help troubleshootinf pickup, 91 f150 6cyl

[SPIKER]

Hi ALl:

usually pretty good at these things but at a bit of a loss on this one.

1991 F150 w a Multi-port EFI 300 6cyl 5speed 2wd.
ran & drove OK in Aug, (only use it for TRUCK needs) so it sets when not TRUCKING something.

went to start it up cranks good battery good. has spark/fire. both in-tank fuel pumps run fine.

SO started troubleshooting.
1 checked for fire, put in line spark plug checker & it has light/spark
2. sprayed a bit of ether into it and it fired up and staid running but no power, so replace fuel filter as I had one.
3. still same issues, dont have a good way to put in-line fuel pressure tester on it YET (making trip for one this weekend.)
SO pulled the Fuel Pressure Regulator, $40 bucks later still same issue... Pulled and cleaned all the plugs (carbon buildup running rich & has been)

NOW I'm not sure what next to look at? Any suggestions>???

thanks all

Mark

[sld]

Doesn't take much fuel to idle an engine. If you verified spark it must be fuel.

How about a fuel volume check from just key on engine off?

[sld]

Also, you could check the timing. Should be 10Deg BTDC with the spout connector removed.

There should even by a couple of scribe marks on the distributor base and clamp piece to get you in the ball park. It is hard to check timing if it won't run.

[mostly_gas]

Fuel injectors. Noid light will tell you if the injectors are being fired.

[dirtyoldman]

There is a different fuel pump on each tank, so switch tanks to eliminate that. Fuel pressure can be checked with a tire gauge on the injector rail. Wear glasses when doing this and keep you mouth closed.

[SPIKER]

Thanks so far,
I have not found any ports on the fuel rail to check fuel pressure at.

I have switched from front to rear tanks, same issue.

I dont think it is fuel pressure as today installed NEW Fuel Pressure regulator. I also jury rigged air pressure test on the OLD regulator and got about 60~100 PSI air into it prior to old one popping off.

Have not checked it's timing it was running well prior to setting for a month. cant see any mouse chew marks but suspect that could be issue. I will take closer look for fuel rail pressure port otherwise will have to TEE in at the fuel filter with some line & gauge.

Mark

[horsepuller]

Spiker - Do both fuel tanks have fuel in them? I have had a no-start situation similar to yours with my old F-150, only to find out that somehow the fuel tank switch has been bumped from the tank that has fuel to the one that is empty. Also, it seems like I read somewhere about a problem with one of the electric fuel pumps pumping from one tank into the other, sorry, I can't recall the details. Good luck.

[SPIKER]

horsepuller:

Both tanks have fuel and worked prior no issue there was a recall on the Pump/Tank switch that ford would fix them for free if they failed. the issue was it would only partly switch from one tank to other the fuel return would go back to wrong tank. so one tank over filled the other and dumped gas out overflow when that happened or would pump 1st tank empty. dont think that is the issue???

picked up fuel injection/inline tester today but not at the farm (where truck is stuck) to do any testing. it is outside and cold raining from this big storm so may not work on it till Monday now as weather has my back in a knot...

Thanks for suggestions so far

Mark

[dirtyoldman]

Looks like it should trigger a code at approximately 40 PSI or less, so that's unlikely.

This should have some kind of cam position sensor - id check that out next.

[SPIKER]

DOM:

I'll take a closer look in AM, I dont think it has any cam/crank sensors it sues side mounted old style distributor, most cam/crank sensors are all distributor-less (coil packs) started in fords about ~95.

Does anyone know for sure if the pumps are supposed to STOP when certain pressure is reached? Mine come on and stay running is why I'm asking and I thought in past after a few seconds to build pressure they went off.

thanks
Mark