Could my problem be a bad fuel press. regulator?

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Old 05 May 2006, 01:05 pm   #1 (permalink)
geronimo
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Default Could my problem be a bad fuel press. regulator?

Its a 1988 Camry wagon, std 4-cyl engine (3S-FE). The engine runs
fine as long as the cars sits parked, You can rev it up, it doesn't
choke. Acceleration is OK at first. However, after being driven for
about ten minutes slowly on residential streets, the engine loses
power. You give it gas, and it just stumbles and chokes. There is an
occasional sound like a muffled back- fire within the intake. The
spark is remaining strong on each plug, although I can't say that the
timing isn't going off....have no way to check that. The engine temp
is staying normal. THe engine does have an oil leak, dripping off of
the RH CV joint, so I guess the oil pump or front seal is leaking. I
got a fuel pressure gauge, and installed a brass manifold (schrader)
tee into the flex fuel line a couple of inches from the fuel filter
(its AFTER the filter, before the fuel regulator and rail). There is
38 PSI at idle, and it goes to about 41 when you rev the engine. Thats
with the car parked.
When you drive it until the engine is stumbling/ lost power, there is
only about 12 PSI...when I finally manage to get back to the driveway
to check it.
I suppose its got to be either the fuel regulator or the fuel
pump, as I replaced the filter, and that did not fix problem.

My question is: if the fuel regulator was malfunctioning, could
that only make the pressure....where I am reading it.... high?
Also what are the specs for normal pressure... max & min?

I have the fuel tank removed and fuel pump removed from tank now,
but there is no way to definitively check it, since it appears to only
flake out after a period of time under load...when driving. If I just
stick it into a jug of gas and run it, I don't imagine I would see
anything wrong. THe screen looks like it is about 50% blocked with
brown crud....but I would think that if it was too plugged up, the
engine would fail to accelerate from the very start. But come to
think of it, wouldn't a bad pump also cause failure to accelerate
normally from the start, also?

I thought I had found a problem....there was a fuel line
disconnected at the rear of the tank, but it was just the fuel
vent...it was sure staying vented with the hose disconnected from it!

Funds are really tight, and since the cheapest price for a new pump
I can find (an internet source) is $140, I really need to be sure
it's the fix.

WHatever the problem is, its not ever setting a fault code....I
guess the system has no way to detect a fuel delivery/pressure
problem.

Ideas?

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Old 05 May 2006, 01:29 pm   #2 (permalink)
davemac
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Default Re: Could my problem be a bad fuel press. regulator?

sounds like your fuel pump to me. Can't be the regulator if you tee'ed
off before that between it and your filter. Not likely the filter would
drop the PSI after warmup like that. It would be a constant drop.
Fuel pump is failing after getting warmed up. Maybe go find a used one
in a junk yard to save some cash.

cheers

davemc

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Old 05 May 2006, 01:29 pm   #3 (permalink)
davemac
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Default Re: Could my problem be a bad fuel press. regulator?

sounds like your fuel pump to me. Can't be the regulator if you tee'ed
off before that between it and your filter. Not likely the filter would
drop the PSI after warmup like that. It would be a constant drop.
Fuel pump is failing after getting warmed up. Maybe go find a used one
in a junk yard to save some cash.

cheers

davemc

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Old 05 May 2006, 02:12 pm   #4 (permalink)
m Ransley
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Default Re: Could my problem be a bad fuel press. regulator?

This is classic Camry Coil issues, try cleaning or replace it, the issue
is so common its ridiculous. Moisture doesnt cook off till its gets hot
then it shorts out.

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Old 05 May 2006, 03:34 pm   #5 (permalink)
davemac
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Default Re: Could my problem be a bad fuel press. regulator?

uhm, not when he's measuring fuel pressure of 12PSI from the filter.
Got to be the pump.

Dave Mc

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Old 05 May 2006, 04:08 pm   #6 (permalink)
geronimo
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Default Re: Could my problem be a bad fuel press. regulator?

