FredR

Noticed that recently my motor does not want to start on the first crank no matter how long I hold it. Crank it briefly, stop and try again it fires immediately.

Thoughts?

Regards

Fred

uncre8tv

What if you leave the key in the on/run for several seconds before cranking?

thinking about fuel pump/pressure issues. seems like there are threads about the system de-pressurizing when parked resulting in hard starts.

Alan

A GTS doesn't do that priming, you'd think it would start on the first go if you crank long enough - assuming its just a fuel pressure loss here...

Alan

FredR

That was my thinking as well. I just wondered if there was some ind of latching going on wherein initially the fuel pump is not firing but for whatever reason does so after an attempt to fire- a quirk in the fuel pump relay perhaps? If it was the LH secondary board failing the thing just would not start period.

Regards

Fred

928 at last

I have a 1995 GMC Suburban with insane mileage on it, and it does the same thing......no idea why, but apparently it's not hurting anything either. Crank it at first, then key off, and starts immediately at the first touch on the second round.

uncre8tv

Any other electrical oddities? Weird starting behavior was a symptom before I cleaned all my grounds.

19psi

Does it have the check valve on the fuel pump like my '82? Mine stuck open and the fuel pressure at the rail dropped to zero as soon as I shut down the engine.
Hot starts were embarrassing...5 to 10 seconds of cranking before it would fire up. Or bump the starter for a second, wait a few seconds and turn key again and it would start right up. Jump the fuel pump relay and it would also start instantly.
A new check valve cured the problem. Still a half assed design imo. Even my '82 Honda motorcycle has a timed prime mode signaled by its ECU.

FredR

I have not ruled the check valve [or some crap stuck in it] out of the equation [yes they have one] or possibly a slightly leaky injector but I have had my fuel rail/fuel hose disconnected many times and all I noticed was it takes a few more turns to fire up but not this carry on. I find it irritating when things are just not quite how you know they ought to be and a good 928 fires up almost instantly you turn the key.

FredR

It is not long since I cleaned the ground points [they needed it]. I think I did them all-perhaps I will check now that the cooler [i.e. very nice] weather is with us.

I have a bit of an issue with the oil pressure indicator on the dash being a bit jerky- I put that down to the front harness being a bit shot. Should not impact this issue though. The wiring in general is not in great condition- I have patched up the worst bits I could find but I do not find anything that shows signs of decrepit behaviour as gthe motor seems to run perfectly well both when it fires and when it is warmed up- indeed it seems to run better than ever since I stopped recycling oily crap through the intake- indeed I might even be able to dial more advance back in.

Regards

fred

Hilton

Fred - first step is measure fuel pressure after engine shutoff.

It does sound like your system isn't holding pressure, and needs to be primed again with the first crank (pump only energises when there's a CPS signal). But until you measure fuel pressure to see, you're just guessing.

If it is a problem with pressure not holding, then I'd expect a hot-start problem too, as once the pressure drops off, the fuel will vaporise in parts of the system.

Mrmerlin

Fred try adding some MMO 6 oz, and techron to the fuel ,
I would guess your check valve and or the FPR is worn and leaking,
smell the vacuum lines for fuel any smell replace all 3, 2 dampers and the FPR.
The check valve is usually included with the new pump but new check valves can be swapped in.

Have the short hard line and 3 new sealing washers on hand as well as a new check valve.
Try the fuel additives first

Alan

Whilst its possible for it to be a sticky relay problem here - this fuel pump relay is a standard 53b - less likely to have an issue than a special purpose one. However it's cheap and easily available to replace - so might as well try that. All the smarts on this one are actually in the LH ECU.

May be worth checking you have no startup issues with either of the pumps.

Alan

FredR

Hilton,

Hot start is not a problem. Measuring the fuel pressure is though- the cap nut galled on the threads and despite counterholding the bloody thing sheared off and that buggered that!

I drilled/tapped the end of the rail and then had the inserted small allen bolt welded up so no pressure gauge hook up possible unfortunately. One of these days I will jury rig an alternative.

Fred

FredR

It is a while since I checked the fpr/dampers. Something else to check this weekend.

fred

Hilton

Ouch! Soo.. random guesswork it is then!

My first choice of likely suspects given the lack of a hot-start problem is a failed in-tank pump, assuming you still have one, being a hot climate and all. The good news is in my experience its unlikely to be a fuel pressure leakdown issue, as that most definitely causes warm start problems in a mildly warm climate.

Remove fuel pump cover, remove one connector from the main pump and insulate it. Then jump the fuel pump relay and go see if the in-tank pump is running.