Fordracer Posted April 30, 2008 Share Posted April 30, 2008 Had an interesting one today. It wouldn't crank over and when you jumped the starter to crank it over it wouldn't start. The only code was a P0231-Fuel Pump Secondary Circuit Low. I figured that had nothing to do with a no crank so I ran codes on all modules and nothing else came up. Then I got to thinking, they probably don't want the motor to crank over if it has no fuel pressure to feed the the high pressure pump to prevent damaging it. It ended up being the fuel pump relay was bad and now it cranks and starts. I don't remember this being brought up in class so I thought it might be good to know about. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted May 1, 2008 Share Posted May 1, 2008 Good info. /forums/images/%%GRAEMLIN_URL%%/thumbup.gif Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted May 1, 2008 Share Posted May 1, 2008 +1 /forums/images/%%GRAEMLIN_URL%%/thumbup.gif Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 1, 2008 Share Posted May 1, 2008 Cool observation. Did you or would you consider calling the HotLine and see what they have to say about this? I am curious because I snooped around in all the literature and nothing points to the fuel pump relay for a no crank or OBD Theory/Operation. Perhaps bugging a truck would be more proof positive. Thanks for the info!!! /forums/images/%%GRAEMLIN_URL%%/thumbup.gif Quote Link to comment Share on other sites More sharing options...
Fordracer Posted May 1, 2008 Author Share Posted May 1, 2008 I didn't talk to the hotline about it. I'll ask them about it the next time I talk to them. The next 6.4 I get in here I'll pull the relay on it and see if it does the same thing. Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted May 1, 2008 Share Posted May 1, 2008 /forums/images/%%GRAEMLIN_URL%%/thumbup.gif Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted May 1, 2008 Share Posted May 1, 2008 Keith, there is a another fellow over at FMC boards backing up this diagnosis on another truck. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 1, 2008 Share Posted May 1, 2008 I'll take that as validation! Not that I didn't beleive... I usually don't believe what I see before my own eyes these days. You would think something like this would have made it into the books, you know, like the OBD Theory and Operation... the symptom charts... makes you wonder what else they are not telling us. Quote Link to comment Share on other sites More sharing options...
Cetane Posted May 2, 2008 Share Posted May 2, 2008 I took a quick look at the logic and it looks like with the fuel pump relay going bad it trips the crash module in the PCM, disabling the starter. The same thing should happen if you trip the inertia switch. Good catch.... Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted May 2, 2008 Share Posted May 2, 2008 This might also explain why the engine died so quickly when I pulled the FP relay out when I was doing scope patterns...... /forums/images/%%GRAEMLIN_URL%%/grin.gif Quote Link to comment Share on other sites More sharing options...
Cetane Posted May 2, 2008 Share Posted May 2, 2008 Yep, it should take about 5 seconds before the ECU disables the engine. Quote Link to comment Share on other sites More sharing options...
GADDIS Posted May 15, 2008 Share Posted May 15, 2008 For what its worth. I did a cab off the other day for an inlet pipe leak. After I got it back together I had a no crank. Found the interia switch triggered. I believe I had a fuel pump code in it also. So I learned that day fuel pump/circuit issues will result in a no crank. And trying to find the interia switch made me feel a rookie. Its well hidden. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted May 30, 2008 Share Posted May 30, 2008 A while ago I had a 6.4l that had a PCM reprogram recall and a MIL lamp on with a EGT dtc. Like a good tech, I did the reprogram first thinking that maybe it would take care of the EGT trouble code.(yeah right) I found out that day (the hard way) that with the new calibration that the engine will not crank if there is a EGT trouble code. Infact it will not crank over for an entire hour after the code is cleared. Now you can trick the truck by pushing the truck with the key on to give is a VSS signal or by jumping the started solinoid. Something else that should have been announced... Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted May 30, 2008 Share Posted May 30, 2008 A while ago I had a 6.4l that had a PCM reprogram recall and a MIL lamp on with a EGT dtc. Like a good tech, I did the reprogram first thinking that maybe it would take care of the EGT trouble code.(yeah right) I found out that day (the hard way) that with the new calibration that the engine will not crank if there is a EGT trouble code. Infact it will not crank over for an entire hour after the code is cleared. Now you can trick the truck by pushing the truck with the key on to give is a VSS signal or by jumping the started solinoid. Something else that should have been announced... Ditto, i did the reprogram when it first came out. There is an SSM to reprogram the PCM for the EGT codes. But, they never stated how this new reprogram affects the vehicle. So the Ford engineer explained exactly how it works. Now i know. I got lucky, and mine cranked right away. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted May 30, 2008 Share Posted May 30, 2008 So the Ford engineer explained exactly how it works. Now i know. Care to elaborate? /forums/images/%%GRAEMLIN_URL%%/smile.gif Quote Link to comment Share on other sites More sharing options...
Mekanik Posted May 31, 2008 Share Posted May 31, 2008 I think it is a saftey precaution if the thing was shooting flames out of the exaust. Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted June 2, 2008 Share Posted June 2, 2008 Originally Posted By: Tony302600 So the Ford engineer explained exactly how it works. Now i know. Care to elaborate? /forums/images/%%GRAEMLIN_URL%%/smile.gif My first case was the EGT13. Monitoring PIDS the sensor would go open, 4.65v /1800F degrees. The PCM and IC see's this and will put the message on saying "please pull to side of road immediatly." My 2nd case the EGT13 sensor read 1.08Kohm's and the degreee went off the charts, set the P242D but still cranked. With the sensor being at 1800F the instrument cluster will not let the engine crank, because the super hot exhaust temp. Here is a thing that bothered me. The engineer told me "some will crank, some will not crank." he said he has no clue why. So it is a safety feature. Mine both cranked. Quote Link to comment Share on other sites More sharing options...
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