Fuel problem has everyone around here stumped.. Please Help!

[mr_smith]

I have read about a hundred articles and I can not for the life of me figure out whats going on..

I bought an 87 F-350 6.9 with a dump box for my tree service, it had sat for a couple years when I purchased it. We put in a new fuel tank, changed all the oil, filters, brakes etc..

For a while we had to start the thing with ether all the time, even if it was warm and only shut off for an hour. A friend of a friend recommended that we change the mechanical lift pump, which we did. After we changed that, the thing started all the time and we stopped carrying ether everywhere we went and cracking the injectors all the time. This lasted for about 3 weeks, it had a good amount of white smoke, but it was starting and running well.

This is how the problem started:
We were going down the highway for a short period of time (10 min) and I felt the truck losing power, after a minute or two of seriously lacking power and not being able to maintain highway speed, I was pulling on the shoulder when it died completely. We got out, looked at the engine and scratched our heads. One of my workers cranked it and after 15 or so seconds, it fired up. I made it to the next exit, parked it, and we took a lunch break. After an hour, we got back in and drove to our job, I could feel the truck losing power intermittently but we made it. Later that day I went to dump the truck and it lost power and stalled.

Over the next day or so it got worse and worse. Now it is at the point where it will start and run for about a minute or two and stall suddenly

We replaced the mechanical pump again
This truck has no fuel pickup in the tank and never has since I have owned it
If we take the fuel filter off, it is pumping fuel
We are getting NOTHING out of the schroder valve
If I crack an injector, it is getting some, but way less than normal fuel

Please help, I cant make money with this truck down

I appreciate your replies in advance

 

[Mulochico]

If we take the fuel filter off, it is pumping fuel
We are getting NOTHING out of the schroder valve
If I crack an injector, it is getting some, but way less than normal fuel

Not to be obvious, but fuel filter clogged? Even if you have recently changed it, there might be algae in the tank, or something, clogging it up.

 

[gandalf]

My first impression also is that the fuel filter might be clogged. You've said that you have had the filter off. What was it's condition? Did you put the same filter back on or did you replace it with a new filter? What you seem to be saying is that you have plenty of fuel going in one side of the filter, and not much coming out the other side.

What is the mileage on the truck? Are the injector pump and injectors original, or have they been replaced? Any possibility of air getting into the fuel line?

"This truck has no fuel pickup in the tank and never has since I have owned it" You state this in your post. Could you explain that a bit? If it has no fuel pickup in the tank, how are you getting fuel out of that tank?

Please fill in your sig block with information about your truck. People can better answer your questions, and help you, if they have a better idea what they're dealing with.

 

[94f450sd]

What do you mean by " no pickup in the tank" ?

Dual tanks?

Kinda sounds like a bad injector pump.next time it dies pour some cool water directly on the ip and see if she fires right back up.if yes,replace ip

 

[riotwarrior]

First Welcome to OB the best place for info on these old trucks, we work collaboratively here to help out people and resolve issues.

I'd be throwing a WAG but lest look at a few things...

As above first and foremost FUEL FILTER, put a new one on and carry a spare! ALWAYS! Don't ask me how I know!

Have you done return lines and caps?

How many miles on this rig?

Do you know if IP and injectors are original or have been replaced?

Does it have the Water seperator on fire wall? That can be a burden and cause problems too!

I'd start if you have not already with replacing fuel filter, return lines O rings and caps and Olives on the fuel lines.

Then once those are done you have a base line of what's fresh and work from there!

Again Welcome to OB

Al

 

[mr_smith]

I just got the truck back to the shop, it did want to die though..

We were able to get fuel out of the schroeder valve, we cracked all the injectors and she ran, all the way to petco about 700 feet from where we started. It was then that we noticed the supply line going from the fuel filter housing to the IP was loose. We tightened it up and it made it to the shop (another 1/2 mile)

Now we noticed the other end of the same line is leaking fuel (where it goes into the IP)

I have changed the fuel filter monthly since owning it, and again since this problem occurred.

