REFLECTOR:FW: Fuel Pressure Reads zero or low/intermittent

Jay Yu reflector@tvbf.org
Wed, 7 May 2003 18:54:35 -0500


FYI.

(I can't believe this! Mine was sitting since last August.)

-----Original Message-----
From: JPI Tech Support [mailto:jpitech@pacbell.net]
Sent: Wednesday, May 07, 2003 11:30 AM
To: Jay Yu
Subject: Re: Fuel Pressure Reads zero or low/intermittent


This is a follow-up from our phone conversation of earlier this morning. We
have reviewed you request and still think that replacing the Fuel Pressure
sensor is the best resolution. The Part number of the Fuel Pressure sensor
is 3060-17 and sells for $100.00 plus shipping.

The main issue is in the sensor where you have a wiper are that after
sitting for a pro-longed period will create an indentation in the pickup in
the sensor and would only read at lower temperature (or pressure), then when
the engine gets warmer, the wiper arm in the sensor would get stuck in this
depression and would not read higher. Another thing is to be certain not to
hard mount the sensor. It must be mounted on a flexible tube about six (6)
inches in length (AEROQUIP 303 line) to protect the sensor from engine
vibration which can damage the sensor's wiper arm and sending unit.

Lastly, to check the instrument you simply disconnect the harness wire and
the instrument head should read a high reading caused by an open circuit,
then connect the wires and the reading on the instrument will read lower due
to the short.

We hope this helps.

Regards,

JPI Product Support


----- Original Message -----
From: "Jay Yu" <jayyu@arczip.com>
To: <jpitech@pacbell.net>
Cc: <jay.yu@bankofamerica.com>
Sent: Tuesday, May 06, 2003 9:10 PM
Subject: Fuel Pressure Reads zero or low/intermittent


> Hi,
>
> I have a SlimLine fuel pressure instrument. Recently I saw 0 pressure
right
> after engine runup (before take off). It seems that when the engine is
cold,
> the reading is ok. Also when I removed the cowls, the reading was ok too.
> This seems to suggest that when the engine compartment is warm/hot. I have
a
> reading problem. Does this make sense?
>
> This evening I measured the resistence between the two wires on the
> connector on the instrument side. I noticed that when there was no fuel
> pressure, the reading was 7.5 Ohms. When I turned on electric boost pump,
> the reading was 29.8 Ohms (I can normally get about 5 - 6 psi when the
> electric boost pump is on). I also plugged the fuel pressure connector to
> oil pressure instrument. I noticed that the reading was 0 when there was
no
> fuel pressure and the reading was 15 psi when I turned on electric boost
> pump.
>
> Based on these observations, can you tell if my fuel pressure instrument
is
> bad or the fuel pressure sender is bad? If it's the fuel pressure sender,
> could it be the temperature in engine compartment causing this problem?
Also
> can you give me some technical specification on the fuel pressure sender
> such as the relationship between resistence and psi? On your web site I
saw
> the correlation between oil pressure and resistence such as 0 Ohm for 0
psi,
> 89 Ohms for 50 psi and 630 psi for open circuit.
>
> Thanks,
>
> Jinquan Yu
>
>