Fuel system problems

Well do I have a good one for you guys. Ok have a 92 bronco that has done this exact same thing so figured I could post this here and get advice on both. Gave up on the bronco and has been sitting with this same problem for sometime.

Anyways just bought a 94 Ford 150 with dual tanks, took it out drove fine. A few weeks later it started acting up where it would lose power going down the road. Pull off to the side and it was barely able to keep it's self running. Turned it off and tried to start it but did not work . Then noticed the fuel pump would stay on as soon as you turned the key to the on postion. Never would go off. Pumps would just pump gas from tank threw fuel rail straight back to the tank. Anyways got this back to the house and started changing parts off of it. Changed fuel filter, relays, Air/idler sensor, tp sensor, egr sensor, Checked fuel pressure, Checked both pumps, Changed map sensor, Checked computer with a code reader( none where found but engine light is on),Checked all fuses, Changed computer out of a buddies truck and this did not work as well. I'm out of ideas at the moment was sure the computer was bad and changing it out would have solved this problem but was wrong once again. Pretty sure this is a electric problem somewhere but I have ran out of places to look. Have 2 fords sitting in my drive way with the same problem now. NEED HELP

Bad thing went threw this same thing on my bronco and never could figure it out. But seems it is a problem they both have in common. Bronco was just sitting and did not start but pumps will continue to run as soon as key is turned on. Not sure what was all checked when I worked on this but was hoping someone had an idea on this problem since it seems to be common for me. Lucky me woo hoo. Lol

Jabster

Did you look for things like arching inside the distributor cap? Ignition module? I've had cars that had similar problems, and it was always the ignition system causing the problem. As far as I can tell, on an EFI engine, there is power to the pumps as long as the key is in Start or Run.

Good luck,

>-

You didn't say if you checked for "spark" at the plugs.....

There's an inline spark checker if the occasional "zap" fr. the coil bothers you. @-)

One other thing, you can remove the SPOUT connector which stops the computer from messing with the timing. It then runs at the default basic timing setting. I would most likely suspect the ignition module on the distributor, but do the spark test that Bully Bob was tslking about first to see the spark looks like.

>-

yo.

re; "Checked computer with a code reader"

Were both KOEO & KOER tests done?

Troubleshooting w/Wiring Diagram in 94-95 F Series;

Miesk5 note that this is for F Series w/dual tanks & pumps; the R/Y wire from Inertia Switch to Fuel Pump is PK/BK on Broncos

Source: by seijirou at SuperMotors.net

Ck out the wiring color codes; should be = to your year



Wiring Diagrams in 89 (INCLUDES BRONCO & Single Tank F 150); 91 (INCLUDES BRONCO & Single Tank & Dual Tanks & Pumps F 150) & 95 F 150 w/Dual Tanks & Pumps from Electrical & Vacuum Troubleshooting Manual (EVTM)

Next up is Test in a 90 F w/dual....check colors again...

"The test light is the best way to check the fuel circuits. Do not test these wires, Yellow with a white stripe, Yellow with a light blue stripe, Dark Blue with a yellow stripe as they are for the fuel gauge only and have nothing to do with the fuel pumps. They get there power from the fuel gauge and they will have a lower voltage on them.

The power wires for your fuel pumps is the red wire with a yellow stripe and it comes from the Fuel Pump Relay by way of the Inertia Switch. This wire should have power on it with pin #6 of the self-test connector grounded and the key on.

If you select the front tank then the Red wire should light your test light.

If you select the rear tank then the Brown wire with a white stripe should light your test light.

If you have power on the Red wire with a yellow stripe and do not have power on the selected tank wire (Brown/white or Red) then you have a bad selector switch." by subford


"Troubleshooting Fuel Injection Problems with a Noid Light;


Occasionally, you may have to troubleshoot a no-start condition, a misfiring or a bad fuel injector in a vehicle. A Fuel Injector Noid Light is one of those indispensable tools that will help you to diagnose the maladies affecting most of the fuel-injected vehicles on the road today. The Noid light test in conjunction with several others will help you find the root cause of the misfire or no-start that your vehicle may be experiencing.

In most vehicles, the fuel injection computer feeds power and switching signals to the fuel injector. With this nifty tool, you can confirm visually that the fuel injector is receiving both. Although the tool will not confirm whether the fuel injector is malfunctioning, it will confirm that the fuel injector is receiving both power as well as the switching/pulse signals. If one of these is not reaching, the fuel injector is not going to work." Read more @ https://www.apexinds.com/blog/troubleshooting-fuel-injection-problems-noid-light/

Rent it @ some parts stores, especially mom and pop owned: unplug one of the fuel injectors and plug the NOID light in. Then crank the engine and if the NOID light flashes the computer is grounding the injectors OK. But if you can smell raw gas at the tailpipe when you crank engine over.

