1999 V6 fuel pressure?????

[codipegrum]

Hello everyone,

I have a 1999 XLT with a V6, SOHC, which has all original factory equipment including a Returnless Fuel System (!!). It appears to be a Mechanical Returnless Fuel System as there is not an electrical pressure tranducer apparent at the rails and there is a mechanical damper on the rear end of the left rail. There is not however a short return from the fuel filter back to the tank, so I assume this is all internal to the tank along with the pump, a check valve and some form of regulator.

Here's my problem: No information was released by Ford to OEM's of Manuals (Chiltons, etc) and I can find no other information source, which makes troubleshooting a tad harder.

On my engine the fuel pressure, both static and dynamic, is 65 psi and pulses during the dynamic condition very rapidly approx 5 psi either sise of this datum. Additionally, upon engine shutdown, pressure returns to zero after approx 5-10 minutes (installed an isolation valve and determined pressure is returning to the tank and not leaking through bad injector/s).

Does anyone know whether the fuel system conditions above are bullsquat? Does anyone know if the check valve (if existent as assumed) goes bad, regulation can be negated?? Does anyone have any information available for this particular type of fuel system?

Yes, slow starting and rough idle issues. Suspecting above after exhaustive troubleshooting, throwing (some) cash at other possibilities and thwarting attempts by local clueless stealaship to swallow all cash reserves in one gulp!!

Thank you all for any and all feedback available.

Kind regards,

Colin

 

[Nate1]

We have the same everything. I know this has been a rather idle thread but my searches haven't turned up anything. We should keep each other updated as to when the problem is!`

 

[codipegrum]

Dear nweibley,

Apologies for the lackadaisical approach to my reply.

My troubleshooting found a few faults, which when cured in total cured the issues.

The norminal fuel pressure is spec'd at 65 psi +/- 8 psi and it should not leakdown quickly when the engine turned-off. Once tracking the failure to the fuel tank, as opposed to leaking injectors, I dropped the tank to remove the fuel-pump (with internal check-valve)/regulator/tank gauge unit. A stealership would have no doubt change the whole unit, but I pressure checked the unit out-of-vehicle and noticed the following:

The output from the pump to the input of the reglator and the output of the regulator to the tank output pipe are connected together with the extreemely cheap and tacky design of using hose and hose clamps. Yes mine were leaking, so I change the hose and clamps and the fuel bleed-down issue and starting problem were no more. If you do this please ensure you do not use flexible hose from somewhere like Autozone, you must purchase Fuel Injection Hose from somewhere like Napa Autoparts, it must have the reinforcing or it will burst.

The rattle at start-up was the timing chain tensioner problem that ALL these engines have. My local Ford stealership repaired for no-charge one I thrust a copy of the TSB that relates to this problem under their noses.

I had a bad oxygen sensor and changed it out.

While the "rattle" was being fixed, I asked my stealership to reflash the PCM to ensure all programming was at factor default.

Voila! A smooth and quiet running engine (at least, as smooth as the V6 can be. I sense it has a bit of a "snappy" camshaft to get the 210 hp).

If I can be of any assistance in your troubleshooting for these or any other matter, please let me know. While this site is good for some faults, the trickier they get, the quieter this site becomes

Kind regards,

Colin

 

[Opera House]

Clamp, that reminds me

I replaced a fuel pump on a Jeep. The pump just fell off the connecting hose. The clamp was never tightened at the factory. Finally it leaked enough so the engine wouldn't run. Put in the new pump but have kept the old one for around the shop uses. Sometimes problems can be simple even on relatively new vehicles.

 

[Nate1]

Originally posted by codipegrum
Dear nweibley,

Apologies for the lackadaisical approach to my reply.

Hey no worries, you wern't required to reply

I'm still hunting mine down, I dont *think* I have a fuel leak (as I remember my pressure remained after I turned off the engine), so I still have a hunch one of my oxygen sensors is giving me hell.
I'm not really sure what is wrong, I just think I'll wait it out and see if something throws me a CEL anytime soon.

Thanks for that wealth of information, you sound like a mechanic or something... very knowledgeable!
-----Nate

 

[codipegrum]

Nate,

FYI: As you are contemplating oxygen sensor issues, I sensed you may be interested in the following:

The V6 control system has three (3) particularly poor items contained within the design, that are equally capable of producing all manner of driveability issues without so much as a passing "hiccup" by the PCM (and therefore WITHOUT diagnostic code provision). By order of ****:

1) Oxygen sensors
2) AIC valve
3) DPFE sensor

If, at any time in the future, you find difficulty in troubleshooting, please do not hesitate to provide further symptom information and I will be more than willing to aid as and where possible.

Not a mechanic, no. An engineer with, perhaps unfortunately, a permanently racing-mind. I therefore attempt to aid others in all manner of issues for mind occupation. Some appreciate it, some are not always so appreciative or polite.

Let me know if you need at troubleshooting assistance.

C