Ford V10 starting and dyeing

[Team_D]

Hi All,

I have a Winnebago Vista, 32K with the Ford Chassis, V10.

I'm supposed to head out of town next weekend after the motorhome has been sitting for a couple of months, so I thought I'd take it out for some exercise.

I went to start it and it struggled. Typically, I turn the key and let go. The starter continues to turn the engine over until it starts. This time, it only turned over while I was holding the key.

It took several tries to get it started and then it would only start for half a second and then immediately die. I then started it while giving it gas and holding the key over. That seemed to work. I figured problem was just that it sat too long and a little drive would remedy the issue.

Drove about 15 miles and it died at a traffic light. I tried for several minutes and it would not start. Finally after about 10 minutes, I was able to start it, again only by holding the key over and giving it gas. Just 5 miles from home, I was able to make it without further issues.

I'll take it to my mechanic as soon as he can squeeze me it, but in the meantime, any ideas on what it could be? Bad relay perhaps?

[Chum_lee]

j3ff9ack wrote:
You might have an ECM or PCM issue. From another forum:

Powertrain Control Module (PCM) or Engine Control Module (ECM) controls the starter relay based on input from the key switch. When the ignition switch is held in the start position for 0.4 seconds, the PCM/ECM start timer is activated. Once the start timer is activated, the PCM/ECM will continue to crank the starter until either the engine starts or a no start time limit is reached.

The other symptoms sound like fuel supply, but if the ECM or PCM is not functioning properly, it could be causing those symptoms also.

In most modern applications (OBD II), the ECM and the PCM have the ability to diagnose themselves in addition to the many functions they monitor/control. Customer states no "check engine" light.

Chum lee

[Team_D]

That sounds expensive. Ouch

Good info though

[j3ff9ack]

You might have an ECM or PCM issue. From another forum:

Powertrain Control Module (PCM) or Engine Control Module (ECM) controls the starter relay based on input from the key switch. When the ignition switch is held in the start position for 0.4 seconds, the PCM/ECM start timer is activated. Once the start timer is activated, the PCM/ECM will continue to crank the starter until either the engine starts or a no start time limit is reached.

The other symptoms sound like fuel supply, but if the ECM or PCM is not functioning properly, it could be causing those symptoms also.

[opnspaces]

The vehicle is supposed to stop cranking when you release the key. If yours did not stop then the lock cylinder is sticky and should be removed cleaned and lubed, or replaced.

This has noting to do with your not starting issue. But the still cranking when you let go of the key is a defect.

[Chum_lee]

Team D wrote:
I considered fuel pump / fuel filter / fuel relay, but none of those would explain why the starter does not continue to turn over until the engine starts. Use to be that I clicked the key over, let go and the starter would continue to crank until it started. Now, the moment I take my hand off the key, it stops turning over.

How does those switches work anyway? Seems to me like an electrical problem related to that switch.

Your ignition switch/starting system is different than any starting system I've ever seen. (and no, I haven't seen them all!) For manual starting systems (no key fob or auto start) the engine should only crank when the key is turned to the start position and then stop cranking when the key is released (to the "on" position) whether the engine starts or not.

If you can confirm that there are no fault codes stored, I would begin by checking for vacuum leaks under the hood in the engine bay, all the while suspecting that it could be the fuel pump or fuel pressure related. (which may require the removal of the fuel tank)

How many miles on this vehicle?

Chum lee

[enblethen]

There is two relays under the hood. One relay is the starter relay the other is ignition. If the ignition relay fails there is no start and no power to dash. The e wiring to the dash is protected by a fuse link attached to the ignition relay. Check for loose connections.

[Team_D]

I considered fuel pump / fuel filter / fuel relay, but none of those would explain why the starter does not continue to turn over until the engine starts. Use to be that I clicked the key over, let go and the starter would continue to crank until it started. Now, the moment I take my hand off the key, it stops turning over.

How does those switches work anyway? Seems to me like an electrical problem related to that switch.

[eHoefler]

If stored with anything but a full tank, most likely water in the fuel and bad gas from not being stabilized

[midnightsadie]

could be water in the fuel. he said it sits for months.

[ScottG]

Next time it stalls and wont start, bang on the bottom of the tank a few times while listening for the pump to start. If it does, the pump is shot.

[ernie1]

Check the throttle position sensor.

[Bruce_Brown]

How's the battery? A low battery would explain some of your symptoms.

[Dutch_12078]

When our 2001 F53 had pretty much the same symptoms, the cause turned out to be a bad MAF (Mass Air Flow) sensor. It's a relatively easy DIY repair, but figuring it out takes more than the average DIY OBD2 scanner.

[StarkNaked]

Does the Class A chassis have the same fuel tank and fuel pump as the Class C models?

It sounds very much like what happened to us when the fuel pump went out on our E450.