Wanted to post my findings here to possibly help any others in a search for a solution to a crank no start situation.

I see that many crank-no-start issues here seem to point to a fuel pressure/pump system issue.

I have a 2004 V10 in a F53 chassis. It sits for a month at a time between use. Even if I don't use it, I make sure I start it and let it run for at least 15-30 minutes on the first weekend of the month.

Today I went to start it and had crank with no start. I could smell fuel, so I was pretty certain it had fuel pressure. Nothing else had changed since the last time it was started so I was getting ready to troubleshoot fuel pressure, confirm that the injectors firing and crank angle sensor wiring to make certain no vermin had gotten to any wiring. If no obvious issues with wiring, I was going to pull a coil, insert a new spark plug and see if I was getting spark before searching farther.

There are other "things" cycling with ignition in ON position like hydraulic pump for leveling jacks and slide outs so I can't hear fuel pump priming during initial key on.

I depressed schrader valve on fuel rail and got a pretty solid blast, so my gut was fuel delivery wasn't an issue unless computer wasn't giving signal to injectors to open or fuel pressure was inadequate.

Before pulling a coil I decided to try starting with boosting batteries with switch on dash that temporarily puts both batteries in parallel. BINGO, cranked substantially faster (original crank didn't seem abnormally slow or labored, but in comparison the difference was apparent) and it fired up right away.

I'm not certain if during cranking the voltage was too low for ignition to fire and/or if a minimum crank speed needs to be there for hall effect on crank angle sensor to work, but in any event low voltage during cranking seemed to be the issue. By the gauge on the dash I'm estimating it was getting about 10v during no start cranking.

Hope this helps somebody before they start tearing things apart or towing to a mechanic.

 

I would check or have checked that device allowing you to connect the RV portion house battery to the starter battery----it could be causing your loss of voltage especially if this is a new issue.

 

I'm tempted to say that one thing has (almost) nothing to do with the other. The last few years I had my '01, the battery went dead plenty of times. And when it was weak, the engine would barely crank over, but it would still fire up.

JWA is right, I'd start looking at the RV equipment, and all your grounds.

 

Thanks, I will look at those. While sitting the RV equipment is completely electrically isolated from the Ford chassis portion. There is a relay that must be switched on to tie them together. There's also the option to run the dash stereo off the house battery or chassis battery (that switch was left in the chassis position which ran that battery too low for what I believe to be inadequate voltage to the ECM and/or coils during cranking).

Anybody know what the minimum acceptable voltage to the ECM and/or ignition coils is for them to properly function?

Is the crank position sensor hall effect or an inductive style pick up? It's my understanding that hall effect types are not RPM dependent while inductive types require some minimum rpm to generate adequate signal.