Reaccuring problem with 94XLT

[cfkane]

Try the diagnostics before you jump right in and replace the pump. Bad vapor return can cause a vacuum in the tank. How about a fuel filter that is plugged. Did you check to see if you were using Ethanol, most states require labeling on the pump. What did the fuel pressure test look like? Does the problem happen with the tank empty or full? All of these items can result in the same symptom.

On the subject of fuel pumps there are about 8 different manufacturers in use out there. In the case of the aftermarket most of those will be repackaged from one of the major vendors. I would not cut corners based on price as you do not want to do the pump replacement in the near future due to poor quality components. Get a pump that is of the same design as the OEM one, in other words take a close look at the pump to compare new vs old. You want the same capacity and pump size. Lots of smaller ones are out there that meet the specs they just do not last as long.

 

[duckdog27]

Cfkane, when the truck was acting up (dying on me) I could hear the fuel pump cranking when I turned the key, but when I cracked the gas cap I heard no pressure excaping. The threads to where the gas cap screws into are quite rusty. Could this be happening because there is a poor seal?? Thanks!

 

[FirstFord]

Check your fuel pump relay under the hood, i had mine go bad, and had your EXACT problem.

 

[cfkane]

A leak in the gas cap seal will not cause a vapor lock type condition. You will fail any emissions inspection that checks for fuel system integrity. If you can hear the pump running check pressure at the rail, if that is ok you may still have low volume, which can contribute to the problem. How about the other items mentioned previously?

 

[duckdog27]

Cfkane, how could I compensate for low volume? It seems to act up worse when there is less gas in the tank, although as I remember it still does when there is almost a full tank of gas. What other things could I replace other than the fuel pump that could fix this low volume situation, though I still have to check the pressure at the fuel rail...?

 

[cfkane]

The fuel pump has to work harder with less fuel in the tank thus that symptom tend to confirm a fuel related condition. Follow the diagnostics mentioned previously and then if no other causes become apparent consider a fuel pump replacement.

 

[duckdog27]

Cfkane, today on the forum I came across discussions on the canister purge solenoid. So today I found the little bugger tucked under my upper intake manifold and when I attempted to pull is out, like the threads advised, I broke the nylon (very brittle) T-joint that connects the vacuum lines from the throttle body to the solenoid and canister tank. I ordered a new solenoid from NAPA and when it arrives I will attempt to replace it. But, I don't know how to reach the broken vacuum line without removing the entire upper intake manifold. Do you have any experience with this? Or can I simply remove the throttle body? Anyway, after I broke the nylon joint I noticed a remarkable gain in acceleration and overall power. Also, there was oil in the broken vacuum line. Could this be causing my symptoms? It would be great to know that this cheap part, and not the fuel pump, is the cause of all my fustrations! Thanks for your help.

 

[duckdog27]

anyone have a clue??!?!?

 

[4544x4]

did you ever check the fuel pressure?get it fixed yet?

 

[cfkane]

Where the line was broken will depend on what you need to do to splice or replace it, in short I would have to see the installation before I could tell you what needed to be removed. Brittleness is the result of the plastisizers being removed from the material over time due to some of the components in the fuel.

Based upon the feedback I have seen from the field the vapor canister purge valve is a far more common failure than the fuel pump. The pump could be bad but why start with the hard stuff when there are other simple things to check and resolve first.

Residue in the line is indicative of deposit issues; I would recommend a can of BG 44K or Chevron Techron in a full tank of gas. Run it down near empty before refilling and that will take care of the vast majority of engine deposit issues. In a generic sense what you are looking for is a fuel additive that contains additives known as PEA or Polyetheramine. These a far more effective products than the petroleum naptha based additives.

 

[duckdog27]

I have not checked the fuel pressure yet...just have not had time. I will soon and get back to you what it reads. The truck still acts up even though I replaced teh canister purge valve.