We did put a new fuel tank on when I first bought the truck

As far as I can tell the only thing taking fuel out of the tank is the lift pump, I thought this was normal..

The water separator was bypassed before I got the truck

I am unsure of the mileage.. it has 80,000 or 180,000 or 280,000 and so on

I don't know how to tell if the injectors and IP are original


Im thinking I may only be dealing with an air intrusion issue here, we are working on it now. Are there any common areas to check??

 

[gandalf]

...

Now we noticed the other end of the same line is leaking fuel (where it goes into the IP)

...

As far as I can tell the only thing taking fuel out of the tank is the lift pump, I thought this was normal..

...

I don't know how to tell if the injectors and IP are original


Im thinking I may only be dealing with an air intrusion issue here, we are working on it now. Are there any common areas to check??

The leak where the hard line goes into the IP: Sounds like you need a new 'olive' there. In the plumbing trade that would be called a compression fitting. There is a short piece of what looks like fuel line in there. You might want to replace it. You might want to do an entire return line kit. See either Agnem or Typ4 here in this forum for the best return line kits.

You must be registered for see images attach

Fuel pickup in the tank: Yes, the fuel pump, the lift pump, sucks the fuel from the tank to the engine. BUT, the fuel line has to go inside the tank, from the top, and down to about the bottom of the tank, and be submerged in the fuel. Otherwise you're sucking air. These older trucks have a bad habit of having that intank pickup breaking off 1/4 way up from the bottom. When that happens you're sucking air with 1/4 tank of fuel remaining.

Original IP and injectors: The originals were painted gray, to match the engine. The best way to determine, if you don't have the service records, is to clean them off and check color. That, of course, is only an indication, not a certainty.

 

[riotwarrior]

Gandalf that's a great image depicting the OLIVE and in all likelyhood sounds to be part of his problem.

Lets hope we can get this resolved promptly!

 

[mr_smith]

I know I need the return line kit..

The truck just went to the dump and back (20 mins) with no issue, then they got in to go to a job and only made it a 1/4 mile..

 

[mr_smith]

Its full of air again..

I have heard people say to hook up a clear tube to narrow down where the air is coming from

Can someone describe how to do this or point me in the right direction?

 

[gandalf]

Its full of air again..

I have heard people say to hook up a clear tube to narrow down where the air is coming from

Can someone describe how to do this or point me in the right direction?

Pictures say it all. I find them easier to understand too, most of the time.

You must be registered for see images attach

Watch the bubbles for direction of flow.

 

[Dsl_Dog_Treat]

There's an 8" piece of rubber line supplying the lift pump. May look there as an air intrusion point.
Also where the supply line coming from the fuel selector valve is plastic then turns to steel about a foot before the engine crossmember. That too is a common leak point for rust belt trucks.

As far as the clear line goes, a piece from the filter head to return line. One from the return line to the top of the IP, and then place a section of clear line in line from the filter head to lift pump. Place a section of clear line from the lift pump to its supply line.
The leak point will be narrowed then be process of elimination.

 

[icanfixall]

Good idea and pics of the clear fuel lines. The line off the filter head will tell you if air is being sucked in before the filter. Sometimes that short piece of 3/8 line at the lift pump rots and sucks air before the mechanical pump. Please change it no matter what. They don't last forever like some want to the to... Now the return line off the top of the injection pump will tel you if the olives are leaking but it sounds like you already said one end of the line was loose. Replace the olives. Any injection pump repair shop will have them. They are 5/16 line size. At the filter head the 3/8 inch line from the lift pump has a 3/8 inch olive in the top end only. Replace that one also. This may very well fix your issues. Welcome to the forum too.

 

[mr_smith]

Thanks for the welcome, my tree service is fairly new, I will be adding several diesels to my fleet so I see my self being here for a while

Thanks for the sizes for those olives, im trying to find a shop around here..

Also trying to figure out how to hook up the clear fuel lines..

Thanks again!

 

[mr_smith]

I forgot to mention, after the truck ran good for 20 mins to the dump and back, we havent been able to get it more than 1/4 mile, we have serious air coming from somewhere