Yea, I still have a strong spark on each plug wire. I head about that
coil problem, so I took the distributor coil assy. apart and checked
it, but there wasn't a trace of moisture (or oil) inside it. Just
have to bite the bullet and get a new fuel pump, I guess, because its
too much a roll-of-the-dice as to whether I get a good one or not from
the junkyard. Could fail the day after I put it in, and they would
not warranty it at all. Just wanted some confirmation that it couldn't
be the fuel press. regulator. Thanks, Geronimo


On 5 May 2006 13:34:53 -0700, "davemac" <davemac2@yahoo.com> wrote:

>uhm, not when he's measuring fuel pressure of 12PSI from the filter.
>Got to be the pump.
>
>Dave Mc


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Old 05 May 2006, 04:44 pm   #7 (permalink)
davidj92
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Default Re: Could my problem be a bad fuel press. regulator?

geronimo wrote:
> Yea, I still have a strong spark on each plug wire. I head about that
> coil problem, so I took the distributor coil assy. apart and checked
> it, but there wasn't a trace of moisture (or oil) inside it. Just
> have to bite the bullet and get a new fuel pump, I guess, because its
> too much a roll-of-the-dice as to whether I get a good one or not from
> the junkyard. Could fail the day after I put it in, and they would
> not warranty it at all. Just wanted some confirmation that it couldn't
> be the fuel press. regulator. Thanks, Geronimo
>


According to the Haynes for my '97 Camry, the fuel pressure should be 44-50
PSI and hold pressure should be 21 PSI after 5 min.
Don't know how many years forward are the same as yours, might be quite a
few so you might be able to get a late model pump. If so, many salvage yards
will with a guarentee, usually at appx 10% more here.
HTH, Dave


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Old 06 May 2006, 03:28 am   #8 (permalink)
geronimo
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Default Re: Could my problem be a bad fuel press. regulator?


David, do you know if it is suppose to maintain that pressure range
under any load/throttle setting?

Also, I found that someone had disconnected the fuel vent line.
Actually there are two fuel vent connections on the top of the tank
that are Y'ed together to one metal fuel line. With the top of the
tank open to the air, it sure never builds up any vacuum as fuel is
consumed. Could have been that way for years. Does it matter whether
the fuel tank vent is connected properly or not?

On Fri, 5 May 2006 16:44:00 -0500, "davidj92"
<davidj92REMOVE@sigecom.net> wrote:

>geronimo wrote:
>> Yea, I still have a strong spark on each plug wire. I head about that
>> coil problem, so I took the distributor coil assy. apart and checked
>> it, but there wasn't a trace of moisture (or oil) inside it. Just
>> have to bite the bullet and get a new fuel pump, I guess, because its
>> too much a roll-of-the-dice as to whether I get a good one or not from
>> the junkyard. Could fail the day after I put it in, and they would
>> not warranty it at all. Just wanted some confirmation that it couldn't
>> be the fuel press. regulator. Thanks, Geronimo
>>

>
>According to the Haynes for my '97 Camry, the fuel pressure should be 44-50
>PSI and hold pressure should be 21 PSI after 5 min.
>Don't know how many years forward are the same as yours, might be quite a
>few so you might be able to get a late model pump. If so, many salvage yards
>will with a guarentee, usually at appx 10% more here.
>HTH, Dave
>


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Old 06 May 2006, 04:46 pm   #9 (permalink)
davidj92
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Default Re: Could my problem be a bad fuel press. regulator?

geronimo wrote:
> David, do you know if it is suppose to maintain that pressure range
> under any load/throttle setting?
>
> Also, I found that someone had disconnected the fuel vent line.
> Actually there are two fuel vent connections on the top of the tank
> that are Y'ed together to one metal fuel line. With the top of the
> tank open to the air, it sure never builds up any vacuum as fuel is
> consumed. Could have been that way for years. Does it matter whether
> the fuel tank vent is connected properly or not?
>


The pressure should stay at least somewhere close to the 44 PSI when
running. If it doesn't then the injectors probably won't work correctly and
you'd get a lean burn, which is probably what is causing the detonation
you're hearing in the intake. When you shut the key off then the pressure
should be at least 21 PSI after 5 min. Does the pump make any loud or
unusual noises after it gets warm? It should not change noise patterns from
cold to warm, if so this is an indicator of a pump failing. Also, the
injectors or a hose could be leaking causing a drop in pressure. When it
starts to run bad, shut it off right away and pull a plug. If it's wet and
no ignition problem then you're getting too much fuel which would indicate a
pressure regulator or injector(s). If plugs are dry then it's probably the
regulator and/or pump.
I don't think the vent will cause a run problem on yours as it is probably
vented to atmosphere. On OBDII the vent goes to a charcoal canister and if
it were off then there could be a vacuum loss when the purge valve cycles.


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