Stumbleing,Backfires, dieseling, missing, hesitation and sometimes seems like not running on all cylinders.

I have been persuing from fuel problem but still have not solved it. 1995 F150 5.0 with 80K.

1) Changed fuel filter ( a lot of crap in there ... probably never changed before.

2) Ran a can of SEAFOAM thru with a 1/2 tank of gas.

3) Next tank ran 2 bottles of ISO-HEET RED with a full tank of hi-test.

4) Now running LUCAS FUEL TREATMENT when I fill up.

I have put on less than 1000 miles since changeing fuel filter and still running pretty crappy.

When should I replace fuel filter again ?

How about getting injectors cleaned at shop with BG SYSTEM ( probably about $150 ... not cheap) ?

or

Go after the electrical side ?

 

1) passed Maryland emissions test 2 days ago

2) NO ENGINE LIGHT ON

 

You need to check the fuel pressure to find out where you stand.
It should be 32 PSI at idle and should go to about 42-45 PSI when you pull the vacuum hose off the nipple of the FPR (Fuel Pressure Regulator).

You check the fuel pressure at the bleed valve on the fuel manifold (rail) with a gauge and a cold engine.

You can get the Fuel Pressure Gauge at most auto part stores.
Some have reported using a dial tire gauge but it does not always work.

EDIT:
When you pull the vacuum hose off the FPR there should be no sign of fuel. If there is the FPR is bad.

 

I would look at the plugs/cap/rotor ect. maybe it needs a tune up.

 

between junk in the tank/fuel system/fuel injectors and electrical/timing and now fuel pump.

Again symptoms STUMBLEING, BACKFIRE and DIESELING. I can still cruise at 80 MPH no problem and I trust it to go most anywhere.

I changed fuel filter a little less than 1000 miles ago and as I said it was full of dirt. When should I change it next ?

 

Have you tried pulling the codes?
Also do the KOER test.

 

 

Not sure what you are asking. All codes are relevant in CM if you have not repaired the item the code is for.
The KOER test is always relevant.

 

Could be 1 or more components lacking in accuracy & performance yet still functioning within acceptable range. Coolant temp sensor,slow switching O2 sensors, Contaminated MAF sensor (if applicable). EGR ports are usually with some level of partial to complete port blockage due to deposit buildup. And there' always loose Vac hoses, PCV function or air bypass of & intake air restriction courtesy of a dirty air filter. Going to a higher octane would be like throwing legweights to someone already having problems keeping their head above water. Introducing Seafoam, 2/3 can through a Vac hose (like the powerbrake assist line) while idleing at normal op. temp. then immediately shutting off allowing it to soak into deposit buildup for 10 or 15 minutes,tossing the remainder in your tank will give you better results. The Lucas product is a great maintanence additive once the bulk of the contaminant buildup is eliminated from the surfaces within the combustion chambers. Toss a can of SeaFoam in with your oil prior to change, it's surpriseing what oozes out when the drain plug is removed! Anyway, scan results should help point you in the best direction to proceed.