1998 Ford F-150 4.6 V8 TRITTON "KNOCKING NOISE"

BOOSHU

MEMBER
1998 FORD F-150

PLEASE HELP! Before I run out of money.

just purchased this truck.4x4, it run great when I tested it. But once I took it in the freeway over 40 MPH, 3RD TO 4TH gear. There was some knocking in the engine and loss of power! It only happens when I need to put gas for power.
If going straigh 60 to 85mph no problem.

engine light is one code told me running fuel slim. Oxygen sensor 1?.

"i changed sensors 1 and 2 of oxygen sensor, per code" those are on headers and after cathalic conv ones.
"i change spark plug wires and its running stronger" it iddles ok.

I had a friend check the fuel pressure, it show 20pnds to 30pnds? He claimed it is the fuel pump now. What do you think? Thanks in advance
Soo I am about to change fuel pump/fuel filter

3 Replies

MERLIN2021

MECHANIC
17,250 POSTS

20psi is low for duel pressure, it could be that, or the transmission may not be kicking down, try going to a oil change place and have the tranny fluid flushed, not dropping the pan, just hook up to the flush machine. See if it will shift better.

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Tuesday, October 23rd, 2007 AT 5:22 PM

BOOSHU

MEMBER
2 POSTS

WHAT IS THE NORM FOR FUEL PRESSUE AFTER CONNECTING THE METER AND CRANKING THE ENGINE?

OUR LAST READING WS 30PNDS AND 2ND TIME WAS 20PNDS.

ON 3RD, 4TH AND 5TH GEAR UPHILL LOOSES POWER OR THE ENGINE STARTS KNOCKING

ENGINE LIGHT IS ON

"I CHANGED SPARK PLUGS, WIRES, 2 OXYGEN SENSORS"

NEXT IS FUEL PUMP? FUEL FILTER?

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Tuesday, October 23rd, 2007 AT 5:28 PM

MERLIN2021

MECHANIC
17,250 POSTS

What does the gauge read whe the truck is at idle?
I think if you have 35psi at idle you will pass. Do the tranny fluid! If fuel pressure is under 35 at idle, replace filter next retest then pump.

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Tuesday, October 23rd, 2007 AT 5:32 PM