Re: Can a badly mis-firing plug cause a fuel pressure drop?
Jim Warman wrote:
> Oh, come now... it can't be that simple, can it? A tech said the fuel pump
> is bad so it MUST be something else... never mind that fuel pressure leaves
> home when the problem occurs....
I only recently found this newsgroup and there seems to be a lot of good
information here. I am only looking to get an unbiased opinion.
> Sarcasm mode = <OFF>.
> I have abo****ely why the original poster is refuting the diagnosis....
> looks pretty cut and dried to my weary old eyes. Original poster... look at
> the FACTS. If there is no fuel pressure when the problem occurs, there must
> be a problem with the fuel system. There's a very good chance that it is
> fuel pump but there are other factors that come into play... most will
> require the removal of the pump to verify.
Yes, I understand no fuel pressure would be a problem. I have not yet
had a problem with an electric fuel pump at such an early age (I bought
it new on 2001) and low mileage. I was hoping that somebody out there
knew if the ECM would shutdown the fuel pump on a sever misfire. A
friend on mine's catalytic converter started on fire a few minutes after
his SAAB started running badly.
I know that the Ford ignition is quite complex. If the ECM can shutdown
the fuel pump, replacing it would be an attempt fix the symptom and not
fix the real cause of the dropped fuel pressure. It just seems that if
the pump was bad, it would cut out at high seed too, not only at city
> You have a problem with it being a pump and I have a problem with it being a
> plug - especially in the abscence of a misfire code.....
I am only looking for this information because they replaced the fuel
pump and strainer yesterday and the drive home was proof that the
problem is not fixed. I will be going again back today...
> "TranSurgeon" <email@example.com> wrote in message
>>no, but if the fuel pressure is insufficient under acceleration, you would
>>have a stumble...............
>>"Mike J" <firstname.lastname@example.org> wrote in message
>>>I have a 2000 E-150 with a 4.6 with coil on plug ignition. There is a
>>>bad stumble / misfire when accelerating. The problem is most noticeable
>>>when the throttle is slightly open as when driving in city traffic. If
>>>the engine downshifts the stumble is gone or at least much less
>>>noticeable. There is never a check engine light.
>>>I took it into one of the major tune-up chains in my area and they
>>>diagnosed the problem to be a bad fuel pump because they are seeing that
>>>the fuel pressure is low (35 PSI) and drops off to almost 0 when the
>>>This van has only 36,500 miles on it and drives fine except for the miss
>>>under acceleration. The van has a new fuel filter and I have always
>>>kept the tank above 1/4 tank since I bought it new, so I am skeptical
>>>that the fuel pump is bad already.
>>>My question is - if I had a bad spark plug or coil causing the misfire,
>>>would the ECM toggle the fuel pump to eliminate damage to the catalytic