Or, try this injector test; "...With eveything connected normally & the key in RUN, pierce the OTHER wire (not the Red one) on any ONE injector & tap it BRIEFLY to ground. Do you hear half the injectors click open & then closed? Put a finger on each one to feel which ones are working. If some of them don't open, repeat the test, holding the ground SLIGHTLY longer each time, but never more than 3 sec continuously...Repeat this for the 2nd bank of injectors (just one with a different color wire)..." by Steve

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Pump Runs w/Ignition Switch Off; "...

If it stays running with the truck off, then most likely you have a bad fuel pump relay; EEC Relay hanging closed; If the EEC relay goes bad, it could be sending the signal to the fuel pump relay to turn the fuel pumps on;

One easy test for this is: Without the key in ignition, bump the starter over @ the starter relay using a screwdriver.

If it is the EEC relay, the truck will start without the key in the ignition..."

MIESK5 NOTE; from Ford EVTM;

The Control Module (PCM) runs the pump{s} for one second when it receives an ignition- on signal. It also runs the pumps as long as it receives a PTP signal from the Hall-effect devices, it continues pump operation even after the key is released from START. If the PTP signals fall below 120RPM, the control module cuts off the signal to the fuel pump relay or the integrated relay control module. The pump will also run when the terminals of the fuel pump test connector are jumped. the Control module signals the pump when it receives a CRANK signal, and when the Control module gets PIP signals that the engine is running. the pump does not run if the PIP indicates the engine is not running even with ignition ON {except for that first one second}.

Source: by sackman9975 (Scott), Redwagon & miesk5

Thanx for all the help everyone but still trying to hunt the problem down. Here's what happen today. Decided to take battery cable off and try to reset the computer to see if this would help. Guess what is worked was amazed when I turned the key and pumps primed like they should have. Was a short lived moment though. Decided to start it up, Started fine ran good but with in about five minutes it started acting up again. Check engine light come on it was running really rough. Finally died and turned key off and back on and pumps where on once again.

Now with all that happening it seems the computer is the problem to me. Also for everyone asking about the spark it is all fine it is all new. From the cap, button, and wires. Now I did change the computer out with a buddies but never let either one of them sit without the battery cable on it to see if that worked. We just switched them and they did not work so marked this off the list. Anyone have anymore insight on this. Should I still focus on the computer or maybe a short in something.

Oh one other thing not sure what you mean by this.

re; Checked computer with a code reader

Were both KOEO & KOER tests done?

Buddy just had a code reader from a while back either OB1 or OB2 not sure which it was. Anyways checked it with it and it did not bring anything up. Should I have done something differnt. Would it also read a computer that is bad or not?

i would start with the fuel pump relay. if that is good, it would seem it might be a line pressure issue. test your pressure at the rail. maybe a bad fuel pressure regulator.

Key On Engine Off

Key On Engine Running.

Forgot to add this at the top regulator, relay's, and fuel pressure all good. checked these all a while back so this is why I'm leaning toward the computer. Everything I can think of that has anything to do with the fuel has been changed and tested unless I'm forgeting something.

Now the same method I posted below I used it 2 more times that night and it worked each time. So this makes me believe it's not a short since it acted the same each time. I could be wrong but just what I'm thinking. So is there another way to check computer or just do the switch like I done before but wait a while with both of the computers in the different trucks with battery cables off and let them reset?

it seems more than a little unlikely that your computer would be bad and not throw a code.

if your check engine light is on there are codes to be had.

you don't need a code reader to do this.

self test procedure

my first bronco was bought cheap because someone misdiagnosed a "bad computer".

the computer seems to be one of the most reliable parts on the truck.

it is the last part i would expect needs replacing and if it does, it will certainly tell you.

The more you describe this problem, the more I suspect that it is an ignition problem. Ford ignition modeles on the distributor have a reputation of for breaking down when the engine warms up and running just fine when the engine is cold.

Attached is some information from a 1992 EVTM

Good luck,

>-

I had the exact problem with my 88 bronco. There is a ground wire that goes from your computer to the fender just behind the hood spring. Check for corrosion and make sure you have agood ground. This fixed mine. Also check the ground wire from the battery to the front of the body. Iworked on mine for a long time before I got it fixed. Good luck.