No worries, I didn't take it as rude.

If I had to guess, the one non motorcraft part of my cooling system is the t-stat, but that will be remedied soon with a motorcraft t-stat, and I bet it fixes the temp consistency...

 

ok so update time.

New reman computer was put in the truck with no change minus another code 556 I want to say. I know it was a fuel pump relay circuit fail or something of that matter. It was a KOEO code.


So tested the EGR posisition sensor (after doing a VREF test) and it tested bad for ohms. New EGR position sensor and EEC relay and Fuel pump relay and fuse and still no change.


The next day at work I was thinking to myself I know on these trucks they do some really weird things so what if the truck is not getting sufficient fuel pressure causing the computer to try and compensate for it pushing to much fuel into the engine causing the 02 sensor to run rich. Remember I haven't done a fuel pressure test since the new injectors.


So I did a fuel pressure test 12 times. First 4-5 times it came up with 22 psi with KOEO. The next few times it went to 43. Never did it get in the 50-60psi the 300 is required to have. However it doesn't leak off so the injectors took care of the leak off.
The engine was at operating temp when I did the test but it still shouldn't matter correct?

So I am thinking I really need a new fuel pump because what else would cause the fuel pressure to be so low before the regulator?
I did buy a new fuel tank switch as I want to see if that is the issue with the front tank not turning on or if the PO got a bad fuel pump.
Trav

 

Pinch off the fuel return line just after the FPR at the rubber section to check it, if the pressure comes up to and over spec the pump is fine.

If very little to no rise in pressure then the pump has likely thrown in the towel.

Use something easy on the fuel line, a small C clamp or vice grips with line protected from their jaws etc. Pinch it off so as very little fuel if any can return to the tank effectively deadheading the pump, quick test then turn the power back off once you've seen the result.

I wouldn't concentrate on the mixture reported by the computer until you have the fuel pressure working at spec, fixing one might correct the other at the same time. IE injectors dribbling fuel into cylinders at that low working pressure.

 

All of my lines are braided stainless steel and I am afraid pinching it off may fray them or they get stuck pinched.


New switch yesterday and now we got the front pump to turn on however we put 5 gallons of gas in the front tank and turned the key and it still showed nothing in the tank. Flipped it back to the rear tank and it had more gas then before.
I could not get the truck to start on the front tank at all except it ran for a few seconds off the fuel in the line. I also tried getting it running on the rear tank then switching to the front tank and it almost immediately died.


My guess would be either clogged lines or the pumps have bitten the bullet. I can not figure out another reason for drain back on these fuel system style trucks. If it was my 88 I would know the exact part that was bad but this truck doesn't have it.


The front tank pump was supposedly replaced by the PO however he keeps saying it is a performance fuel pump I still don't get what a performance fuel would be on a 6cyl truck.


I never tried pulling the FP off the front tank as I knew it would be either 0 or almost nothing just because the truck wouldn't start off it.


We will try pulling the lines and using our air compressor to blow the lines out I don't see what it could hurt.


On my 88 I had a clogged fuel line and it would cause it barely run sometimes wouldn't run just like this truck is doing. It always had just enough fuel pressure to run. I am afraid though that it may turn out like my 88 where I ran it for so long like that I burnt up the brand new fuel pump.
Trav

 

Your rear fdm in the tank is bad if the front tank is filling the rear.

 

Well turns out it wasn't a fuel delivery crossover issue I guess I misunderstood what dad was saying (I didn't know how much gas was in the truck before we ran it).


So he dropped the tanks and cleaned both fuel pumps and assemblys and blew out the lines. The check valve on both were sticking badly so with the air compressor dad was able to blow enough air pressure to free it up and get it working properly.


I personally wanted to put new pumps on since we were this far but dad didn't want to so we reinstalled the tanks and drove the truck. Rear tank now works fine and no 173 code (I drove it a bunch too). CEL does come on periodically but not as much. I drove it 80 mile round trip with stop and go and it did good.
The front pump however is not working so we have to get a new pump for it.


Dad is going to be driving it for a while till we fix the rocker arm issue on his 90 302 F150 then we will share the truck till I get my Chevy going for my back up.
Trav