uninformed, I realize. I'll rig up a test guage this week maybe) The other trucks I have driven that didn't spool the turbo seemed to really blow black smoke. I don't know what I am missing.

 

[Forrest Nearing]

torn/leaking AFC diaphragm

 

[JAmos]

Take the afc off and take the foot out(the piece that sticks down into the pump). Pay attention on how it comes apart so you can put it back together. If you get power and smoke then your prob lies in the afc.



Jordan

 

[Hammer]

I have yet to see anyone tell you to make sure the fuel lines are not leaking or allowing air to weep into them. White/grey smoke and power loss complaints to me shows sign of air in the fuel and you may want to check the factory lines over,beginning with the always going bad rubber return line.



Also check the hoses where they connect to the fuel tank as I have seen them corrode and allow air into the lines there also... ... ... . Andy

 

[JAmos]

Very true Andy. If you have an air leak somewhere, it won't always be a visible fuel leak, but can be a very hard to spot source of air getting into the fuel system, robbing power and causing timing like symptoms due to the fact that air compresses and can delay the timing of the injection. My 95 had a prob somewhere on the feed line from the tank, so I ran a new one and noticed an improvement. Looking back at it, when going through the hassle of replacing one line, just do them both and have piece of mind. I went from the tank to the lift pump, bypassing all the different connections. Explain what you did to the preheater. Did you remove the whole unit including the prefilter screen? If any part of the prefilter/heater unit is still in service/in use, it is still possible to have a leak there. If you have trouble finding parts to fix the heater/prefilter-let me know as I worked on the one in my 95.



Jordan

 

[NKenny]

Thanks for all the feedback. I will pull the AFC this evening and have a look at the diaphram as well as run it a second to see if it fuels. I'll also check the fuel lines that go to the tank.



With the preheater, I completely removed it. At the same time, I replaced all of the rubber lines that are underneath the hood and replaced the lift pump. I have not touched the lines that go to the tank. I've not had any sort of priming issue since I did all of the repairs listed.



As an update, my truck was hazing white/gray smoke at idle pretty bad this morning. I haven't see it like this before.