Hi all,
97 Dakota 5.2L here.
I did a reading of my fuel pressure on the weekend and got
a 45 psi. FSM says fuel pump should give a reading
at operational temps. of 49.2 +/- 5 psi (44.2 to 54.2).
So, my pump is on the really low side of the acceptable range.
My Dak is normally aspirated and the motor pretty well
modified with high lift cam, beefed up valvetrain components
complimented with diy ported heads, M1 intake and ported tb.
Sig. gives an indication on how much power it's putting out.
On the track, I've been experiencing an intermittent backfire
through the exhaust for the past couple of years. Extensive
diagnostics during this time on the ignition and mechanical sides
have not turned up anything. The fuel filter and tank are
extraordinary clean for the amount of time that I've had the Dak.
The backfire occurs under prolonged heavy load always at
nearly the same distance on the track, after the 1000' marker
and around 5200 to 5300.rpm in 3rd gear with OD OFF.
How far past the 1000' mark seems to depend on where
I set the fuel sync. When it backfires, the converter unlocks
and OD comes ON, possibly as a safety precaution by the pcm.
Is it possible that, under these conditions, the fuel pressure
drops enough to cause a lean condition? I've searched the archives
and have found only one post that states that pressure does not
change that much under wot. At part throttle ops, there is no problem.
Idle may be a tic rough but this might be because of the high lift
cam. I'm trying to find out as much as I can about fuel pressure
in our Daks and under these conditions before deciding whether
to go to the expense of replacing the pump. TIA.
Bob Tom Ontario, Canada
97 Dakota CC Sport, na modded 5.2L, 4x2, 44RE w transgo, 4.56 SG,
3000 stall converter, 4175 lb race weight, 13.76 @ 99.65
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