91 f-150 will not start
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91 f-150 will not start
New to site, need help.. I have good fuel pressure at schrader valve by firewall. Already changed fuel pressure regulator valve and today changed the ignition module on distributor because it tested bad. Still won't start. If I srpay starter fluid into throttle body it starts, but dies after burning that off. Fuel pumps both seem to be working fine. It ran fine the day I parked it. Next day, this! I don't have a code reader but I figure someone has had this happen to them with their Ford truck. It must be getting spark or starting fluid wouldn't burn. Help??
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From: Easton,Ks
Sounds like the injectors are not firing, if you hear them firing check the fuel pressure with a gauge. You may have fuel pressure at schrader valve but it may not be enough.
What engine do you have?
What year and model truck is it?
What is the Fuel Pressure reading with pin 6 of the test connector grounded and the key on?
What engine do you have?
What year and model truck is it?
What is the Fuel Pressure reading with pin 6 of the test connector grounded and the key on?
Last edited by IB Tim; Jan 13, 2006 at 06:07 AM.
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This is a 1991 f-150 with an in-line 300 efi. Fuel pressure reading was 45-50 lbs with gauge while cranking. I can hear both front and rear tank fuel pumps come on and pump up to pressure and go off. It has duel tanks with switch on dash. It has one high pressure pump in each tank. No pump on frame rail as some did that model year. It seems that whatever part tells the injectors to spray fuel is not working. Since I can't drive it to get codes pulled, it's been a real guessing game. I'm not sure about checking the voltage at pin six..need more detail for that and I had borrowed the gauge set and already returned them. Hope this helps.
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From: Easton,Ks
Grounding pin 6 on the test connector was for checking the fuel pressure.
The PCM (EEC, MCU) fires the injectors when it receives the PIP from the Distributor CPS using strategies.
But without this PIP you will not get any spark also.
So you (we) need to know if the injectors are firing. One side of the injector plug has 12 Volts on it and the other side is sunk to ground in banks by the PCM. Make sure they do have 12 Volts, power comes on with the PCM Power Relay, this power also goes to the coil of the Fuel Pump Relay so its OK.
Bottom line is if you have 12 Volts on the injectors with the other side not flashing with your test light while you crank it and have spark with good fuel pressure then you could have a bad PCM or bad PCM ground/wiring/plug pins.
If they do flash the IAB (IAC) may be stuck closed, also you can pull your own codes with a test light. Check this URL out. <!--StartFragment --> How To Run a Self-Test
The PCM (EEC, MCU) fires the injectors when it receives the PIP from the Distributor CPS using strategies.
But without this PIP you will not get any spark also.
So you (we) need to know if the injectors are firing. One side of the injector plug has 12 Volts on it and the other side is sunk to ground in banks by the PCM. Make sure they do have 12 Volts, power comes on with the PCM Power Relay, this power also goes to the coil of the Fuel Pump Relay so its OK.
Bottom line is if you have 12 Volts on the injectors with the other side not flashing with your test light while you crank it and have spark with good fuel pressure then you could have a bad PCM or bad PCM ground/wiring/plug pins.
If they do flash the IAB (IAC) may be stuck closed, also you can pull your own codes with a test light. Check this URL out. <!--StartFragment --> How To Run a Self-Test
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Ran the self test
I pulled codes from computer by grounding self test pin. The koeo codes listed 15 different codes. ( 11,61,26,45,22,55,81,16,12,61,14,52,25,58 ) I looked these up on pages you provided me and still don't really know which of these would actually prevent the truck from at least starting up. The check engine light had been on for quite some time even prior to this no start problem and some codes are likely old although it never ran bad. I still haven't checked voltage at the injectors as you mentioned to do. It's outside and I can only work on this when weather is permitting me to. I have another vehicle to drive but this is really irking me.... Thanks for any and all help. Rob
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From: Easton,Ks
Some of these codes were more than likely from the bad ignition module.
You need to pull off the neg battery cable for about 30 minutes to clear the codes, do the code thing again and run it with the starting fluid to get the running codes and report back.
If your codes were for real it would have pointed to a bad CPS sensor in the distributor. However it should not run at all even on starting fluid with those codes.
You need to pull off the neg battery cable for about 30 minutes to clear the codes, do the code thing again and run it with the starting fluid to get the running codes and report back.
If your codes were for real it would have pointed to a bad CPS sensor in the distributor. However it should not run at all even on starting fluid with those codes.
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I am going to check for codes in just a few minutes today as the weather has finally warmed up. Already pulled off neg. battery cable an hour ago. I was wondering what you meant by the IAB(IAC) possibly being stuck closed. I don't know that abbreviation. It will also be impossible to get running codes because it will take two people and quite a bit of starting fluid to keep it running long enough for the flash sequence with engine light to start and finish. I will spray some in and get it to run hopefully long enough to pull something from it. I will reply to this message aqs soon as I am finished. I hope you can help. Rob.
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pulled codes again
after disconnecting battery for over an hour and rechecking codes, the same 15 codes appear but continuos memory has been erased. key on engine off self test. I checked voltage at front injector and it reads 3 volts d.c. on lower connection and 0 volts on top plug-in with or without engine cranking over. Any ideas ?? The truck seemed to nearly start up while trying to check the voltage at the injector. The battery is now in need of a recharge. Help
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codes are different
The codes were different than the last self-test. There are only 6 codes reported and they repeat themselves. 12,61,14,52,25,58. After looking then up I still don't know which of these would be the real problem. Help
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From: Easton,Ks
I think I would try another PCM/EEC Computer, should be able to pick one up for about $20 to $40. I just picked up one for a spare last week for my 95 F150 for $40. Just make sure it is out the same type of truck, engine and transmission.
It should also have the same program code on it.
It should also have the same program code on it.