Thor 4.6 Cold Start Tissues

[Keithy P38]

Hey guys

The last three days I've had a bit of fun getting my P38 to start! It cranks hard and fast (as always) but doesn't fire until about the third or fourth time I have a go. This only happens in the morning. Once it has started it'll start first crank for the rest of the day.

Background info:
- 1/4 to 1/3 of a tank of fuel when it happens. Haven't filled it up and let it sit overnight with heaps of fuel since a few weeks ago (I have put some serious k's on it this week).
- Battery/ies live on charge when not being driven daily (i.e. When I'm away at work)
- "Cold" in Townsville is 29 degrees.
- Only two weeks ago it was perfectly fine on cold start.
- I did sit with the engine idling for a long period of time on a hot day four or five days ago while waiting for SWMBO to see the doc, unexpectedly - of course.
- Leads are 3yrs old, plugs have 15,000km on them.
- Could just be me, but it does smell a tad rich out back.
- Used a bit more fuel on a highway run than it normally would just this weekend. Usually sits around 12.5 to 13L/100km, this time it averaged 15.

I haven't played with relays or fuses (although I replaced the fuse box two months ago).

I haven't had a proper look at battery voltage, etc, as yet. I would imagine it to be ok as the engine does not labour or hesitate during cranking.

Drives like always, not rough and no hesitation under hard acceleration or towing (of which I've been doing a lot lately).

Will plug the Nanocom in and check fuel pressure and temp before I start it today.

Cheers
Keithy

[PhilipA]

One reason for slow start could be that the non return valve in the fuel pump has given up and it is draining back overnight.

Thors have a one way injection system with the fuel pressure regulator in the tank . Or an injector may be drooling.

Have you tried doing a prime several times ie ign on 10 seconds , turn off, ignition on 10 seconds . etc.
Regards Philip A

[Keithy P38]

Battery voltage after sitting overnight is 12.65 (at the terminals), so I'll rule that out!

Thanks for the reply mate, I plugged in the Nanocom and couldn't get fuel pressure or temp readings before starting, sat with the ignition "on" while using the Nanocom for 30 seconds, then when I turned the engine over, it fired straight up. No issues.

I had one fault on the EMS - Battery Voltage not plausible drive cycle A, occurred 4 times, signal missing. Currently not present.

Not too sure what that means, but it cleared and hasn't returned.

Fuel pressure and tank pressure readings were both around 33 (I'm assuming that's PSI?).

Cheers
Keithy

[Keithy P38]

Update:

At 3/4 of a tank of fuel it has not played up of a morning. Will have to wait a week or so before I use the fuel in the tank now to check again.

Would that be a sign of the fuel pump getting old?

Cheers
Keithy

[mtb_gary]

Update:

At 3/4 of a tank of fuel it has not played up of a morning. Will have to wait a week or so before I use the fuel in the tank now to check again.

Would that be a sign of the fuel pump getting old?

Cheers
Keithy



Keith


I wouldn't have thought fuel level (unless you were down to the last dregs) would make a difference for the fuel pump given its intake is so low in the tank.


Gary

[clubagreenie]

Given having it sit ign on while nancoming sounds like the non return valve allowing drain back.
And if its anything like the D2 it'll run to past empty (by volume) and still pick up fuel.

[bee utey]

If the fuel level is below the top of the pump then given enough time a faulty check valve will allow enough fuel to run out so the pump outlet and filter may contain a volume of air or vapour. That bubble will have to clear before enough pressure builds up to start. A full tank keeps just enough pressure on the pump to stop this happening. A new fuel pump should fix it.

[Keithy P38]

Thanks lads

I've got a new pump at home, I think I might fit it up when I get the chance!

Cheers
Keithy

[Keithy P38]

Update: This issue hasn't happened again! Currently sitting above half a tank of fuel.