I recently bought a ’97 F-250 SuperCab 2WD PSD (auto, dual tanks, 84k) and it is the first diesel that I’ve owned. Last night I was on the freeway (cruise on) and I accelerated to pass someone and suddenly the truck quit pulling. As I was coasting down to a stop in neutral I switched tanks (from front to rear). After coming to a stop I turned the ignition off and immediately restarted it with no problems. Not wanting to tempt fate I left the rear tank lined up until I started home. On the way home once I was up to speed (cruise on) I switched to the front tank for a few miles and it ran fine. For trouble shooting purposes I tried to accelerate and a few seconds after depressing the throttle further it stopped pulling again. I tried to ride it out as I coasted to a stop again but to no avail. As I was nearly stopped the motor seemed to be “missing” if diesels do that. After stopping I switched to the rear tank started it up and carried on with out a problem. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

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The guy I bought it from said that he replaced one of the pumps in one of the tanks but can’t remember which (my guess would be the rear).<o:p></o:p>

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My questions are:<o:p></o:p>

1: Do these PSD’s have a fuel pump on the engine and in the tank?<o:p></o:p>

2: Is there a screen on the pickup in the tank?<o:p></o:p>

3: Is this some other problem that I’m missing?<o:p></o:p>

4: Do diesels “vapor lock” (I would think not likely)?<o:p></o:p>

5: What is your recommendation for a service manual?<o:p></o:p>

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I’ve searched this forum for fuel pump troubles and my symptoms seem to match but I’m looking for some clarification/second opinion. I have not been able to check the pump to see if it is leaking since discovering this information.

Any help would be appreciated.<o:p></o:p>

 

I asked once before if these trucks had electric pumps in the tanks and from what I got out of it they don't only the mechanical one on the motor.

I think that you have a problem with the fuel bypass thing in the tank that is giving you problems. I believe that there is a built in bypass in the tank in the pickup tube so that if they fill up with crap, or gel up it will suck fuel out at a little higher point in the tank. I think. I have never pulled my tank and looked at it, try filling that tank up and see if it still does it.


Diesel Rod

 

Welcome to the site-
I'll tell you your answers to the best of my knowledge, but if you hang out here for a while you will learn to not listen to anything I say.

1. The only fuel pump on my 97 that I'm aware of is a mechanical pump in the lifter valley.

2. I think that there is a sock style screen on the pickup in the tank.

3. I would tend to believe that your trouble only happens when running on the front tank based on your experimenting. Does it only happen when you're under hard acceleration? Does it happen under hard acceleration on the rear tank? Is it possible that you have a partially pinched fuel line coming from the front tank? Many of our trucks have had modifications done to the tanks to help them fill up faster. If you have not had trouble filling up rapidly it is possible that someone may have already worked on the tanks and there's a problem with the work they did.

4. I have not heard of a diesel vapor locking. the fuel system on our trucks has a return line to the tank nd I believe that any vaporization that did occur would be routed back to the tank through the return line but I'm just guessing.

5. I have a Chilton's manual that covers the basics but I would love something better. I think the part number is either 26666 or 76666.

Good luck with it and don't forget to check the fuel filter also. Keep us posted on what you find.

 

I learned that trick some time ago.

 

bodabdan-
If I did that I'd have to call you my wife!

So far it only appears to happen under hard acceleration on the front tank. I haven't tried any hard acceleration maneuvers on the rear tank yet.

444dieselrod-
I assume the only way to inspect/troubleshoot this bypass scenario (besides a fill up) is to pull the tank. I'll fill it up on Friday and see what happens.


Thanks for the info/suggestions!

Joe

 

Well, I've filled up both tanks and changed both fuel and air filters all to no avail. I can get it to happen on both tanks and it seems to only happen under heavy acceleration. At this point I assume it is the fuel pump but since I'm new to PSD's I'd like to know if there are any sensors that might cause a similar problem. I've looked into the CPS problems but this only happens under heavy acceleration. The previous owner said he had injectors replaced last year. Anything else I may not be aware of?

Oh by the way, I bought the Haynes Diesel repair manual which covers Ford and GM Diesels and it is not a Haynes manual at least not like any Haynes manual I've ever seen. It's just a piece of dung with Haynes on the cover. To justify the $15.99 they included a section on how to set up your garage. I would have rather them spend those pages explaining what sensors/solenoids are on the engine and what their function is. You know car repair kinda stuff?@#$^^**#?!!

 

If I had to bet I would say fuel pump. There is a schrader valve on the filter housing to check your fuel pressure but I don't what the specs are. I have learned that you must be driving or loading the engine to get maximum fuel demand to really see what the fuel pressure is doing.

 

I read somewhere on one of the threads in this forum that there is a screen somewhere adjacent to the fuel filter bowl.. don't have my chilton's book handy to tell you positively... Let us know what you figure out.

 

55-65 psi would be good, if its below that you can try doing the fpr shim, but I would do a fuel pump first if it is real low, anything more than 75 psi and you will start burning up fuel pumps pretty quick. check your fuel pressure and see what you get. you can do it at idle with a regular tire pressure gauge and alot of shop rags. I got diesel all over the engine when i tried it, so make sure you have alot of towels.



Diesel Rod

 

Hey! If the truck has the mechanical pump in the valley on top the engine, it is likely to have failed. It is a two stage pump, 1 stage pumps to only 6-9 psi, the second stage higher psi to injectors. I had been having long crank times and poor performance. I replaced mine with a Autozone mail order unit which happened to be a Carter O.E.M. pump. It has run perfect since.
The Haynes manual you refer to is suitable for bird cage liner. I bought a pirated CD off ebay that is a factory service manual-it's awesome.
ALSO don't pull the turbo off as per manual- it can be done without.
Good luck and merry Christmas-Tony D.

 

Well, on Christmas Eve I put in the new fuel pump using the the old banjo bolt washers hoping they would seal, not wanting to wait until Monday to find new ones. Surprise, surprise it leaked. On Monday, I found new washers at a FORD dealer 60 miles away (FYI: Ford P/N F4TZ9A375A). As I pulled the banjo bolt I realized that the washer between the pump and the banjo fitting fell down out of the way. So, after I put it all together with new hoses (Aeroquip FCC332-06 AQP 3/8") and new washers it ran great and no leaks. I did it with out pulling the turbo which requires some patience and triple jointed fingers. The only advantage that I can see to pulling the turbo is to use a torque wrench on the banjo bolt and getting new bolts for the turbo exhaust flange because you broke the brittle ones.