fuel system trouble

[Ncgomez65]

I need some help. How can you tell if your lift pump, injector pump, or injectors are failing. Everytime I start my truck it stalls out and takes awhile to get it to start. Once it starts it runs very hard and then start to run ok. But the truck surges and when I drive it, it has no power at all. Takes all it has to stay at 55mph. The truck is an 1986 f250 6.9 4x4 4spd. Not sure of the true mileage of the truck bought it from a guy that bought it from a family that let the truck sit for almost 8 years. The truck showed 56605 when I bought it. It has a 96650 now. Never changed the injectors or any of the pumps. Any help with this will help alot. Thanks

 

[Wyreth]

Firstly, put your truck info in your signature, that helps ALOT when diagnosing, or guessing about problems.

Sounds like you have a lot of little problems.
The start up problem is classic symptoms of Air Intrusion. That will also cause the surging, and likely some fuel starvation. The first thing to do, is replace your return caps/lines/orings. PM type4, he sells a higher quality kit than any parts store, and for less to boot. Next, if you have a 6.9, read up on the Stanadyne water separator in the tech section. That's a common failure part. If you have a 7.3. There is a check valve on the fuel filter head that goes bad, and will let fuel drain back to the tank. Causing that symptom.

Next, it sounds like you're fuel starved. Change the fuel filter.

Next, have you ever had it timed? Timing makes a HUGE difference in how these trucks run. Never trust a shop that says they can time it by ear. Ear timing is, at best, just a way to get you moving until you can get it really timed.


Now, a dead lift pump will not pump enough pressure. You should see about 7psi after the filter. Also, check your oil and sniff it. If it smells of diesel, or if it's getting higher, then your lift pump diaphragm may have ruptured, and is now filling the crankcase with diesel. (that's a REALLY fast way to loose your main bearings)

Take a look at all of that before you start worrying about the IP and injectors.

 

[SparkandFire]

Sounds like you have a multitude of issues going on...

Some common issues;

1) Truck fires right up, runs a few seconds, then dies and requires lots of cranking to start back up = Air intrusion
2) Truck barely makes it up to speed, very low power = Fuel filter plugged or failing lift pump
3) Truck makes metallic knocking sound, sometimes comes and goes = Injector sticking open, opening too soon

First thing to check is air intrusion. Do you have wet return lines? You should not see ANY wet areas around the return line caps or lines. There are a couple areas where a compression grommet (Olive) are installed, on the return line system, those olives get dry and cracked and let air in, sometimes without letting fuel out. The fitting on the top of the IP and the hard line tee/coupler at the back of the engine are common places for air intrusion. Pull your filter off and look inside after letting the truck sit overnight. If the filter isn't filled to the brim with fuel, air is getting in somewhere... I like to dump the filter contents into a clear empty water jug and look at the quality of the fuel. Sometimes you will be surprised how much junk comes out, plus it's a good time to change the filter...

 

[icanfixall]

Usually what you are posting is air intrusion but it can easily be a worn out injection pump too. Is any of the injecters wet or any lines to them wet. If so you have perssure to them and the fuel is leaking out.. Air gets sucked in too. That will cause hard starts. A low fuel tank level can allow sir in too. Thats because these fuel pickups in the tanks breaks off and we can't draw out the last 1/4 tank of fuel. Now the injection pump can also be gummed up. Adding two quarts of automatic trans fluid to a tank of fuel will clean up the pump. Your injection pump is probably worn out but lets not just throw money and parts at it just yet...

 

[Ncgomez65]

Thanks for the information. Another question what are the best injectors to buy and from where.

 

[icanfixall]

Buying the best injecter is going to be a new set of Bb codes. Thats about all there is for these engines any longer. Sometimes we come across a set of G codes called turbo injecters... They are not that at all and will decrease your power and mileage. I ran them for years till I bought a set of Bb codes from typ4 here. What a world of differance. It felt like I added two extra cylinders to my engine... Mileage went up too. The G codes were about 1 year old with less than 5 thousand miles on them...

 

[id_bowhunter]

If still having a problem check your check ball valve on that fitting on top of your ip (just before the elbow fitting) for blockage and you could blow air through return line for blockage if the return is blocked it will build up pressure in the pump and give smoke and lack of power . Still check for air intrusions , keep in mind not all our trucks work the same w/ the fuel filter some are completely full and some will operate just great only being 2/3-1/2 full . One of life's mysteries don't know why they are different they just are