i just finished putting in a new rear tank with sending unit and lines 2 the selector valve. Got it all put in and the truck started on the back tank and ran 4 about 3 to 4 min then started to spit and sputter then died????? Now it will not start unless u switch back 2 the front tank. And i just put in a new selector valve last summer but have not used the back tank since. ANY IDEAS??????????

 

Fuel pressure when running on the back and front tank?

 

dont know if thers pressure the pump turns on i can hear it when i turn the key??? im kinda thinkin it mite be the selector valve again the pressure plate might be stuck but then i dont know how it got fuel 2 start the first time tho???/

 

Does the fuel pump turn on for a second or two then shut off? It should.....If it stays on you may have a stuck fuel pump relay or a bad PCM.

 

no the pump just primes then stops

 

so ya the pump comes on for a few sec then shuts

 

That is a good sign. Now you need to get a fuel pressure gauge to check to fuel pressure on the fuel rail test port. Many auto part stores will rent/loan one of these. You should be expecting 30-38 PSI with the engine running at idle. Pull off the vacuum from the regulator the pressure should go up to ~ 42-45 PSI.

It would not be the first time I saw a "new" pump bad out of the box.

 

I finally put two and two together here......your truck uses two low pressure in tank pumps, a tank selector aka dual fuel reservoir and a single in-line high pressure pump. What all that means is the fuel reservoir is could be at fault here. Yes, you said you replaced it before but that does not mean anything now.

The fuel system on your truck is unnecessarily complicated. Pull off the fuel line from the rear tank, cycle the key on a few times, verify fuel is pumping out. If it is the fuel reservoir is probably the culprit. If not, proceed with figuring out the new rear pump gave out so quickly. Perhaps a connector came off?

 

ya thanks 4 the info. Im going 2 crawl back under it in the next couple of days and check the selector valve first. I hear the go often when u dont use the switch often. I really hope the sending unit its fine thats like 400 $ lol anyways thanks 4 the help

 

hey guys im still havin the same problems ive checked all fuel ans spark avens and there good it starts and runs cold but after a while when i gets warmed up its spits and sputters and dies now some told me it mite be my ecm i have a ecm out of a 93 f250 7.5l 2wheel drive auto i was wondering if i could use it i know its gona throw some codes but im fine with that if it fixes the problem. any ideas??? HELP PLEASE

 

Did you ever verify what the fuel pressure was when the truck is spitting/sputtering? How di you check for spark under the same conditions? You need to figure out which part of successful combustion is missing here. Oxygen/air is a given. Now you are down to fuel and spark. Stick to the basics before introducing a new problem, i.e. swapping in a ECM (aka PCM). The Powertrain Control Module rarely goes bad, even with the symptoms you are describing.

 

yes i had 41 psi at the time it screws up and i also had spark thru a tester but put new msd high output coil on anyway tryed new fuel filter and an o2 sensor also. i have fuel and spark that i swhy im thinking electral problem if i let it sit for a few hrs it will start rite up and run for a bit again

 

oh and i am only running off the front tank i decied 2 just forget about the rear tank untill i get this problem resloved

 

Now that we know you have fuel pressure we can focus on other pieces of the puzzle. When you tested for spark was the truck running well or was it sputtering again? What color is the spark? Should be a nice blue/purple color.

This vintage Ford is notorious for the Ignition Control Module breaking down under heat, especially the distributor mounted version like your 1989 should have. To add to the misery the PIP sensor (Stator) inside the distributor is equally bad at failing when it is heated up.

Then add in the poor quality of aftermarket vendors for each of these pieces. It can get a little frustrating to figure out which part is bad. It is much easier to diagnose the root cause if the ICM or PIP were to go bad and stay bad...

The Ignition Control Module (ICM) can be removed and tested at a parts store. IF you do so, have them re-run the test several times in order to heat it up. The PIP is located inside the distributor. It can be replaced, but it does take some effort. Many choose to replace the entire distributor. The caveat is many of the so-called "rebuilt" units have bad a PIP sensor in them. Most "rebuilders" do not heat test them.

I have referenced this thread a few times when trying to diagnose this issue: 30 Minute Ignition System Test for Remote Mounted TFI Bronco - FSB Forums

Keep in mind your Ignition Control Module (ICM aka TFI) is distributor mounted. Either version works the same, it's the physical location that changes.

I am leaning towards a PIP issue in light of some other info I read on another one of your posts. You stated if you pour in some fuel the truck will run. That leads me to believe you are not getting the signal for the PCM to fire the injectors. That signal is also triggered by the PIP sensor (aka stator). I have seen a few cases of the PIP putting out enough signal to trigger spark, albeit weak and erratic, but not enough to trigger the PCM for injector firing.

 

Runs fine cold, then bad when it warms up?

I'm thinking either the TFI/ICM module as mentioned earlier, or the engine coolant temperature sensor is faulty.

Try unplugging the coolant temperature sensor, and see if stops acting up. It should be around the front of the engine, threaded into the water pump area, or near the thermostat housing. It will have a 2-wire connector going into it.