Hello guys and gals. I just got a 92 F250 with a 7.3 Navi Diesel. I'm new to the diesel world, been reading on here to see if I could fix the problem. But, no luck so far. The truck has under 140K and is super clean. My problem is that it shakes bad like a gas motor does when it's missing on two or three cylinders. It also smokes like a freight train (smells like raw diesel, and is black, looks to be a hint of blue, but doesn't smell to be oil). Also, when I was under the truck, welding up the exhaust pipe, I noticed (looked to be motor oil) oil coming from the spot the needed to be welded. So far, I've changed the GP Controller, cracked open the injectors, and felt the lines to the injectors, drained and checked the fuel filter, no water that I seen. I still need to change the GP's themselves, because my WTS light flashes for a split second then the relay starts clicking. The truck will start and run, but has no power, and shakes and smoke like you wouldn't believe. Any help would be appreciated. Thanks.

 

Im not sure id say - Needs a refresh new injectors,ip,liftpump,filters,coolant then maybe it will be good as new or worst case its worse than this there will be a guru along to help u more i might be toattly wrong.

 

Well, at least you didn't say the things I was fearing. I.E. cracked block, bad head, valves.

 

When you mentioned about the fuel line were you sayin there was no fuel coming out or couldnt feel a pulse. If so sounds like a injection pump. If not, if you know the cylinders that are missing try switchin out the injectors to different spots to see if its the injector itself missing.

 

I read that you could tell if a injector was bad by feeling the line to see if it was warm/hot than the rest of the lines. Fuel squirted from the top of the injectors, so there's fuel getting to them. Is the pressure as touchy as a fuel injected gas engine? I also drained and checked the fuel filter, no water that I seen.

 

Id still say get new remans from pensocola injectors and ip and then see where u are normally u replace these items every 100,000 miles so u are overdo

 

I gotta say, I am pretty much with Stroker on this. New Injectors and pump would do you a world of good... However, If you don't have the money. You can pull the injectors and pump, have the injectors pop tested and have the pump bench tested. Not sure how much this will cost. It is possible you will now be out the cost of the testing PLUS the cost of new injectors and pump. It's your call.


There are a couple of other things. How is the Air intake? Is the filter clogged? What about timing? Have you read any of the post here and checked out the timing?

 

Oh yeah, There is fuel getting to your injectors, that seems to be the main problem. Black smoke indicates Too much fuel, or not enough air or both. I also think timing can produce black smoke though not exactly sure.

 

I know I should of checked the air filter, I will. I thought of timing, need to read about that then. So, around 100K the IP and injectors need replaced? I guess that I need to check in to the testing and new prices. Thanks.

 

Injectors in these diesels aren't like the car injectors. They open by pressure, so if the spring gets weak, they can open too early, which is about the way it kind of sounds. I checked into get a pop tested, and for the price, you might as well get the injector set, as it was about the same price you can pick up a set from Pensacola for.

 

if i could go back in time to when i first bought my truck the very first thing i would have done was to check the engine condition. compression, leak down, crank case decompression regulator, coolant additives.


you purchased the truck with this issue or did it just start?

 

You could end up replacing quite a bit of expensive equipment for no reason.

The first thing is diagnosis......start with fuel pressure.

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when starter cranking engine over. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of starter engine cranking, route fuel to a suitable container with a hose. When all finished hook up the FSS wire .

If there is a problem with the lift pump and you are changing it, ensure the new pump comes with instructions as to correct installation procedure if it is the newer model pump with the almost straight arm.

next......Check the steel lines are connected in the right places on the IP.

Starting at 1 oclock position next to the screw.....54372186

The engine timing is........
Cylinder numbers are assigned 1,3,5,7 on the right (passenger USA) bank from front of truck to back, and 2,4,6,8 on the driver's side (USA), front to back. Firing order is 1,2,7,3,4,5,6,8.

If everything is ok with the lines and you have fuel we need to see which injectors are working correctly.

Take your time and loosen each line at the injector, then just snug it up to seal(engine off).

Now with engine running at idle..... loosen the line nut on one injector, ensure the injector is covered with a rag... there will be high pressure fluid squirting. Safety glasses are also advised.

If you notice an increased engine stumble(s) when that injector is "off line" tighten the injector line nut (torque is 22ftlbs). That indicates a good injector!!!!!

Consequently if no noticeable difference is seen/felt that indicates a problem at that cylinder.

Repeat this procedure on all injectors and mark down good or bad cylinders.

Make a post here as to findings....

 

Thank you guys. Question, when I loosen the nut on top of the injector, should fuel spray out or will it spit out? Mine just spits out droplets. They spit out about 8" to 12" from the nut. Should it be spraying out like a crack line would? I would think that the truck would smoke that bad if it was low on pressure. I'll get a gauge this weekend though, and check the pressure. Same with the compression.

 

It isn't going to hose all over, if that is what you mean. If it shoots 8-12 inches, then it is way more powerful than any diesel I have cracked the nuts on... they usually spurt out a little, but not that far. You don't build up the same kind of pressure shooting into the air with no resistance as you would if the nuts are semi-snug. The volume of each pulse is not that major.

The pressure in the injection lines is what actually opens the pintle in the injector. If the spring pressure is low, it shoots out too early, then also doesn't spray as well, so sometimes they will smoke easy. Sometimes the pintle gets hung up, and doesn't pop off until too late. Sometimes it is just a poor spray pattern, but burn ok enough if the injection pump is still turned down enough. Crack the nuts loose as you have it idling, and you will learn if each cylinder is carrying the load. It is essentially the same as pulling plug wires on a gasser to balance test them.

 

Sorry. I need to clarify. The droplets spray upward 8 to 12" when the nut is semi-snug. It's not a stream of fuel. It may of not been that far then, but it spit out droplets aways though. I've done the test that you are talking about, and each cylinder dropped when the injector nut was loosened.